Patent Application
20230384160
The present disclosure relates to a light receiving device, and more specifically, to a light receiving device including a photoelectric conversion element with a wire grid polarizer and a quarter wavelength layer.
A photoelectric conversion element and a light receiving device that include a wire grid polarizer (Wire Grid Polarizer, WGP) and a quarter wavelength layer are known from Japanese Unexamined Patent Application Publication No. 2020-013842, for example. Specifically, the photoelectric conversion element includes the quarter wavelength layer, the wire grid polarizer, and a photoelectric conversion section that are disposed in this order from a light entrance side.
The photoelectric conversion element disclosed in this patent publication makes it possible to change a polarized state of light entering the photoelectric conversion element into another polarized state, and allows the polarized state thus changed to be efficiently detected by the photoelectric conversion section via the wire grid polarizer. Accordingly, it is possible to provide a light receiving device for examining whether the polarized state is a left-handed circularly polarized state or a right-handed circularly polarized state, for example. However, there is strong demand for a light receiving device that makes it possible to easily know what polarized light component is included in a large amount in light, a light receiving device that makes it possible to easily know a so-called degree of polarization, or a light receiving device that makes it possible to extract light having specific linear polarization.
Accordingly, it is desirable to provide a light receiving device that makes it possible to easily know what polarized light component is included in a large amount in light. Further, it is desirable to provide a method of easily measuring a polarized state of an object to be observed. Moreover, it is desirable to provide a light receiving device that makes it possible to easily know the so-called degree of polarization. Further, it is desirable to provide a light receiving device that makes it possible to extract light having specific linear polarization.
A light receiving device according to a first aspect of the present disclosure includes a plurality of photoelectric conversion element units.
Each of the photoelectric conversion element units includes a plurality of photoelectric conversion elements, the photoelectric conversion elements being M×N in total number, with M photoelectric conversion elements arranged in a first direction, and N photoelectric conversion elements arranged in a second direction different from the first direction,
A polarized state measuring method for an object according to the present disclosure is a polarized state measuring method for an object using a light receiving device.
The light receiving device includes a plurality of photoelectric conversion element units,
The polarized state measuring method includes
A light receiving device according to a second aspect of the present disclosure includes a plurality of photoelectric conversion element units.
Each of the photoelectric conversion element units includes a first photoelectric conversion element, a second photoelectric conversion element, a third photoelectric conversion element, a fourth photoelectric conversion element, a fifth photoelectric conversion element, and a sixth photoelectric conversion element,
A light receiving device according to a third aspect of the present disclosure includes a plurality of photoelectric conversion element units.
Each of the photoelectric conversion element units includes a first photoelectric conversion element, a second photoelectric conversion element, a third photoelectric conversion element, and a fourth photoelectric conversion element,
In the following, the present disclosure will be described on the basis of Examples with reference to the drawings. However, the present disclosure is not limited to Examples, and various numerical values and materials included in Examples are presented by way of example. Note that the description will be given in the following order.
In a light receiving device according to a first aspect of the present disclosure, or a light receiving of the first aspect of the present disclosure in a polarized state measuring method for an object of the present disclosure (hereinafter, for convenience, these light receiving devices will be collectively referred to as a “light receiving device or the like according to the first aspect of the present disclosure” in some cases), each of photoelectric conversion element units may include M kinds of wire grid polarizers and N kinds of quarter wavelength layers.
In the light receiving device or the like according to the first aspect of the present disclosure including the preferred embodiment described above, M=N=2a may be satisfied (where a is an integer greater than or equal to 2, and preferably, a=3, 4, or 5). In addition, in this case, polarization orientations of the M kinds of wire grid polarizers may be (180/2a)×m [degrees] (where m=0, 1, 2, 3 . . . , [2a−1]), and fast axis orientations of the N kinds of quarter wavelength layers may be (180/2a)×n [degrees] (where n=0, 1, 2, 3 . . . , [2a−1]).
An order of arrangement, in a first direction, of the M kinds of wire grid polarizers having different polarization orientations may substantially be any order, and an order of arrangement, in a second direction, of the N kinds of quarter wavelength layers having different fast axis orientations may substantially be any order. However, different image data are obtainable depending on the order of arrangement of the M kinds of wire grid polarizers in the first direction and the order of arrangement of the N kinds of quarter wavelength layers in the second direction, and therefore it is desirable that standard polarized state data be prepared in advance by determining a polarized state of a standard object. The respective M kinds of wire grid polarizers may be provided substantially continuously along the second direction. Further, the respective N kinds of quarter wavelength layers may be provided substantially continuously along the first direction.
According to the polarized state measuring method for an object of the present disclosure, an image of the object may be captured with the light receiving device by applying light having a predetermined polarized state and wavelength to the object. That is, an image of the object may be captured with the light receiving device by applying light having one kind of polarized state and one kind of wavelength (light of a single wavelength) to the object from a light source. It is sufficient that the predetermined polarized state and the predetermined wavelength are appropriately determined in advance in accordance with the object targeted for measurement of the polarized state.
According to the polarized state measuring method for an object of the present disclosure including the preferred embodiment described above, a surface state of the object may be evaluated by obtaining a comparison result. In this case, it is desirable that standard polarized state data be prepared in advance by determining a polarized state of a standard object, using an object having a desired surface state as the standard object. Alternatively, according to the polarized state measuring method for an object of the present disclosure including the preferred embodiment described above, a state of a film thickness of an object in a thin-film form may be evaluated by obtaining a comparison result on the object. In this case, it is desirable that standard polarized state data be prepared in advance by determining a polarized state of a standard object, using an object (a thin film) having a desired film thickness as the standard object. Alternatively, according to the polarized state measuring method for an object of the present disclosure including the preferred embodiment described above, the presence of a foreign substance in the object may be evaluated by obtaining a comparison result. In this case, it is desirable that standard polarized state data be prepared in advance by determining a polarized state of a standard object, using an object in a state without any foreign substance as the standard object.
In a light receiving device according to a second aspect of the present disclosure, α′=(β±45) degrees may be satisfied.
According to the light receiving device of the second aspect of the present disclosure including the preferred embodiment described above, each of the photoelectric conversion element units may include a total of 3×2 photoelectric conversion elements, with three photoelectric conversion elements in the first direction, and two photoelectric conversion elements in the second direction different from the first direction. A first photoelectric conversion element, a second photoelectric conversion element, and a fifth photoelectric conversion element may be disposed in no particular order in a first row along the first direction, and a third photoelectric conversion element, a fourth photoelectric conversion element, and a sixth photoelectric conversion element may be disposed in no particular order in a second row along the first direction.
Where the first photoelectric conversion element, the second photoelectric conversion element, the third photoelectric conversion element, and the fourth photoelectric conversion element are each referred to as a “photoelectric conversion element of a first type” for convenience, and the fifth photoelectric conversion element and the sixth photoelectric conversion element are each referred to as a “photoelectric conversion element of a second type” for convenience, two photoelectric conversion elements of the first type and one photoelectric conversion element of the second type may be disposed in no particular order in the first row along the first direction, and two photoelectric conversion elements of the first type and one photoelectric conversion element of the second type may be disposed in no particular order in the second row along the first direction, as described above. However, this is non-limiting, and also possible are an embodiment in which any one photoelectric conversion element of the first type among the four photoelectric conversion elements of the first type and two photoelectric conversion elements of the second type are disposed in no particular order in the first row along the first direction and the remaining three photoelectric conversion elements of the first type are disposed in no particular order in the second row along the first direction, and an embodiment in which any three photoelectric conversion elements of the first type among the four photoelectric conversion elements of the first type are disposed in no particular order in the first row along the first direction and the remaining one photoelectric conversion element of the first type and two photoelectric conversion elements of the second type are disposed in no particular order in the second row along the first direction.
In the light receiving device of the second aspect of the present disclosure including the preferred embodiment described above, at least light including a linearly polarized light component and light including a circularly polarized light component may enter the photoelectric conversion element unit in a mixed state.
In addition, in such an embodiment, the light receiving device may have a configuration in which:
Moreover, in such a configuration, an embodiment is possible in which:
degree of polarization=ΔAL/(ΔAL+ΔAL′),
and moreover, the data processor may display, of obtained image data, a region where the degree of polarization is high and a region where the degree of polarization is low in different colors. Here, ΔAL represents the amount of light (light intensity) of the polarized light component or the amount of light (light intensity) of specularly reflected light, and is a kind of fluctuation component, whereas ΔAL′ represents the amount of light (light intensity) of a non-polarized light component or the amount of light (light intensity) of diffusely reflected light, and is a kind of fixed component. The degree of polarization represents a component ratio in reflected light, and is an indicator of the state of a reflection surface. It is to be noted that the photoelectric conversion element unit may include not only the light including the linearly polarized light component and the light including the circularly polarized light component but also light of a non-polarized light component; however, it is possible to substantially eliminate an influence of the light of the non-polarized light component by determining ΔAL′.
According to the light receiving device of a third aspect of the present disclosure, α=β may be satisfied.
It is to be noted that the wording “a polarization orientation targeted for transmission by the wire grid polarizer is α degrees” includes a meaning that the polarization orientation targeted for transmission by the wire grid polarizer does not have to be exactly α degrees, and the wire grid polarizer thus transmits light with some range of angle (for example, α±5 degrees) of the polarization orientation.
According to the light receiving device of the first aspect of the present disclosure including the various preferred embodiments and configurations described above,
Further, according to the light receiving device of the second aspect of the present disclosure including the various preferred embodiments and configurations described above, the following embodiments are possible:
Moreover, according to the light receiving device of the third aspect of the present disclosure including the various preferred embodiments and configurations described above, the following embodiments are possible:
The photoelectric conversion element included in the light receiving device according to any of the first to third aspects of the present disclosure including the various preferred embodiments and configurations described above, or the photoelectric conversion element included in the light receiving device according to the first aspect of the present disclosure to be used in the polarized state measuring method for an object of the present disclosure including the various preferred embodiments and configurations described above will be collectively referred to as a “photoelectric conversion element or the like of the present disclosure” in some cases, for convenience. Further, the light receiving device according to any of the first to third aspects of the present disclosure including the various preferred embodiments and configurations described above will be collectively referred to as a “light receiving device or the like of the present disclosure” in some cases, for convenience.
In the light receiving device or the like of the present disclosure, while the plurality of photoelectric conversion elements is arranged in a two-dimensional matrix, the first direction and the second direction are preferably orthogonal to each other. For example, the first direction is a so-called row direction or a so-called column direction, and the second direction is the column direction or the row direction.
As described above, the photoelectric conversion element unit may include an existing photoelectric conversion element that is provided with neither the quarter wavelength layer nor the wire grid polarizer.
The photoelectric conversion element in the light receiving device according to either of the second aspect and the third aspect of the present disclosure may include a filter layer on an as-needed basis.
That is, the light receiving device according to either of the second aspect and the third aspect of the present disclosure may include a plurality of photoelectric conversion element unit groups that is two-dimensionally arranged, and may have a configuration in which
As has been described, the photoelectric conversion section included in the first photoelectric conversion element unit receives light in the first wavelength range, the photoelectric conversion section included in the second photoelectric conversion element unit receives light in the second wavelength range, the photoelectric conversion section included in the third photoelectric conversion element unit receives light in the third wavelength range, and the photoelectric conversion section included in the fourth photoelectric conversion element unit receives light in the fourth wavelength range.
Here, the light in the first wavelength range may be red light, the light in the second wavelength range and the light in the third wavelength range may be green light, and the light in the fourth wavelength range may be blue light. Alternatively, the light in the first wavelength range may be red light, the light in the second wavelength range may be green light, the light in the third wavelength range may be blue light, and the light in the fourth wavelength range may be infrared light. In this case, the fourth photoelectric conversion element unit may have a configuration including a fourth filter layer that passes none of the light in the first wavelength range, the light in the second wavelength range, and the light in the third wavelength range.
Examples of the filter layer may include not only a filter layer that transmits the light in the first wavelength range such as red light, the light in the second wavelength range or the third wavelength range such as green light, and the light in the fourth wavelength range such as blue light, but also a filter layer that transmits a specific wavelength such as cyan, magenta, yellow, or the like and a filter layer that passes none of the light in the first wavelength range, the light in the second wavelength range, and the light in the third wavelength range. In addition, in a case of a purpose other than the purposes of color separation and spectral diffraction, or in a case of a photoelectric conversion element that itself has sensitivity to a specific wavelength, the filter layer may be unnecessary. In a case where a photoelectric conversion element including the filter layer and a photoelectric conversion element including no filter layer coexist, a transparent resin layer may be formed in place of the filter layer on the photoelectric conversion element including no filter layer, in order to secure flatness with the photoelectric conversion element including the filter layer. The filter layer (color filter layer) may be configured not only by an organic material-based color filter layer including an organic compound such as a pigment or a dye, but also by a photonic crystal, a wavelength selection element to which plasmon is applied (a color filter layer having a conductor grid structure including a conductor thin film provided with a grid-shaped hole structure, see Japanese Unexamined Patent Application Publication No. 2008-177191, for example), or a thin film including an inorganic material such as amorphous silicon.
In the case of a purpose other than the purposes of color separation and spectral diffraction, or in the case of a photoelectric conversion element that itself has sensitivity to a specific wavelength, the filter layer may be unnecessary. As described above, the photoelectric conversion element may include a combination of a red light photoelectric conversion element having sensitivity to red light, a green light photoelectric conversion element having sensitivity to green light, and a blue light photoelectric conversion element having sensitivity to blue light, or a combination of these photoelectric conversion elements and an infrared photoelectric conversion element having sensitivity to infrared light. The light receiving device or the like of the present disclosure may be a light receiving device (a solid-state imaging device) that obtains a monochromatic image, or a light receiving device (a solid-state imaging device) that obtains a combination of a monochromatic image and an image based on infrared light.
In addition, the light receiving device according to either of the second aspect and the third aspect of the present disclosure may have a configuration in which
The light receiving device according to either of the second aspect and the third aspect of the present disclosure may have a configuration in which one photoelectric conversion element unit group (one pixel) including a plurality of photoelectric conversion element units has a Bayer arrangement. However, the arrangement of the photoelectric conversion element unit group is not limited to the Bayer arrangement, and other examples thereof may include an interline arrangement, a G-stripe RB checkered arrangement, a G-stripe RB complete checkered arrangement, a checkered complementary color arrangement, a stripe arrangement, a diagonal stripe arrangement, a primary color difference arrangement, a field color difference sequential arrangement, a frame color difference sequential arrangement, a MOS type arrangement, an improved MOS type arrangement, a frame interleave arrangement, and a field interleave arrangement.
Alternatively, in the light receiving device or the like of the present disclosure, one photoelectric conversion element unit (one pixel) may include a plurality of photoelectric conversion elements (sub-pixels). In addition, for example, each of the sub-pixels includes one photoelectric conversion element. A relationship between the pixel and the sub-pixel will be described later. The photoelectric conversion element itself or the photoelectric conversion section itself may each have a well-known configuration and structure.
In addition, the light receiving device according to either of the second aspect and the third aspect of the present disclosure may have a configuration in which the first quarter wavelength layer, the second quarter wavelength layer, the third quarter wavelength layer, and the fourth quarter wavelength layer are disposed in different layers. It is to be noted that the light receiving device or the like of the present disclosure of such an embodiment will be referred to as a “light receiving device of an A configuration of the present disclosure” for convenience. In addition, the light receiving device of the A configuration of the present disclosure may have a configuration in which
Alternatively, the light receiving device according to either of the second aspect and the third aspect of the present disclosure may have a configuration in which the first quarter wavelength layer, the second quarter wavelength layer and the third quarter wavelength layer, and the fourth quarter wavelength layer are disposed in the same layer. It is to be noted that the light receiving device or the like of the present disclosure of such an embodiment will be referred to as a “light receiving device of a B configuration of the present disclosure” for convenience. In addition, the light receiving device of the B configuration of the present disclosure may further have a configuration in which
In the light receiving device or the like of the present disclosure, as described above, the quarter wavelength layer may include the first dielectric layer including the material having the refractive index n1 and the second dielectric layer including the material having the refractive index n2 that are alternately disposed side by side. In addition, where a normal line (light entrance direction) of the entire photoelectric conversion element is in a Z direction, the first dielectric layer and the second dielectric layer are included in a YZ plane. Further, the first dielectric layer and the second dielectric layer are alternately disposed side by side along an X direction, the thicknesses of the first dielectric layer and the second dielectric layer are thicknesses along the X direction, and the layer thickness of the quarter wavelength layer is a thickness along the Z direction. It is to be noted that the X direction is the fast axis, and a Y direction is a slow axis.
When the thickness of the first dielectric layer is denoted by t1 and the thickness of the second dielectric layer is denoted by t2, in a case where the quarter wavelength layer has a structure in which a value of (t1+t2) is smaller than a wavelength of light, the quarter wavelength layer has effective refractive indexes nTE and nTM that are different between the direction (the X direction) in which the first dielectric layer and the second dielectric layer are disposed side by side and a direction (the Y direction) orthogonal to the X direction and the Z direction, and thus behaves as if the quarter wavelength layer includes a birefringent material. The difference between these effective refractive indexes nTE and nTM generates a difference between propagation speeds of pieces of light in respective polarization directions, thus causing a phase difference between the pieces of light passing through the quarter wavelength layer. That is, a phase difference is given to the pieces of light passing through the quarter wavelength layer. As a result, a function as a wavelength plate is achieved. Where “f” is a filling factor, f, nTE, and nTM are expressed as follows.
f=t
1/(t1+t2)
n
TE
={f×n
12+(1−f)×n22}½
n
TM
={f/n
12+(1−f)/n22}½
Where the layer thickness (i.e., a height and a thickness in the Z direction) of the quarter wavelength layer is denoted by H and the wavelength of light passing through the quarter wavelength layer is denoted by λ, that is, the wavelength of light that passes through the quarter wavelength layer and is given a phase difference is denoted by λ (also any of λ1, λ2-3, and λ4 to be described later), the phase difference δ is expressed as follows.
(λ/4)=δ=(nTE−nTM)×H
Accordingly, in a case where H is fixed, a desired value of λ is obtainable by varying the value of f, that is, the values of t1 and t2. Further, in a case where the values of t1 and t2 are fixed, a desired value of λ is obtainable for the quarter wavelength layer by varying the value of H.
The layer thickness of the first quarter wavelength layer is denoted by H1, the layer thickness of the second quarter wavelength layer is denoted by H2, the layer thickness of the third quarter wavelength layer is denoted by H3, and the layer thickness of the fourth quarter wavelength layer is denoted by H4. In addition, in the first quarter wavelength layer, the thickness of the first dielectric layer is denoted by t11, and the thickness of the second dielectric layer is denoted by t12; in the second quarter wavelength layer, the thickness of the first dielectric layer is denoted by t21, and the thickness of the second dielectric layer is denoted by t22; in the third quarter wavelength layer, the thickness of the first dielectric layer is denoted by t31, and the thickness of the second dielectric layer is denoted by t32; and in the fourth quarter wavelength layer, the thickness of the first dielectric layer is denoted by t41, and the thickness of the second dielectric layer is denoted by t42.
In the light receiving device of the A configuration of the present disclosure, the first quarter wavelength layer, the second quarter wavelength layer, the third quarter wavelength layer, and the fourth quarter wavelength layer are disposed in different layers. In this case, because the values (t11, t12), (t21, t22), (t31, t32), and (t41, t42) are the same, it is sufficient that the values H1, H2, H3, and H4 are varied. Depending on cases, H1=H2=H3=H4 may be satisfied. In this case, it is sufficient that the values (t11, t12), (t21, t22), (t31, t32), and (t41, t42) are varied. In the light receiving device of the B configuration of the present disclosure, the first quarter wavelength layer, the second quarter wavelength layer, the third quarter wavelength layer, and the fourth quarter wavelength layer are disposed in the same layer. In this case, H1=H2=H3=H4, and accordingly, it is sufficient that the values (t11, t12), (t21, t22), (t31, t32), and (t41, t42) are varied.
In the photoelectric conversion element or the like of the present disclosure, examples of the material included in the first dielectric layer may include SiN, and examples of the material included in the second dielectric layer may include SiO2; however, these examples are non-limiting.
In the photoelectric conversion element or the like of the present disclosure, the wire grid polarizer may include at least a plurality of stack structures disposed side by side with a space therebetween (i.e., may have a line-and-space structure), the stack structures each including a light reflection layer and a light absorption layer (the light absorption layer being located on a light entrance side) that have a band shape. Alternatively, the wire grid polarizer may include a plurality of stack structures disposed side by side with a space therebetween, the stack structures each including a light reflection layer, an insulating film, and a light absorption layer (the light absorption layer being located on the light entrance side) that have a band shape. It is to be noted that in this case, possible configurations include a configuration in which the light reflection layer and the light absorption layer in each of the stack structures are separated from each other by the insulating film (that is, a configuration in which the insulating film is formed on an entire top surface of the light reflection layer and the light absorption layer is formed on an entire top surface of the insulating film), and a configuration in which a portion of the insulating film is cut away to allow contact between the light reflection layer and the light absorption layer at the cut-away portion of the insulating film. In addition, in these cases, the light reflection layer may include a first electrically-conductive material, and the light absorption layer may include a second electrically-conductive material. Such a configuration makes it possible for entire regions of the light absorption layer and the light reflection layer to be electrically coupled to a region having an appropriate potential in the light receiving device. As a result, it is possible to reliably avoid the occurrence of an issue that during formation of the wire grid polarizer, the wire grid polarizer becomes electrically charged to generate a kind of discharge, which results in damage to the wire grid polarizer or the photoelectric conversion section. Alternatively, the wire grid polarizer may have a configuration including the light absorption layer and the light reflection layer that are stacked from the light entrance side, with the insulating film being omitted.
For example, the wire grid polarizer is manufacturable in accordance with the steps of:
Further, an underlying film may be formed below the light reflection layer. This makes it possible to improve roughness of the light-reflection-layer-forming layer and the light reflection layer. Examples of a material included in the underlying film (a barrier metal layer) may include Ti, TiN, and a layered structure of Ti/TiN.
The wire grid polarizer in the photoelectric conversion element or the like of the present disclosure may have a configuration in which a direction of extension of the band-shaped stack structure coincides with an orientation of polarized light to be extinguished, and a direction of repetition of the band-shaped stack structure coincides with an orientation of polarized light to be transmitted. That is, the light reflection layer functions as a polarizer. Of light entering the wire grid polarizer, the light reflection layer attenuates a polarized wave (one of TE wave/S wave and TM wave/P wave) including an electric field component in a direction parallel to the direction of extension of the stack structure, and transmits a polarized wave (the other of the TE wave/S wave and TM wave/P wave) including an electric field component in a direction (the direction of repetition of the band-shaped stack structure) orthogonal to the direction of extension of the stack structure. That is, the direction of extension of the stack structure corresponds to a light absorption axis of the wire grid polarizer, while the direction orthogonal to the direction of extension of the stack structure corresponds to a light transmission axis of the wire grid polarizer. The direction of extension of the stack structure having a band shape (that is, configuring the line part of the line-and-space structure) will be referred to as a “P direction” for convenience in some cases, and the direction of repetition of the band-shaped stack structure (line part) (the direction orthogonal to the direction of extension of the band-shaped stack structure) will be referred to as a “Q direction” for convenience in some cases. The Q direction corresponds to the polarization orientation.
The Q direction may be parallel to the first direction or the second direction. An angle formed between α described above and the Q direction may substantially be any angle, and examples thereof may include 0 degrees and 90 degrees. However, this is non-limiting.
As illustrated in a conceptual diagram of
In the photoelectric conversion element or the like of the present disclosure, light enters from the light absorption layer. Then, the wire grid polarizer attenuates a polarized wave (either one of TE wave/S wave and TM wave/P wave) including an electric field component parallel to the P direction, and transmits a polarized wave (the other of the TE wave/S wave and TM wave/P wave) including an electric field component parallel to the Q direction, by using four actions of light transmission, reflection, and interference, and selective light absorption of polarized waves by optical anisotropy. That is, one of the polarized waves (e.g., the TE wave) is attenuated by the selective light absorption operation on polarized waves by the optical anisotropy of the light absorption layer. The band-shaped light reflection layer functions as a polarizer, and the one of the polarized waves (e.g., the TE wave) that has passed through the light absorption layer and the insulating film is reflected by the light reflection layer. Here, if the insulating film is configured such that the phase of the one of the polarized waves (e.g., the TE wave) that has passed through the light absorption layer and has been reflected by the light reflection layer is shifted by a half wavelength, the one of the polarized waves (e.g., the TE wave) reflected by the light reflection layer is attenuated by being canceled due to interference with the one of the polarized waves (e.g., the TE wave) reflected by the light absorption layer. In this manner, it is possible to selectively attenuate one of the polarized waves (e.g., TE wave). It is to be noted that improvement in contrast is achievable even without optimization of the thickness of the insulating film, as described above. Accordingly, for practical use, it is sufficient that the thickness of the insulating film is determined on the basis of balance between a desired polarization characteristic and an actual fabrication process.
In the following description, the stack structure included in the wire grid polarizer provided above the photoelectric conversion section will be referred to as a “first stack structure” for convenience in some cases, and the stack structure surrounding the first stack structure will be referred to as a “second stack structure” for convenience in some cases. The second stack structure couples a wire grid polarizer (first stack structure) included in a certain photoelectric conversion element and a wire grid polarizer (first stack structure) included in a photoelectric conversion element adjacent to the certain photoelectric conversion element. The second stack structure may be configured by a stack structure having the same configuration as that of the stack structure included in the wire grid polarizer (i.e., the second stack structure including at least the light reflection layer and the light absorption layer, or the light reflection layer, the insulating film, and the light absorption layer, for example, and having a so-called solid film structure without being provided with a line-and-space structure). The second stack structure may be provided with a line-and-space structure like the wire grid polarizer if the second stack structure does not serve as a wire grid polarizer. That is, the second stack structure may be structured to have the wire grid formation pitch Q0 sufficiently greater than an effective wavelength of entering electromagnetic waves. It is sufficient that a frame part to be described later also includes the second stack structure. Depending on cases, the frame part may include the first stack structure. The frame part is preferably coupled to the line part of the wire grid polarizer. The frame part may be allowed to serve as a light-blocking section.
The light reflection layer (the light-reflection-layer-forming layer) may include a metal material, an alloy material, or a semiconductor material. The light absorption layer may include a metal material, an alloy material, or a semiconductor material. Specifically, examples of an inorganic material to be included in the light reflection layer (the light-reflection-layer-forming layer) may include a metal material such as aluminum (Al), silver (Ag), gold (Au), copper (Cu), platinum (Pt), molybdenum (Mo), chrome (Cr), titanium (Ti), nickel (Ni), tungsten (W), iron (Fe), silicon (Si), germanium (Ge), or tellurium (Te), and an alloy material and a semiconductor material that include any of these metals.
The light absorption layer (or the light-absorption-layer-forming layer) may include a metal material, an alloy material, or a semiconductor material having an extinction coefficient k other than zero, that is, exhibiting a light-absorbing action, specifically, a metal material such as aluminum (Al), silver (Ag), gold (Au), copper (Cu), molybdenum (Mo), chrome (Cr), titanium (Ti), nickel (Ni), tungsten (W), iron (Fe), silicon (Si), germanium (Ge), tellurium (Te), or tin (Sn), and an alloy material and a semiconductor material that include any of these metals. In addition, a silicide-based material such as FeSi2 (particularly β-FeSi2), MgSi2, NiSi2, BaSi2, CrSi2, or CoSi2 may be used. Particularly, high contrast (high extinction ratio) is achievable in a visible light region by using aluminum or an alloy thereof, or a semiconductor material including ß-FeSi2, germanium, or tellurium as the material to be included in the light absorption layer (the light-absorption-layer-forming layer). It is to be noted that, to provide a polarization characteristic in a wavelength band other than the visible light region, such as an infrared region, it is preferable to use silver (Ag), copper (Cu), gold (Au), or the like as the material to be included in the light absorption layer (the light-absorption-layer-forming layer). One reason for this is that resonance wavelengths of these metals are close to the infrared region.
The light-reflection-layer-forming layer and the light-absorption-layer-forming layer are formable in accordance with a known method, such as any of various chemical vapor deposition methods (CVD methods), a coating method, any of various physical vapor deposition methods (PVD methods) including a sputtering method and a vacuum vapor deposition method, a sol-gel method, a plating method, an MOCVD method, or an MBE method. In addition, examples of a patterning method for the light-reflection-layer-forming layer and the light-absorption-layer-forming layer may include a combination of a lithography technique and an etching technique (e.g., an anisotropic dry etching technique using carbon tetrafluoride gas, sulfur hexafluoride gas, trifluoromethane gas, xenon difluoride gas, or the like, and a physical etching technique), a so-called lift-off technique, and a so-called self-align double patterning technique using a sidewall as a mask. Examples of the lithography technique may include photolithography techniques (a lithography technique using a g-line and an i-line of a high-pressure mercury lamp, KrF excimer laser, ArF excimer laser, EUV, or the like as a light source, and a liquid immersion lithography technique, an electron beam lithography technique, and X-ray lithography thereof). Alternatively, the light reflection layer and the light absorption layer are also formable in accordance with a fine processing technique using an ultrashort pulsed laser such as a femtosecond laser, or a nanoimprint method.
Examples of materials to be included in the insulating film (or the insulating-film-forming layer), an interlayer insulating layer, an underlying insulating layer, and a planarization layer may include insulating materials that are transparent to entering light and have no light-absorbing characteristic, specifically, SiOx-based materials (materials each forming a silicon-based oxide film) including silicon oxide (SiO2), NSG (nondoped silicate glass), BPSG (boron phosphorus silicate glass), PSG, BSG, PbSG, AsSG, SbSG, and SOG (spin-on glass), SiN, silicon oxynitride (SiON), SiOC, SiOF, SiCN, low dielectric constant insulating materials (e.g., fluorocarbon, cycloperfluorocarbon polymer, benzocyclobutene, cyclic fluororesin, polytetrafluoroethylene, amorphous tetrafluoroethylene, polyarylether, arylether fluoride, fluorinated polyimide, organic SOG, parylene, fullerene fluoride, and amorphous carbon), polyimide-based resins, fluorine-based resins, Silk (which is a trademark of The Dow Chemical Co. and a coating type low dielectric constant interlayer insulating film material), Flare (which is a trademark of Honeywell Electronic Materials Co. and a polyarylether (PAE) based material). These materials may be used alone or in combination on an as-needed basis. Alternatively, examples thereof may include: polymethyl methacrylate (PMMA); polyvinyl phenol (PVP); polyvinyl alcohol (PVA); polyimide; polycarbonate (PC); polyethylene terephthalate (PET); polystyrene; silanol derivatives (silane coupling agents) including N-2(aminoethyl)3-aminopropyltrimethoxysilane (AEAPTMS), 3-mercaptopropyl trimethoxy silane (MPTMS), and octadecyltrichlorosilane (OTS); novolac type phenol resin; fluorine-based resin; and organic insulating materials (organic polymers) including, for example, straight-chain hydrocarbons having a functional group that is couplable to a control electrode at one end, such as octadecanethiol or dodecyl isocyanate. Combinations of any of these materials are also usable. The insulating-film-forming layer is formable in accordance with a known method such as any of various CVD methods, a coating method, any of various PVD methods including a sputtering method and a vacuum vapor deposition method, any of various printing methods such as a screen printing method, or a sol-gel method. The insulating film serves as an underlying layer of the light absorption layer and is formed for the purpose of adjusting phases of polarized light that has been reflected by the light absorption layer and polarized light that has passed through the light absorption layer and has been reflected by the light reflection layer, improving the extinction ratio and transmittance by an interference effect, and reducing reflectance. Accordingly, it is desirable that the insulating film have a thickness that causes a phase shift of a half wavelength in one reciprocation. However, the light absorption layer has a light absorption effect and thus absorbs reflected light. Accordingly, improvement in extinction ratio is achievable even if the thickness of the insulating film is not optimized as described above. Thus, for practical use, it is sufficient that the thickness of the insulating film is determined on the basis of balance between a desired polarization characteristic and an actual fabrication process. For example, the thickness of the insulating film may range from 1×10−9 m to 1×10−7 m, and more preferably, from 1×10−8 m to 8×10−8 m. In addition, the refractive index of the insulating film is greater than 1.0, and is preferably, but not limited to, 2.5 or smaller.
In the photoelectric conversion element or the like of the present disclosure, the space part of the wire grid polarizer may be an empty space (that is, the space part may be filled with at least air). By forming the space part of the wire grid polarizer as an empty space in this manner, it is possible to reduce the value of the average reflective index nave, and as a result, it is possible for the wire grid polarizer to achieve improvement in transmittance and improvement in extinction ratio. In addition, because it is possible to increase the value of the formation pitch Q0, improvement in manufacturing yield of the wire grid polarizer is achievable. An embodiment is also possible in which a protective film is formed on the wire grid polarizer. This makes it possible to provide a photoelectric conversion element and a light receiving device that each have high reliability. By providing the protective film, it is possible to improve reliability, such as improvement in moisture resistance of the wire grid polarizer. It is sufficient that the protective film has a thickness in a range that does not affect the polarization characteristic. A reflectance for entering light varies also depending on the optical thickness of the protective film (refractive index× film thickness of protective film). Accordingly, it is sufficient that the material and the thickness of the protective film are determined in consideration of these factors. For example, the thickness may be 15 nm or smaller. Alternatively, the thickness may be smaller than or equal to ¼ of a distance between the stack structures. As a material to be included in the protective film, it is desirable to use a material having a refractive index of 2 or lower and an extinction coefficient close to zero. Examples of the material may include an insulating material such as SiO2 including TEOS-SiO2, SiON, SiN, SiC, SiOC, or SiCN, and a metal oxide such as aluminum oxide (AlOx), hafnium oxide (HfOx), zirconium oxide (ZrOx), or tantalum oxide (TaOx). Alternatively, perfluorodecyltrichlorosilane or octadecyltrichlorosilane may be used. Although the protective film is formable through a known process such as any of various CVD methods, a coating method, any of various PVD methods including a sputtering method and a vacuum vapor deposition method, or a sol-gel method, it is more preferable to employ a so-called atomic layer deposition method (ALD method, Atomic Layer Deposition method) or an HDP-CVD method (a high density plasma chemical vapor deposition method). It is possible to form a thin protective film on the wire grid polarizer in a conformal manner by employing the ALD method or the HDP-CVD method. The protective film may be formed on an entire surface of the wire grid polarizer; however, the protective film may be formed only on a side surface of the wire grid polarizer and not over the underlying insulating layer located between the wire grid polarizers. In addition, by forming the protective film in such a manner as to cover the side surface where the metal material or the like included in the wire grid polarizer is exposed, it is possible to block moisture and organic matters in atmosphere to thereby reliably suppress the occurrence of an issue such as corrosion or abnormal precipitation of the metal material or the like included in the wire grid polarizer. Moreover, it is possible to achieve improvement in long-term reliability of the photoelectric conversion element, which makes it possible to provide the photoelectric conversion element that includes a highly reliable wire grid polarizer as an on-chip element.
In a case of forming the protective film on the wire grid polarizer, a second protective film may further be formed between the wire grid polarizer and the protective film, and n1′>n2′ may be satisfied where n1′ represents the refractive index of the material included in the protective film and n2′ represents a refractive index of a material included in the second protective film. By satisfying n1′>n2′, it is possible to reduce the value of the average refractive index nave with reliability. Here, it is preferable that the protective film include SiN and the second protective film include SiO2 or SiON.
Moreover, a third protective film may be formed at least on a side surface of the line part facing the space part of the wire grid polarizer. That is, the space part is filled with air, and additionally, the third protective film is present in the space part. Here, as a material to be included in the third protective film, it is preferable to use a material having a refractive index of 2 or lower and an extinction coefficient close to zero. Examples of the material may include an insulating material such as SiO2 including TEOS-SiO2, SiON, SiN, SiC, SiOC, or SiCN, and a metal oxide such as aluminum oxide (AlOx), hafnium oxide (HfOx), zirconium oxide (ZrOx), or tantalum oxide (TaOx). Alternatively, perfluorodecyltrichlorosilane or octadecyltrichlorosilane may be used. Although the third protective film is formable through a known process such as any of various CVD methods, a coating method, any of various PVD methods including a sputtering method and a vacuum vapor deposition method, or a sol-gel method, it is more preferable to employ a so-called atomic layer deposition method (ALD method, Atomic Layer Deposition method) or an HDP-CVD method (high density plasma chemical vapor deposition method). Although it is possible to form a thin third protective film on the wire grid polarizer in a conformal manner by employing the ALD method, it is more preferable to employ the HDP-CVD method from the viewpoint of forming a further thinner third protective film on the side surface of the line part. Alternatively, if the space part is filled with the material included in the third protective film and the third protective film is provided with a clearance, a hole, a void, or the like, it is possible to reduce the refractive index of the entire third protective film.
If a metal material or an alloy material included in the wire grid polarizer (hereinafter referred to as a “metal material or the like” for convenience in some cases) comes into contact with outside air, corrosion resistance of the metal material or the like can deteriorate due to adhesion of moisture or organic matters from the outside air, and this can deteriorate long-term reliability of the photoelectric conversion section. If moisture adheres to the line part (the stack structure) including the metal material or the like, the insulating material, and the metal material or the like, in particular, such moisture can act as an electrolytic solution because CO2 and O2 are dissolved in the moisture, and this can generate a local battery between two kinds of metals. In addition, if such a phenomenon occurs, a reduction reaction such as hydrogen generation proceeds on a cathode (positive electrode) side, whereas an oxidation reaction proceeds on an anode (negative electrode) side, and this causes abnormal precipitation of the metal material or the like or a shape change of the wire grid polarizer to occur. As a result, originally expected performance of the wire grid polarizer or the photoelectric conversion section can deteriorate. For example, in a case of using aluminum (Al) as the light reflection layer, abnormal precipitation of aluminum as expressed in the following reaction expression can occur. However, it is possible to avoid the occurrence of such an issue with reliability by forming the protective film, and also by forming the third protective film.
Al→Al3++3e−
Al3++3OH−→Al(OH)3
In the light receiving device or the like of the present disclosure, a length of the light reflection layer along the P direction may be the same as a length of a photoelectric conversion region along the P direction, the photoelectric conversion region being a region where the photoelectric conversion element practically performs photoelectric conversion, may be the same as a length of the photoelectric conversion element, or may be an integral multiple of the length of the photoelectric conversion element along the P direction. However, these examples are non-limiting.
In the photoelectric conversion element or the like of the present disclosure, an on-chip microlens may be disposed on the light entrance side relative to the quarter wavelength layer. Alternatively, the on-chip microlens (OCL) may include a main on-chip microlens provided above the quarter wavelength layer or the wire grid polarizer, or may include a sub on-chip microlens (an inner lens, OPA) provided above the quarter wavelength layer or the wire grid polarizer and a main on-chip microlens provided above the sub on-chip microlens (OPA).
In addition, in such a configuration of the light receiving device according to either of the second aspect and the third aspect of the present disclosure, a wavelength selection means (specifically, a well-known filter layer, for example) may be disposed between the wire grid polarizer and the on-chip microlens. By adopting such a configuration, it is possible to optimize the wire grid polarizer independently in a wavelength band of light to be transmitted through each wire grid polarizer, and to achieve further reduction in reflectance throughout the visible light region. A planarization film may be formed between the wire grid polarizer or the quarter wavelength layer and the wavelength selection means, and an underlying insulating layer including an inorganic material such as a silicon oxide film and serving as a base of a process in wire grid polarizer manufacturing steps may be formed below the wire grid polarizer. In a case where the main on-chip microlens is provided above the sub on-chip microlens (OPA), the wavelength selection means (a well-known filter layer) may be disposed between the sub on-chip microlens and the main on-chip microlens.
For example, a plurality of layers of various wiring lines (wiring layers) including aluminum (Al), copper (Cu), or the like is formed below the wire grid polarizer in order to drive the photoelectric conversion element. In addition, the wire grid polarizer is coupled to a substrate (specifically, a semiconductor substrate) via the various wiring lines (wiring layers) and contact hole parts. This makes it possible to apply a predetermined potential to the wire grid polarizer. Specifically, the wire grid polarizer is grounded, for example. Examples of the semiconductor substrate may include a compound semiconductor substrate such as a silicon semiconductor substrate or an InGaAs substrate.
Configurations and structures of, for example, a floating diffusion layer, an amplifier transistor, a reset transistor, and a selection transistor included in a controller for controlling driving of the photoelectric conversion element may be similar to configurations and structures of a floating diffusion layer, an amplifier transistor, a reset transistor, and a selection transistor of an existing controller. Thus, the controller may have a well-known configuration and structure, and may be provided on the substrate described above.
Between the photoelectric conversion elements in the photoelectric conversion element unit, there may be provided a waveguide structure or a light condensing tube structure. This makes it possible to achieve reduction in optical crosstalk. The waveguide structure here includes a thin film that is formed in a region (for example, a cylindrical region) located between the photoelectric conversion sections in an interlayer insulating layer covering the photoelectric conversion sections and that has a refractive index of a value greater than a value of a refractive index of a material included in the interlayer insulating layer. Light entering from above the photoelectric conversion section is totally reflected by this thin film and reaches the photoelectric conversion section. That is, an orthographic projection image of the photoelectric conversion section with respect to the substrate is located inside an orthographic projection image of the thin film included in the waveguide structure with respect to the substrate, and the orthographic projection image of the photoelectric conversion section with respect to the substrate is surrounded by the orthographic projection image of the thin film included in the waveguide structure with respect to the substrate. In addition, the light condensing tube structure includes a light-blocking thin film including a metal material or an alloy material and formed in a region (for example, a cylindrical region) located between the photoelectric conversion sections in the interlayer insulating layer covering the photoelectric conversion sections. Light entering from above the photoelectric conversion section is reflected by this thin film and reaches the photoelectric conversion section. That is, the orthographic projection image of the photoelectric conversion section with respect to the substrate is located inside an orthographic projection image of the thin film included in the light condensing tube structure with respect to the substrate, and the orthographic projection image of the photoelectric conversion section with respect to the substrate is surrounded by the orthographic projection image of the thin film included in the light condensing tube structure with respect to the substrate.
In a case of applying the light receiving device or the like of the present disclosure to a solid-state imaging device, examples of the photoelectric conversion element may include a CCD element, a CMOS image sensor, a CIS (Contact Image Sensor), and a CMD (Charge Modulation Device) type signal amplification image sensor. The photoelectric conversion element is a front-illuminated type photoelectric conversion element or a back-illuminated type photoelectric conversion element. For example, a digital still camera, a video camera, a camcorder, a monitoring camera, an on-vehicle camera, a smartphone camera, a game user interface camera, and a biometric authentication camera may be configured using the solid-state imaging device. In addition, it is possible to provide a solid-state imaging device that is able to acquire polarization information simultaneously as well as performing ordinary imaging. Further, it is also possible to provide a solid-state imaging device that captures a three-dimensional image. In a case where a solid-state imaging device is configured using the light receiving device or the like of the present disclosure, it is possible for the solid-state imaging device to configure a single-plate type color solid-state imaging device.
Example 1 relates to the light receiving device according to the first aspect of the present disclosure and the polarized state measuring method for an object of the present disclosure.
The light receiving device of Example 1 includes a plurality of photoelectric conversion element units 10A. Each of the photoelectric conversion element units 10A includes a plurality of photoelectric conversion elements 11A (in
The M photoelectric conversion elements disposed side by side along the first direction include the quarter wavelength layers 60 that have the same fast axis orientation,
Specifically, each of the photoelectric conversion element units includes M kinds of wire grid polarizers 50 and N kinds of quarter wavelength layers 60. Here, in the light receiving device of Example 1, M=N=2a (where a is an integer greater than or equal to 2, and preferably, a=3, 4, or 5). In addition, in this case, the polarization orientations of the M kinds of wire grid polarizers 50 are (180/2a)×m [degrees] (where m=0, 1, 2, 3 . . . , [2a−1]), and the fast axis orientations of the N kinds of quarter wavelength layers 60 are (180/2a)×n [degrees] (where n=0, 1, 2, 3 . . . , [2a−1]). It is to be noted that the cross section of the wire grid polarizer 50 in each of
In the illustrated example, a=3 and M=N=8. The polarization orientations of the M kinds of wire grid polarizers 50 are set to 0 degrees, 22.5 degrees, 45.0 degrees, 67.5 degrees, 90.0 degrees, 112.5 degrees, 135.0 degrees, and 157.5 degrees. Although the P direction of the wire grid polarizer having a polarization orientation of 0 degrees is assumed to be parallel to the first direction and the Q direction is assumed to be parallel to the second direction, these are non-limiting. Further, as illustrated in
The order of arrangement, in the first direction, of the M kinds of wire grid polarizers 50 having different polarization orientations may substantially be any order, and is not limited to the state illustrated in
In addition, in each of the photoelectric conversion elements 11, an on-chip microlens 81 is disposed on the light entrance side relative to the quarter wavelength layer 60. This also applies to Examples 2 and 3.
In the light receiving device of Example 1, all the photoelectric conversion element units are constituted by the plurality of photoelectric conversion element units 10A. The light receiving device of Example 1 is applicable to, for example, a light receiving device (e.g., a sensor) that is not intended for color separation or spectral diffraction, and the photoelectric conversion element itself has sensitivity to a specific wavelength (monochromatic light), which makes it unnecessary to provide a filter layer.
As illustrated in a schematic perspective diagram in
In Example 1, if
If H=125 nm,
Schematic diagrams of
Here, in an example illustrated in
An image obtainable in a state similar to that in
In the light receiving device of Example 1, or in the light receiving device of each of Examples 2 and 3 to be described later, the photoelectric conversion sections 21 having a well-known configuration and structure are formed in a silicon semiconductor substrate 31 by a well-known method. The photoelectric conversion sections 21 are covered with lower interlayer insulating layers 33, an underlying insulating layer 34 is formed on the lower interlayer insulating layers 33, and the wire grid polarizers 50 are formed on the underlying insulating layer 34. The wire grid polarizers 50 and the underlying insulating layer 34 are covered with a planarization film 35, and the quarter wavelength layers 60 are formed on the planarization film 35. An upper interlayer insulating layer 36 is formed on the quarter wavelength layers 60 and the planarization film 35, and the on-chip microlenses 81 are disposed on the upper interlayer insulating layer 36. In the illustrated example, the lower interlayer insulating layers 33 are in a five-layered arrangement and the wiring layers 32 are in a four-layered arrangement; however, this is non-limiting, and the lower interlayer insulating layers 33 and the wiring layers 32 may be provided in any number of layers. In
As illustrated in a schematic perspective view in
The light reflection layer 51, the insulating film 52, and the light absorption layer 53 are common to the photoelectric conversion elements 11. As illustrated in
It is possible to fabricate the wire grid polarizer 50 by the following method. That is, an underlying film (not illustrated) including Ti, TiN, or a layered structure of Ti/TiN, and a light-reflection-layer-forming layer 51A including the first electrically-conductive material (specifically, aluminum) are provided on the underlying insulating layer 34 in accordance with a vacuum vapor deposition method (see
Thereafter, the light-absorption-layer-forming layer 53A, the insulating-film-forming layer 52A, the light-reflection-layer-forming layer 51A, and moreover, the underlying film are patterned in accordance with a lithography technique and a dry etching technique. This makes it possible to obtain the wire grid polarizer 50 having the line-and-space structure including a plurality of line parts (stack structures) 54 disposed side by side with a space therebetween, the line parts 54 each including the light reflection layer 51, the insulating film 52, and the light absorption layer 53 that have a band shape. Thereafter, it is sufficient that the planarization film 35 is formed to cover the wire grid polarizer 50 in accordance with a CVD method. The wire grid polarizer 50 is surrounded by the frame part 59 including the light reflection layer 51, the insulating film 52, and the light absorption layer 53.
As a modification example of the wire grid polarizer 50, a configuration may be adopted in which, as illustrated in a partial end view in
Further, as illustrated in a partial end view in
Such a structure is obtained by producing the wire grid polarizer 50 having the line-and-space structure and thereafter forming the second protective film 57 including SiO2 and having an average thickness of 0.01 μm to 10 μm over the entire surface in accordance with a CVD method. A top of the space part 55 located between the line parts 54 is closed with the second protective film 57. Subsequently, the protective film 56 including SiN and having an average thickness of 0.1 μm to 10 μm is formed on the second protective film 57 in accordance with a CVD method. By forming the protective film 56 including SiN, it is possible to obtain the wire grid polarizer 50 that is high in reliability. However, SiN has a relatively high dielectric constant. Accordingly, a reduction in average refractive index nave is achieved by forming the second protective film 57 including SiO2.
In this way, forming the space part of the wire grid polarizer as an empty space (specifically, filling the space part with air) makes it possible to reduce the value of the average refractive index nave, and consequently makes it possible to achieve improvements in transmittance and extinction ratio of the wire grid polarizer. In addition, because it is possible to increase the value of the formation pitch Q0, improvement in manufacturing yield of the wire grid polarizer is achievable. Moreover, by forming the protective film on the wire grid polarizer, it is possible to provide the photoelectric conversion section and the light receiving device that each have high reliability. In addition, by coupling the frame part and the line part of the wire grid polarizer to each other and forming the frame part into the same structure as that of the line part of the wire grid polarizer, it is possible to form a homogeneous and uniform wire grid polarizer with stability. Accordingly, it is possible to resolve an issue of peeling occurring at portions in a peripheral part of the wire grid polarizer corresponding to four corners of the photoelectric conversion section, an issue of performance deterioration of the wire grid polarizer itself caused by a difference between a structure of the peripheral part of the wire grid polarizer and a structure of a middle part of the wire grid polarizer, and an issue of easy leakage of light having entered the peripheral part of the wire grid polarizer into the adjacent photoelectric conversion section having a different polarization direction, and it is thus possible to provide the photoelectric conversion section and the light receiving device that each have high reliability.
The wire grid polarizer may have a configuration without the insulating film, that is, a configuration in which the light reflection layer (including aluminum, for example) and the light absorption layer (including tungsten, for example) are stacked from the side opposite to the light entrance side. Alternatively, the wire grid polarizer may include a single electrically-conductive and light-blocking material layer. Examples of a material included in the electrically-conductive and light-blocking material layer may include an electrically-conductive material that has a low complex refractive index in a wavelength region to which the photoelectric conversion section has sensitivity, such as aluminum (Al), copper (Cu), gold (Au), silver (Ag), platinum (Pt), tungsten (W), or an alloy containing any of these metals.
Depending on cases, a third protective film 58 including SiO2, for example, may be formed on a side surface of the line part 54 facing the space part 55, as illustrated in a schematic partial end view of the wire grid polarizer in
Depending on cases, a portion of the insulating film 52 may be cut away to allow the light reflection layer 51 and the light absorption layer 53 to be in contact with each other at a cut-away portion 52a of the insulating film 52, as illustrated in a schematic perspective view of a modification example of the wire grid polarizer in
The quarter wavelength layer 60 illustrated in a schematic perspective diagram in FIG. 32 may be fabricated by the following method. Specifically, the first dielectric layer 61 is provided on the planarization film 35 in accordance with a CVD method. Thereafter, the first dielectric layer 61 is patterned in accordance with a lithography technique and a dry etching technique. It is thereby possible to obtain a line-and-space structure in which a plurality of first dielectric layers 61 having a band shape is disposed side by side with a space therebetween. Thereafter, the second dielectric layer 62 is formed on an entire surface in accordance with an ALD method, following which the second dielectric layer 62 is subjected to a planarization process. It is thereby possible to obtain the quarter wavelength layer 60.
The photoelectric conversion section 21 having a well-known configuration and structure is formed in the silicon semiconductor substrate 31 by a well-known method. In the semiconductor substrate 31, a memory section TRmem that is coupled to the photoelectric conversion section 21 and temporarily holds electric charge generated at the photoelectric conversion section 21 may be formed as illustrated in
The memory section TRmem includes the photoelectric conversion section 21, a gate section 22, a channel formation region, and a high-concentration impurity region 23. The gate section 22 is coupled to a memory selection line MEM. In addition, the high-concentration impurity region 23 is formed in the silicon semiconductor substrate 31 at a distance from the photoelectric conversion section 21 by a well-known method. A light-blocking film 24 is formed above the high-concentration impurity region 23. That is, the high-concentration impurity region 23 is covered with the light-blocking film 24. This prevents light from entering the high-concentration impurity region 23. By providing the memory section TRmem that temporarily holds electric charge, it is possible to easily implement a so-called global shutter function. Examples of a material included in the light-blocking film 24 may include chromium (Cr), copper (Cu), aluminum (Al), tungsten (W), and a resin that does not allow light to pass therethrough (e.g., polyimide resin).
A transfer transistor TRtrs illustrated only in
A reset transistor TRrst illustrated only in
An amplifier transistor TRamp illustrated only in
A selection transistor TRset illustrated only in
The photoelectric conversion section 21 is also coupled to one source/drain region of an electric charge discharging control transistor TRABG. A gate section of the electric charge discharging control transistor TRABG is coupled to an electric charge discharging control transistor control line ABG, and another source/drain region is coupled to the power source VDD.
A series of operations including electric charge accumulation, reset operation, and electric charge transfer to be performed by the photoelectric conversion section 21 is similar to a series of operations including electric charge accumulation, reset operation, and electric charge transfer to be performed by an existing photoelectric conversion section. Accordingly, a detailed description thereof is omitted.
The photoelectric conversion section 21, the memory section TRmem, the transfer transistor TRtrs, the reset transistor TRrst, the amplifier transistor TRamp, the selection transistor TRsel, and the electric charge discharging control transistor TRABG are covered with the lower interlayer insulating layer 33.
The drive control circuit 116 generates a clock signal and a control signal serving as references for operations of the vertical drive circuit 112, the column signal processing circuit 113, and the horizontal drive circuit 114, on the basis of a vertical synchronized signal, a horizontal synchronized signal, and a master clock. Thereafter, the clock signal and the control signal thus generated are inputted to the vertical drive circuit 112, the column signal processing circuit 113, and the horizontal drive circuit 114.
The vertical drive circuit 112 includes, for example, a shift register, and selectively scans the photoelectric conversion elements 101 in the imaging region 111 row by row sequentially in the vertical direction. Thereafter, a pixel signal (an image signals) based on a current (signal) generated in accordance with an amount of light received at each of the photoelectric conversion elements 101 is transmitted to the column signal processing circuit 113 via signal lines (data output lines) 117 and VSL.
The column signal processing circuit 113 is provided, for example, for each column of the photoelectric conversion elements 101 and performs signal processing for noise removal or signal amplification on the image signals outputted from one row of the photoelectric conversion elements 101 in accordance with a signal from a black reference pixel (formed around the effective pixel region, although not illustrated) for each of the photoelectric conversion sections. A horizontal selection switch (not illustrated) is provided in an output stage of the column signal processing circuit 113 and coupled between the column signal processing circuit 113 and a horizontal signal line 118.
The horizontal drive circuit 114 includes, for example, a shift register, and sequentially selects the column signal processing circuits 113 by sequentially outputting horizontal scanning pulses, and outputs signals from the respective column signal processing circuits 113 to the horizontal signal line 118.
The output circuit 115 performs signal processing on signals sequentially supplied from the respective column signal processing circuits 113 via the horizontal signal line 118, and outputs the processed signals.
The photoelectric conversion element unit in the light receiving device of Example 1 includes combinations of photoelectric conversion elements in each of which the quarter wavelength layer having a desired fast axis orientation, the wire grid polarizer having a desired polarization orientation, and the photoelectric conversion section are disposed in this order from the light entrance side. Accordingly, it is possible to easily recognize the polarized state of light entering the photoelectric conversion elements, and to easily know what polarized light component is included in a large amount in the light. It is therefore possible to provide a light receiving device (for example, a small-sized sensor) for determining a state of polarized light. With an existing light receiving device in which only a wire grid polarizer having a desired polarization orientation and a photoelectric conversion section are disposed in this order, it is difficult to know whether an entire image is polarized in a certain direction, and it is also difficult to know the polarized state in a narrow region of an image. In contrast, with the light receiving device of Example 1, it is possible to easily know whether the entire image is polarized in a certain direction, and it is also possible to know the polarized state in a narrow region of an image with accuracy. In addition, it is possible for an operator to know that an abnormality has occurred in a subject (an object) upon looking at the image, and it is possible to automatically detect the occurrence of an abnormality by performing image processing.
In a polarized state measuring method for an object (a subject) of Example 1,
The polarized state measuring method includes
According to the polarized state measuring method for an object of Example 1, it is sufficient that light having a predetermined polarized state (for example, any of the polarized states described with reference to
In addition, according to the polarized state measuring method for an object of Example 1, it is possible to evaluate a surface state of the object (the subject) by obtaining the comparison result. Specifically, it is possible to measure birefringence of the object (the subject) and, as one example, it is possible to grasp a molded state of a lens which is the object (the subject). Alternatively, by obtaining the comparison result on the object that is in a thin-film form, it is possible to evaluate a state of a film thickness of the object (the subject). Specifically, it is possible to perform measurements of the film thickness by using the light receiving device of Example 1 in an ellipsometer. Alternatively, the presence of a foreign substance in the object (the subject) may be evaluated by obtaining the comparison result.
Example 2 relates to the light receiving device according to the second aspect of the present disclosure.
The light receiving device of Example 2 includes a plurality of photoelectric conversion element units 10B.
Each of the photoelectric conversion element units 10B includes a first photoelectric conversion element 11B1, a second photoelectric conversion element 11B2, a third photoelectric conversion element 11B3, a fourth photoelectric conversion element 11B4, a fifth photoelectric conversion element 11B5, and a sixth photoelectric conversion element 11B6,
In addition,
Here, an angle formed between α and the second direction may substantially be any angle, and examples of the angle may include 0 degrees and 90 degrees. In Example 2, α=0 degrees. Further, an angle formed between R and the second direction may substantially be any angle, and examples of the angle may include 45 degrees and 135 degrees. In Example 2, β=45 degrees. That is, the angle formed between R and the second direction is 45 degrees. Accordingly, a relationship that β=(a±45) degrees is satisfied. Moreover, an angle formed between β and α′ satisfies α′=(β±45) degrees. In Example 2, α′=(β−45). That is, with respect to the second direction,
It is to be noted that in
In addition, in the light receiving device of Example 2,
Moreover, in the light receiving device of Example 2, at least light including a linearly polarized light component and light including a circularly polarized light component enter the photoelectric conversion element unit 10B in a mixed state. In an example illustrated in
A relationship between a polarization orientation of α′ degrees and a fast axis orientation of β degrees is, in a broad sense, preferably set to:
Alternatively, the relationship between the polarization orientation of α′ degrees and the fast axis orientation of β degrees satisfies, for example, α′=(β+45) degrees. Therefore,
Moreover, in the light receiving device of Example 2,
By way of example, suppose that light which is a mixture of linearly polarized light (which will hereinafter be referred to as “linearly polarized light of about 15 degrees” for convenience) that forms an angle of 15 degrees with respect to the second direction (an angle of 75 degrees with respect to the first direction) and left-handed circularly polarized light enters each of the photoelectric conversion element units 10B in the light receiving device of Example 2. In the light receiving device of Example 2, each of the photoelectric conversion elements has sensitivity to a specific wavelength (monochromatic light), which makes it unnecessary to provide a filter layer. One photoelectric conversion element unit 10B constitutes one pixel (a pixel). The light receiving device of Example 2 displays a monochromatic image.
In addition, in this case, the wire grid polarizer 50 included in the first photoelectric conversion element 11B1 passes light including a component having a polarization orientation of α degrees (0 degrees with respect to the second direction), of the light including the linearly polarized light component, and light including a component having the polarization orientation of α degrees, of the light including the circularly polarized light component. Specifically, the wire grid polarizer 50 included in the first photoelectric conversion element 11B1 passes light (amount of light: AL1-1) including the component having the polarization orientation of α degrees, of the linearly polarized light of about 15 degrees, and light (amount of light: ALCP) of about (¼) of the left-handed circularly polarized light. That is, the first photoelectric conversion element 11B1, or the second photoelectric conversion element 11B2, the third photoelectric conversion element 11B3, and the fourth photoelectric conversion element 11B4 to be described later are able to extract about (¼) of the light including the left-handed circularly polarized light component.
In addition, the wire grid polarizer 50 included in the second photoelectric conversion element 11B2 passes light including a component having the polarization orientation of (α+45) degrees (45 degrees with respect to the second direction), of the light including the linearly polarized light component, and light including a component having the polarization orientation of (α+45) degrees, of the light including the circularly polarized light component. Specifically, the wire grid polarizer 50 included in the second photoelectric conversion element 11B2 passes light (amount of light: AL1-2) including the component having the polarization orientation of (α+45) degrees, of the linearly polarized light of about 15 degrees, and light (amount of light: ALCP) of about (¼) of the left-handed circularly polarized light.
Moreover, the wire grid polarizer 50 included in the third photoelectric conversion element 11B3 passes light including a component having the polarization orientation of (α+90) degrees (90 degrees with respect to the second direction), of the light including the linearly polarized light component, and light including a component having the polarization orientation of (α+90) degrees, of the light including the circularly polarized light component. Specifically, the wire grid polarizer 50 included in the third photoelectric conversion element 11B3 passes light including the component having the polarization orientation of (α+90) degrees, of the linearly polarized light of about 15 degrees, and light (amount of light: ALCP) of about (¼) of the left-handed circularly polarized light. It is to be noted that the light including the component having the polarization orientation of (α+90) degrees, of the linearly polarized light of about 15 degrees, is substantially blocked by the wire grid polarizer 50 included in the third photoelectric conversion element 11B3.
In addition, the wire grid polarizer 50 included in the fourth photoelectric conversion element 11B4 passes light including a component having the polarization orientation of (α+135) degrees (135 degrees with respect to the second direction), of the light including the linearly polarized light component, and light including a component having the polarization orientation of (α+135) degrees, of the light including the circularly polarized light component. Specifically, the wire grid polarizer 50 included in the fourth photoelectric conversion element 11B4 passes light including the component having the polarization orientation of (α+135) degrees, of the linearly polarized light of about 15 degrees, and light (amount of light: ALCP) of about (¼) of the left-handed circularly polarized light. It is to be noted that the light including the component having the polarization orientation of (α+135) degrees, of the linearly polarized light of about 15 degrees, is substantially blocked by the wire grid polarizer 50 included in the fourth photoelectric conversion element 11B4.
In the quarter wavelength layer 60 included in the fifth photoelectric conversion element 11B5, the fast axis orientation β with respect to the second direction is 45 degrees. Further, an angle formed between the linearly polarized light of about 15 degrees and the fast axis orientation p is about 120 degrees. Accordingly, the quarter wavelength layer 60 outputs left-handed circularly polarized light on the basis of entry of the linearly polarized light of about 15 degrees (see the left figure in
Further, the quarter wavelength layer 60 included in the fifth photoelectric conversion element 11B5 outputs linearly polarized light inclined at 45 degrees with respect to the fast axis orientation (linearly polarized light parallel to the first direction) on the basis of entry of left-handed circularly polarized light (see the left figure in
In the quarter wavelength layer 60 included in the sixth photoelectric conversion element 11B6, the fast axis orientation (β+90) with respect to the second direction is 135 degrees. Further, the angle formed between the linearly polarized light of about 15 degrees and the fast axis orientation β is about 30 degrees. Accordingly, the quarter wavelength layer 60 outputs right-handed circularly polarized light on the basis of entry of the linearly polarized light of about 15 degrees (see the left figure in
Further, the quarter wavelength layer 60 included in the sixth photoelectric conversion element 11B6 outputs linearly polarized light inclined at 45 degrees with respect to the fast axis orientation (linearly polarized light parallel to the second direction) on the basis of entry of left-handed circularly polarized light (see the left figure in
Amounts of light obtainable by the photoelectric conversion section of the sixth photoelectric conversion element 11B6 are as follows.
Also in case where right-handed circularly polarized light enters the quarter wavelength layers included in the fifth photoelectric conversion element 11B5 and the sixth photoelectric conversion element 11B6, the following results are obtainable (see
Further, amounts of light obtainable by the photoelectric conversion section of the sixth photoelectric conversion element 11B6 are as follows.
In this way, it is possible to find whether the circularly polarized light component is large or small in amount and whether the right-handed circularly polarized light component is large in amount or the left-handed circularly polarized light component is large in amount, on the basis of the fifth photoelectric conversion element 11B5 and the sixth photoelectric conversion element 11B6.
The above-described situations are schematically illustrated in
Moreover, the light receiving device of Example 2 further includes a data processor. Where:
degree of polarization=ΔAL/(ΔAL+ΔAL′).
Moreover, the data processor displays, of obtained image data, a region where the degree of polarization is high and a region where the degree of polarization is low in different colors.
the degree of polarization=ΔAL/(ΔAL+ΔAL″)
the degree of polarization=ΔAL/(ΔAL+ΔAL″)
The amounts of received light (light intensities) at the photoelectric conversion elements 11B1, 11B2, 11B3, 11B4, 11B5, and 11B6 in the light receiving device of Example 2 described above are summarized as follows.
Amount of light based on the linearly polarized light of about 15 degrees: AL1-1
Amount of light based on the left-handed circularly polarized light: ALCP
Amount of light based on the linearly polarized light of about 15 degrees: AL1-2
Amount of light based on the left-handed circularly polarized light: ALCP
Amount of light based on the linearly polarized light of about 15 degrees: 0
Amount of light based on the left-handed circularly polarized light: ALCP
Amount of light based on the linearly polarized light of about 15 degrees: 0
Amount of light based on the left-handed circularly polarized light: ALCP
Amount of light based on the linearly polarized light of about 15 degrees: ALLP′
Amount of light based on the left-handed circularly polarized light: 0.
Amount of light based on the linearly polarized light of about 15 degrees: ALLP′
Amount of light based on the left-handed circularly polarized light: ALCP′
Here, because AL5<AL6,
ΔAL′=AL6−AL5=ALCP′.
In addition,
ALCP≈ALCP′/4.
Therefore, by subtracting (ΔAL′/4) from the respective amounts of light received by the first photoelectric conversion elements 11B1, 11B2, 11B3, and 11B4, it is possible to determine the respective amounts of light ALLP-1, ALLP-2, ALLP-3, and ALLP-4 of the linearly polarized light received by the first photoelectric conversion elements 11B1, 11B2, 11B3, and 11B4. That is, according to the light receiving device of Example 2, it is possible to separate the linearly polarized light component and the circularly polarized light component from each other.
In addition, on the basis of the respective amounts of light AL1, AL2, AL3, and AL4 (specifically, the amounts of light ALLP-1, ALLP-2, ALLP-3, and ALLP-4 of the linearly polarized light) received by the first photoelectric conversion elements 11B1, 11B2, 11B3, and 11B4 determined in such a manner, it is possible to determine, as described above,
the degree of polarization=ΔAL/(ΔAL+ΔAL′),
and moreover, an image may be displayed on the basis of these amounts of light. An image obtained on the basis of the first photoelectric conversion element 11B1 in each photoelectric conversion element unit is presented as “0°” in
In these images, regions where the amounts of light ALLP-1, ALLP-2, ALLP-3, and ALLP-4 are large are indicated in a “light” color. Such regions are high in the degree of polarization. In contrast, regions where the amounts of light ALLP-1, ALLP-2, ALLP-3, and ALLP-4 are small are indicated in a “dark” color. Such regions are low in the degree of polarization. In addition, an image resulting from combining the four images of
According to the light receiving device of Example 2, it is possible to color and thereby display such a region where no polarization information has been acquired. This makes it possible to appropriately obtain polarization information from regions other than such a region where no polarization information has been acquired (a region lacking in polarization information). That is, according to the light receiving device of Example 2, it is possible to easily know the so-called degree of polarization, and a person who views the image is able to easily identify a region in the image where no polarization information has been acquired. In addition, by using the circularly polarized light component in calculating the degree of polarization, it is possible to achieve improvement in substantial resolution of the entire image. Moreover, by performing desired processing on, for example, a portion of a captured image of the sky or a window pane, a portion of a captured image of a water surface, or the like, it is possible to emphasize or reduce the polarized light component or to separate various polarized light components from each other. It is thus possible to improve image contrast and delete unwanted information.
In the light receiving device of Example 2, all the photoelectric conversion element units are constituted by the photoelectric conversion element units-2A of the foregoing case (2-1). It is to be noted that in this case, the photoelectric conversion elements in the photoelectric conversion element unit-2A may have the same configuration and structure. Alternatively, the light receiving device of Example 2 may be in any of the embodiments of the foregoing cases (2-2) to (2-10).
In addition, a modification example of the light receiving device of Example 2 may include a plurality of photoelectric conversion element unit groups that is two-dimensionally arranged, and may have a configuration in which
Specifically, one photoelectric conversion element unit group includes four photoelectric conversion element units disposed in the Bayer arrangement, for example. The light in the first wavelength range may be red light, the light in the second wavelength range and the light in the third wavelength range may be green light, and the light in the fourth wavelength range may be blue light. Alternatively, the light in the first wavelength range may be red light, the light in the second wavelength range may be green light, the light in the third wavelength range may be blue light, and the light in the fourth wavelength range may be infrared light. In this case, the fourth photoelectric conversion element unit may have a configuration including a fourth filter layer that passes none of the light in the first wavelength range, the light in the second wavelength range, and the light in the third wavelength range. Alternatively, the arrangement of the photoelectric conversion element units may include various kinds of arrangements described above. In addition, a configuration may be adopted in which
In addition, in the modification example of the light receiving device of Example 2, the first quarter wavelength layer, the second quarter wavelength layer and the third quarter wavelength layer, and the fourth quarter wavelength layer are disposed in the same layer. Moreover,
In Example 2, as described above, one photoelectric conversion element unit group includes four photoelectric conversion element units disposed in the Bayer arrangement, for example. Therefore, t21=t31, and t22=t32. Further, H1=H2=H3=H4=115 nm.
Regarding the first quarter wavelength layer,
Further, regarding the second quarter wavelength layer and the third wavelength layer,
Moreover, regarding the fourth quarter wavelength layer,
Alternatively, in the modification example of the light receiving device of Example 2, the first quarter wavelength layer, the second quarter wavelength layer, the third quarter wavelength layer, and the fourth quarter wavelength layer are disposed in different layers. In addition, a configuration may be adopted in which
Note that because one photoelectric conversion element unit group includes, for example, four photoelectric conversion element units disposed in the Bayer arrangement, H2=H3. The first quarter wavelength layer occupies, for example, a first layer, the second quarter wavelength layer and the third quarter wavelength layer occupy, for example, a second layer, and the fourth quarter wavelength layer occupies, for example, a third layer; however, such a state is non-limiting, and the order of the layer occupied by the first quarter wavelength layer, the layer occupied by the second quarter wavelength layer and the third wavelength layer, and the layer occupied by the fourth wavelength layer may substantially be any order.
Here,
In addition, regarding the first quarter wavelength layer, if:
Further, regarding the second quarter wavelength layer and the third wavelength layer, if:
Moreover, regarding the fourth quarter wavelength layer, if:
The description of the modification example of the light receiving device of Example 2 above also applies to a light receiving device of Example 3.
Example 3 relates to the light receiving device according to the third aspect of the present disclosure.
The light receiving device of Example 3 includes a plurality of photoelectric conversion element units 10C.
Each of the photoelectric conversion element units 10C includes a first photoelectric conversion element 11C1, a second photoelectric conversion element 11C2, a third photoelectric conversion element 11C3, and a fourth photoelectric conversion element 11C4,
In addition, one photoelectric conversion element unit 10C constitutes one pixel (a pixel). The light receiving device of Example 3 displays a monochromatic image. It is to be noted that, as described in the modification example of the light receiving device of Example 2, the modification example of the light receiving device of Example 2 is applicable to the light receiving device of Example 3. In this case, one photoelectric conversion element unit group constitutes one pixel (a pixel), and the four photoelectric conversion element units disposed 2×2 constitute one sub-pixel (a sub-pixel). Such a configuration makes it possible to display a color image.
Here, although not limited thereto, α=β may be satisfied. An angle formed between α and the second direction may substantially be any angle, and examples of the angle may include 0 degrees and 90 degrees. In Example 3, α=0 degrees. That is, an angle formed between α and the Q direction is set to 0 degrees, and an angle formed between α and the P direction is set to 90 degrees. In addition, an angle formed between R and the second direction may substantially be any angle, and examples of the angle may include 0 degrees and 90 degrees. In Example 3, β=0 degrees. That is, the angle formed between R and the second direction is set to 0 degrees.
In the following, a description is given first of a state when, in the photoelectric conversion element unit in the light receiving device of Example 3, linearly polarized light that is polarized in the second direction enters the first quarter wavelength layer 60A from above in the direction perpendicular to the sheet plane of
In the first photoelectric conversion element 11C1 located in the second quadrant of
In the second photoelectric conversion element 11C2 located in the first quadrant of
In the third photoelectric conversion element 11C3 located in the fourth quadrant of
In the fourth photoelectric conversion element 11C4 located in the third quadrant of
As has been described, when the linearly polarized light that is polarized in the second direction enters the first quarter wavelength layer 60A from above in the direction perpendicular to the sheet plane of
Next, a description is given of a state when, in the photoelectric conversion element unit in the light receiving device of Example 3, linearly polarized light that is polarized in the first direction enters the first quarter wavelength layer 60A from above in a direction perpendicular to the sheet plane of
In the first photoelectric conversion element 11C1 located in the second quadrant of
In the second photoelectric conversion element 11C2 located in the first quadrant of
In the third photoelectric conversion element 11C3 located in the fourth quadrant of
In the fourth photoelectric conversion element 11C4 located in the third quadrant of
As has been described, when the linearly polarized light that is polarized in the first direction enters the first quarter wavelength layer 60A from above in the direction perpendicular to the sheet plane of
Next, a description is given of a state when, in the photoelectric conversion element unit in the light receiving device of Example 3, linearly polarized light that is polarized at −45 degrees with respect to the first direction enters the first quarter wavelength layer 60A from above in a direction perpendicular to the sheet plane of
In the first photoelectric conversion element 11C1 located in the second quadrant of
In the second photoelectric conversion element 11C2 located in the first quadrant of
In the third photoelectric conversion element 11C3 located in the fourth quadrant of
In the fourth photoelectric conversion element 11C4 located in the third quadrant of
As has been described, when the linearly polarized light that is polarized at −45 degrees with respect to the first direction enters the first quarter wavelength layer 60A from above in the direction perpendicular to the sheet plane of
Next, a description is given of a state when, in the photoelectric conversion element unit in the light receiving device of Example 3, linearly polarized light that is polarized at +45 degrees with respect to the first direction enters the first quarter wavelength layer 60A from above in a direction perpendicular to the sheet plane of
In the first photoelectric conversion element 11C1 located in the second quadrant of
In the second photoelectric conversion element 11C2 located in the first quadrant of
In the third photoelectric conversion element 11C3 located in the fourth quadrant of
In the fourth photoelectric conversion element 11C4 located in the third quadrant of
As has been described, when the linearly polarized light that is polarized at +45 degrees with respect to the first direction enters the first quarter wavelength layer 60A from above in the direction perpendicular to the sheet plane of
The description has been given above of the passing states, through the wire grid polarizers, of the linearly polarized light polarized at −45 degrees, 0 degrees, +45 degrees, and +90 degrees with respect to the first direction, upon entering the first quarter wavelength layer 60A. When linearly polarized light that is polarized at “a certain angle” with respect to the first direction enters the first quarter wavelength layer 60A, the certain angle is determinable by analyzing the amounts of light (light intensities) received by the wire grid polarizer in the first photoelectric conversion element, the wire grid polarizer in the second photoelectric conversion element, the wire grid polarizer in the third photoelectric conversion element, and the fourth photoelectric conversion element.
As described above, according to the light receiving device of Example 3, it is possible to easily know the polarized state of light entering the photoelectric conversion element unit in the light receiving device by determining the amount of light (light intensity) received at each of the first photoelectric conversion element, the second photoelectric conversion element, the third photoelectric conversion element, and the fourth photoelectric conversion element. It is also possible to easily extract light having specific linear polarization on the basis of each of the first photoelectric conversion element, the second photoelectric conversion element, the third photoelectric conversion element, and the fourth photoelectric conversion element, and it is also possible to provide a function as a PL filter or a CPL filter.
In addition, according to any of the light receiving devices described in Examples 1 to 3, it is possible to obtain light intensity, polarized light component intensity, and polarization direction at each of the photoelectric conversion elements (imaging elements). Accordingly, it is possible to process image data on the basis of polarization information after imaging, for example. By performing desired processing on, for example, a portion of a captured image of the sky or a window pane, a portion of a captured image of a water surface, or the like, it is possible to emphasize or reduce the polarized light component or to separate various polarized light components from each other. It is thus possible to improve image contrast and delete unwanted information. It is to be noted that, specifically, such processing is achievable by defining an imaging mode in performing imaging with use of a solid-state imaging device, for example. Moreover, with use of the solid-state imaging device, it is possible to remove reflected glare on a window pane and to achieve sharpening of boundaries (outlines) of a plurality of objects by adding polarization information to image information. Alternatively, it is possible to detect a state of a road surface and to detect an obstacle on the road surface. Moreover, application to or practical use in various fields is possible, examples of which include imaging of patterns reflecting birefringence of an object, measurement of retardation distribution, acquisition of a polarizing microscopic image, acquisition of a surface shape of an object and measurement of surface properties of the object, detection of a moving body (a vehicle or the like), and weather observation such as measurement of cloud distribution or the like. Further, it is also possible to provide a solid-state imaging device for capturing a three-dimensional image.
Although the description has been given above of the present disclosure on the basis of preferred examples, the present disclosure is not limited to these examples. The structures and configurations, manufacturing methods, and materials used of the photoelectric conversion elements (light receiving elements and imaging elements), the light receiving devices, and the solid-state imaging devices described in Examples are merely illustrative, and are modifiable on an as-needed basis. It is possible to shoot a moving image and perform sensing with use of a solid-state imaging device based on the light receiving device of the present disclosure.
Further, in Examples described above, the wire grid polarizer is used only for acquisition of polarization information at the photoelectric conversion section having sensitivity to a visible light wavelength band; however, in a case where the photoelectric conversion section has sensitivity to infrared light or ultraviolet light, implementation as a wire grid polarizer functioning in any wavelength band is possible by increasing or decreasing the formation pitch Q0 of the line section accordingly.
Depending on cases, a trench (a kind of element separation region) extending from the substrate to a position below the wire grid polarizer and filled with an insulating material or a light-blocking material may be formed at an edge part of the photoelectric conversion section. Examples of the insulating material may include the material included in the insulating film (insulating-film-forming layer) or the interlayer insulating layer. Examples of the light-blocking material may include the material included in the light-blocking film 24 described above. By forming such a trench, it is possible to prevent reduction in sensitivity, occurrence of polarization crosstalk, and reduction in extinction ratio.
A waveguide structure may be provided between the photoelectric conversion sections 21. The waveguide structure includes a thin film that is formed in a region (e.g., a cylindrical region) located between the photoelectric conversion sections 21 in the lower interlayer insulating layer 33 (specifically, a portion of the lower interlayer insulating layer 33) covering the photoelectric conversion sections 21 and has a refractive index of a value greater than a value of a refractive index of the material included in the lower interlayer insulating layer 33. Light entering from above the photoelectric conversion sections 21 is totally reflected by this thin film and reaches the photoelectric conversion sections 21. An orthographic projection image of the photoelectric conversion sections 21 with respect to the semiconductor substrate 31 is located inside an orthographic projection image of the thin film included in the waveguide structure with respect to the semiconductor substrate 31. The orthographic projection image of the photoelectric conversion sections 21 with respect to the semiconductor substrate 31 is surrounded by the orthographic projection image of the thin film included in the waveguide structure with respect to the semiconductor substrate.
Alternatively, a light-condensing tube structure may be provided between the photoelectric conversion sections 21. The light-condensing tube structure includes a light-blocking thin film including a metal material or an alloy material and formed in a region (e.g., a cylindrical region) located between the photoelectric conversion sections 21 in the lower interlayer insulating layer 33 covering the photoelectric conversion sections 21. Light entering from above the photoelectric conversion sections 21 is reflected by this thin film and reaches the photoelectric conversion sections 21. That is, the orthographic projection image of the photoelectric conversion sections 21 with respect to the semiconductor substrate 31 is located inside an orthographic projection image of the thin film included in the light-condensing tube structure with respect to the semiconductor substrate 31. In addition, the orthographic projection image of the photoelectric conversion sections 21 with respect to the semiconductor substrate 31 is surrounded by the orthographic projection image of the thin film included in the light-condensing tube structure with respect to the semiconductor substrate 31. For example, the thin film is obtainable by forming an annular trench in the lower interlayer insulating layer 33 after forming all of the lower interlayer insulating layer 33, and filling the trench with a metal material or an alloy material.
A 2×2 pixel sharing method is adoptable in which a selection transistor, a reset transistor, and an amplifier transistor are shared among 2×2 photoelectric conversion sections. In an imaging mode involving no pixel addition, it is possible to perform imaging including polarization information, whereas in a mode involving FD addition of accumulated electric charge in 2×2 sub-pixel regions, it is possible to provide an ordinary captured image in which all polarized components have been integrated.
In addition, in Examples, the description has been given of an example case of application to a CMOS type solid-state imaging device including unit pixels arranged in a matrix form, the unit pixels detecting signal electric charge corresponding to the amount of entering light as a physical quantity; however, possible applications are not limited to the CMOS type solid-state imaging device and may include a CCD type solid-state imaging device. In the latter case, the signal electric charge is transferred in a vertical direction by a vertical transfer register having a CCD type structure and is transferred in a horizontal direction by a horizontal transfer register. The transferred signal electric charge is amplified and is thereby outputted as a pixel signal (image signal). Further, the applications are not limited to a column type solid-state imaging device in general that includes pixels arranged in a two-dimensional matrix form with a column signal processing circuit provided for each pixel column. Moreover, depending on cases, the selection transistor may be omitted.
Moreover, the photoelectric conversion element (imaging element) of the present disclosure is applicable not only to a solid-state imaging device that detects a distribution of entering light amounts of visible light and captures the distribution as an image, but also to a solid-state imaging device that captures a distribution of amounts of entry of infrared light, X-rays, particles, or the like as an image. In addition, in a broad sense, the photoelectric conversion element of the present disclosure is applicable to a solid-state imaging device (physical quantity distribution detection device) in general, such as a fingerprint detection sensor, that detects a distribution of any of other physical quantities including pressure and electrostatic capacitance.
Moreover, the application is not limited to a solid-state imaging device that sequentially scans unit pixels in an imaging region on a row-by-row basis and reads respective pixel signals from the unit pixels. Possible applications also include an X-Y address type solid-state imaging device that selects any pixels on a pixel-by-pixel basis and reads pixel signals from the selected pixels on a pixel-by-pixel basis. The solid-state imaging device may be formed as one chip, or may be in a module form with an imaging function in which an imaging region and a drive circuit or an optical system are integrated into a package.
In addition, the possible applications are not limited to the solid-state imaging device, and may include an imaging device. The imaging device here refers to a camera system such as a digital still camera or a video camera, and an electronic apparatus having an imaging function, such as a cellular phone. In some cases, the imaging device may be in a module form to be mounted on an electronic apparatus, that is, the imaging device may be a camera module.
An example in which a solid-state imaging device 201 of the present disclosure is used in an electronic apparatus (a camera) 200 is illustrated in
It is to be noted that the present disclosure may have the following configurations.
A light receiving device including a plurality of photoelectric conversion element units, in which
The light receiving device according to [A01], in which each of the photoelectric conversion element units includes M kinds of wire grid polarizers and N kinds of quarter wavelength layers.
The light receiving device according to [A01] or [A02], in which M=N=2a (where a is an integer greater than or equal to 2).
The light receiving device according to [A03], in which polarization orientations of the M kinds of wire grid polarizers are (180/2a)×m [degrees] (where m=0, 1, 2, 3 . . . , [2a−1]), and fast axis orientations of the N kinds of quarter wavelength layers are (180/2a)×n [degrees] (where n=0, 1, 2, 3 . . . , [2a−1]).
A polarized state measuring method for an object using a light receiving device, in which
The polarized state measuring method for an object according to [B01], including applying light having a predetermined polarized state and wavelength to the object to thereby capture an image of the object with the light receiving device.
The polarized state measuring method for an object according to [B01] or [B02], including evaluating a surface state of the object by obtaining the comparison result.
The polarized state measuring method for an object according to [B01] or [B02], including evaluating a state of a film thickness of the object that is in a thin-film form, by obtaining the comparison result on the object.
The polarized state measuring method for an object according to [B01] or [B02], including evaluating presence of a foreign substance in the object by obtaining the comparison result.
A light receiving device including a plurality of photoelectric conversion element units, in which
The light receiving device according to [C01], in which α′=(β±45) degrees is satisfied.
The light receiving device according to [C01] or [C02], in which
The light receiving device according to any one of [C01] to [C03], in which at least light including a linearly polarized light component and light including a circularly polarized light component enter the photoelectric conversion element units in a mixed state.
The light receiving device according to [C04], in which
The light receiving device according to [C05], further including a data processor, in which
The light receiving device according to [C06], in which the degree of polarization is determined by:
The light receiving device according to [C07], in which the data processor displays, of obtained image data, a region where the degree of polarization is high and a region where the degree of polarization is low in different colors.
A light receiving device including a plurality of photoelectric conversion element units, in which
The light receiving device according to [D01], in which α=β.
The light receiving device according to any one of [C01] to [D02], including a plurality of photoelectric conversion element unit groups that is two-dimensionally arranged, in which
The light receiving device according to [E01], in which
The light receiving device according to [E02], in which the first quarter wavelength layer, the second quarter wavelength layer, the third quarter wavelength layer, and the fourth quarter wavelength layer are disposed in different layers.
The light receiving device according to [E03], in which
The light receiving device according to [E02], in which the first quarter wavelength layer, the second quarter wavelength layer, the third quarter wavelength layer, and the fourth quarter wavelength layer are disposed in the same layer.
The light receiving device according to [E05], in which
The light receiving device according to any one of [A01] to [E06], in which the quarter wavelength layer includes a first dielectric layer including a material having a refractive index n1 and a second dielectric layer including a material having a refractive index n2 that are alternately disposed side by side,
The light receiving device according to any one of [A0l] to [E07], in which
The light receiving device according to [F01], in which
The light receiving device according to [F02], in which the protective film includes SiN and the second protective film includes SiO2 or SiON.
The light receiving device according to any one of [F01] to [F03], in which a third protective film is provided at least on a side surface of a line part facing the space part of the wire grid polarizer.
The light receiving device according to any one of [F01] to [F04], further including a frame part surrounding the wire grid polarizer, in which
The light receiving device according to any one of [F01] to [F05], in which a line part of the wire grid polarizer includes a stack structure in which a light reflection layer including a first electrically-conductive material, an insulating film, and a light absorption layer including a second electrically-conductive material are stacked from side of the photoelectric conversion section.
The light receiving device according to [F06], in which the light reflection layer and the light absorption layer are common to the photoelectric conversion elements.
The light receiving device according to [F06] or [F07], in which the insulating film is formed on an entire top surface of the light reflection layer, and the light absorption layer is formed on an entire top surface of the insulating film.
The light receiving device according to any one of [F06] to [F08], in which an underlying insulating layer is formed below the light reflection layer.
The light receiving device according to any one of [F06] to [F09], in which the insulating film is formed on an entire top surface of the light reflection layer, and the light absorption layer is formed on an entire top surface of the insulating film.
The light receiving device according to any one of [A01] to [F10], in which a memory section is formed in a semiconductor substrate, the memory section being coupled to the photoelectric conversion section and temporarily holding electric charge generated at the photoelectric conversion section.
The present application claims the benefit of Japanese Priority Patent Application JP2020-182692 filed with the Japan Patent Office on Oct. 30, 2020, the entire contents of which are incorporated herein by reference.
It should be understood by those skilled in the art that various modifications, combinations, sub-combinations, and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-182692 | Oct 2020 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/034101 | 9/16/2021 | WO |
