Patent Application
20180012069
This application claims the benefit of Korean Patent Application Nos. 10-2016-0085697, filed on Jul. 6, 2016, 10-2016-0100360, filed on Aug. 5, 2016, and 10-2016-0184352, filed on December 30, 2016, in the Korean Intellectual Property Office, the disclosures of each of which are incorporated herein in their entirety by reference.
Inventive concepts relate to a fingerprint sensor such as an optical fingerprint sensor and a fingerprint sensor package using light sources of a display panel.
A fingerprint sensor or a fingerprint recognition sensor is a sensor for sensing a fingerprint of a user. Recently, smart phones and wearable devices, on which a fingerprint sensor is mounted, have been widely used. Such a fingerprint sensor, which is mounted on the smart phone and the wearable device, may sense a fingerprint of the user using an electrical measurement method or an optical measurement method.
An optical fingerprint sensor using an optical measurement method may obtain a fingerprint image using a principle in which light reflected by ridges of a fingerprint and valleys between the ridges is sensed through an image sensor.
In order to apply such a fingerprint sensor to the smart phone and the wearable device, a size of the fingerprint sensor and improve the performance of fingerprint recognition is reduced.
Inventive concepts provide an on-display fingerprint sensor, a fingerprint sensor package, and a fingerprint sensing system including a fingerprint sensor.
According to an aspect of inventive concepts, there is provided a fingerprint sensor including an image sensor including a plurality of sensor pixels, the plurality of sensor pixels configured to sense light reflected by a fingerprint and generate image information corresponding to the fingerprint and a pinhole mask defining a plurality of pinholes, wherein each of the pinholes forms a focus for transmitting the light reflected by the fingerprint to the image sensor, and the light is emitted from a plurality of organic light-emitting diodes (OLEDs) and is reflected by the fingerprint.
According to another aspect of inventive concepts, there is provided a fingerprint sensor package, which is attached to one surface of a display panel including a plurality of organic light-emitting diodes (OLEDs) configured to generate light, the package including a package substrate, an image sensor on the package substrate, the image sensor defining a light-receiving region configured to sense the light generated by the OLEDs and reflected by a fingerprint, the light-receiving region configured to output an electrical signal, the image sensor further defining a logic region configured to generate image data by signal processing the electrical signal, generate a fingerprint image using the generated image data, and output the fingerprint image, and a pinhole mask between the plurality of OLEDs and the image sensor, the pinhole mask including a plurality of pinholes, the plurality of pinholes forming focuses for transmitting the light reflected by the fingerprint to the image sensor.
According to still another aspect of inventive concepts, there is provided a fingerprint sensing system including a display panel including light sources, the light sources configured to emit light having one or more colors in relation to a display operation, an image sensor attached to one surface of the display panel and configured to sense light from the light sources that is reflected by a fingerprint located on another surface of the display panel, the image sensor configured to generate image information according to a sensing result, and a pinhole mask between the display panel and the image sensor, the pinhole mask having a plurality of pinholes for forming a focus of the light reflected by the fingerprint, wherein, in a fingerprint sensing operation, the image sensor senses light having some of the one or more colors and generates the image information.
In at least one example embodiment, a sensing system includes a display panel configured to generate light and receive reflected light based on the generated light and a sensor, the sensor including a mask defining a plurality of holes, the mask configured to guide a first portion of the reflected light through the mask, a first side of the mask being on the display panel and an image sensor on a second side of the mask, the image sensor including a plurality of sensor pixels, the plurality of sensor pixels configured to sense the first portion of the reflected light and generate electrical signals based on the sensed light, the mask being configured to guide the first portion of the reflected light to the image sensor without a lens.
Example embodiments of inventive concepts will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings in which:
Hereinafter, some example embodiments of inventive concepts will be described in detail with reference to the accompanying drawings.
Referring to
Various types of display panels may be applied to the display panel 11. According to an example embodiment, the display panel 11 may be an organic light-emitting diode (OLED) display panel including an OLED layer in which OLEDs which emit light having one or more colors and perform a display operation are formed. However, example embodiments of inventive concepts are not limited thereto, and the fingerprint sensing system 10 according to an example embodiment of inventive concepts may correspond to one of various types of display panels such as a liquid crystal display (LCD) panel which performs a display operation using general backlights or OLEDs. Alternatively, in addition to the above-described OLED display panel and LCD panel, when light emitted from a light source of a display panel is reflected by a fingerprint and is transmitted in a direction towards a backplane of the display panel (or in a direction towards a fingerprint sensor 12), the corresponding display panel may be applied to the display panel 11 according to an example embodiment of inventive concepts.
Meanwhile, the fingerprint sensor 12 may be implemented as a semiconductor chip or semiconductor package and attached to one surface of the display panel 11. According to one example embodiment, the image sensor 12_2 may be implemented as a semiconductor layer or semiconductor chip in which a plurality of photoelectric conversion elements (e.g., photodiodes (PDs), phototransistors, photo gates, pinned PDs, etc.) are formed. According to one example embodiment, the image sensor 12_2 may be a semiconductor layer in which an image sensor such as a complementary metal-oxide-semiconductor (CMOS) image sensor (CIS) and a charge coupled device (CCD) is implemented. In the following description, it is assumed that the photoelectric conversion elements in the image sensor 12_2 are implemented as PDs.
According to one example embodiment, in implementing the fingerprint sensor 12, in a process of packaging the image sensor 12_2, the pinhole mask 12_1 may be stacked on the image sensor 12_2. Alternatively, in a process of implementing the image sensor 12_2, the pinhole mask 12_1 may be stacked on one or more layers constituting the image sensor 12_2 in the form of a layer. That is, the fingerprint sensor 12 may be implemented in a form in which the pinhole mask 12_1 is embedded in the image sensor 12_2, and a packaging process may be performed on the image sensor 12_2 in which the pinhole mask 12_1 is embedded. That is, according to one example embodiment, the pinhole mask 12_1 and the image sensor 12_2 may be integrally formed.
The pinhole mask 12_1 may be implemented by various methods using a material having a low transmittance and a low reflectivity. For example, the pinhole mask 12_1 may be implemented using a material, that has a low reflectivity (or a high absorption rate) while blocking light and maintains its hardness even with temperature or humidity change. For example, the pinhole mask 12_1 may be implemented by forming pinholes after applying a titanium nitride (TiN) material on a silicon material. Alternatively, other non-silicon materials such as black nickel or anodized aluminium may be materials of the pinholes.
According to one example embodiment, the OLED layer included in the OLED display panel and the pinhole mask 12_1 may be substantially disposed in parallel. Accordingly, light emitted from the plurality of OLEDs in the OLED layer may be transmitted in a direction towards the fingerprint located on a cover glass, and the light reflected by the fingerprint may be transmitted to the pinhole mask 12_1 within an angle of view formed by the pinhole in the pinhole mask 12_1. Accordingly, in fingerprint sensors according to example embodiments of inventive concepts, it is not necessary to provide a separate light guiding unit for controlling a path through which light is transmitted for fingerprint sensing.
The fingerprint sensor 12 senses a fingerprint which comes in contact with the display panel 11 or is located near the display panel 11. In the fingerprint sensing system 10 according to example embodiments of inventive concepts, a fingerprint touched on a display of a wearable device such as a smart phone or the like may be recognized without the need of mounting a separate button for fingerprint recognition. For example, when the display panel 11 corresponds to an OLED display panel and the fingerprint of a user is placed on the cover glass of the display panel 11, the light emitted from the OLED in the display panel 11 may be transmitted to and reflected by the fingerprint of the user as a light source, and the reflected light may be transmitted through the backplane of the display panel and transmitted to the image sensor 12_2 through the pinhole mask 12_1.
The image sensor 12_2 includes a plurality of sensor pixels, and each of the sensor pixels senses lights reflected by different regions of the fingerprint, and generates electrical signals corresponding to the sensed lights. Each of the sensor pixels may generate an electrical signal corresponding to light reflected by ridges of the fingerprint, or generate an electrical signal corresponding to light reflected by valleys between the ridges. An amount of light sensed in the PD may vary according to a shape of the fingerprint by which the light is reflected, and electrical signals having different levels may be generated according to the amount of sensed light. That is, the electrical signals generated from the plurality of sensor pixels may each include contrast information (or image information), it may be determined whether a region corresponding to each of the sensor pixels is a ridge or a valley through a processing operation on the electrical signal, and the entire fingerprint image may be configured by combining the determined information.
Regions of the fingerprint which are optically sampled in the fingerprint sensing system 10 may be defined. For example, a plurality of fingerprint pixels WFP may be defined to correspond to the plurality of sensor pixels of the image sensor 12_2, and each of the fingerprint pixels WFP may correspond to an object region shown by one pinhole and one sensor pixel. A shape and size of the fingerprint pixel WFP corresponding to each pinhole may be determined according to variable factors such as a distance between the display panel 11 and the pinhole mask 12_1, a distance between the pinhole mask 12_1 and the image sensor 12_2, a thickness of the pinhole mask 12_1, a diameter of the pinhole, a shape of the pinhole, and the like.
Each of the fingerprint pixels WFP may correspond to one pinhole in the pinhole mask 12_1. A region which reflects light that may pass through one pinhole may be included in each of the fingerprint pixels WFP, and the corresponding region may be defined as an optical sampling region. According to the optical sampling region, an optical sensing region corresponding to the optical sampling region may also be defined in the image sensor 12_2. For example, the optical sensing region may include the sensor pixel.
Meanwhile, although the fingerprint pixels WFP are illustrated as being located in the entire region of the display panel 11 in
Also, each of the plurality of pinholes in the pinhole mask 12_1 may correspond to each of the plurality of sensor pixels in the image sensor 12_2. For example, one sensor pixel corresponding to one pinhole may include one PD. Alternatively, one sensor pixel corresponding to one pinhole may include two or more PDs. In
According to one example embodiment, a region in the image sensor 12_2 may be defined to correspond to each of the fingerprint pixels WFP, and the region corresponding to each of the fingerprint pixels WFP may include a plurality of PDs. Also, the sensor pixel may correspond to a region including at least some of the plurality of PDs corresponding to the fingerprint pixels WFP. That is, one sensor pixel senses light corresponding to the fingerprint pixel WFP corresponding thereto, and light corresponding to another fingerprint pixel WFP is prevented from overlapping. In
Meanwhile, the fingerprint sensing system 10 is described as sensing the fingerprint of the user. However, example embodiments of inventive concepts are not limited thereto. For example, when a predetermined and/or desired object is located on the display panel 11, the fingerprint sensor 12 may sense light reflected by the predetermined and/or desired object to generate a sensing result thereof. When each fingerprint pixel of the fingerprint sensor 12 generates image data as a sensing result, an image of the object located on the display panel 11 may be reconfigured using the image data generated from each fingerprint pixel of the fingerprint sensor 12.
An example in which one sensor pixel includes 3*3 of PDs is illustrated in
According to an example embodiment of inventive concepts, a center of the sensor pixel or a center of the optical sensing region may be aligned with a center of the pinhole. Also, the optical sensing region to which the reflected light in the optical sampling region of the fingerprint pixel is transmitted may be located over the plurality of PDs. For example, a diameter of the optical sensing region may have a value corresponding to the diameter Fd. The diameter Fd of the optical sensing region may be adjusted through various parameters such as a distance between the display panel and the pinhole mask, a distance between the pinhole mask and the image sensor, a shape of the pinhole, and the like. As described above, the diameter Fd of the optical sensing region is determined so that light from two or more fingerprint pixels does not overlap each sensor pixel.
The number of PDs in one sensor pixel in which light is actually sensed may be determined according to the diameter Fd of the optical sensing region. An electrical signal corresponding to one fingerprint pixel may be generated according to sensing results from the plurality of PDs. According to one example embodiment, the electrical signal may be generated through a process of merging data values of the plurality of PDs included in one sensor pixel.
Referring to
When it is assumed that a size of the PD is fixed, the number of PDs included in one sensor pixel may vary according to the arrangement of the fingerprint pixel, pinhole, and sensor pixel. For example, when the pinhole is located relatively close to the sensor pixel, the size of the sensor pixel corresponding to one fingerprint pixel may be reduced, and in some cases, one PD may be disposed in one sensor pixel. On the other hand, as illustrated in
In some of the following example embodiments, a predetermined and/or desired interval between fingerprint pixels is illustrated for convenience of description of the light propagation path, but example embodiments of inventive concepts are not limited thereto. For example, boundaries of the fingerprint pixels may be defined to come in contact with each other so that the entire image of the fingerprint may be configured as illustrated in
Referring to
Meanwhile, the pinhole mask 12_1 may be located between the display panel 11 and the image sensor 12_2. The pinhole mask 12_1 may be referred to as a pinhole mask layer since the pinhole mask 12_1 is implemented as a separate layer. In the example of
According to one example embodiment, the pinhole mask 12_1 may be stacked on the image sensor 12_2 in a process of implementing the image sensor 12_2. In this case, an intermediate layer such as a transparent passivation layer through which light may be transmitted and an oxide layer may be interposed between the pinhole mask 12_1 and the image sensor 12_2. That is, when the pinhole mask 12_1 is implemented to be embedded in the image sensor 12_2, the image sensor 12_2 may be described as including the pinhole mask 12_1. Also, a distance between the pinhole and the sensor pixel may be defined based on a thickness of the intermediate layer in the embedded structure described above, and a size of the sensor pixel corresponding to one fingerprint pixel may be defined based on the distance.
The display panel 11 may correspond to one of various types of display panels which may generate light toward the fingerprint and transmit the light reflected by the fingerprint in a direction towards the backplane of the display panel 11 (or in a direction towards the fingerprint sensor). According to one example embodiment, the display panel 11 may be an OLED panel, and include a plurality of OLEDs 405 as light sources. For example, the plurality of OLEDs 405 may be light emitting elements that emit light in various colors by themselves, and the plurality of OLEDs that emit red color (R), green color (G), and blue color (B) may be included in the display panel 11. At least one of the plurality of OLEDs 405 included in the display panel 11 may be used as light sources for sensing the fingerprint.
Although not illustrated in
According to one example embodiment, the plurality of pinholes formed in the pinhole mask 12_1 are aligned with the plurality of sensor pixels of the image sensor 12_2. Also, a diameter W1 of the optical sampling region including a size of the fingerprint pixel and a diameter W2 of the optical sensing region including a size of the sensor pixel may be determined by a distance between the pinhole mask 12_1 and the fingerprint, that is, a pinhole-to-fingerprint distance D1, a distance between the pinhole mask 12_1 and the image sensor 12_2, that is, a pinhole-to-sensor distance D2, a diameter of the pinhole, and a thickness of the pinhole mask. Also, a pitch Wpitch between the fingerprint pixels may also be considered when the diameter W1 of the optical sampling region is determined. According to an example embodiment of inventive concepts, the pinhole mask 12_1 including the plurality of pinholes may be disposed on the image sensor 12_2 in order to form a focus instead of applying a lens as a focus forming unit in the image sensor 12_2.
Specifically, when the fingerprint of the user is located on the display panel 11, light emitted from the OLEDs 405 in the display panel 11 is emitted in a direction towards the cover glass of the display panel 11, the emitted light is reflected by ridges and valleys of the fingerprint located on the cover glass and transmitted toward the backplane of the display panel 11, and the image sensor 12_2 senses the light transmitted through the backplane of the display panel 11 and the pinholes. Accordingly, an image of the fingerprint may be captured by the image sensor 12_2. According to example embodiments of inventive concepts, the fingerprint sensor 12 may be implemented as an ultra-thin optical sensor, and thus the image of the fingerprint may be captured by the fingerprint sensor 12 without a focusing lens.
Meanwhile, in aligning the fingerprint pixels, pinholes, and sensor pixels, a diameter d and thickness T of the pinhole correspond to parameters which determine an angle of view θ with respect to an upper surface and a lower surface based on the pinhole. Also, in addition to the determined angle of view θ, the above-described distance D1 between the pinhole mask 12_1 and the fingerprint, and the above-described distance D2 between the pinhole mask 12_1 and the image sensor 12_2 may correspond to parameters which determine the diameter W1 of the optical sampling region including the size of the fingerprint pixel and the diameter W2 of the optical sensing region including the size of the sensor pixel. Also, the angle of view θ, the diameter W1 of the optical sampling region corresponding to the size of the fingerprint pixel, and the diameter W2 of the optical sensing region corresponding to the size of the sensor pixel may be calculated using formulas illustrated in
The fingerprint sensor and the fingerprint sensing system illustrated in the above-described example embodiments may be applied to various fields. As an application of inventive concepts, the fingerprint sensor and the fingerprint sensing system may be applied to a system including a display panel, and, for example, may be applied to a system in which light emitted from a light source included in a display panel has a transmittance in a backplane direction of the display panel. Also, as an example of the application, at least some example embodiments of inventive concepts may be applied to a smart phone (including a tablet computer) or a wearable device (e.g., a smart watch). Alternatively, the fingerprint sensor and the fingerprint sensor package according to example embodiments of inventive concepts may be applied to an Internet of things (IoT) type ultra-thin camera.
Referring to
Meanwhile, the fingerprint sensor may be implemented using a semiconductor wafer. As illustrated in
As an example implementation, the metal wirings 121a and 121b are respectively formed in various forms in the first and second layers 120a and 120b to prevent light from passing through a region except for the pinholes 122. For example, the metal wirings 121a formed in the first layer 120a may be disposed in parallel in a first direction, and the metal wirings 121b formed in the second layer 120b may be disposed in parallel in a second direction perpendicular to the first direction. According to the example embodiment illustrated in
For example, the metal wirings 121a and 121b may be additionally formed regardless of wirings for transmitting electrical signals for an actual operation of an image sensor. Also, the first and second layers 120a and 120b may be additionally provided in addition to a layer in which wirings for an actual operation of the image sensor are formed. Also, the device layer 130 in which PDs are formed may be disposed under the pinholes 122. In this case, since the pinholes 122 are implemented in a semiconductor process for implementing a fingerprint sensor, the pinholes 122 may be defined as being embedded in the fingerprint sensor.
Meanwhile, referring to
For example, the pinhole mask layer 220 may be implemented as a silicon wafer, a metal layer, or any material layer through which light does not pass, and may include a plurality of pinholes 221. Also, the device layer 230 may be an image sensor layer in which PDs are formed and may correspond to a component, which senses light passing through the plurality of pinholes 221 and generates an electrical signal. As described above, the pinhole mask layer 220 and the device layer 230 may be configured as different layers. According to one example embodiment, the pinhole mask layer 220 may be stacked on the device layer 230 in a semiconductor process for implementing the device layer 230. In one example embodiment, the pinhole mask layer 220 may be located to be aligned with the device layer 230.
Referring to
Referring to
According to the above structure, an air gap having a length corresponding to a height of the support 330 may be formed in the fingerprint sensor package 300. A distance between the image sensor 320 and the pinhole mask 340 may be adjusted according to the height of the air gap, and thus the height of the support 330 may correspond to a parameter which determines a diameter of the optical sensing region corresponding to a size of the sensor pixel.
The image sensor 320 may include a light-receiving region 321 which senses light transmitted through a plurality of pinholes of the pinhole mask 340, and a logic region 322 which generates image data through logic processing on an electrical signal from the light-receiving region 321. The light-receiving region 321 and the logic region 322 may be formed in different wafers (or separate semiconductor substrates). In this case, the light-receiving region 321 and the logic region 322 may be classified as separate chips. Alternatively, in another embodiment, the light-receiving region 321 and the logic region 322 may be implemented in one semiconductor chip.
The light-receiving region 321 may include the plurality of sensor pixels described in the above embodiments, and each of the sensor pixels may include one or more PDs. Since light is reflected by ridges or valleys of the fingerprint, a difference in an amount of light which is sensed in the sensor pixels may be generated, and the light-receiving region 321 provides electrical signals which are differently generated for each sensor pixel to the logic region 322. Logic circuits included in the logic region 322 may generate contrast or partial image data in units of a fingerprint pixel used to configure the entire fingerprint image by performing a processing operation such as an analog-digital conversion on the electrical signals, and an fingerprint image may be configured by using the contrast or partial image data. Also, the fingerprint image generated in this way may be provided to an external device or system through the package substrate 310.
Meanwhile, in the embodiment illustrated in
Referring to
The fingerprint sensor package 410A may include a package substrate 411, an image sensor 412 mounted on the package substrate 411, a support 413 formed on the image sensor 412, and a pinhole mask 414 including a plurality of pinholes. In the same or similar way as described above, an air gap may be formed between the image sensor 412 and the pinhole mask 414. The board 430 may correspond to a mother board such as a printed circuit board (PCB) of a smart phone and the like. As the fingerprint sensor package 410A is connected to the board 430, the fingerprint sensor package 410A may be mounted in the form of a chip on board (CoB). Also, image data may be provided to the board 430 through connection terminals formed on one surface of the fingerprint sensor package 410A, According to one example embodiment, the image data may be provided to the board 430 through a plurality of solder balls formed on one surface of the fingerprint sensor package 410A.
The fingerprint sensor package 410A may further include a molding 416A, and may be attached to the display panel 420 through an adhesive element 415A. An element capable of maintaining an adhesive force even in a change of temperature, humidity, or the like may be applied to the adhesive element 415A as an adhesive film or a liquid-type (or a resin) adhesive. For example, the adhesive element 415A may be implemented as an optical clear adhesive (OCA).
For example, the adhesive element 415A may be disposed on an upper surface of the fingerprint sensor package 410A. Alternatively, the adhesive element 415A may be disposed on one surface of the fingerprint sensor package 410A in a packaging process for the fingerprint sensor. In this case, the fingerprint sensor package 410A may be defined to further include the adhesive element 415A layer. The adhesive element 415A may serve as a buffer support when the fingerprint sensor package 410A is attached to the display panel 420, and a thickness of the adhesive element 415A may affect a distance between the fingerprint pixel and the pinhole. As the thickness of the adhesive element 415A is increased, an area of the fingerprint pixel seen by the pinhole may be increased, and the thickness of the adhesive element 415A may be adjusted as long as different fingerprint pixels do not overlap each other.
Meanwhile, referring to
A fingerprint sensing system 400B includes a fingerprint sensor package 410B, and the fingerprint sensing system 400B may further include a display panel 420 to which the fingerprint sensor package 410B is attached and a board 430 for mounting the fingerprint sensor package 410B. Also, the fingerprint sensor package 410B may include a package substrate 411, an image sensor 412, a support 413, and a pinhole mask 414. Also, the fingerprint sensor package 410B may further include an adhesive element 415B and a molding 416B. According to one example embodiment, the adhesive element 415B may be disposed along an outer region of an upper surface of the fingerprint sensor package 410B, that is, an edge region thereof, to bond the fingerprint sensor package 410B to the display panel 420. Also, the pinhole mask 414, the support 413, the adhesive element 415B, and the like, as various components illustrated in
Referring to
A fingerprint sensing system 400C includes a fingerprint sensor package 410C, and the fingerprint sensing system 400C may further include a display panel 420 to which the fingerprint sensor package 410C is attached and a board 430 for mounting the fingerprint sensor package 410C. Also, the fingerprint sensor package 410C may include a package substrate 411, an image sensor 412, a support 413, a pinhole mask 414, and a molding 416C. Also, the pinhole mask 414, the support 413, and the like, as various components illustrated in
In the present embodiment, the adhesive element in the above-described embodiment may be removed from the fingerprint sensing system 400C. In this case, a height of the molding 416C included in the fingerprint sensor package 410C may be greater than those in the embodiments illustrated in
Referring to
The film 530 may be implemented using a flexible element, and wirings for electrical transmitting of signals may be formed on at least one surface of the film 530. Also, wirings passing through the film 530 may be further formed in the film 530 to transmit signals from one surface of the film 530 to the other surface thereof. For example, when the fingerprint sensor package 510 is attached to the display panel 520, a surface of the film 530 facing the display panel 520 may be referred to as a first surface and the opposite surface as a second surface.
For example, the fingerprint sensor package 510 may be implemented in the same or similar manner as the fingerprint sensor package illustrated in the above-described embodiments. Also, although an example, in which the image sensor is mounted on one surface of the package substrate and the solder ball is formed on another surface of the package substrate to provide the image data to the board through the solder ball, is described in the above-described embodiments, an example in which the image data is provided to the film 530 including the wiring for interface instead of the package substrate is illustrated in the embodiment illustrated in
Meanwhile, referring to
Although a size of the adhesive element 514 is illustrated as being the same as a size of an upper surface of the fingerprint sensor package 510 for convenience of illustration in
Meanwhile, signals generated in the fingerprint sensor package 510 may be transmitted to an external device or system through the plurality of wirings in the film 530. For example, the signals (e.g., image data) generated from the fingerprint sensor package 510 may be transmitted to the second surface of the film 530. As an example implementation, a connection terminal ct may be disposed on a logic region of the image sensor 511, and electrically connected to wirings formed in the second surface of the film 530. Connectors 532 for electrically connecting to other devices or systems may be provided in the film 530. For example, the image data generated from the fingerprint sensor package 510 may be transmitted to an external device or system mounted on a main board (not illustrated) through the connectors 532.
According to the above-described embodiment, since a transmission path of the image data generated from the fingerprint sensor package 510 may be flexibly implemented through the film 530, ease of arrangement of the devices in the fingerprint sensing system 500 may be improved. Also, the entire thickness of the fingerprint sensor package 510 mounted in the form of a COF on the film 530 may be reduced.
Referring to
As an example implementation, the device wafer 610A may include a semiconductor substrate (e.g., P-Sub) and one or more layers formed on the semiconductor substrate. For example, one or more epitaxial layers growing as the same crystal structure as the semiconductor substrate may be formed.
One or more photoelectric conversion regions for sensing light reflected by a fingerprint in the image sensor may be formed in the epitaxial layers. For example, the PDs in the above-described embodiment may be formed in the photoelectric conversion regions through an ion implantation process. As a modified embodiment, various types of photoelectric conversion elements such as a phototransistor, a photo gate, a pinned PD, and the like may be formed in the photoelectric conversion regions.
Meanwhile, since the fingerprint sensor is implemented using a FSI method, one or more metal layers may be formed on the epitaxial layer in which the PDs are formed. In
Meanwhile, the sustain wafer 620A may be disposed on the metal layers M1 to M5. The sustain wafer 620A may be used for holding or supporting an epitaxial layer. According to example embodiments of inventive concepts, the pinholes formed in the sustain wafer 620A may form a focus of light reflected and transmitted by a fingerprint. The fingerprint sensor 600A including the device wafer 610A and the sustain wafer 620A may be packaged and attached to one surface of the display panel, and a packaging process of the fingerprint sensor 600A may be performed in the same manner as the packaging processes illustrated in the above-described embodiments. Also, various mounting methods may be applied to the packaged fingerprint sensor 600A. For example, the packaged fingerprint sensor 600A may be mounted on the board in the form of a COB, or the packaged fingerprint sensor 600A may be mounted on the film in the form of a COF. Although the display panel is illustrated as being disposed on the sustain wafer 620A for convenience of illustration in
Also, an example in which at least one layer is further disposed between the metal layers M1 to M5 and the sustain wafer 620A is illustrated in
According to the fingerprint sensor 600A implemented as described above, the sustain wafer 620A corresponding to the pinhole mask may be stacked on the device wafer 610A in a process for implementing the image sensor. Accordingly, in a packaging process for the image sensor, a process of stacking a separate pinhole layer on the image sensor may be omitted. Also, in the packaged fingerprint sensor package, since it is not necessary to provide a separate holder for fixing a pinhole layer, the entire thickness of the fingerprint sensor package may be reduced.
Referring to
As an example implementation, since the image sensor in the fingerprint sensor 600B is implemented using a BSI method, a layer (e.g., an epitaxial layer) in which PDs are formed in the image sensor may be located between the sustain wafer 620B and the metal layers M1 to M5. Accordingly, light, which is reflected by a fingerprint and passes through the pinholes of the sustain wafer 620B, may be provided to the PDs without passing through the metal layers M1 to M5. Also, a separate wafer for a function same as or similar to a supporting or holding function of the above-described sustain wafer may be disposed under the metal layers M1 to M5 in the drawing.
Similar to the above-described embodiment, the plurality of pinholes of the sustain wafer 620B may form a focus of light reflected and transmitted by a fingerprint. In the embodiment illustrated in
Referring to
The image sensor 712 may include a light-receiving region 712_1 and a logic region 712_2. The light-receiving region 712_1 may be implemented according to the above-described embodiment illustrated in
The image sensor included in the fingerprint sensor may include a light-receiving region, which senses light reflected by a fingerprint and generates an electrical signal corresponding thereto, and a logic region which generates image data through logic processing on the electrical signal from the light-receiving region. According to one example embodiment, the light-receiving region and the logic region may be manufactured as separate chips (e.g., chips in a die unit) on different semiconductor substrates, and a sensor chip including the light-receiving region and a logic chip including the logic region may be packaged in one semiconductor package. Alternatively, the light-receiving region and the logic region may be manufactured on one semiconductor substrate and packaged in an image sensor chip. According to the above-described embodiments, a separate pinhole mask (not illustrated) may be stacked on the sensor chip in the packaging process. Alternatively, according to the above-described embodiments, in a semiconductor process for manufacturing a sensor chip, a sustain wafer in which pinholes are formed may be stacked on PDs.
Hereinafter, for convenience of description, in description of features of example embodiments of inventive concepts, an example in which the light-receiving region and the logic region are manufactured on the same substrate may be referred. Accordingly, a chip in which the light-receiving region (or a sensor region) and the logic region are manufactured on the same semiconductor substrate may be referred to as an image sensor chip. However, example embodiments of inventive concepts are not limited to such terms. For example, a chip including both the sensor region and the logic region may be referred to as a sensor chip.
Referring to a fingerprint sensor package 800 of
Meanwhile, an example in which the sensor region 810 is implemented by a FSI method in the above-described example embodiment is illustrated in the example embodiment of
The fingerprint sensor package 800 may be mounted in the form of a CoB according to the above-described embodiment. Connection terminals for transmitting signals between the sensor region 810 and the logic region 850 in the fingerprint sensor package 800 and a board 820 may be formed on one surface of the package substrate, and an example in which a plurality of solder balls 840 are attached to one surface of the package substrate is illustrated in the embodiment of
Meanwhile, since the sensor region 810 is implemented by a FSI method, a pad for electrically connecting to the outside may be present at a top of the sensor region 810, and in the sensor region 810, the metal lines 812_1 located thereon and the package substrate may be electrically connected through the pad. For example, the pad of the sensor region 810 and the package substrate may be electrically connected through one of the bonding wires 830. The electrical signal from the sensor region 810 in the fingerprint sensor package 800 may be provided to the logic region 850, and the image data from the logic region 850 may be provided to an external system through the solder balls 840 and the board 820.
Referring to
According to the above-described embodiments, since the sensor region and the logic region do not have a stacked structure in the fingerprint sensor package, a thickness of the fingerprint sensor package may be reduced. Also, as illustrated in
Referring to
According to one example embodiment, in the fingerprint sensor package 1000, the sensor chip 1010 may be stacked on the logic chip 1020. The sensor chip 1010 may sense light reflected by a fingerprint to generate an electrical signal, and the electrical signal may be provided to the logic chip 1020 through a metal line formed in an upper metal layer of one or more metal layers 1012 in the sensor chip 1010. According to one example embodiment, a back via stack (BVS) 1060 passing through the semiconductor substrate 1011 of the sensor chip 1010 from at least one metal layer of the sensor chip 1010 may be formed in the sensor chip 1010, and the electrical signal from the sensor chip 1010 may be provided to the logic chip 1020 through the BVS 1060.
Meanwhile, the logic chip 1020 may include various circuits for processing the electrical signal to generate image data, and a plurality of metal layers for implementing various logic circuits. The electrical signal transmitted through the BVS 1060 may be provided to at least one metal layer in the logic chip 1020.
The logic chip 1020 may be mounted on the package substrate Package PCB and electrically connected to the package substrate. According to one example embodiment, one or more metal layers may be stacked on the semiconductor substrate of the logic chip 1020, and thus electrically connected to the package substrate through the pad located at a top of the logic chip 1020. For example, the logic chip 1020 may be electrically connected to the package substrate through the pad and a bonding wire 1040.
The fingerprint sensor package 1000 may be mounted on a board 1030 in a CoB form. For example, the logic chip 1020 may be connected to the board 1030 through solder balls 1050. Also, the logic chip 1020 may provide image data to an external system (e.g., a device for reconfiguring fingerprints) through the package substrate, the solder balls 1050, and the board 1030.
According to the embodiment illustrated in
Also, according to the stacked structure of the sensor chip 1010 and the logic chip 1020, since the fingerprint sensor package 1000 recognizes the entire fingerprint of the finger, an area of the sensor chip 1010 which should sense light reflected by the fingerprint may be relatively large, but the area of the fingerprint sensor package 1000 may be prevented from increasing due to logic circuits other than the sensor chip 1010.
Meanwhile, referring to
Meanwhile, the logic chip 1120 may include various circuits for processing an electrical signal from the sensor chip 1110 to generate image data, and a plurality of metal layers for implementing the various circuits may be stacked on the semiconductor substrate. Also, the logic chip 1120 may be mounted on the package substrate, and the fingerprint sensor package 1100 may be connected to a board 1130 through a solder ball 1150. Also, a pad of the logic chip 1120 may be present at a top, and the logic chip 1120 and the package substrate may be electrically connected to each other through a bonding wire 1140.
Meanwhile, when the sensor chip 1110 is implemented by a BSI method, the metal layers 1112 of the sensor chip 1110 are located at a lower portion thereof, whereas the metal layers of the logic chip 1120 are located at an upper portion thereof. In this case, a metal line (e.g., a metal line of a lowermost metal layer) of the sensor chip 1110 and a metal line (e.g., a metal line of an uppermost metal layer) of the logic chip 1120 may be electrically connected through a through silicon via (TSV) 1160. For example, a separate layer 1170 such as an interposer and the like may be disposed between the sensor chip 1110 and the logic chip 1120, and an electrical signal generated in the sensor chip 1110 may be provided to at least one metal layer in the logic chip 1120 through the TSV 1160 passing through the separate layer 1170.
According to the embodiment illustrated in
Meanwhile, a case in which a sensor region and a logic region are manufactured on the same semiconductor substrate is illustrated in
Referring to
In such an embodiment, the sensor region 1210 may be attached to a display panel (not illustrated) while being located under the film 1220, and thus light reflected by a fingerprint may be provided to the PDs through the film 1220 and one or more metal layers 1212. According to one example embodiment, as illustrated in
Meanwhile, referring to
Since the sensor region 1310 is implemented by a BSI method, a semiconductor substrate 1311 in which a plurality of PDs are formed may be located on the image sensor chip 1301, and one or more metal layers 1312 in which metal lines are formed may be located under the semiconductor substrate 1311. Also, a pad of the image sensor chip 1301 may be located at a lowermost end, and thus one or more lower metal lines of the sensor region 1310 may be electrically connected to a film 1320 through the pad and a connection terminal (e.g., a bump 1330). According to one example embodiment, the sensor region 1310 may be attached to a display panel (not illustrated) while being located on the film 1320, and thus light reflected by a fingerprint may be directly provided to the PDs without passing through the film 1320 or the metal layers 1312.
According to the embodiment illustrated in
In
Referring to
Meanwhile, in the fingerprint sensor package 1400, the logic chip 1420 may be electrically connected to a film 1430, and thus the logic chip 1420 may generate image data based on an electrical signal from the sensor chip 1410 to transmit the generated image data to the film 1430. For example, the plurality of metal layers of the logic chip 1420 may be stacked on a semiconductor substrate, a pad is located at a top of the logic chip 1420, and thus a metal line formed in at least one metal layer (e.g., a top metal layer) may be connected to the film 1430 through a connection terminal (e.g., a bump 1450). That is, the logic chip 1420 may receive the electrical signal from the sensor chip 1410 through the BVS 1440 and a metal line formed in a top metal layer and provide the electrical signal to lower metal layers, and image data generated by processing the electrical signal may be transmitted to the film 1430 through the metal line formed in the top metal layer and a bump 1450.
According to the embodiment illustrated in
Meanwhile, referring to
Meanwhile, in the above-described embodiment, a metal line formed in at least one metal layer (e.g., a top metal layer) of the logic chip 1520 may be electrically connected to a film 1530 through a bump 1550. Also, a hole having an area so that the sensor chip 1510 may pass therethrough may be formed in the film 1530, and the fingerprint sensor package 1500 may have a structure in which the sensor chip 1510 is inserted into the hole of the film 1530.
Meanwhile, in the above-described embodiments, although an example in which the hole is formed in the film when the fingerprint sensor package having a stacked structure is connected to the film is described, inventive concepts are not limited thereto. For example, as illustrated in
The fingerprint sensor 1600 may include a semiconductor substrate 1610 in which a PD is formed and one or more metal layers 1620 stacked on the semiconductor substrate 1610. Also, a dielectric formed in the form of an ILD or an IMD may be disposed between the metal layers 1620, and each of the metal layers may include metal lines and contacts. Also, the dielectric may be implemented with a transparent or translucent material through which light may pass.
According to one example embodiment, a function of a pinhole may be implemented through the arrangement of the metal lines in the metal layers 1620 without a pinhole layer separately formed in the fingerprint sensor 1600. For example, when the sensor chip of the fingerprint sensor 1600 is implemented by a FSI method, light reflected by a fingerprint may be transmitted to the PD through the metal layers 1620. In this case, since the metal lines formed in the metal layers are implemented with a material through which light does not pass, the light may be transmitted through a space between the metal lines. According to the above-described embodiment, a diameter and height of the pinhole may serve as parameters which determine sizes of the fingerprint pixel and sensor pixel, and the metal lines may be formed so that a function (e.g., a function of transmitting the brightness of the reflected light to the PD) similar to the pinhole in the above-described embodiments is performed by the space between the metal lines.
Referring to
According to one example embodiment, in a molding 1730 of the fingerprint sensor package 1700, one or more holes 1731 may be formed in a region located on the image sensor 1720. For example, a thickness of the molding 1730 located on the fingerprint sensor package 1700 may have a value suitable for forming a focus of light according to the above-described embodiments, and a region in which the holes 1731 are formed in the molding 1730 may correspond to a region in which PDs (not illustrated) are formed in the image sensor 1720. According to one example embodiment, the molding 1730 may be implemented using an element having a low transmittance. For example, the molding 1730 may be implemented with an epoxy resin such as an epoxy molding compound (EMC).
The fingerprint sensor package 1700 implemented as illustrated in FIG, 26 may be attached to a display panel in various methods. For example, the fingerprint sensor package 1700 may be attached to the display panel through a transparent or translucent adhesive element having a plane form. Alternatively, for example, the fingerprint sensor package 1700 may be attached to the display panel through a transparent, translucent, or opaque adhesive element having a window frame form. Alternatively, for example, a height of an edge region in the molding 1730 of the fingerprint sensor package 1700 may be greater than a height of a region in which the holes 1731 are formed, and thus an edge region of the molding 1730 of the fingerprint sensor package 1700 may be attached to the display panel.
Referring to
According to one example embodiment, the fingerprint sensor package 1800 may further include a light-intensity boosting micro lens array 1850. The micro-lens array 1850 may be located on an upper portion of the fingerprint sensor package 1800, and may include a plurality of micro-lenses corresponding to a plurality of pinholes included in the pinhole mask 1840. For example, the plurality of micro-lenses included in the micro-lens array 1850 may be aligned with the pinholes. Also, a molding located at an edge region in the fingerprint sensor package 1800 may be used as a unit for supporting the micro-lens array 1850. For example, the micro-lens array 1850 may be attached to the molding located at the edge region.
According to the structure illustrated in
Also, since two focuses are formed in the light propagation path to the image sensor 1820, an image reversal which occurs when passing through the focus occurs twice, and thus the image sensed by the image sensor 1820 may correspond to an original fingerprint image. Also, when a distance between the fingerprint pixel and the pinhole mask 1840 is relatively large, a ratio of a diameter of the pinhole to a thickness thereof is relatively small. However, according to an example embodiment, since a concentrating effect is generated by the micro-lens array 1850 and the pinhole mask 1840 passes light from a closely located micro-lens of the micro-lens array 1850, an angle of view of the pinhole may be increased. That is, according to the embodiment, since a process condition for implementing the ratio of the thickness of the pinhole to the diameter thereof may be loosened, a thickness of the pinhole mask 1840 may be reduced. Therefore, a manufacturing process of the pinhole mask 1840 may be made easier.
Meanwhile, when the pinhole mask 1840 is implemented with an opaque element, the pinhole mask 1840 may also function to block other lights (i.e., lights unrelated to fingerprint sensing) transmitted through a region except for the micro-lens array 1850.
Also, according to one example embodiment, the micro-lenses of the micro-lens array 1850 may be located to be aligned with the sensor pixels of the image sensor 1820 together with the pinholes of the pinhole mask 1840. According to one example embodiment, when the micro-lenses of the micro-lens array 1850 are not aligned with the sensor pixels, the image sensor 1820 may perform a compensation operation on offsets between the micro-lenses and the sensor pixels in software. For example, the sensor pixel may include a plurality of PDs (or a plurality of sub-pixels), a center of the pinhole may be determined by sensing light transmitted to the sensor pixel, the offset compensation operation may be performed in software, and thus an electrical signal (or corresponding image data) corresponding to a case in which the sensor pixel is aligned with the center of the pinhole may be generated.
Although an example in which the pinhole mask 1840 is attached to the image sensor 1820 in the packaging process is illustrated as an externally mounted method in the above-described embodiment, the embodiment may be variously modified. For example, in the above-described embodiment using the micro-lens array 1850, the pinhole mask 1840 may be embedded in the image sensor 1820 in a process for implementing the image sensor 1820. According to the above-described embodiment, a sustain wafer having a plurality of holes may perform a function of the pinhole mask 1840 as an embedded method.
Also, the fingerprint sensor packages 1700 and 1800 of
Referring to
Meanwhile,
Referring to
According to one example embodiment, the fingerprint sensor package 1910 may be attached to the display panel 1920 through the hole of the film 1930. Also, although not illustrated in
Referring to
The plurality of OLEDs of the display panel 2010 may be elements which emit light having different colors and the wavelength bands by themselves. For example, the display panel 2010 may include an OLED which emits red (R) color, an OLED which emits blue (B) color, and an OLED which emits green (G) color. When the OLEDs emit light having different colors, wavelengths of light of respective colors may have different values.
According to one example embodiment, OLEDs which emit any one color among the OLEDs which emit a plurality of colors may be selectively used in relation to a fingerprint sensing operation. For example, light from the OLED which emits the red (R) color may be reflected by a fingerprint and provided to the image sensor 2030 through the pinhole mask 2020. In this case, when only the OLED which emits the red (R) color is selectively activated in relation to the fingerprint sensor, a separate color filter needs not to be disposed in the image sensor 2030. Alternatively, only a red color filter corresponding to an OLED in which only the red (R) color is selectively activated to emit light may be implemented in the image sensor 2030 as a mono filter for filtering only one color corresponding to a plurality of PDs. That is, a color filter through which only the same color passes may be used according to the selected color of the light source, or a filter may not be disposed in the image sensor 2030.
When using OLEDs which emit a plurality of colors, a difference in a focus length due to chromatic aberration may occur for each wavelength of light. In this case, since the focuses may not be concentrated into one, the sharpness in a sensing result may be degraded. On the other hand, according to the above-described embodiment, since a fingerprint sensing operation according to example embodiments of inventive concepts is performed selectively using only an OLED, which emits light having the same wavelength, among the plurality of OLEDs, a uniform focus may be formed in a plurality of pinholes in one pinhole mask, and thus the sharpness of the fingerprint sensing result may be improved.
Meanwhile,
Referring to
The pinhole mask 2121 may include a plurality of pinholes and each of the pinholes may form a focus of light reflected and transmitted by a fingerprint. Also, the display panel 2110 may include OLEDs which emit light of a plurality of colors by themselves without backlight, and OLEDs which emit light of at least some of the plurality of colors among the OLEDs may be used for a fingerprint sensing operation.
The image sensor 2122 may include a plurality of sensor pixels corresponding to a plurality of pinholes, and each of the sensor pixels may include one or more PDs. Also, according to one example embodiment, a color filter may be formed to correspond to each of the plurality of sensor pixels, and the same color filter (or a filter through which light having the same wavelength passes) may be formed to correspond to the sensor pixels. In the embodiment of
According to the embodiment illustrated in
Meanwhile, in
Meanwhile, although an example in which a pinhole mask is provided in an externally mounted form is illustrated in the above-described embodiments, a pinhole mask having an embedded structure in the above-described embodiment may be provided. For example, in the embodiments of
Meanwhile, in
Referring to
In order to additionally obtain a resolution of the fingerprint image, a pitch of the fingerprint pixel is reduced. To this end, an angle of view of each pinhole is reduced by reducing a diameter thereof, and a pitch between the pinholes is reduced. However, increasing the resolution by reducing the diameter or pitch of the pinhole may cause limitations in a manufacturing process.
According to the example embodiment of inventive concepts illustrated in
Referring to
The processing system 2220 may include a display driving circuit 2221, a touch screen controller 2222, and a fingerprint sensor 2223. The display driving circuit 2221 may perform various control operations for implementing an image on the display panel 2210. For example, the display driving circuit 2221 may provide gradation data related to image implementation on the display panel 2210. Also, the touch screen controller 2222 may sense a capacitance change of the sensing units of the touch panel TP to generate a touch sensing result. For example, the touch screen controller 2222 may provide a driving signal for driving the touch panel TP, and receive and process an electrical signal corresponding to the capacitance change of the sensing units in the touch panel TP. Also, the fingerprint sensor 2223 may correspond to any of the various embodiments described above, and generate a fingerprint image by using OLEDs as light sources and sensing light reflected by a fingerprint of the user.
Meanwhile, according to one example embodiment, the processing system 2220 may be implemented as one semiconductor chip. For example, functions of the display driving circuit 2221, the touch screen controller 2222, and the fingerprint sensor 2223 may be integrated on one semiconductor substrate. According to one example embodiment, the fingerprint sensor 2223 may be implemented to include at least some of various functions described in the above-described embodiments. For example, as the fingerprint sensor 2223 includes a PD, the fingerprint sensor 2223 may include a light-receiving region, or may further include a logic region for generating the image data described in the above-described embodiment.
According to one example embodiment, the display driving circuit 2221, the touch screen controller 2222, and the fingerprint sensor 2223 may be formed in the same semiconductor chip to transmit and receive various pieces of information or signals. For example, an operation of the fingerprint sensor 2223 may be controlled by the display driving circuit 2221 and/or the touch screen controller 2222. For example, power and control signals required for sensing timing or a sensing operation of the fingerprint sensor 2223 may be generated by the display driving circuit 2221 and/or the touch screen controller 2222.
In the embodiment illustrated in
Meanwhile, although some example embodiments applied to inventive concepts have been described with reference to the separate drawings, the fingerprint sensor, the fingerprint sensor package, or the fingerprint sensing system according to example embodiments of inventive concepts may be configured by combining two or more embodiments.
The technical scope of inventive concepts is for a fingerprint recognition field which is most widely used among biometrics fields in which market demand is increasing, and provides a structure of an on-display fingerprint sensor for a smart phone or a wearable device. For example, currently, in most smart phones, a fingerprint sensor is mounted on a home button which is located at a lower center of the phone, or a back surface of the phone. According to example embodiments of inventive concepts, an optical sensor structure for directly recognizing a fingerprint on a display of the smart phone without the fingerprint sensor mounted on a home button, which is located at a lower center of the phone or a back surface of the phone may be provided.
In the optical fingerprint sensor, the fingerprint sensor package, and the fingerprint sensing system according to the technological scope of inventive concepts, since a thickness of the fingerprint sensor package can be minimized, an ultra-thin fingerprint sensing system can be provided.
Also, in the optical fingerprint sensor, the fingerprint sensor package, and the fingerprint sensing system according to the technological scope of inventive concepts, since light sources for a display operation which is provided in a display panel are used as light sources for optical sensing of a fingerprint, there is no need to add additional light sources, so that a manufacturing cost can be reduced.
While inventive concepts have been particularly shown and described with reference to embodiments thereof, it will be understood that various changes in form and details may be made therein without departing from the spirit and scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2016-0085697 | Jul 2016 | KR | national |
| 10-2016-0100360 | Aug 2016 | KR | national |
| 10-2016-0184352 | Dec 2016 | KR | national |
