Patent Application
20100177393
This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2009-0002730, filed on Jan. 13, 2009 with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference.
1. Field
Example embodiments relate to a reflective structure, a display apparatus including the reflective structure, and a method of manufacturing the reflective structure and display apparatus.
2. Description of the Related Art
Pigments are conventionally used to realize colors via the absorption of light. However, conventional color realization technology using light absorption has efficiency problems as well as problems controlling chromaticity. To address such problems, color realization technology using reflection and interference of light, which is referred to as structural color technology, has been proposed. In structural color technology, because efficiency is determined according to a reflectance of a reflector, it is possible to realize colors more efficiently. Also, because chromaticity is determined according to the wavelength of light that is reflected, it may be easier to control chromaticity. However, in structural color technology, a color may be differently realized depending on an angle of light incident on the reflector and a viewing angle, and multi-coloration may occur, because the color may be relatively bright or dim at a specific angle due to constructive and destructive interference of diffracted light.
Example embodiments include an omni-directional reflective structure (which does not result in a color change because of the viewing angle) and a method of manufacturing the omni-directional reflective structure. Example embodiments also include a display apparatus including the reflective structure and a method of manufacturing the display apparatus.
A reflective structure according to example embodiments may include an understructure having a first uneven surface, the understructure being a plurality of nanoparticles of non-uniform size on a substrate or being a sublayer having a non-uniform surface that resembles a plurality of nanoparticles or that is equivalent to surfaces of the plurality of nanoparticles; and a reflective layer on the understructure, the reflective layer having a second uneven surface.
The reflective layer may have a structure in which a first layer and a second layer are alternately stacked. The first layer and the second layer may be different dielectric layers. One of the first layer and the second layer may be a dielectric layer, and the other one of the first layer and the second layer may be a non-dielectric layer. The non-dielectric layer may be a metal layer. The metal layer may include a transition metal.
A reflective structure according to example embodiments may also include an understructure having a first uneven surface; and a reflective layer on the first uneven surface of the understructure, the reflective layer having a second uneven surface, and wherein the reflective layer includes at least one non-dielectric layer and at least one dielectric layer, the non-dielectric layer and the dielectric layer being alternately stacked.
A reflective structure according to example embodiments may also include a substrate having an uneven part which is arranged on a top surface of the substrate; and a reflective layer covering the uneven part, and having a random height and a structure in which a non-dielectric layer and a dielectric layer are alternately stacked. The non-dielectric layer may be a metal layer. The metal layer may include a transition metal.
A method of manufacturing a reflective structure according to example embodiments may include coating a substrate with a plurality of nanoparticles of non-uniform size; and forming a reflective layer on the plurality of nanoparticles, the reflective layer having an uneven surface that corresponds to a contour of the plurality of nanoparticles. The reflective layer may have a structure in which a first layer and a second layer are alternately stacked. The first layer and the second layer may be different dielectric layers. One of the first layer and the second layer may be a dielectric layer, and the other one of the first layer and the second layer may be a non-dielectric layer. The non-dielectric layer may be a metal layer. The metal layer may include a transition metal.
A method of manufacturing a reflective structure according to example embodiments may also include coating a supporting material with a plurality of nanoparticles of non-uniform size; forming a mold layer covering the plurality of nanoparticles; separating the mold layer from the supporting material to attain a master stamp having an under surface that corresponds to a contour of the plurality of nanoparticles; forming a first uneven surface on a substrate by imprinting the substrate with the master stamp; and forming a reflective layer covering the first uneven surface, the reflective layer having a second uneven surface that corresponds to a contour of the first uneven surface.
The reflective layer may have a structure in which a first layer and a second layer are alternately stacked. The first layer and the second layer may be different dielectric layers. One of the first layer and the second layer may be a dielectric layer, and the other one of the first layer and the second layer may be a non-dielectric layer. The non-dielectric layer may be a metal layer. The metal layer may include a transition metal.
A method of manufacturing a reflective structure according to example embodiments may also include coating a substrate with a plurality of first nanoparticles; etching the plurality of first nanoparticles and exposed portions of the substrate between the plurality of first nanoparticles to form an etched substrate having a first uneven surface; and forming a reflective layer on the etched substrate, the reflective layer having a second uneven surface that corresponds to a contour of the first uneven surface. The plurality of first nanoparticles may be of non-uniform size. Alternatively, the plurality of first nanoparticles may be of uniform size.
Forming the etched substrate having the first uneven surface may include initially etching the plurality of first nanoparticles to expose portions of the substrate between the plurality of first nanoparticles; and etching the exposed portions of the substrate. Alternatively, forming the etched substrate having the first uneven surface may include simultaneously etching the plurality of first nanoparticles and the exposed portions of the substrate between the plurality of first nanoparticles.
After forming the etched substrate having the first uneven surface, the method may further include removing the plurality of first nanoparticles. After the removing the plurality of first nanoparticles, the method may further include coating the substrate with a plurality of second nanoparticles; and etching the plurality of second nanoparticles and exposed portions of the substrate between the plurality of second nanoparticles.
The reflective layer may have a structure in which a first layer and a second layer are alternately stacked. The first layer and the second layer may be different dielectric layers. One of the first layer and the second layer may be a dielectric layer, and the other one of the first layer and the second layer may be a non-dielectric layer. The non-dielectric layer may be a metal layer. The metal layer may include a transition metal.
A display apparatus may include a reflective structure according to example embodiments. The display apparatus may be a liquid crystal display (LCD). The reflective layer of the reflective structure may have a structure in which a first layer and a second layer are alternately stacked. The first layer and the second layer may be different dielectric layers. One of the first layer and the second layer may be a dielectric layer, and the other one of the first layer and the second layer may be a non-dielectric layer. The non-dielectric layer may be a metal layer. The metal layer may include a transition metal.
The above and/or other aspects of example embodiments may become more readily appreciated when the following detailed description is read in conjunction with the accompanying drawings of which:
It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or,” includes any and all combinations of one or more of the associated listed items.
It will be understood that when an element or layer is referred to as being “formed on,” another element or layer, it can be directly or indirectly formed on the other element or layer. That is, for example, intervening elements or layers may be present. In contrast, when an element or layer is referred to as being “directly formed on” another element, there are no intervening elements or layers present. Other words used to describe the relationship between elements or layers should be interpreted in a like fashion (e.g., “between,” versus “directly between,” “adjacent,” versus “directly adjacent,” etc.).
Spatially relative terms, e.g., “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the term “below” may encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a,” “an,” and “the,” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
Example embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of example embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, example embodiments should not be construed as limited to the shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an implanted region illustrated as a rectangle will, typically, have rounded or curved features and/or a gradient of implant concentration at its edges rather than a binary change from implanted to non-implanted region. Likewise, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation takes place. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of example embodiments.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. It will be further understood that terms, including those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Hereinafter, a reflective structure, a display apparatus including the reflective structure, and a method of manufacturing the reflective structure and the display apparatus according to example embodiments will be described with reference to the accompanying drawings. In this regard, example embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. In the drawings, the thicknesses and/or positions of various layers and/or regions may have been exaggerated for clarity. Like reference numerals in the drawings denote like elements.
The first layer 10 and the second layer 20 may have different refractive indexes. Because the refractive indexes of the first and second layers 10 and 20 are different from each other, reflection of light may occur at an interface between the first layer 10 and the second layer 20. By adjusting materials and thicknesses of the first and second layers 10 and 20, a wavelength of the reflected light may vary. Thus, according to the materials and the thicknesses of the first and second layers 10 and 20, colors exhibited at the reflective layer 300 may vary.
One of the first and second layers 10 and 20 may be a non-dielectric layer, and the other one of the first and second layers 10 and 20 may be a dielectric layer. The non-dielectric layer may be a metal layer. For example, the first layer 10 may be the metal layer and the second layer 20 may be the dielectric layer. Thus, the reflective layer 300 may have a structure in which the metal layer and the dielectric layer are alternately stacked. In the case where the first layer 10 is the metal layer, the first layer 10 may be formed of a transition metal (e.g., Cr, Ni, Co, etc.). However, the first layer 10 may be formed of another metal along with the transition metal. When the first layer 10 is the metal layer, the first layer 10 may be formed to be relatively thin so that absorbance of light via the first layer 10 may be minimized. For example, the first layer 10 may be formed to have a thickness less than about 50 nm at the thicker portions, or less than about 20 nm at the thinner portions. In the case where the second layer 20 is the dielectric layer, the second layer 20 may be formed of SiO2, CaF2, LiF, MgF2 or the like but a material forming the second layer 20 may vary. The second layer 20 may have an optical thickness corresponding to λ/2 (here, λ indicates a center wavelength of light to be reflected). When the second layer 20 has the optical thickness corresponding to λ/2, constructive interference of diffracted light may occur.
Alternatively, the first and second layers 10 and 20 may be formed as different dielectric layers. That is, the reflective layer 300 may have a structure in which a first dielectric layer and a second dielectric layer are alternately and repeatedly stacked. In this structure, reflection of light having a specific wavelength may also occur at an interface between the first layer 10 and the second layer 20.
In
In addition, in the case where the reflective layer 300 is formed to have a non-dielectric layer (e.g., a metal layer)-dielectric layer structure, the number of stacked layers for forming the reflective layer 300 may be reduced, compared to using a dielectric layer-dielectric layer structure. This is because a refractive index difference between the non-dielectric layer (e.g., metal layer) and the dielectric layer may be greater than a refractive index difference between the dielectric layer and the dielectric layer. For example, in the case where the reflective layer 300 is formed using the dielectric layer-dielectric layer structure, about 20 layers (10 pairs) may be need to be stacked to realize a color.
On the other hand, in the case where the non-dielectric layer (e.g., metal layer)-dielectric layer structure is used, about 6 layers (3 pairs) or more may be sufficient to realize the color. Accordingly, when the non-dielectric layer (e.g., metal layer)-dielectric layer structure is used, the manufacturing process may be simplified and the size of the reflective structure may be reduced. Also, in the case of the non-dielectric layer (e.g., metal layer)-dielectric layer structure, because a bandwidth of a reflection spectrum is smaller than that in the dielectric layer-dielectric layer structure, higher chromaticity may be realized with greater ease.
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The reflective structure according to example embodiments may have a plurality of reflective layers for exhibiting different colors on a substrate. For example, first through third reflective layers may be formed in different regions of the substrate, and by varying thicknesses and/or materials of layers for forming the first through third reflective layers, the first through third reflective layers may be formed to reflect different colors (e.g., red, green, and blue).
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According to example embodiments, the reflective layer 300 having the random heights may be formed with relative ease using the plurality of nanoparticles 200. In contrast, to conventionally form an uneven surface on a substrate with an etching method that uses an e-beam, an e-beam lithography process has to be performed several times. Thus, this conventional procedure may increase the complexity and costs of the manufacturing process. On the other hand, the method according to example embodiments uses the plurality of nanoparticles 200 so that the reflective layer 300 having the random heights may be formed at a relatively low cost and in a relatively simple manner. Also, the method according example embodiments may be advantageous with respect to increasing the area of the reflective layer 300.
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On the other hand, the plurality of nanoparticles 200 may be first etched to some extent by performing isotropic etching and then anisotropic etching may be performed on the underlayer 110 by using the etched nanoparticles 200′ as etching barriers. The isotropic etching with respect to the plurality of nanoparticles 200 may be performed using an O2 gas, and the anisotropic etching with respect to the underlayer 110 may be performed using a gas including O2 and CF4. When the underlayer 110 is etched, the plurality of nanoparticles 200 may also be etched. Etching with respect to the plurality of nanoparticles 200 and the underlayer 110 may be performed several times. The etched underlayer 110′ may have concaves and convexes, which are not uniform. Because the plurality of nanoparticles 200 have non-uniform sizes, the concaves and convexes having non-uniform sizes and shapes may be formed with relative ease in the underlayer 110.
Although not illustrated in the drawings, a reflective layer (e.g., reflective layer 300 of
In addition, after removing the plurality of etched nanoparticles 200′ of
Referring to
On the other hand, the plurality of first nanoparticles 200a may be first etched to some extent by performing isotropic etching and then anisotropic etching may be performed on the underlayer 110 by using the plurality of etched first nanoparticles 200a′ as etching barriers. The isotropic etching with respect to the plurality of first nanoparticles 200a may be performed using an O2 gas, and the anisotropic etching with respect to the underlayer 110 may be performed using a gas including O2 and CF4. Because the plurality of first nanoparticles 200a have a uniform size, concaves and convexes having relatively uniform sizes may be formed in the etched underlayer 110′.
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Although not illustrated in the drawings, a reflective layer (e.g., reflective layer 300 of
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The reflective structure and the method of manufacturing the reflective structure according to example embodiments may be applied to various display apparatuses. For example, the reflective structure may be applied to a dynamic device (e.g., liquid crystal display (LCD)) or to a static information providing medium (e.g., signboard). Also, the reflective structure may be applied to pigments (e.g., paint) or to cosmetics.
The reflective structure according to example embodiments may be substituted for a color filter of an LCD. A conventional absorption-type color filter has a relatively low transmittance and chromaticity, but a relatively high transmittance and chromaticity may be possible via the reflective structure according to example embodiments. In the case where the reflective structure according to example embodiments is applied to pigments or cosmetics, the reflective structure may be cut into relatively small sizes and mixed with the pigments or cosmetics. As a result, colors, which are difficult to realize using general pigments, may be attained.
An absorption layer A1 may be further arranged under the color reflector R1. The absorption layer A1 may function to absorb light which is not reflected by the color reflector R1, that is, the light passing through the color reflector R1. For example, in the red reflecting region of the color reflector R1, light that exhibits a color other than a red color may pass through the color reflector R1 and then may be absorbed by the absorption layer A1. This absorption layer A1 is optional. Also, a substrate or nanoparticles of the color reflector R1 may be used as an absorbing component. According to other embodiments, the nanoparticles of the color reflector R1 may be coated with a predetermined color.
In addition, properties of the layers forming the reflective layer of the reflective structure according to example embodiments may change in response to a physical force. To be more specific, refractive indexes or thicknesses of the layers (dielectric layers or non-dielectric layers) forming the reflective layer may change in response to electric force or heat. In this case, by applying a suitable physical force (e.g., electric force or heat) to the reflective layer, it is possible to control or change the colors realized in the reflective layer. Therefore, a reflective structure according to example embodiments may be color controllable and/or color changeable. By using the reflective structure, it is possible to attain a reflective display apparatus that does not require a liquid crystal layer for controlling colors.
While example embodiments have been disclosed herein, it should be understood that other variations may be possible. Such variations are not to be regarded as a departure from the spirit and scope of example embodiments of the present application, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2009-0002730 | Jan 2009 | KR | national |
