JP2015146003A - Reflecting plate for display device, and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the collection of a larger quantity of light to an observer.SOLUTION: A reflecting plate 11 for a display device includes a line and space pattern that is provided on a substrate 10 and comprises a plurality of foundation members having a substantially trapezoidal cross-sectional shape, and a reflecting film 24 that is provided on the plurality of foundation members. The plurality of foundation members each have a first slope and a second slope steeper than the first slope and comprise a lower layer film 20 and an upper layer film 21 laminated on the lower layer film 20, and the upper layer film 21 is thinner than the lower layer film 20.

Description

  The present invention relates to a reflector for a display device and a method for manufacturing the same.

  Display devices installed in mobile information devices are required to have low power consumption performance in order to extend battery life. In particular, a device such as an electronic book reader that allows monochrome still image display uses electronic paper and a fully reflective display device such as a polymer-dispersed liquid crystal display device. This is because the power consumption of the constantly lit backlight accounts for the largest proportion of the power consumption of the display device.

  Among perfect reflection type display devices, PNLC (Polymer Network Liquid Crystal) or PDLC (Polymer Dispersion Type Liquid Crystal) with the scattering state displayed in white and the transmission state displayed in black is a reflector for effectively using incident light. Is provided. This is because, in order to realize white display with sufficient brightness without an auxiliary light source, a synergistic effect between the light reflected by the reflector and the liquid crystal in the scattering state is necessary. The reflector can be installed either inside the device (inside the liquid crystal cell) or outside the device (outside the liquid crystal cell), but if installed outside the device, double images will be generated, so installation inside the device is common. It is.

  A reflection plate in a liquid crystal cell (hereinafter simply referred to as a reflection plate) has been developed for a reflective or transflective liquid crystal display device. Usually, the reflecting plate is formed of a metal film (a material having high reflectivity such as aluminum (Al) or silver (Ag)) is preferable. The reflector is installed on the cell inner surface of the substrate on the back side beyond the liquid crystal layer as viewed from the user (observer). Various positional relationships with the TFT (Thin Film Transistor) structure as a color filter or a switching element can be considered, but in the following description, for the sake of simplicity, it is assumed that the reflector 11 is formed on the substrate (for example, a glass substrate) 10. This part is also used for illustrations.

The reflection plate is required to have the following characteristics (1) to (3) in addition to the reflection performance of the material.
(1) There are few flat parts When the surface shape of the reflecting plate 11 is flat, when the liquid crystal layer is in a transmissive state, the user (observer) 12 who is viewing the display device from the front is reflected (correct) Reflection) and display quality deteriorates (FIG. 1). In order to avoid this, as shown in FIG. 2 and FIG. 3, the surface of the reflector 11 is made uneven to reduce the flat portion and scatter the reflected light. FIG. 2 is a schematic view of the reflecting plate 11 with irregularities having no anisotropy. FIG. 3 is a schematic view of the reflecting plate 11 with unevenness having anisotropy. As the flat portion of the reflector 11 is smaller, the regular reflection component (reflection) is reduced.

(2) Having a scattering profile that can effectively use illumination light including sunlight When the reflective display device is used, the observer 12 is positioned substantially in front of the display device. As shown in FIG. 4, the illumination light (incident light) reaches the display device from a direction that is not shielded by the body of the observer 12. For this reason, it is better to consider the incident light direction as a range of slightly over 90 degrees from the front of the observer 12 around the 12 o'clock direction. A scattering profile having anisotropy to be collected is required.

  5 and 6 are diagrams for explaining the state of incident light from the front of the viewer 12. As shown in FIG. 5, when the scattering profile of the reflecting plate 11 has no anisotropy, the reflected scattered light distribution is centered on the regular reflection direction, so that the scattered light does not reach the observer 12 direction sufficiently. On the other hand, as shown in FIG. 6, the scattered light can be guided toward the viewer if the reflecting plate 11 has an anisotropy. 5 and 6 show only the incident light from the front of the observer 12, but in reality, as shown in FIG. 4, since the incident direction has a large spread, the incident light from any of the illustrated directions is not affected. However, a scattering profile that effectively scatters in the direction of the viewer is desirable.

(3) Less roughness and moire due to the scattering pattern As described above, in order to reduce the flat part of the reflecting plate or to form an anisotropic scattering profile, the surface shape of the reflecting plate must be changed. It is necessary to apply some kind of scattering pattern processing. If the size of the pattern is not sufficiently small compared to the pixels of the display device, the display has a rough feeling, and moire occurs due to the periodicity of the pattern. Since these are factors that degrade the display quality, miniaturization of scattering patterns (reduction of roughness) and diversification of periodicity (reduction of moire) are important items.

  In order to satisfy the above requirements, various methods for forming an anisotropic reflector have been proposed. For example, in Patent Document 1, an island-shaped resin film is placed under the reflector. After processing the resin film into an island shape, the substrate is erected and heated, and shape anisotropy is obtained by the effect that the dissolved resin island hangs down in the direction of gravity. An anisotropic reflector is formed by forming a reflective film using this as a base. Moreover, in patent document 2, the resin pattern is formed in two steps, and the inclined pattern with anisotropy is formed by shifting the shape. Further, Patent Document 3 proposes a method of forming an anisotropic inclined surface by performing slit exposure or halftone exposure on a resin film.

  Although the anisotropic reflector can be formed by these methods, the above three characteristic requirements are not completely satisfied and there is room for improvement. One of the reasons is that it is difficult to miniaturize the anisotropic gradient pattern. For example, when an inclined surface is formed on a resin film by slit exposure, it is necessary to dispose light shielding portions (lines) and exposure portions (spaces) having a width equal to or larger than the slit portions on both sides of the slit portions. Even if each is formed with the minimum width, the width of one inclined surface is at least three times the minimum dimension (“minimum dimension” is the lower limit value of the processing dimension mainly defined by the resolution of the exposure apparatus). . If the minimum dimension is 3 μm, a width of 9 μm or more is required only on one inclined surface, and when an island-like scattering pattern as in Patent Document 3 is formed, it is difficult for the pattern pitch to fall below 15 μm.

  When the pattern size of the reflecting plate is large, the flat portion included in the pattern also becomes large, so that regular reflection increases, and the individual pattern is easily visually recognized, so that the feeling of roughness increases. Furthermore, if the pattern size is large, the feeling of roughness tends to be affected, so the degree of design freedom for reducing moire due to the pattern shape and arrangement also decreases. As described above, since the pattern size of the reflector greatly affects the performance of the display device, it is necessary to reduce the pattern size.

JP-A-10-177106 JP-A-11-160507 JP 2005-539271 A JP 2010-199556 A

  The present invention provides a reflector for a display device that can collect more scattered light to an observer and can reduce moire, and a method for manufacturing the same.

  The reflection plate for a display device according to one embodiment of the present invention is provided on a substrate, and is provided on a line and space pattern including a plurality of base members having a substantially trapezoidal cross-sectional shape, and the plurality of base members. Each of the plurality of base members has a first slope and a second slope that is steeper than the first slope, and is composed of a laminated lower layer film and upper layer film, The upper film is thinner than the lower film.

  According to one aspect of the present invention, there is provided a method of manufacturing a reflective plate for a display device, comprising: laminating a lower layer film and an upper layer film having an etching rate larger than that of the lower layer film on the substrate; Forming a plurality of first resists having a line and space pattern; etching the upper layer film using the plurality of first resists as a mask; and shifting the first layer and space pattern by a predetermined distance; Forming a plurality of second resists having a second line and space pattern on the lower layer film and the upper layer film so that one line overlaps the lower layer film and the upper layer film; and Etching the upper layer film and the lower layer film using a resist as a mask, and forming a reflective film on the lower layer film and the upper layer film And wherein the Rukoto.

  According to the present invention, it is possible to provide a reflection plate for a display device that can collect more scattered light to an observer and reduce moiré, and a method for manufacturing the same.

The schematic diagram explaining an example of a reflecting plate. The schematic diagram explaining an example of a reflecting plate. The schematic diagram explaining an example of a reflecting plate. The schematic diagram explaining the range of the incident light to a reflecting plate. The schematic diagram explaining the scattered light of a reflecting plate. The schematic diagram explaining the scattered light of a reflecting plate. Sectional drawing which shows the manufacturing process of the reflecting plate which concerns on 1st Embodiment. Sectional drawing which shows the manufacturing process of the reflecting plate following FIG. Sectional drawing which shows the manufacturing process of the reflecting plate following FIG. Sectional drawing which shows the manufacturing process of the reflecting plate following FIG. Sectional drawing which shows the manufacturing process of the reflecting plate following FIG. The cross-sectional SEM photograph of the real sample in the manufacturing process of FIG. Sectional drawing which shows the manufacturing process of the reflecting plate following FIG. The schematic diagram explaining the horizontal stripe pattern of the reflecting plate which concerns on 1st Embodiment. The schematic diagram explaining the relationship between incident light and scattered light. The schematic diagram explaining the cross-sectional shape of an ideal base member. Sectional drawing of a reflecting plate. Sectional drawing which extracted the base member shown in FIG. Sectional drawing of the reflecting plate containing an upper film. Sectional drawing which extracted the base member shown in FIG. The schematic diagram explaining the plane pattern of the reflecting plate which concerns on 2nd Embodiment. The schematic diagram explaining the plane pattern of the reflecting plate which concerns on 3rd Embodiment. The schematic diagram explaining the plane pattern of the reflecting plate which concerns on 4th Embodiment. The schematic diagram explaining the plane pattern of the reflecting plate which concerns on 5th Embodiment. The schematic diagram explaining the plane pattern of the reflecting plate which concerns on 6th Embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. However, it should be noted that the drawings are schematic or conceptual, and the dimensions and ratios of the drawings are not necessarily the same as the actual ones. Further, even when the same portion is represented between the drawings, the dimensional relationship and ratio may be represented differently. In particular, the following embodiments exemplify an apparatus and a method for embodying the technical idea of the present invention, and the technical idea of the present invention depends on the shape, structure, arrangement, etc. of components. Is not specified. In the following description, elements having the same function and configuration are denoted by the same reference numerals, and redundant description will be given only when necessary.

  The reflective plate of this embodiment can be used for a reflective display device and a transflective display device. Further, the reflector of the present embodiment can be used for a liquid crystal display device, a polymer dispersion type liquid layer display device, an organic EL (Electroluminescence) display device, and the like.

[First Embodiment]
[1. Reflector manufacturing method]
In the first embodiment, the processing of the laminated film constituting the base member is performed by dividing it into two etchings (including two photolithography processes). The processing pattern of the base member is a line and space (line and space) pattern. Further, in order to minimize the flat portion of the base member, a plurality of lines are arranged side by side with a minimum interval or an interval close thereto.

  That is, a resist pattern (line & space pattern) for the first etching is formed on a base member (a laminated film of a lower layer film and an upper layer film). In the first etching, the upper film having a high etching rate is removed. Then, only the lower layer film having a low etching rate is formed in the space portion of the resist pattern, and the laminated film is formed in the portion where the photoresist is formed.

  Next, a resist pattern (line & space pattern) for the second etching is formed on the base member. The second resist pattern is formed in a state that is almost the same as the first resist pattern and is shifted by a predetermined distance from the first resist pattern. Further, one side of the photoresist is already on the laminated film. One side is overlaid on the lower layer film after the first etching. In this state, the second etching is performed. The second etching is performed under conditions for etching the lower layer film. Then, the pattern edge on the laminated film side has a gentle taper angle, and the pattern edge on the lower layer film side has a relatively steep taper angle. By such a manufacturing method, a base pattern having anisotropy in the taper angle is formed. Therefore, if a reflective film is formed thereon, an anisotropic reflector can be formed.

  Below, the manufacturing method of the reflecting plate (anisotropic reflecting plate) which concerns on 1st Embodiment of this invention is demonstrated, referring drawings. In the present embodiment, a line and space with the minimum pitch that can be processed is a basic pattern, and therefore, the drawing is expressed as a cross-sectional view in a direction perpendicular to the line.

  First, as shown in FIG. 7, a film for forming a sloped base member is formed on a substrate 10 made of, for example, a glass substrate. In the present embodiment, the film for the sloped base member has a two-layer structure of an upper film / lower film. That is, the lower layer film 20 and the upper layer film 21 are sequentially stacked on the substrate 10. The etching rate of the upper layer film 21 is set to be larger than the etching rate of the lower layer film 20. For example, a method of changing the etching rates of the lower layer film 20 and the upper layer film 21 includes a method of changing the material of the lower layer film 20 and the upper layer film 21 and a method of changing etching conditions when the lower layer film 20 and the upper layer film 21 are etched. There is.

The lower layer film 20 and the upper layer film 21 are made of, for example, an insulating material. For example, the material of the lower layer film 20 and the upper layer film 21 is selected so that the etching rate of the upper layer film 21 is larger than the etching rate of the lower layer film 20. The lower layer film 20 and the upper layer film 21 are made of an inorganic material such as silicon nitride (SiN or Si ₃ N ₃ ) or silicon oxide (SiO ₂ ), for example. When the lower layer film 20 and the upper layer film 21 are composed of silicon nitride, the etching rate from the side can be increased as the silicon nitride contains more nitrogen. The nitrogen in the silicon nitride can be increased, for example, by increasing the flow rate of ammonia as the auxiliary source gas during film formation. When the lower layer film 20 and the upper layer film 21 are made of the same material, the etching rate can be varied by changing the composition ratio of the compounds. Further, the material, the film forming method, and the etching method of the lower layer film 20 and the upper layer film 21 are the same as those of the second insulating film 25 and the third insulating film 26 disclosed in JP 2010-199556 A, respectively. Can be used.

  Subsequently, a photoresist pattern 22 is formed on the upper layer film 21 using a photolithography process. The photoresist pattern 22 has a line & space pattern and is composed of a plurality of line-shaped photoresists. The pitch of the line & space pattern 22 is formed at the resolution limit of the exposure apparatus. The lines and spaces of the line & space pattern 22 have the same width. The pitch is the total length of one line width and one space width.

  Subsequently, as shown in FIG. 8, the upper layer film 21 is etched using the photoresist pattern 22 as a mask. The etching conditions at this time are set so that the upper layer film 21 can be etched but the lower layer film 20 is not etched as much as possible. Thus, the etching can be completed in a state where the upper layer film 21 is completely removed and the lower layer film 20 is slightly shaved in the region not covered with the photoresist pattern 22. In order to make the shape of the lower layer film 20 processed after this into a desired shape, it is desirable that the thickness of the upper layer film 21 is as thin as possible (0.2 μm or less). After the etching of the upper layer film 21, the photoresist pattern 22 is peeled off as shown in FIG. 9, and the first photolithography process is completed.

  Subsequently, a second photolithography process is performed. As shown in FIG. 10, a photoresist pattern 23 is formed on the lower layer film 20 and the upper layer film 21. The photoresist pattern 23 has a line & space pattern and is composed of a plurality of line-shaped photoresists. The pitch of the line & space pattern 23 is formed at the resolution limit of the exposure apparatus. That is, the pitch of the line & space pattern 23 is the same as the pitch of the line & space pattern 22.

  At this time, one side of the line portion of the photoresist pattern 23 is arranged in a portion where the upper layer film 21 remains, and the other side is arranged in a portion where the upper layer film 21 is removed (only the lower layer film 20). The processing of the photoresist pattern 23 is performed by making the photoresist pattern 23 into a pattern composed of lines and spaces having the same pitch as the photoresist pattern 22 in principle, and shifting it by a predetermined distance from the position where the photoresist pattern 22 is formed. This can be realized by forming at different positions.

  Subsequently, as shown in FIG. 11, the laminated film (upper layer film 21 / lower layer film 20) is continuously etched using the photoresist pattern 23 as a mask. The etching conditions at this time are conditions for etching the lower layer film 20. Since the etching rate under this condition is “lower layer film 20 <upper layer film 21”, the side on which the laminated film is etched has a gentle taper shape due to the large amount of side etching by upper layer film 21, and only lower layer film 20 is etched. The etched side has a steep taper because of little side etch progress. In this way, etching shapes having different taper angles on the left and right of the line portion of the photoresist pattern 23 can be obtained. FIG. 12 is a cross-sectional SEM photograph of a real sample in the manufacturing process of FIG. In the sample of FIG. 12, the lower layer film 20 having a different taper shape on the right and left of the cross section can be realized. Subsequently, the photoresist pattern 23 is peeled off, and the second photolithography process is completed.

  Subsequently, as illustrated in FIG. 13, the reflective film 24 is formed on the substrate 10 and the base member (the lower layer film 21 and the upper layer film 21). The reflective film 24 is made of a metal material having a high reflectance, such as aluminum (Al), silver (Ag), and an alloy (Al-based or Ag-based) containing any of these. The thickness of the reflective film 24 is preferably 0.03 μm or more. In this way, the anisotropic inclined reflector 11 is completed. The above is an example of the vertical structure forming process of the anisotropic reflector 11.

[2. Plane pattern of base material]
The scattering profile (reflection scattering profile) of the reflecting plate 11 is determined by the combination of the cross-sectional structure and the planar pattern in the reflecting plate 11 formed as described above. In the case of black-and-white display, the pixel is a square pixel with an aspect ratio of 1: 1, but considering the color display (RGB) correspondence, here, the configuration of a planar pattern is shown by taking a vertically long pixel with an aspect ratio of 3: 1 as an example. In the case of square pixels, it can be dealt with by expanding the plane pattern of vertically long pixels or arranging them repeatedly.

  The basic plane pattern is a horizontal stripe pattern. FIG. 14 is a schematic diagram for explaining a horizontal stripe pattern of the reflector 11 according to the first embodiment. FIG. 14 shows a pattern for one pixel. The pixel is a pixel having an aspect ratio of 3: 1. A stripe pattern design is usually expressed in lines and spaces. In actual pixel design, since there are wirings, thin film transistor placement regions, and the like at the pixel boundaries, the plane pattern of the anisotropic inclined reflector 11 must correspond to this, but this is not the essence of the invention. I won't mention it here.

  In FIG. 14, the horizontal direction corresponds to the X direction and the vertical direction corresponds to the Y direction. X pitch: Y pitch = 3: 1. The plurality of lines extend in the X direction. The line & space pattern in FIG. 14 corresponds to the planar pattern of the base member (the lower layer film 20 and the upper layer film 21) in FIG. The planar pattern of the photoresist 22 in FIG. 7 and the planar pattern of the photoresist 23 in FIG. 10 are also the same as the line and space pattern in FIG.

  In this embodiment, both the line width and the space (interval) are basically set to the lower limit determined by the process capability. The lower limit of the line and space is the resolution limit of the exposure apparatus (for example, the line width + space = pitch is about 4 to 6 μm), but this includes an inclined region of taper processing, variation in processing dimensions, and the like (these are the upper layer film 21). And the thickness of the lower layer film 20), the thickness may be increased to the extent of adding twice the laminated film thickness. That is, the pitch of the line and space pattern formed by the base member (the lower layer film 20 and the upper layer film 21) is a length obtained by combining the pitch that is the resolution limit of the exposure apparatus and twice the thickness of the base member. It is as follows. As can be seen from FIG. 13, since the inclined reflecting surface is the side surface (one side) of the line, the area is proportional to the number of lines arranged in a certain area. Minimizing the line and space pitch maximizes the number of lines, resulting in the maximum area of the inclined reflecting surface.

  If processing is performed so that the upper side of FIG. 14 is the left side of FIG. 13 (the gentle slope is above the line), a scattering profile as shown in FIG. Of course, depending on the requirements of the scattering profile, the upper part of FIG. 14 can be the right side of FIG. 13 (the gentle slope is below the line).

[3. Conditions for the base material]
Next, conditions for the base member will be described. FIG. 15 is a schematic diagram for explaining the relationship between incident light and scattered light. When incident light from the front of the viewer 12 is scattered (reflected) by the reflector 11, it is ideal that the peak of the scattered light (scattered peak) is observed by the viewer 12. Scattered light is brightest. The angle between the incident light and the scattering peak is θ.

  FIG. 16 is a schematic diagram for explaining a cross-sectional shape of an ideal lower layer film (underlying member) 20. The base member 20 has a triangular cross-sectional shape and has elevation angles α and β (α <β). The elevation angle α side of the base member 20 is a gentle slope, and the elevation angle β side of the base member 20 is a steep slope. The horizontal length B of the gentle slope and the horizontal length D of the steep slope. At this time, the angle formed between the incident light and the scattered light is 2α. When the scattering peak is directed to the observer 12, “α = θ / 2” and “β = 90 ° −θ” are obtained. For example, if θ = 40 °, α = 20 ° and β = 50 °. As shown in FIG. 16, when one base member 20 satisfies the above-described conditions of the elevation angles α and β, and a plurality of base members 20 are continuously arranged without leaving a space, the angle θ from the perpendicular line The incident light incident on the reflecting plate 11 with the light can be delivered to the observer 12 as scattered light with less loss.

  However, due to process restrictions, it is difficult to eliminate the space between adjacent base members 20 and process the cross-sectional shape of the base member 20 into a triangle. As a result, as shown in FIG. 13, a plurality of base members (lower layer film 20 and upper layer film 21) having a substantially trapezoidal cross-sectional shape are arranged with a predetermined space therebetween.

  FIG. 17 is a cross-sectional view of the reflecting plate 11. FIG. 18 is a sectional view of the base member 20 shown in FIG. 17 extracted. The base member 20 has a substantially trapezoidal cross-sectional shape, and has elevation angles α and β (α <β). The elevation angle α side of the base member 20 is a gentle slope, and the elevation angle β side of the base member 20 is a steep slope. The horizontal length B of the gentle slope and the horizontal length D of the steep slope. Adjacent base members 20 are arranged with a space A therebetween. The upper base C of the base member 20 and the thickness E of the base member 20.

  Consider applying the ideal condition of FIG. 16 to FIG. As in FIGS. 15 and 16, the angle formed between the incident light and the scattered light on the gentle slope B is θ. The incident light of interest here is incident light from a direction that is not obstructed by the observer 12, as shown in FIG. 6, and is incident light from a direction that contributes most to the scattering peak. This angle θ is appropriately set according to the use conditions of the display device in which the reflector 11 is used, the required specifications, and the like. In this case, the base member 20 is set to “α = θ / 2” and “β = 90 ° −θ”. Thereby, in the reflector 11 which has the base member formed by the line & space, the scattering peak toward an observer can be made the largest.

  Next, conditions that take process restrictions into account will be described.

<Conditions for space A>
In order to reduce the specular reflection component, it is desirable that the space A is smaller, but A = 0 cannot be set due to process limitations. The space A is preferably 0 <A ≦ 4 μm.

<Condition for gentle slope>
In linear approximation, it is desirable that 10 ° ≦ α ≦ 40 °. The horizontal length B of the gentle slope is expressed by “B≈ (cos (α) / sin (α)) · E”. “≈” means approximation.

<Conditions for the upper base C of the base member 20>
In order to reduce the specular reflection component, it is desirable that the upper base C is smaller. The upper base C including the upper layer film 21 and the portion without the upper layer film 21 is preferably 0 <C ≦ 4 μm.

<Steep slope conditions>
In a linear approximation, it is desirable that 40 ° <β ≦ 80 °. The horizontal length D of the steep slope is represented by “D≈ (cos (β) / sin (β)) · E”.

<The length of the base member 20 in the horizontal direction>
When E ≦ 1 μm, the horizontal length (A + B + C + D) of the base member 20 is desirably 15 μm or less.

  As shown in FIG. 18, the elevation angles α and β are angles from the substrate obtained by dividing a gentle slope and a steep slope into three equal parts and linearly approximating the central part.

  FIG. 19 is a cross-sectional view of the reflecting plate 11 including the upper layer film 21. 20 is a cross-sectional view of the base member (the lower layer film 20 and the upper layer film 21) extracted from FIG.

  The upper base C of the base member having a substantially trapezoidal cross section is composed of a portion F that is a laminated film of the upper layer film 21 / lower layer film 20 and a portion G that is only the lower layer film 20 (with the upper layer film removed). That is, “C = F + G”. In order to reduce the regular reflection component, it is desirable that the upper base C (= F + G) is “0 <C ≦ 4 μm”. The portion F is preferably “0 ≦ F ≦ 3 μm”.

  The step H between the portion F and the portion G exists only when 0 <F, and the step H = “the thickness of the upper layer film 21” + “the amount of decrease in the lower layer film 20 when the upper layer film 21 is etched”. When the level difference H exists, the cross-sectional shape of the reflecting plate 11 reflects this and becomes as shown in FIG. On the other hand, when all of the upper layer film 21 is etched, F = 0, and the cross-sectional shape of the reflecting plate 11 is as shown in FIG.

  Further, in order to realize a gentle slope (surface that reflects incident light) at a desired angle, the upper layer film 21 is desirably thinner, and the thickness of the upper layer film 21 is 0.2 μm or less. desirable.

[4. effect]
As described above in detail, in this embodiment, preparation for anisotropic etching is prepared by the first photolithography process, the first etching process, and the second photolithography process, and both sides are prepared by the second etching process. A line & space pattern made of a base member having a different taper is formed. The second resist pattern formation can be performed with the alignment accuracy of the exposure apparatus for the first photolithography process. Usually, the alignment accuracy is 1/2 or less of the resolution limit of the pitch (line & space) by the exposure apparatus, so the fine pattern at the line & space processing limit (this becomes a bottleneck for miniaturization) An anisotropic reflection pattern can be created. Specifically, the pitch of the line & space pattern can be reduced to about 4 μm to 6 μm.

  Moreover, since this line & space can be designed freely such as a straight line or a curved line, a desired scattering profile can be created. Thereby, it becomes possible to collect more scattered light to an observer. As a result, by using the reflective plate 11 of this embodiment for a reflective display device or a transflective display device, it is possible to realize a display device capable of brighter display using reflected light.

  Also, the fine line and space pattern means that more lines and spaces can be arranged within the unit area. Since the inclined reflecting surface is a pattern edge (one side) of a line & space, a large number of lines in a unit area means that the ratio of the inclined reflecting area is large (occupation ratio of the flat portion is suppressed). Therefore, there is an effect that reflection can be reduced.

[Second Embodiment]
In the first embodiment, a simple horizontal stripe pattern is shown as the line and space pattern, but this pattern sufficiently exhibits the effect of inclined reflection with respect to incident light from a wide range as shown in FIG. May be difficult. Therefore, in the second embodiment, a bent pattern is used as the line & space pattern.

  FIG. 21 is a schematic diagram for explaining a planar pattern of the reflector 11 according to the second embodiment of the present invention. FIG. 21 shows a pattern for one pixel. The pixel is a pixel having an aspect ratio of 3: 1. 21 corresponds to the planar pattern of the base member (the lower layer film 20 and the upper layer film 21) in FIG. Also, the planar pattern of the photoresist 22 in FIG. 7 and the planar pattern of the photoresist 23 in FIG. 10 are the same as the line and space pattern in FIG. The planar patterns of the following embodiments have the same relationship as in FIG.

  As shown in FIG. 21, the line can be bent while keeping the line and space constant. That is, a bending pattern is formed so that two straight lines intersect at a predetermined opening angle. As shown in FIG. 4, when it is intended to scatter incident light from the first quadrant and the second quadrant, the pattern is desirably convex upward, and in the case of a bent pattern, a so-called inverted V-shape Become a shape. In the case of the horizontal stripe of FIG. 14 (corresponding to a line opening angle of 180 degrees), it can be said that it can cope well with incidence from the 12:00 direction. On the other hand, in the case of FIG. 21 (a) (line opening angle 120 degrees), the incident is from the 2 o'clock direction and 10 o'clock direction, and in the case of FIG. 21 (b) (line opening angle 90 degrees), 1 is applied. It can be said that it corresponds well to incidence from half past and half past 10.30. There is an advantage that it is possible to adjust from which direction the incident is preferentially handled according to the setting of the opening angle.

  Further, depending on the required scattering profile, a bending pattern having a downwardly convex V-shaped line may be selected.

[Third Embodiment]
FIG. 22 is a schematic diagram for explaining a planar pattern of the reflector 11 according to the third embodiment of the present invention. In the third embodiment, a linear pattern is eliminated and a concentric arc pattern is used. By arranging a plurality of concentric arcs instead of arranging a plurality of arcs of the same shape, a line & space pattern can be arranged on the entire surface of the pixel while keeping the lines and spaces constant.

  FIG. 22 shows an example of a concentric circular arc pattern in which the center point is located outside the pixel area. If the center point is placed at the lower part of the pixel (a range from the lower end of the pixel area to the lower part outside the pixel area is desirable), the arc has a convex shape. In the case of the concentric circular arc pattern, similar reflection / scattering characteristics are shown for incident light from a wide range.

  The curvature of the arc can be changed depending on the position of the center point. When the center point is at the lower end of the pixel area, the innermost arc has a semicircular shape with the minimum radius, but as the center point moves away from the lower end of the pixel area outside the pixel area, the curvature of the arc increases and approaches a straight line. (Approaches the characteristics of the horizontal stripe pattern).

  Also, depending on the required scattering profile, a concentric arc pattern having a downwardly convex arc may be selected.

[Fourth Embodiment]
In the case of a pixel with an aspect ratio of 3: 1, even if the center point of the concentric arc pattern is placed at the lower end of the pixel area, the curvature of the arc at the upper part of the pixel increases and approaches the characteristics of the horizontal stripe. In order to make use of the object of the arc, it is desirable to reduce the curvature, but this can be realized by dividing the pixel area and treating each divided area as an independent pattern.

  FIG. 23 is a schematic diagram for explaining a planar pattern of the reflector 11 according to the fourth embodiment of the present invention. The fourth embodiment is a configuration example when one pixel is divided into two. A concentric arc pattern is arranged in each of the two divided areas. In this way, an arc having a small curvature can be used as a line & space pattern. FIG. 22 shows an example in which one pixel is divided into two, but one pixel can be divided into three or more. Also in this case, a concentric arc pattern is arranged for each divided region.

[Fifth Embodiment]
In a line and space pattern formed by photolithography, moire often occurs due to the periodicity of the pattern. In order to reduce moiré, it is necessary to provide diversity in patterns and make it difficult for interference to occur. In the case of a concentric arc pattern, the pattern shape changes variously only by changing the position of the center point. Therefore, the pattern can be made diverse by using this, and moire can be reduced.

  FIG. 24 is a schematic diagram for explaining a planar pattern of the reflector 11 according to the fifth embodiment of the present invention. FIG. 24 shows a pattern of two pixels. Of the two pixels adjacent in the X direction (left and right in the figure), the pattern of the left pixel is the same as in FIG. 23, but the pattern of the right pixel is a pattern (center point) of a predetermined distance in the Y direction from the pattern of the left pixel. , And the pixel division position is also shifted accordingly. In the example of FIG. 24, the pattern (center point) of the right pixel pattern is shifted from the left pixel pattern by 1/4 pixel in the Y direction.

  In this way, moire is reduced as compared with the case where the pattern of FIG. 23 is simply repeated. The center point can be shifted not only in the Y direction (up and down) but also in the X direction (left and right) (not shown), and the combination can further reduce moire.

[Sixth Embodiment]
FIG. 25 is a schematic diagram for explaining a planar pattern of the reflector 11 according to the sixth embodiment of the present invention.

  As shown in FIG. 25, by extending a pattern for a vertically long pixel having an aspect ratio of 3: 1 in the horizontal direction (X direction), it is possible to correspond to a square pixel having an aspect ratio of 1: 1 used in monochrome display. it can. FIG. 25 is an example in which the pattern of FIG. 23 (fourth embodiment) is expanded. That is, in FIG. 25, the pattern of FIG. 23 is expanded in the + X direction and the −X direction, respectively, thereby forming a line and space pattern for square pixels having an aspect ratio of 1: 1.

  In this way, a desired scattering profile can be obtained even in a square pixel with an aspect ratio of 1: 1. In addition, by selecting a pattern with low periodicity, the effect of reducing moire can be exhibited.

  The present invention is not limited to the above embodiment, and can be embodied by modifying the constituent elements without departing from the scope of the invention. Further, the above embodiments include inventions at various stages, and are obtained by appropriately combining a plurality of constituent elements disclosed in one embodiment or by appropriately combining constituent elements disclosed in different embodiments. Various inventions can be configured. For example, even if some constituent elements are deleted from all the constituent elements disclosed in the embodiments, the problems to be solved by the invention can be solved and the effects of the invention can be obtained. Embodiments made can be extracted as inventions.

  DESCRIPTION OF SYMBOLS 10 ... Board | substrate, 11 ... Reflector, 12 ... Observer, 20 ... Lower layer film, 21 ... Upper layer film, 22, 23 ... Photoresist pattern, 24 ... Reflective film.

Claims (14)

A line-and-space pattern provided on the substrate and composed of a plurality of base members having a substantially trapezoidal cross-sectional shape;
A reflective film provided on the plurality of base members;
Comprising
Each of the plurality of base members has a first slope and a second slope that is steeper than the first slope, and is composed of a laminated lower layer film and upper layer film,
The reflection plate for a display device, wherein the upper layer film is thinner than the lower layer film. If the elevation angle α of the first slope and the elevation angle β of the second slope,
10 ° ≦ α ≦ 40 °
40 ° <β ≦ 80 °
The reflection plate for a display device according to claim 1, wherein: When the angle θ formed between the incident light and the normal of the substrate, the elevation angle α of the first slope, and the elevation angle β of the second slope,
α = θ / 2
β = 90 ° -θ
The reflection plate for a display device according to claim 1, wherein: The space is greater than 0 and less than or equal to 4 μm;
4. The reflection plate for a display device according to claim 1, wherein an upper base of the base member is greater than 0 and 4 μm or less. The thickness of the lower layer film is 1 μm or less,
5. The reflection plate for a display device according to claim 1, wherein a pitch of the line and space pattern is 15 μm or less.   5. The pitch of the line and space pattern is equal to or less than a total length of a pitch that is a resolution limit of an exposure apparatus and twice the thickness of the base member. A reflector for a display device according to claim 1. The upper layer film is partially formed on the lower layer film,
The upper base of the lower layer film is greater than 0 and 4 μm or less,
The display device reflector according to claim 1, wherein a width of the upper layer film is 0 to 3 μm.   8. The reflection plate for a display device according to claim 1, wherein the upper layer film has a thickness of 0.2 μm or less.   9. The reflection plate for a display device according to claim 1, wherein the line and space pattern has a stripe shape.   9. The reflection plate for a display device according to claim 1, wherein the line and space pattern is a bent shape having an inverted V-shaped or V-shaped line.   9. The reflection plate for a display device according to claim 1, wherein the line-and-space pattern has a concentric arc shape that is convex upward or convex downward. One pixel is divided into multiple regions,
The concentric circular arc pattern is arrange | positioned for every said division area, The reflecting plate for display apparatuses of Claim 11 characterized by the above-mentioned.   The reflection plate for a display device according to claim 12, wherein the center points of the concentric arc patterns are shifted between adjacent pixels. Laminating a lower layer film and an upper layer film having an etching rate larger than that of the lower layer film on the substrate;
Forming a plurality of first resists having a first line and space pattern on the upper layer film;
Etching the upper layer film using the plurality of first resists as a mask;
A plurality of second line and space patterns on the lower layer film and the upper layer film so as to be shifted from the first line and space pattern by a predetermined distance and so that one line overlaps the lower layer film and the upper layer film. Forming a second resist of
Etching the upper layer film and the lower layer film using the plurality of second resists as a mask;
Forming a reflective film on the lower film and the upper film;
The manufacturing method of the reflecting plate for display apparatuses characterized by comprising.