Reflector, method of fabricating the same, reflective display device comprising reflector, and method of fabricating the same

Abstract

A reflector comprises a substrate provided with a plurality of projecting and depressed structures which are groups of columnar portions each serving as a basic unit and composed of a plurality of minute columnar portions, which are separate from each other or at least partially connected to each other, and with a light reflecting thin film provided over the projecting and depressed structures. This allows incident light to be scattered and reflected in a forward direction or the like, not in the regular reflection direction, and provides a reflector having a superior contrast property and a superior paper-white property, a fabrication method therefor, and a reflective display device comprising the reflector. The reflective display device has a liquid crystal layer provided between a pair of substrates. One of the pair of substrates is provided with projecting and depressed portions covered with a metal film and with a support portion for supporting the counter substrate, which are molded integrally. The arrangement reduces reflection in the regular reflection direction and enhances brightness and whiteness, while reducing the occurrence of uneven display by providing a uniform cell gap.

What is claimed is:  
     
         1 . A reflector comprising: 
 a substrate provided with a plurality of projecting and depressed structures each having a plurality of projecting and depressed portions and serving as a basic unit: and 
 a light reflective thin film provided over the projecting and depressed structures.  
   
     
     
         2 . The reflector of  claim 1 , wherein the projecting and depressed structures provided on the substrate are arranged randomly and dispersively in an arbitrary direction.  
     
     
         3 . The reflector of  claim 1 , wherein the projecting portions of the projecting and depressed structures have top portions at different heights and the depressed portions of the projecting and depressed structures have bottom portions at different depths.  
     
     
         4 . The reflector of  claim 1 , wherein the projecting and depressed structures are groups of columnar portions each composed of a plurality of minute columnar portions having different heights, the columnar portions being separate from each other or at least partially connected to each other.  
     
     
         5 . The reflector of  claim 4 , wherein 
 a height distribution of each of the projecting and depressed structures has a peak at a position deviated in a specified direction from a center portion of the structure and tends to decrease with distance from the peak toward a periphery thereof and    the light reflecting thin film covering the projecting and depressed structures has a curved surface having a curvature larger in the specified direction than in a direction opposite to the specified direction.    
     
     
         6 . The reflector of  claim 5 , wherein at least one polymer resin layer is provided between the projecting and depressed structures and the light reflecting thin film.  
     
     
         7 . The reflector of  claim 1 , wherein the projecting and depressed structures are staircase structures each having a plurality of stepped portions.  
     
     
         8 . The reflector of  claim 7 , wherein 
 a height distribution of each of the projecting and depressed structures has a peak at a position deviated in a specified direction from a center portion of the structure and tends to decrease with distance from the peak toward a periphery of the structure and    the light reflecting thin film covering the projecting and depressed structures has a curved surface having a curvature larger in the specified direction than in a direction opposite to the specified direction.    
     
     
         9 . The reflector of  claim 8 , wherein at least one polymer resin layer is provided between the projecting and depressed structures and the light reflecting thin film.  
     
     
         10 . The reflector of  claim 1 , wherein the reflector is a grating reflector for reflecting and diffracting light, the grating reflector having the plurality of projecting and depressed structures provided periodically on the substrate.  
     
     
         11 . The reflector of  claim 1 , wherein each of the projecting and depressed structures in plan view has a size in the range of 
   1  μm to      100  μm.    
     
     
         12 . The reflector of  claim 1 , wherein each of the plurality of projecting and depressed structures has a periodic structure for reflecting and diffracting light, the projecting and depressed structures being provided such that positions thereof are random and/or a direction in which periodicity is recognized is random.  
     
     
         13 . A reflector comprising: 
 a substrate provided with a nonlinear element;    a photosensitive resin layer provided on the substrate, the photosensitive resin layer having projecting and depressed structures in specified regions; and    a pixel electrode with a light reflecting property provided on the photosensitive resin layer, the pixel electrode being electrically connected to the nonlinear element via a contact hole formed in the photosensitive resin layer, wherein    a light reflecting film is provided on a bottom portion of the contact hole.    
     
     
         14 . The reflector of  claim 13 , wherein a degree of crosslinking in the photosensitive resin layer is higher in a surrounding portion of an inner wall surface of the contact hole than in the other portion thereof.  
     
     
         15 . A reflector comprising: 
 a substrate provided with a nonlinear element;    a photosensitive resin layer provided on the substrate, the photosensitive resin layer having projecting and depressed structures in specified regions; and    a pixel electrode with a light reflecting property provided on the photosensitive resin layer, the pixel electrode being electrically connected to the nonlinear element via a contact hole formed in the photosensitive resin layer, wherein    a thin film having a surface energy higher than that of the photosensitive resin layer is provided on a bottom portion of the contact hole.    
     
     
         16 . A reflector comprising: 
 a substrate provided with a nonlinear element;    a photosensitive resin layer provided on the substrate, the photosensitive resin layer having projecting and depressed structures in specified regions; and    a pixel electrode with a light reflecting property provided on the photosensitive resin layer, the pixel electrode being electrically connected to the nonlinear element via a contact hole formed in the photosensitive resin layer, wherein    the contact hole is provided such that a degree of crosslinking is higher in a surrounding portion of an inner wall surface of the contact hole than in the other portion thereof.    
     
     
         17 . A reflector comprising: 
 a substrate provided with a nonlinear element and with a plurality of projecting and depressed portions; and    a pixel electrode with a light reflecting property provided over the projecting and depressed portions, wherein    the projecting and depressed portions are composed of a single layer or a plurality of layers selected arbitrarily from layers composing the nonlinear element.    
     
     
         18 . A reflective display device comprising: 
 a counter substrate with transparency;    a reflector disposed in opposing relation to the counter substrate, the reflector including a substrate provided with a plurality of projecting and depressed structures each having a plurality of projecting and depressed portions and serving as a basic unit and a light reflecting thin film provided over the projecting and depressed structures; and    a liquid crystal layer held between the counter substrate and the reflector.    
     
     
         19 . The reflective display device of  claim 18 , wherein the reflector is a grating reflector for reflecting and diffracting light, the grating reflector having the plurality of projecting and depressed structures provided periodically on the substrate.  
     
     
         20 . The reflective display device of  claim 18 , wherein the projecting portions of the projecting and depressed structures have top portions at different heights and the depressed portions of the projecting and depressed structures have bottom portions at different depths.  
     
     
         21 . The reflective display device of  claim 18 , wherein the projecting and depressed structures are groups of columnar portions each composed of a plurality of minute columnar portions having different heights, the columnar portions being separate from each other or at least partially connected to each other.  
     
     
         22 . The reflective display device of  claim 21 , wherein 
 a height distribution of each of the projecting and depressed structures has a peak at a position deviated in a specified direction from a center portion of the structure and tends to decrease with distance from the peak toward a periphery thereof and    the light reflecting thin film covering the projecting and depressed structures has a curved surface having a curvature larger in the specified direction than in a direction opposite to the specified direction.    
     
     
         23 . The reflective display device of  claim 22 , wherein at least one polymer resin layer is provided between the projecting and depressed structures and the light reflecting thin film.  
     
     
         24 . The reflective display device of  claim 18 , wherein the projecting and depressed structures are staircase structures each having a plurality of stepped portions.  
     
     
         25 . The reflective display device of  claim 24 , wherein 
 a height distribution of each of the projecting and depressed structures has a peak at a position deviated in a specified direction from a center portion of the structure and tends to decrease with distance from the peak toward a periphery thereof and    the light reflecting thin film covering the projecting and depressed structures has a curved surface having a curvature larger in the specified direction than in a direction opposite to the specified direction.    
     
     
         26 . The reflective display device of  claim 25 , wherein at least one polymer resin layer is provided between the projecting and depressed structures and the light reflecting thin film.  
     
     
         27 . The reflective display device of  claim 18 , wherein the reflector is a grating reflector for reflecting and diffracting light, the grating reflector having the plurality of projecting and depressed structures provided periodically on the substrate.  
     
     
         28 . The reflective display device of  claim 18 , wherein each of the projecting and depressed structures in plan view has a size in the range of 1 μm to 100 μm.  
     
     
         29 . The reflective display device of  claim 18 , wherein each of the plurality of projecting and depressed structures has a periodic structure for reflecting and diffracting light, the projecting and depressed structures being provided such that positions thereof are random and/or a direction in which periodicity is recognized is random.  
     
     
         30 . A reflective display device comprising: 
 a substrate provided with a nonlinear element;    a photosensitive resin layer provided on the substrate, the photosensitive resin layer having projecting and depressed structures in specified regions; and    a pixel electrode with a light reflecting property provided on the photosensitive resin layer, the pixel electrode being electrically connected to the nonlinear element via a contact hole formed in the photosensitive resin layer, wherein    a light reflecting film is provided on a bottom portion of the contact hole.    
     
     
         31 . The reflective display device of  claim 30 , wherein a degree of crosslinking in the photosensitive resin layer is higher in a surrounding portion of an inner wall surface of the contact hole than in the other portion thereof.  
     
     
         32 . A reflective display device comprising: 
 a substrate provided with a nonlinear element;    a photosensitive resin layer provided on the substrate, the photosensitive resin layer having projecting and depressed structures in specified regions; and    a pixel electrode with a light reflecting property provided on the photosensitive resin layer, the pixel electrode being electrically connected to the nonlinear element via a contact hole formed in the photosensitive resin layer, wherein    a thin film having a surface energy higher than that of the photosensitive resin layer is provided on a bottom portion of the contact hole.    
     
     
         33 . The reflective display device of  claim 32 , wherein a degree of crosslinking in the photosensitive resin layer is higher in a surrounding portion of an inner wall surface of the contact hole than in the other portion thereof.  
     
     
         34 . A reflective display device comprising: 
 a substrate provided with a nonlinear element;    a photosensitive resin layer provided on the substrate, the photosensitive resin layer having projecting and depressed structures in specified regions; and    a pixel electrode with a light reflecting property provided on the photosensitive resin layer, the pixel electrode being electrically connected to the nonlinear element via a contact hole formed in the photosensitive resin layer, wherein    the contact hole is provided such that a degree of crosslinking is higher in a surrounding portion of an inner wall surface of the contact hole than in the other portion thereof.    
     
     
         35 . A reflective display device comprising: 
 a substrate provided with a nonlinear element and with a plurality of projecting and depressed portions; and    a pixel electrode with a light reflecting property provided over the projecting and depressed portions, wherein    the projecting and depressed portions are composed of a single layer or a plurality of layers selected arbitrarily from layers composing the nonlinear element.    
     
     
         36 .A reflective display device having a liquid crystal layer provided between a pair of substrates, wherein one of the pair of substrates is provided with projecting and depressed portions covered with a metal film and with a support portion for supporting the other of the pair of substrates, the projecting and depressed portions and the support portion being molded integrally.  
     
     
         37 . The reflective display device of  claim 36 , wherein the projecting and depressed portions are pyramidal or conical.  
     
     
         38 . The reflective display device of  claim 37 , wherein if an angle formed between an inclined surface of the pyramidal projecting and depressed portions and a horizontal surface or an angle formed between a generating line of the conical projecting and depressed portions and a horizontal surface is assumed to be a slope angle, the projecting and depressed portions are dispersively arranged at different slope angles and the slope angles are in the range of 4° to 16°.  
     
     
         39 . The reflective display device of  claim 36 , further comprising a polymer resin layer molded integrally with the projecting and depressed portions and with the support portion for supporting the other of the substrates, the polymer resin layer being provided on one of the substrates.  
     
     
         40 . The reflective display device of  claim 39 , wherein a plurality of nonlinear elements are provided on one of the substrates and a contact hole for providing an electric connection between the nonlinear elements and the metal film is provided in the polymer resin layer.  
     
     
         41 . The reflective display device of  claim 36 , wherein a resin film molded integrally with the projecting and depressed portions and with the support portion for supporting the other of the substrates is laminated on one of the substrates.  
     
     
         42 . The reflective display device of  claim 41 , wherein the resin film is made of a photosensitive resin.  
     
     
         43 . The reflective display device of  claim 36 , wherein one of the substrates is a plastic substrate molded with the projecting and depressed portions and with the support portion for supporting the other of the substrates.  
     
     
         44 . A reflective display device having a photosensitive resin layer provided on a substrate and a metal film provided on the photosensitive resin layer, wherein 
 the photosensitive resin layer is formed by exposing, to light, a photosensitive resin coated on the substrate via a photomask and developing the exposed photosensitive resin, the photosensitive resin layer having a projecting and depressed surface formed by exposing the photosensitive resin to the light via the photomask having a light shielding pattern composed of groups of minute halftone dots smaller than a resolution limit of an exposing device used for the exposure and a resolution limit of the photosensitive resin, a mean light transmittance of the light shielding pattern being nonuniform over a surface of the photomask.    
     
     
         45 .A method of fabricating a reflector, the method comprising: 
 a step of forming a photosensitive resin layer on a substrate;    an exposing step of irradiating the photosensitive resin layer with light via a photomask having light shielding portions patterned into specified configurations;    a developing step of developing the photosensitive resin layer irradiated with the light to form a plurality of resist columns;    a heat treatment step of performing a heat treatment with respect to the substrate formed with the plurality of resist columns and thereby forming groups of columnar portions each composed of a plurality of minute columnar portions having different heights, the columnar portions being separate from each other or at least partially connected to each other; and    a step of forming a light reflecting thin film over the groups of columnar portions, wherein    as the photomask, a mask formed with a plurality of unit components each composed of a plurality of minute shielding portions having different heights is used.    
     
     
         46 . A method of fabricating a reflector, the method comprising: 
 a step of forming a photosensitive resin layer on a substrate;    an exposing step of irradiating the photosensitive resin layer with light via a photomask having light shielding portions each having a progressively varying light shielding rate;    a developing step of developing the photosensitive resin layer irradiated with the light to form a plurality of staircase resist columns;    a heat treatment step of performing a heat treatment with respect to the substrate formed with the plurality of staircase resist columns to round off respective angular edges of the resist columns and thereby forming staircase structures each having a plurality of stepped portions; and    a step of forming a light reflecting thin film over the staircase structures.    
     
     
         47 . A method of fabricating a reflector, the method comprising: 
 a step of forming a photosensitive resin layer on a substrate;    a step of preparing a plurality of photomasks each having light shielding portions patterned into specified configurations, each of the light shielding portions of the different photomasks covering a light shielding range which is different in size from one photomask to another, each of the light shielding portions of any of the photomasks covering a larger shielding range and each of the light shielding portions of the photomask covering a next smaller shielding range having a relationship therebetween such that the next smaller light shielding range is included in the larger light shielding range;    an exposing step of irradiating the photosensitive resin layer with light by successively using the photomasks in the order of decreasing size of the light shielding range of the shielding portion;    a developing step of developing the photosensitive resin layer irradiated with the light to form a plurality of staircase resist columns;    a heat treatment step of performing a heat treatment with respect to the substrate formed with the staircase resist columns to round off respective angular edges of the resist columns and thereby forming staircase structures each having a plurality of stepped portions; and    forming a light reflecting thin film over the staircase structures.    
     
     
         48 . A method of fabricating a reflector having a substrate provided with a nonlinear element, a photosensitive resin layer provided on the substrate and having projecting and depressed structures in specified regions, and a pixel electrode with a light reflecting property provided on the photosensitive resin layer, the pixel electrode being electrically connected to the nonlinear element via a contact hole formed in the photosensitive resin layer, the method comprising: 
 a step of forming the nonlinear element on the substrate;    a light-reflecting-film forming step of forming, at a position at which the contact hole is to be formed, a light reflecting film patterned into a specified configuration;    a coating step of coating a photosensitive resin material over the substrate and the light reflecting film;    an exposing step of irradiating the photosensitive resin material with light via a photomask having light shielding portions patterned into specified configurations;    a developing step of developing the photosensitive resin material irradiated with the light to form the photosensitive resin layer comprising the contact hole and a plurality of resist columns formed in specified regions;    a heat treatment step of performing a heat treatment with respect to the photosensitive resin layer and thereby thermally deforming and rounding off respective edge portions of the plurality of resist columns;    a post-baking step of performing a heat treatment with respect to the photosensitive resin layer and thereby curing the photosensitive resin layer; and    a pixel-electrode forming step of forming the pixel electrode with the light reflecting property on the photosensitive resin layer.    
     
     
         49 . A method of fabricating a reflector having a substrate provided with a nonlinear element, a photosensitive resin layer provided on the substrate and having projecting and depressed structures in specified regions, and a pixel electrode with a light reflecting property provided on the photosensitive resin layer, the pixel electrode being electrically connected to the nonlinear element via a contact hole formed in the photosensitive resin layer, the method comprising: 
 a step of forming the nonlinear element on the substrate;    a thin-film forming step of forming, at a position at which the contact hole is to be formed, a frame-shaped thin film having a surface energy higher than that of the photosensitive resin layer;    a coating step of coating a photosensitive resin material over the substrate and the thin film;    an exposing step of irradiating the photosensitive resin material with light via a photomask having light shielding portions patterned into specified configurations;    a developing step of developing the photosensitive resin material irradiated with the light to form the photosensitive resin layer comprising the contact hole and a plurality of resist columns formed in specified regions;    a heat treatment step of performing a heat treatment with respect to the photosensitive resin layer and thereby thermally deforming and rounding off respective edge portions of the plurality of resist columns;    a post-baking step of performing a heat treatment with respect to the photosensitive resin layer and thereby curing the photosensitive resin layer; and    a pixel-electrode forming step of forming the pixel electrode with the light reflecting property on the photosensitive resin layer.    
     
     
         50 . A method of fabricating a reflector having a substrate provided with a nonlinear element, a photosensitive resin layer provided on the substrate and having projecting and depressed structures in specified regions, and a pixel electrode with a light reflecting property provided on the photosensitive resin layer, the pixel electrode being electrically connected to the nonlinear element via a contact hole formed in the photosensitive resin layer, the method comprising: 
 a step of forming the nonlinear element on the substrate;    a thin-film forming step of forming, on a drain electrode of the nonlinear element, a thin film having a surface energy higher than that of the photosensitive resin layer;    a coating step of coating a photosensitive resin material over the substrate and the thin film;    an exposing step of irradiating the photosensitive resin material with light via a photomask having light shielding portions patterned into specified configurations;    a developing step of developing the photosensitive resin material irradiated with the light to form the photosensitive resin layer comprising the contact hole and a plurality of resist columns formed in specified regions;    a heat treatment step of performing a heat treatment with respect to the photosensitive resin layer and thereby thermally deforming and rounding off respective edge portions of the plurality of resist columns;    a removing step of removing the thin film by ashing;    a post-baking step of performing a heat treatment with respect to the photosensitive resin layer and thereby curing the photosensitive resin layer; and    a pixel-electrode forming step of forming the pixel electrode with the light reflecting property on the photosensitive resin layer.    
     
     
         51 . A method of fabricating a reflector having a substrate provided with a nonlinear element, a photosensitive resin layer provided on the substrate and having projecting and depressed structures in specified regions, and a pixel electrode with a light reflecting property provided on the photosensitive resin layer, the pixel electrode being electrically connected to the nonlinear element via a contact hole formed in the photosensitive resin layer, the method comprising: 
 a step of forming the nonlinear element on the substrate;    a coating step of coating a photosensitive resin material on the substrate;    an exposing step of irradiating the photosensitive resin material with light via a photomask having light shielding portions patterned into specified configurations;    a developing step of developing the photosensitive resin material irradiated with the light to form the photosensitive resin layer comprising the contact hole and a plurality of resist columns formed in specified regions;    a light irradiating step of irradiating a surrounding portion of the contact hole with light at a shorter wavelength;    a heat treatment step of performing a heat treatment with respect to the photosensitive resin layer and thereby thermally deforming and rounding off respective edge portions of the plurality of resist columns;    a post-baking step of performing a heat treatment with respect to the photosensitive resin layer; and    a pixel-electrode forming step of forming the pixel electrode with the light reflecting property on the photosensitive resin layer, wherein    a degree of crosslinking is higher in a surrounding portion of an inner wall surface of the contact hole.    
     
     
         52 . The method of  claim 51 , further comprising, after the heat treatment step, a light irradiating step of irradiating the surrounding portion of the contact hole with light at a shorter wavelength.  
     
     
         53 . A method of fabricating a reflector, the method comprising: 
 a step of forming a photosensitive resin layer on a substrate;    an exposing step of irradiating the photosensitive resin layer with light via a first photomask having light shielding portions patterned into specified configurations;    a developing step of developing the photosensitive resin layer irradiated with the light to form a plurality of resist columns;    an irradiating step of irradiating respective specified regions of the plurality of resist columns with light at a shorter wavelength via a second photomask having openings patterned into specified configurations;    a heat treatment step of performing a heat treatment with respect to the resist columns and thereby thermally deforming respective edge portions of the plurality of resist columns to form projecting and depressed structures each having an asymmetrical cross-sectional configuration;    a post-baking step of performing a heat treatment with respect to the photosensitive resin layer; and    a pixel-electrode forming step of forming a pixel electrode with a light reflecting property on the photosensitive resin layer.    
     
     
         54 . The method of  claim 53 , further comprising, after the heat treatment step, a light irradiating step of irradiating the plurality of projecting and depressed structures with light at a shorter wavelength.  
     
     
         55 . A method of fabricating a reflective display device comprising a light modulating layer between a pair of substrates, the method comprising the steps of: 
 forming a polymer resin layer on one of the pair of substrates;    pressing a platen provided with a projecting and depressed pattern composed of a group of minute projecting and depressed patterns and a hole against the polymer resin layer;    curing the polymer resin layer and mold releasing the platen from the polymer resin layer;    forming a metal film on the polymer resin layer; and    thereby shaping the polymer resin layer into the projecting and depressed pattern to integrally mold minute projecting and depressed portions in a surface of the polymer resin layer with a support portion for supporting the other of the pair of substrates.    
     
     
         56 . The method of  claim 55 , wherein, if the polymer resin layer formed on one of the substrates is a photosensitive resin layer, a platen with transparency is used as the platen and the polymer resin layer is cured by irradiating the photosensitive resin layer with light via the platen.  
     
     
         57 . The method of  claim 55 , wherein, if the polymer resin layer formed on one of the substrates is a thermoplastic resin layer, the platen is pressed against the thermoplastic resin layer with the application of heat.  
     
     
         58 . The method of  claim 55 , wherein 
 a nonlinear element is provided on one of the substrates and    a platen having a projecting portion for forming a contact hole at a position corresponding to an output terminal portion of the nonlinear element is used as the platen.    
     
     
         59 . The method of  claim 58 , wherein a bottom portion of the contact hole in the polymer resin layer is etched immediately after the platen is mold released from the polymer resin layer till the output terminal portion of the nonlinear element is exposed.  
     
     
         60 . A method of fabricating a reflective display device comprising a light modulating layer between a pair of substrates, the method comprising the steps of: 
 pressing a platen provided with a projecting and depressed pattern composed of a group of minute projecting and depressed patterns and a hole against one of the pair of substrates;    curing one of the substrates and mold releasing the platen from one of the substrates;    forming a metal film on one of the substrates; and    thereby shaping one of the substrates into the projecting and depressed pattern to integrally mold minute projecting and depressed portions in a surface of one of the substrates with a support portion for supporting the other of the substrates.    
     
     
         61 . The method of  claim 60 , wherein, if one of the substrates is made of a photosensitive resin, a platen with transparency is used as the platen and one of the substrates is cured by irradiating one of the substrates with light via the platen.  
     
     
         62 . The method of  claim 60 , wherein, if one of the substrates is made of a thermoplastic resin, the platen is pressed against one of the substrates with the application of heat.  
     
     
         63 . A method of fabricating a reflective display device comprising a light modulating layer between a pair of substrates, the method comprising the steps of: 
 forming a polymer resin layer over a mold provided with a projecting and depressed pattern composed of a group of minute projecting and depressed patterns;    bonding the mold to one of the pair of the substrates such that the polymer resin layer faces the substrate and releasing the mold from the polymer resin layer to laminate the polymer resin layer on one of the substrates;    forming a metal film over the polymer resin layer; and    thereby shaping the polymer resin layer into the projecting and depressed pattern to form minute projecting and depressed portions in a surface of the polymer resin layer.    
     
     
         64 . The method of  claim 63 , wherein a base film made of a polymer resin is used as the mold.  
     
     
         65 . The method of  claim 63 , wherein a mold having, at a specified position, a hole for forming a support portion for supporting the other of the pair of substrates is used as the mold.  
     
     
         66 . A method of fabricating a reflector, the method comprising the steps of: coating a photosensitive resin layer on a substrate; exposing the photosensitive resin layer to light via a photomask; developing the exposed photosensitive resin layer to form projecting and depressed portions in the photosensitive resin layer; and forming a reflective film over the projecting and depressed surface, wherein 
 the photomask has a light shielding pattern composed of groups of minute half-tone dots smaller than a resolution limit of an exposing device used in the exposing step and a resolution limit of the photosensitive resin layer and    a mean light transmittance of the light shielding pattern is nonuniform over a surface of the photomask.    
     
     
         67 . The method of  claim 66 , wherein a nonlinear element is provided on the substrate and a mask having a light shielding portion or a light non-shielding portion provided at a portion corresponding to an output portion of the non-linear element is used as the photomask.