JP2009080387A - Liquid crystal device, projection-type display device and manufacturing method for the liquid crystal device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal device, wherein the number of components can be reduced, the surface of a wire-grid type polarization element is flattened, when the wire-grid type polarization element is formed and both of [transmittance] and [contrast] of the wire-grid type polarization element can be enhanced, to provide a projection-type display device, and to provide a manufacturing method for the liquid crystal device. <P>SOLUTION: The wire-grid type polarization element 107 is formed on a counter substrate 50 of the liquid crystal device 100 and the wire-grid type polarization element 107 has a structure, wherein metal grids 20 are embedded in a plurality rows of groove-shaped recessed parts 11 formed on one substrate surface 15 of a light-transmissive substrate 10. Hence, in the wire grid type polarization element 107, the substrate surface 15 of the light-transmissive substrate 10 constitutes a smooth surface, wherein regions where the metal grids 20 are formed and regions, where the metal grids 20 are not formed, are continued. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal device, a projection display device, and a method for manufacturing a liquid crystal device.

  As shown in FIG. 9, the projection display device using the liquid crystal light valve separates the white light emitted from the light source unit into red (R), green (G), and blue (B) color lights, and then displays each color. The liquid crystal light valves 100 (R), (G), and (B) are made incident and the modulated light emitted from the liquid crystal light valves 100 (R), (G), and (B) is synthesized by the cross dichroic prism 119. Then, it projects with a projection optical system. Here, the liquid crystal light valves 100 (R), (G), and (B) are the liquid crystal panels 101 (R), (G), and (B), and the liquid crystal panels 101 (R), (G), and (B). The dust-proof glass 103 (R), (G), (B), 104 (R), (G), (B) affixed on both sides of the incident side polarizing plate 108 (R), ( G), (B), and emission side polarizing plates 105 (R), (G), (B) located on the emission side.

  In the projection type display device, a reflective inorganic polarizing plate as shown in FIGS. 10A and 10B is joined to the liquid crystal panels 101 (R), (G), and (B) to be integrated. Have been proposed (see, for example, Patent Document 1).

  The reflective inorganic polarizing plate shown in FIGS. 10A and 10B includes a plurality of rows of metal gratings 20A on the substrate surface of the translucent substrate 10A, and the pitch (period) of the metal gratings 20A is that of incident light. If the wavelength is shorter than the wavelength, the polarization component oscillating in the direction perpendicular to the longitudinal direction of the metal grating 20A is transmitted, while the polarization component oscillating in the direction parallel to the longitudinal direction of the metal grating 20A is reflected. In the wire grid type polarizing element 107A, conventionally, after forming a metal film on the substrate surface of the translucent substrate 10A, the surface of the metal film is etched with a groove-like opening in a region where the metal lattice 20A is to be formed. A mask is formed, and in this state, the metal film is patterned to produce the mask.

  In forming the etching mask, after applying a resin to the surface of the metal film, the concavo-convex pattern formed on the mold member is transferred to form a resist having groove-shaped openings in the region where the metal lattice 20A is to be formed. There is also a method for obtaining a mask.

  In the wire grid type polarizing element 107A, the metal grating 20A absorbs a part of the incident light. Therefore, even when the pitch of the metal grating 20A is shorter than the wavelength of the incident light, the metal grating 20A is perpendicular to the longitudinal direction of the metal grating 20A. The oscillating polarization component cannot be transmitted 100%. For this reason, the performance of the wire grid type polarizing element 107 </ b> A is expressed by “Transmittance” and “Contrast”. “Transmittance” is the transmittance of the polarization component that vibrates in the direction perpendicular to the longitudinal direction of the metal grating 20A, and “Contrast” is the polarization component that vibrates in the direction perpendicular to the longitudinal direction of the metal grating 20A. Is divided by the transmittance of the polarization component that vibrates in the direction parallel to the longitudinal direction of the metal grating 20A.

Here, in order to increase “contrast”, the pitch of the metal grating 20 must be considerably shorter than the wavelength of incident light. To increase “transmittance”, the width dimension of the metal grating 20 is reduced, In addition, the width dimension and the thickness dimension of the metal grid 20 must satisfy predetermined conditions.
Japanese Patent Laid-Open No. 2004-245871

  However, the conventional technique has the following problems. First, as in Patent Document 1, when a reflective inorganic polarizing plate is bonded to and integrated with a liquid crystal panel, the number of components cannot be reduced.

  Further, in the case where a plurality of rows of metal gratings 20A are formed on the substrate surface of the translucent substrate 10A, such as the reflective inorganic polarizing plates shown in FIGS. 10A and 10B, the surface has a large number of irregularities. Therefore, in order to planarize the surface, a process such as polishing after forming a thick protective film separately is required.

  Furthermore, in the reflective inorganic polarizing plate shown in FIGS. 10A and 10B, it is necessary to form the metal grid 20A by etching the metal film. In such a method, the width dimension and thickness dimension of the metal grid 20A are limited. It is affected by both the etching accuracy for the metal film and the film thickness accuracy when the metal film is formed. For this reason, for example, there is a restriction that the pitch of the metal grating 20A is limited to about 140 nm. Therefore, with regard to “transmittance” and “contrast”, it is the limit to obtain the performance shown in FIG. The “transmittance” has a problem that there is a large difference in the visible light band. Therefore, when a liquid crystal device using the conventional wire grid type polarizing element 107A is used as a light valve for red (R), green (G), and blue (B) light in a projection display device, red (R) However, there is a problem that the amount of light is reduced.

  In view of the above problems, an object of the present invention is to provide a liquid crystal device capable of reducing the number of parts, a projection display device, and a method for manufacturing the liquid crystal device.

  Another object of the present invention is to provide a liquid crystal device, a projection display device, and a method of manufacturing the liquid crystal device in which the surface of the wire grid type polarizing element is flattened when the wire grid type polarizing element is formed. It is in.

  Furthermore, the subject of this invention is providing the manufacturing method of the liquid crystal device which can improve both the "transmittance" and "contrast" of a wire grid type polarizing element, a projection type display apparatus, and a liquid crystal device.

  In order to solve the above problems, in the present invention, an element substrate on which a pixel electrode and a pixel switching element are formed, a counter substrate disposed opposite to the element substrate, and the element substrate and the counter substrate are held between the element substrate and the counter substrate. In at least one of the element substrate and the counter substrate, a plurality of rows of groove-like recesses are formed on the substrate surface and embedded in the groove-like recesses. A wire grid type polarizing element is formed by a metal lattice.

  In the present invention, since the wire grid type polarization element is formed on at least one of the element substrate and the counter substrate, at least one polarizing plate can be omitted, and the number of components can be reduced. Further, in the wire grid type polarizing element, a plurality of rows of groove-like recesses are formed on the substrate surface of the translucent substrate, and a metal grid is embedded in the plurality of rows of groove-like recesses. The substrate surface is already flat at the time of construction. Therefore, after forming the wire grid type polarizing element, it is not necessary to polish the surface after forming the thick light-transmitting film. Moreover, in the wire grid type polarizing element to which the present invention is applied, a plurality of rows of groove-like recesses are formed on the substrate surface of the translucent substrate, and a metal lattice is embedded in the plurality of rows of groove-like recesses, It is not necessary to form a metal grid by etching the metal film. For this reason, the width and pitch of the metal grid are defined by the width and pitch of the groove-like recesses formed on the substrate surface of the translucent substrate and are not affected by the etching accuracy with respect to the metal film. The dimension can be reduced to less than 70 nm, for example 35 nm, and the pitch of the metal grating can be reduced to less than 140 nm, for example 70 nm. Further, the thickness dimension of the metal grid is defined by the depth of the groove-shaped recess formed on the substrate surface of the translucent substrate, and is not affected by the film thickness accuracy when the metal film is formed. The ratio of the thickness dimension to the width dimension can be accurately set to 1: 1, for example. Therefore, both “transmittance” and “contrast” of the wire grid type polarizing element can be improved.

  In the present invention, a liquid crystal device having an element substrate on which a pixel electrode and a pixel switching element are formed, a counter substrate disposed opposite to the element substrate, and a liquid crystal held between the element substrate and the counter substrate In the manufacturing method, when forming a wire grid type polarizing element having a plurality of rows of metal gratings on one of the element substrate and the counter substrate, the substrate surface A mask forming step of forming an etching mask having a groove-like opening in a region where a metal lattice is to be formed; and etching the substrate surface to form a groove-like recess in a region overlapping the groove-like opening on the substrate surface. An etching step for forming, a metal film forming step for filling the groove-like recesses with a metal film to form the metal lattice, and polishing the substrate surface to form the groove-like shape. While leaving the metal film part, and having a polishing step of removing the metal film protruding from the groove-like recess.

  According to such a manufacturing method, the groove-shaped recess is completely embedded by the metal grid, and the region where the groove-shaped recess is formed and the region sandwiched by the groove-shaped recess are continuous on the substrate surface. It becomes the structure which forms the flat surface.

  In the present invention, the wire grid type polarizing element has a transmittance of a polarization component that vibrates in a direction perpendicular to the longitudinal direction of the metal grating being 80% or more over the entire wavelength band of 460 nm to 780 nm. preferable.

  In the present invention, it is preferable that the wire grid type polarizing element is formed on a substrate on a side on which light modulated by the liquid crystal layer is incident, of the element substrate and the counter substrate. In this case, it is preferable that the wire grid type polarizing element is formed on the counter substrate. In other words, it is preferable that the counter substrate is disposed on the side of the element substrate and the counter substrate on which the light modulated by the liquid crystal layer is incident.

  The liquid crystal device according to the present invention can be used as a display portion of an electronic device such as a mobile computer or a mobile phone, and can be used as a light valve in a projection display device. The projection display device includes a light source unit that makes light incident on the liquid crystal device, and a projection optical system that enlarges and projects light modulated by the liquid crystal device, and the light emitted from the light source unit The light can be modulated by the liquid crystal device and enlarged and projected by the projection optical system. In this case, the configuration used in the projection type display device in which the three liquid crystal devices are respectively used as light valves corresponding to red (R), green (G), and blue (B) can be adopted, and the light is emitted from the light source unit. It is also possible to adopt a configuration in which the light is optically modulated by a liquid crystal device incorporating a color filter and enlarged and projected by a projection optical system. In any of these projection type display devices, if the wire grid type polarizing element to which the present invention is applied is used, a high transmittance is obtained for any color light of red (R), blue (B), and green (G). Therefore, a color image with high quality can be displayed.

  In the method of manufacturing a wire grid type polarizing element according to the present invention, in the mask forming step, a photosensitive resin is applied to the substrate surface, and then exposed and developed to form the etching mask. In the present invention, “exposure” means not only exposure by ultraviolet light but also exposure by extreme ultraviolet light (EUV: Extreme Ultra Violet), electron beam, X-ray or the like.

  In the manufacturing method of the wire grid type polarizing element according to the present invention, in the mask forming step, a mask material layer is formed on the substrate surface, and then a mold member is provided with a protrusion at a portion corresponding to the groove-shaped opening. A configuration may be adopted in which the etching mask with the groove-like opening formed thin is formed by pressing the surface and transferring the projection formation pattern to the mask material layer. According to such a configuration, the etching mask can be formed without using much labor such as exposure and development or using a curing apparatus.

  In the method for manufacturing a wire grid type polarizing element according to the present invention, it is preferable that a chemical mechanical polishing treatment is performed as the polishing treatment in the polishing step. If comprised in this way, while being able to remove the metal film which protruded from the groove-shaped recessed part, since the board | substrate surface itself can also be grind | polished, a board | substrate surface can be finished into a smooth surface.

  Embodiments of the present invention will be described below. In the drawings to be referred to in the following description, the scales of the layers and the members are different from each other in order to make the layers and the members large enough to be recognized on the drawings. In the following description, common portions are described with the same reference numerals so that the comparison with the configuration described with reference to FIGS. 9 to 11 can be easily understood.

[Configuration example of a projection display device]
1A and 1B are a schematic configuration diagram of a projection display device (liquid crystal projector) to which the present invention is applied and a schematic configuration diagram of a liquid crystal light valve, respectively. A projection display device 110 shown in FIGS. 1A and 1B irradiates light onto a screen 111 (projected surface) provided on the observer side, and observes the light reflected by the screen 111. This is a liquid crystal projector. The projection display device 110 includes a light source unit 150 including a light source 112 and dichroic mirrors 113 and 114, liquid crystal light valves 100 (R), (G), and (B) each including a liquid crystal device described later, and a projection optical system. 118, a cross dichroic prism 119 (color synthesis optical system), and a relay system 120.

  In the light source unit 150, the light source 112 is configured by an ultrahigh pressure mercury lamp that supplies light including red light, green light, and blue light. The dichroic mirror 113 is configured to transmit red light from the light source 112 and reflect green light and blue light. The dichroic mirror 114 is configured to transmit blue light and reflect green light among green light and blue light reflected by the dichroic mirror 113. Thus, the dichroic mirrors 113 and 114 constitute a color separation optical system that separates the light emitted from the light source 112 into red light, green light, and blue light.

  Here, between the dichroic mirror 113 and the light source 112, an integrator 121 and a polarization conversion element 122 are arranged in order from the light source 112. The integrator 121 is configured to make the illuminance distribution of the light emitted from the light source 112 uniform. Further, the polarization conversion element 122 is configured to change the light from the light source 112 into polarized light having a specific vibration direction such as s-polarized light.

  The liquid crystal light valve 100 (R) is a transmissive liquid crystal device that modulates the red light transmitted through the dichroic mirror 113 and reflected by the reflecting mirror 123 according to an image signal, and is a λ / 2 phase difference plate 102 (R). And a liquid crystal panel 101 (R) and an output side polarizing plate 105 (R). In addition, an incident-side dustproof glass 103 (R) and an emission-side dustproof glass 104 (R) are attached to both surfaces of the liquid crystal panel 101 (R), respectively. The dust-proof glass prevents dust and the like from appearing on the projected image.

  In this embodiment, as will be described later, the liquid crystal panel 101 (R) itself is provided with a polarizing element that blocks s-polarized light and transmits p-polarized light. It does not have a board.

  The red light incident on the liquid crystal light valve 100 (R) remains as s-polarized light because the polarization of the light does not change even if it passes through the dichroic mirror 113. The λ / 2 retardation film 102 (R) is an optical element that converts s-polarized light incident on the liquid crystal light valve 100 (R) into p-polarized light. The liquid crystal panel 101 (R) blocks the s-polarized light and transmits the p-polarized light by a polarizing element formed on the liquid crystal panel 101 (R). To elliptically polarized light. The exit-side polarizing plate 105 (R) is a polarizing plate that blocks p-polarized light and transmits s-polarized light. Accordingly, the liquid crystal light valve 100 (R) is configured to modulate the red light in accordance with the image signal and emit the modulated red light toward the cross dichroic prism 119.

  The liquid crystal light valve 100 (G) is a transmissive liquid crystal device that modulates green light reflected by the dichroic mirror 114 after being reflected by the dichroic mirror 113 in accordance with an image signal, and is similar to the liquid crystal light valve 100 (R). And a liquid crystal panel 101 (G) and an output side polarizing plate 105 (G). In addition, an incident-side dustproof glass 103 (G) and an emission-side dustproof glass 104 (G) are attached to both surfaces of the liquid crystal panel 101 (G), respectively.

  In this embodiment, as will be described later, the liquid crystal panel 101 (G) itself is provided with a polarizing element that blocks p-polarized light and transmits s-polarized light. It does not have a board.

  The green light incident on the liquid crystal light valve 100 (G) is s-polarized light that is reflected by the dichroic mirrors 113 and 114 and incident. The liquid crystal panel 101 (G) blocks the p-polarized light and transmits the s-polarized light by the polarizing element formed on the liquid crystal panel 101 (G). (Ellipse polarization). The exit-side polarizing plate 105 (G) is a polarizing plate that blocks s-polarized light and transmits p-polarized light. Accordingly, the liquid crystal light valve 100 (G) is configured to modulate green light in accordance with an image signal and emit the modulated green light toward the cross dichroic prism 119.

  The liquid crystal light valve 100 (B) is a transmissive liquid crystal device that reflects blue light that is reflected by the dichroic mirror 113 and passes through the dichroic mirror 114 and then passes through the relay system 120 in accordance with an image signal. Similarly to 100 (R), a λ / 2 phase difference plate 102 (B), a liquid crystal panel 101 (B), and an emission side polarizing plate 105 (B) are provided. In addition, an incident-side dustproof glass 103 (B) and an emission-side dustproof glass 104 (B) are attached to both surfaces of the liquid crystal panel 101 (B), respectively.

  In this embodiment, as will be described later, the liquid crystal panel 101 (B) itself is formed with a polarizing element that blocks s-polarized light and transmits p-polarized light. It does not have a board.

  The blue light incident on the liquid crystal light valve 100 (B) is reflected by two reflecting mirrors 125a and 125b (to be described later) of the relay system 120 after being reflected by the dichroic mirror 113 and transmitted through the dichroic mirror 114. It has become. The λ / 2 retardation film 102 (B) is an optical element that converts s-polarized light incident on the liquid crystal light valve 100 (B) into p-polarized light. The liquid crystal panel 101 (B) is configured to convert p-polarized light into s-polarized light (circularly polarized light or elliptically polarized light in the case of halftone) by modulation according to an image signal. The exit-side polarizing plate 105 (B) is a polarizing plate that blocks p-polarized light and transmits s-polarized light. Accordingly, the liquid crystal light valve 100 (B) is configured to modulate blue light in accordance with an image signal and emit the modulated blue light toward the cross dichroic prism 119.

  The relay system 120 includes relay lenses 124a and 124b and reflection mirrors 125a and 125b. The relay lenses 124a and 124b are provided to prevent light loss due to a long blue light path. Here, the relay lens 124a is disposed between the dichroic mirror 114 and the reflection mirror 125a. The relay lens 124b is disposed between the reflection mirrors 125a and 125b. The reflection mirror 125a is disposed so as to reflect the blue light transmitted through the dichroic mirror 114 and emitted from the relay lens 124a toward the relay lens 124b. The reflection mirror 125b is disposed so as to reflect the blue light emitted from the relay lens 124b toward the liquid crystal light valve 100 (B).

  The cross dichroic prism 119 is a color combining optical system in which two dichroic films 119a and 119b are arranged orthogonally in an X shape. The dichroic film 119a is a film that reflects blue light and transmits green light, and the dichroic film 119b is a film that reflects red light and transmits green light. Accordingly, the cross dichroic prism 119 combines the red light, the green light, and the blue light modulated by the liquid crystal light valves 100 (R), (G), and (B), respectively, and emits the light toward the projection optical system 118. Is configured to do.

  The light incident on the cross dichroic prism 119 from the liquid crystal light valves 100 (R) and (B) is s-polarized light, and the light incident on the cross dichroic prism 119 from the liquid crystal light valve 100 (G) is p-polarized light. In this way, by making the light incident on the cross dichroic prism 119 into different types of polarized light, the light incident from the liquid crystal light valves 100 (R), (G), and (B) in the cross dichroic prism 119 is effectively combined. it can. Here, in general, the dichroic films 119a and 119b are excellent in the reflection characteristics of s-polarized light. For this reason, red light and blue light reflected by the dichroic films 119a and 119b are s-polarized light, and green light transmitted through the dichroic films 119a and 119b is p-polarized light. The projection optical system 118 has a projection lens (not shown) and is configured to project the light combined by the cross dichroic prism 119 onto the screen 111.

[Configuration of liquid crystal light valve]
FIG. 2 is a plan view of one pixel of an element substrate of the liquid crystal device used as the liquid crystal light valves 100 (R), (G), and (B) in the projection display device 110 shown in FIG. It is sectional drawing when a liquid crystal device is cut | disconnected in the position corresponded to C 'line. Since the basic configuration of each of the liquid crystal light valves 100 (R), (G), and (B) is substantially the same, in the following description, when the corresponding color type is not relevant, the liquid crystal light valve 100 (R), (G), and (B) are simply referred to as “liquid crystal light valve 100”, and the liquid crystal panels 101 (R), (G), and (B) are simply referred to as “liquid crystal panel 101”.

  Liquid crystal light valves 100 (R), (G), and (B) shown in FIG. 1B are all-transmissive liquid crystal devices 100. In the liquid crystal panel 101, a quartz substrate, a heat-resistant glass substrate, or the like is used as a base material. The element substrate 40 to be bonded and the light-transmitting counter substrate 50 having a quartz substrate or a heat-resistant glass substrate as a base material are bonded to each other with a sealant 109 through a predetermined gap, and the liquid crystal layer 70 is sealed in the gap. ing. The liquid crystal layer 70 takes a predetermined alignment state by the alignment films formed on the element substrate 40 and the counter substrate 50 in a state where an electric field from the pixel electrode 9a is not applied. The liquid crystal layer 70 is made of, for example, one or a mixture of several types of nematic liquid crystals. The counter substrate 50 is disposed on the side where the color light is incident from the light source unit 150, and the element substrate 40 is disposed on the modulated light emission side.

  As shown in FIGS. 2A and 2B, in the element substrate 40, translucent pixel electrodes 9a are formed in a matrix on the surface side of the translucent substrate 40b. Data lines 6a and scanning lines 3c are formed along vertical and horizontal boundaries. Each of the data line 6a and the scanning line 3c extends linearly. A thin film transistor 45 is formed in a region where the data line 6a and the scanning line 3c intersect. On the element substrate 40, a capacitor line 5b is formed so as to overlap the scanning line 3c. In this embodiment, the capacitor line 5b includes a main line portion that extends linearly so as to overlap the scanning line 3c, and a sub-line portion that extends so as to overlap the data line 6a at the intersection of the data line 6a and the scanning line 3c. It has.

  The element substrate 40 includes a translucent substrate 40b such as a quartz substrate or a glass substrate on which a base protective film 40c is formed, a pixel electrode 9a formed on the surface of the liquid crystal layer 70, a thin film transistor 45 for pixel switching, And the alignment film 46 as a main component. The thin film transistor 45 has an LDD structure. The semiconductor layer 1a includes a channel region 1g, a low concentration source region 1b, a low concentration drain region 1c, a high concentration region facing the scanning line 3c via the gate insulating layer 2. A concentration source region 1d and a high concentration drain region 1e are formed. The semiconductor layer 1a is composed of a polycrystalline silicon layer, and the gate insulating layer 2 is formed of a thermal oxide film for the semiconductor layer 1a. The scanning line 3c is made of a conductive polycrystalline silicon film containing impurities. The semiconductor layer 1a is, for example, a low-temperature polysilicon film (low-temperature polysilicon film) that is polycrystallized by laser annealing or lamp annealing after an amorphous silicon film is formed on the translucent substrate 40b, and exceeds 1000 °. It is a high-temperature polysilicon film obtained by polycrystallizing an amorphous silicon film at a temperature, or a single crystal silicon layer. Note that a light shielding layer is preferably formed in a region overlapping with the thin film transistor 45 between the light-transmitting substrate 40b and the base protective film 40c. If such a light shielding layer is formed, light emitted from the liquid crystal panel 101 is emitted. It is possible to prevent the light from being reflected and entering the channel region 1g of the thin film transistor 45.

  On the upper layer side of the scanning line 3c, a first interlayer insulating film 41 made of a silicon oxide film or the like provided with a contact hole 82 leading to the high concentration source region 1d and a contact hole 83 leading to the high concentration drain region 1e is formed. Yes. Relay electrodes 4 a and 4 b are formed on the first interlayer insulating film 41. The relay electrode 4a is formed in a substantially L shape extending along the scan line 3c and the data line 6a with the position where the scan line 3c and the data line 6a intersect as a base point. It is formed along the data line 6a at a position separated from 4b. The relay electrode 4a is electrically connected to the high-concentration drain region 1e through the contact hole 83, and the relay electrode 4b is electrically connected to the high-concentration source region 1d through the contact hole 82.

  A dielectric film 42 made of a silicon nitride film or the like is formed on the upper layer side of the relay electrodes 4a and 4b, and a capacitor line 5b is formed through the dielectric film 42 so as to face the relay electrode 4a. A storage capacitor 47 is formed. The relay electrodes 4a and 4b are made of a conductive polysilicon film, a metal film, or the like, and the capacitor line 5b is made of a conductive polysilicon film, a metal silicide film containing a refractory metal, a laminated film thereof, or a metal film.

  On the upper layer side of the capacitor line 5b, a second interlayer insulating film 43 made of a silicon oxide film having a contact hole 87 leading to the relay electrode 4a and a contact hole 81 leading to the relay electrode 4b is formed. A data line 6 a and a drain electrode 6 b are formed on the second interlayer insulating film 43. The data line 6a is electrically connected to the relay electrode 4b through the contact hole 81, and is electrically connected to the high concentration source region 1d through the relay electrode 4b. The drain electrode 6b is electrically connected to the relay electrode 4a through the contact hole 87, and is electrically connected to the high concentration drain region 1e through the relay electrode 4a. The data line 6a and the drain electrode 6b are made of a conductive polysilicon film, a metal silicide film containing a refractory metal, a laminated film thereof, and a metal film.

  A third interlayer insulating film 44 made of a silicon oxide film or the like is formed on the upper side of the data line 6a and the drain electrode 6b, and a contact hole 86 leading to the drain electrode 6b is formed in the third interlayer insulating film 44. Yes. A translucent pixel electrode 9 a made of an ITO film or the like is formed on the third interlayer insulating film 44. The pixel electrode 9 a is electrically connected to the drain electrode 6 b through the contact hole 86. Yes. An alignment film 46 is formed on the surface of the pixel electrode 9a.

(Structure of counter substrate 50 and wire grid type polarizing element)
3A and 3B are a cross-sectional view and a plan view, respectively, schematically showing the configuration of a wire grid type polarizing element to which the present invention is applied.

  In the counter substrate 50, on the side where the liquid crystal layer 70 is located in the translucent substrate 1, a light shielding film called a black matrix or a black stripe in a region facing the vertical and horizontal boundary regions of the pixel electrode 9 a of the element substrate 40. 23a is formed, and a planarizing film 24, a counter electrode 25 made of an ITO film, and an alignment film 26 are formed on the surface side thereof.

  Further, in the counter substrate 50, a wire grid type polarizing element 107 (reflective inorganic polarizing plate) is configured on the substrate surface 15 on the side where light from the light source unit 150 enters in the translucent substrate 10. Further, a surface protective layer 31 made of a metal oxide film such as a silicon oxide film or a metal nitride film such as a silicon nitride film is formed on the counter substrate 50 so as to cover the wire grid type polarizing element 107. Furthermore, an anti-reflection layer 32 is formed on the counter substrate 50 so as to cover the surface protection layer 31, and the anti-reflection layer 32 has a structure in which, for example, five layers of silicon oxide films and titanium oxide films are laminated. I have.

  2 (b), 3 (a), and 3 (b), the wire grid type polarizing element 107 of this embodiment includes a plurality of rows of metal gratings 20 on one substrate surface 15 of the translucent substrate 10. . The metal lattice 20 is, for example, silver, gold, copper, palladium, platinum, aluminum, rhodium, silicon, nickel, cobalt, manganese, iron, chromium, titanium, ruthenium, niobium, neodymium, ytterbium, yttrium, molybdenum, tungsten, indium. , Bismuth, a light-shielding metal film made of a single layer film or a multilayer film thereof.

  Further, in the wire grid type polarizing element 107 of this embodiment, a plurality of rows of groove-like recesses 11 are formed on the substrate surface 15 along the metal lattice 20, and the metal lattice 20 is placed in the plurality of rows of groove-like recesses 11. Is embedded. Therefore, in the wire grid type polarizing element 107, the substrate surface 15 of the translucent substrate 10 is sandwiched between the region where the metal lattice 20 is formed and the region where the metal lattice 20 is not formed (groove-shaped recess 11 is sandwiched between the regions. Both areas constitute a continuous smooth surface.

  In this embodiment, in the wire grid type polarizing element 107, both the width dimension of the metal grid 20 (opening width dimension of the groove-shaped recess 11) and the interval between the metal grids 20 are 35 nm, and the pitch of the metal grid 20 is 70 nm. . The thickness dimension of the metal grid 20 (depth dimension of the groove-shaped recess 11) is also 35 nm, and the aspect ratio of the metal grid cross section (the aspect ratio of the groove-shaped recess 11) is 1: 1.

  In this embodiment, a surface made of a metal oxide film such as a silicon oxide film or a metal nitride film such as a silicon nitride film on the substrate surface 15 of the translucent substrate 10 so as to cover the wire grid type polarizing element 107. A protective layer 31 is formed, and an antireflection layer 32 having a structure in which, for example, five layers of a silicon oxide film and a titanium oxide film are stacked is formed thereon. When such an antireflection layer 32 is formed, the reflection loss can be reduced, so that the “transmittance” of the wire grid type polarizing element 107 can be improved.

  In the wire grid type polarizing element 107 configured as described above, when the pitch (period) of the metal grating 20 is shorter than the wavelength of the incident light, the polarization component that vibrates in the direction perpendicular to the longitudinal direction of the metal grating 20 is transmitted. On the other hand, the polarization component that vibrates in the direction parallel to the longitudinal direction of the metal grating 20 is reflected.

(Manufacturing method of wire grid type polarization element 107)
Hereinafter, with reference to FIGS. 4A to 4G, the configuration of the wire grid type polarizing element 107 according to the present embodiment will be described in detail while explaining the manufacturing method of the wire grid type polarizing element 107 according to the present embodiment. 4A to 4G are process cross-sectional views illustrating a method for manufacturing the wire grid type polarizing element 107 to which the present invention is applied.

  In order to manufacture the wire grid type polarizing element 107 of this embodiment, first, as shown in FIG. 4A, a translucent substrate 10 having smooth both surfaces is prepared.

  Next, a mask formation process is performed for forming an etching mask on the substrate surface 15 on the side that becomes the light incident surface of the wire grid type polarizing element 107 out of both surfaces of the translucent substrate 10.

  For this purpose, as shown in FIG. 4B, a photosensitive resin 60 is applied to the substrate surface 15 of the translucent substrate 10, and then the photosensitive resin is exposed through an exposure mask 64 as shown in FIG. 4C. Resin 60 is exposed. Next, the photosensitive resin 60 is developed, and then a baking process is performed, and as shown in FIG. 4D, an etching mask 61 having groove-shaped openings 62 in the region where the metal grid 20 is to be formed. (Resist mask) is formed. Here, since the opening width dimension of the groove-shaped openings 62 is 35 nm, and the interval between the portions located between the groove-shaped openings 62 is 35 nm, the pitch of the groove-shaped openings 62 is 70 nm. In FIG. 4C, the positive photosensitive resin 60 is irradiated with ultraviolet light through the exposure mask 64 to form the etching mask 61. However, extreme ultraviolet light may be used as the ultraviolet light. Instead of ultraviolet light, the photosensitive resin may be exposed to an electron beam or X-ray, and in this case, direct drawing may be performed without using the exposure mask 64.

  Next, as shown in FIG. 4E, etching is performed on the substrate surface 15 of the translucent substrate 10 while the etching mask 61 is formed on the substrate surface 15 of the translucent substrate 10 to form a groove shape. A recess 11 is formed. In this embodiment, as this etching, anisotropic dry etching, for example, reactive ion etching is performed using an etching gas containing fluorine and oxygen. As a result, on the substrate surface 15, the portion exposed in the groove-shaped opening 62 of the etching mask 61 is etched to a depth of 35 nm to form the groove-shaped recess 11, while the etching mask 61 is also etched and thinned. Become.

  Next, as shown in FIG. 4 (f), after removing the etching mask 61 from the substrate surface 15 of the translucent substrate 10, the metal lattice 20 is formed on the entire surface of the substrate surface 15 as shown in FIG. 4 (g). The metal film 21 to be formed is formed, and the groove-shaped recess 11 is completely filled with the metal film 21. At that time, the metal film 21 is also formed outside the groove-like recess 11. In this embodiment, as the metal film 21, for example, silver, gold, copper, palladium, platinum, aluminum, rhodium, silicon, nickel, cobalt, manganese, iron, chromium, titanium, ruthenium, niobium, neodymium, ytterbium, yttrium, molybdenum A single-layer film of tungsten, indium, bismuth, or an alloy thereof, or a multilayer film of these metals is formed to a thickness of 35 nm or more by vacuum deposition or sputtering.

  Next, a polishing process is performed on the substrate surface 15 of the translucent substrate 10 to leave the metal film 21 in the groove-shaped recess 11 while removing the metal film 21 protruding from the groove-shaped recess 11, and FIG. And as shown to Fig.3 (a), (b), the metal grating | lattice 20 is formed. In this embodiment, chemical mechanical polishing is performed in the polishing step. In this chemical mechanical polishing, a smooth polished surface can be obtained at high speed by the action of chemical components contained in the polishing liquid and the relative movement between the abrasive and the light-transmitting substrate 10. More specifically, in a polishing apparatus, while rotating a surface plate on which a polishing cloth (pad) made of a nonwoven fabric, polyurethane foam, porous fluororesin, or the like is attached, and a holder that holds the translucent substrate 10 are relatively rotated. Polish. At that time, for example, an abrasive containing cerium oxide particles having an average particle diameter of 0.01 to 20 μm, an acrylate derivative as a dispersant, and water is interposed between the polishing cloth and the substrate surface 15 of the light-transmitting substrate 10. To supply. In this embodiment, after polishing until the substrate surface 15 of the translucent substrate 10 is exposed, the substrate surface 15 of the translucent substrate 10 is also slightly polished.

  Next, the surface protective layer 31 is formed on the substrate surface 15 of the translucent substrate 10. In this embodiment, as the surface protective layer 31, a metal oxide film such as a silicon oxide film, a metal nitride film such as a silicon nitride film, or the like is formed by a CVD method, a sputtering method, or the like. Further, an antireflection layer 32 is formed on the translucent substrate 10 so as to cover the surface protective layer 31. In this embodiment, as the antireflection layer 32, silicon oxide films and titanium oxide films are alternately formed by CVD, sputtering, or the like.

  As a result, the metal lattice 20 is embedded in the groove-shaped recess 11 formed on the substrate surface 15 of the translucent substrate 10, and the surface protective layer 31 and the antireflection layer are formed on the substrate surface 15 of the translucent substrate 10. The wire grid type polarizing element 107 in which 32 is formed is completed.

  Then, the light shielding layer 23a, the counter electrode 25, and the like are formed on the substrate surface 16 opposite to the translucent substrate 10 to obtain the counter substrate 50. Thereafter, the counter substrate 50 and the element substrate 40 are bonded together, and then the liquid crystal layer 70 is sealed to obtain the liquid crystal panel 101.

(Another manufacturing method of the wire grid type polarizing element 107)
5A to 5G are process cross-sectional views illustrating another method for manufacturing the wire grid type polarizing element 107 to which the present invention is applied.

  In order to manufacture the wire grid type polarizing element 107 of this embodiment, first, as shown in FIG. 5A, a light-transmitting substrate 10 having smooth both surfaces is prepared.

  Next, a mask formation process is performed for forming an etching mask on the substrate surface 15 on the side that becomes the light incident surface of the wire grid type polarizing element 107 out of both surfaces of the translucent substrate 10.

  For this purpose, as shown in FIG. 5B, after applying a photosensitive resin layer as a mask material layer 65 to the substrate surface 15 of the translucent substrate 10, as shown in FIG. In the mold member 70, the molding surface provided with the protrusions 71 is pressed against the mask material layer 65 to transfer the formation pattern of the protrusions 71 to the mask material layer 65. Meanwhile, the mask material layer 65 is cured by irradiating the mask material layer 65 with ultraviolet light from the translucent substrate 10 side. Next, the mold member 70 is pulled away from the translucent substrate 10 side. As a result, as shown in FIG. 5D, an etching mask 66 having a groove-shaped opening 67 that is pressed and thinned by the protrusion 71 is formed on the substrate surface 15 of the light-transmitting substrate 10. . Here, the projection 71 of the mold member 70 and the groove-shaped opening 67 of the etching mask 66 are both wire grid type polarizing elements 107 described with reference to FIGS. 2B, 3A, and 3B. It has a dimension corresponding to the groove-shaped recess 11. That is, the height, width dimension, and interval of the protrusion 71 in the mold member 70 are all 35 nm, and the depth dimension, opening width dimension, and interval of the groove-like opening 62 of the etching mask 66 are all 35 nm.

  According to such a method, there is an advantage that when the etching mask 66 is formed, a process that requires a great amount of labor such as exposure and development and an expensive apparatus is not required. When a thermosetting resin layer is formed as the mask material layer 65, the mask material layer 65 is cured by heating while pressing the mold member 70 against the mask material layer 65.

  Next, with the etching mask 66 being formed on the substrate surface 15 of the translucent substrate 10, the substrate surface 15 of the translucent substrate 10 is etched to form the groove-shaped recess 11. In this embodiment, as this etching, anisotropic dry etching is performed using an etching gas containing fluorine and oxygen. As a result, while the etching mask 66 is being etched, the substrate surface 15 of the translucent substrate 10 is partially exposed in the portion corresponding to the groove-shaped opening 67 of the etching mask 66, and further etching is continued. Then, the exposed portion of the translucent substrate 10 is etched to a depth of 35 nm to form the groove-shaped recess 11.

  Next, as shown in FIG. 5 (f), the etching mask 66 is removed from the substrate surface 15 of the translucent substrate 10, and then the metal lattice 20 is formed on the entire surface of the substrate surface 15 as shown in FIG. 5 (g). The metal film 21 to be formed is formed, and the groove-shaped recess 11 is completely filled with the metal film 21. As a result, the metal film 21 is also formed outside the groove-like recess 11.

  Next, a polishing process is performed on the substrate surface 15 of the translucent substrate 10 to leave a metal film in the groove-like recess 11, while removing the metal film 21 protruding from the groove-like recess 11, and FIG. As shown in FIGS. 3A and 3B, a metal grid 20 is formed. Also in this embodiment, chemical mechanical polishing is performed in the polishing step, and after polishing is performed until the substrate surface 15 of the light-transmitting substrate 10 is exposed, the substrate surface 15 of the light-transmitting substrate 10 is also slightly polished.

  Next, the surface protective layer 31 is formed on the substrate surface 15 of the translucent substrate 10. In this embodiment, as the surface protective layer 31, a metal oxide film such as a silicon oxide film, a metal nitride film such as a silicon nitride film, or the like is formed by a CVD method or the like. As a result, the metal lattice 20 was embedded in the groove-shaped recess 11 formed on the substrate surface 15 of the translucent substrate 10, and the surface protective layer 31 was formed on the substrate surface 15 of the translucent substrate 10. A wire grid type polarizing element 107 is completed.

(Effect of this embodiment)
FIG. 6 is a graph showing transmittance characteristics and contrast characteristics of a wire grid type polarizing element to which the present invention is applied.

  As described above, in the liquid crystal device 100 to which the present invention is applied, since the wire grid type polarizing element 107 is formed on the light incident side substrate surface 15 of the counter substrate 50, the incident side polarizing plate can be omitted, and the component The number of points can be reduced.

  Further, in the wire grid type polarizing element 107, a plurality of rows of groove-like recesses 11 are formed on the substrate surface of the translucent substrate 10, and the metal lattice 20 is embedded in the plurality of rows of groove-like recesses 11. The substrate surface 15 is already flat when the grid-type polarizing element 107 is configured. Therefore, after forming a thick light-transmitting film on the surface of the wire grid type polarizing element 10, the surface protective layer 31 and the antireflection layer 32 are made to have a uniform thickness on the smooth substrate surface 15 without polishing the surface. It can be formed easily.

  In the wire grid type polarizing element 107 to which the present invention is applied, a plurality of rows of groove-like recesses 11 are formed on the substrate surface 15 of the translucent substrate 10, and the metal grid 20 is embedded in the plurality of rows of groove-like recesses 11. Therefore, it is not necessary to form the metal lattice 20 by etching the metal film. For this reason, the width dimension and pitch of the metal lattice 20 are defined by the width dimension and pitch of the groove-shaped recess 11 formed in the substrate surface 15 of the translucent substrate 10, and are not affected by the etching accuracy with respect to the metal film. The width dimension of the metal grating 20 can be reduced to less than 70 nm, for example, 35 nm, and the pitch of the metal grating 20 can be decreased to less than 140 nm, for example, 70 nm.

  Further, the thickness dimension of the metal grating 20 is defined by the depth of the groove-like recess 11 formed in the substrate surface 15 of the translucent substrate 10 and is affected by the film thickness accuracy when the metal film 21 is formed. Therefore, the ratio of the thickness dimension to the width dimension of the metal grid 20 can be set to exactly 1: 1, for example.

  Therefore, the wire grid type polarizing element 107 of this embodiment has transmittance characteristics and contrast characteristics as shown in FIG. 6 and is a polarization component that vibrates in a direction perpendicular to the longitudinal direction of the metal grating 20. The “transmittance” is 80% or more over the entire wavelength band from 460 nm to 780 nm. Further, the wire grid type polarizing element 107 of this embodiment vibrates the transmittance of the polarization component that vibrates in a direction perpendicular to the longitudinal direction of the metal grating 20 in a direction parallel to the longitudinal direction of the metal grating 20. The value (contrast) divided by the transmittance of the polarization component is 170000 or more over the entire wavelength band from 460 nm to 780 nm.

  Therefore, when the liquid crystal device 100 including the wire grid type polarizing element 107 of this embodiment is used for the light valve of the projection display device for color display described with reference to FIG. 1, red (R), green (G ) And blue (B), a high transmittance can be obtained with respect to any color light, and a high-quality color image can be displayed.

(Another embodiment)
In the above embodiment, the wire grid type polarization element 107 is formed on the substrate surface 15 on the side where the light from the light source unit 150 is incident on the counter substrate 50. However, as shown in FIG. The wire grid type polarizing element 107 may be formed on the substrate surface 16 on the side from which the light from the light is emitted (the substrate surface on the side where the liquid crystal layer 70 is located). In this case, a plurality of rows of groove-like recesses 11 are formed on the substrate surface 16 of the translucent substrate 10, and the metal grid 20 is embedded in the plurality of rows of groove-like recesses 11. For this reason, the substrate surface 15 is already flat when the wire grid type polarizing element 107 is formed. Therefore, after the surface protective film 22 is formed on the surface of the wire grid type polarizing element 10, the light shielding layer 23a, the counter electrode 25, and the like can be formed without performing polishing or the like.

  In addition, it is preferable to form an antireflection layer 32 on the substrate surface 16 on the light incident side of the translucent substrate 10, and the antireflection layer 32 includes, for example, five layers of silicon oxide film and titanium oxide film, It has a laminated structure.

  In the liquid crystal light valves 100 (R), (G), and (B) described with reference to FIGS. 1A and 1B, the incident side dustproof glass 103 and the emission side dustproof glass are provided on both sides of the liquid crystal panel 101. 104, each of the light-transmitting substrates 40b constituting the element substrate 40 and the light-transmitting substrate 10 constituting the counter substrate 50 is dust-proof glass as shown in FIG. In this case, the wire grid type polarizing element 10 may be formed on the thick translucent substrate 10.

  Furthermore, in the said form, although the wire grid type polarizing element 10 was formed in the opposing board | substrate 50, you may form in the direction of the element board | substrate 40, Moreover, a wire grid type polarizing element may be formed in both the opposing board | substrate 50 and the element board | substrate 40. 10 may be formed.

(A), (b) is the schematic block diagram of the projection type display apparatus (liquid crystal projector) to which this invention is applied, respectively, and the schematic block diagram of a liquid crystal light valve. FIG. 1 is a plan view of one pixel of an element substrate used for a liquid crystal light valve (liquid crystal device) in the projection display device shown in FIG. 1, and a cross section when the liquid crystal device is cut at a position corresponding to the line CC ′. FIG. (A), (b) is sectional drawing and the top view which each show typically the structure of the wire grid type polarizing element to which this invention is applied. It is process sectional drawing which shows the manufacturing method of the wire grid type polarizing element to which this invention is applied. It is process sectional drawing which shows another manufacturing method of the wire grid type polarizing element to which this invention is applied. It is a graph which shows the transmittance | permeability characteristic and contrast characteristic of the wire grid type polarizing element to which this invention is applied. It is sectional drawing of another liquid crystal light valve (liquid crystal device) used for the projection type display apparatus shown in FIG. It is a schematic block diagram of another liquid crystal light valve used for the projection type display apparatus (liquid crystal projector) to which this invention is applied. It is a schematic block diagram of another liquid crystal light valve used for the conventional projection type display apparatus (liquid crystal projector). (A), (b) is sectional drawing and the top view which respectively show the structure of the conventional wire grid type polarizing element typically. It is a graph which shows the transmittance | permeability characteristic and contrast characteristic of the conventional wire grid type polarizing element.

Explanation of symbols

10 .. Translucent substrate, 11 .. Groove-shaped recess, 15 .. Substrate surface, 20 .. Metal lattice, 40 .. Element substrate, 50 .. Opposite substrate, 100 .. Liquid crystal device, 100 (R), (G), (B) ... Liquid crystal light valve, 107 ... Wire grid type polarizing element

Claims (10)

In a liquid crystal device comprising: an element substrate on which a pixel electrode and a pixel switching element are formed; a counter substrate disposed opposite to the element substrate; and a liquid crystal held between the element substrate and the counter substrate.
At least one of the element substrate and the counter substrate has a plurality of rows of groove-like recesses formed on the substrate surface, and a wire grid type polarization element is formed by a metal grid embedded in the groove-like recesses. A liquid crystal device characterized by being made. The groove-like recess is completely embedded by the metal grid,
2. The liquid crystal device according to claim 1, wherein on the substrate surface, a formation surface of the groove-shaped recess and a region sandwiched by the groove-shaped recess form a continuous flat surface.   The wire grid type polarizing element has a transmittance of a polarization component oscillating in a direction perpendicular to the longitudinal direction of the metal grating of 80% or more over the entire wavelength band of 460 nm to 780 nm. Item 3. The liquid crystal device according to item 1 or 2.   4. The wire grid type polarizing element is formed on a substrate on a side on which light modulated by the liquid crystal layer is incident, of the element substrate and the counter substrate. The liquid crystal device according to one item.   The liquid crystal device according to claim 4, wherein the wire grid type polarizing element is formed on the counter substrate. A projection type display device using the liquid crystal device according to any one of claims 1 to 5,
A light source unit for allowing light to enter the liquid crystal device;
A projection optical system for enlarging and projecting light modulated by the liquid crystal device;
A projection display device characterized by comprising: In a method for manufacturing a liquid crystal device, comprising: an element substrate on which a pixel electrode and a pixel switching element are formed; a counter substrate disposed opposite to the element substrate; and a liquid crystal held between the element substrate and the counter substrate. ,
In forming a wire grid type polarizing element including a plurality of rows of metal gratings on at least one of the element substrate and the counter substrate,
A mask forming step of forming an etching mask having a groove-like opening in a region where the metal lattice is to be formed with respect to the substrate surface;
An etching step of etching the substrate surface to form a groove-shaped recess in a region overlapping the groove-shaped opening on the substrate surface;
A metal film forming step of filling the groove-shaped recess with a metal film to form the metal lattice;
A polishing process for removing the metal film protruding from the groove-shaped recess while polishing the substrate surface and leaving the metal film in the groove-shaped recess;
A method for manufacturing a liquid crystal device, comprising:   8. The method of manufacturing a liquid crystal device according to claim 7, wherein, in the mask forming step, after the photosensitive resin is applied to the substrate surface, the etching mask is formed by performing exposure and development.   In the mask forming step, a mask material layer is formed on the substrate surface, and then a molding surface provided with a protrusion is pressed against a portion corresponding to the groove-shaped opening in the mold member to form a pattern of the protrusion on the mask material layer. The method of manufacturing a liquid crystal device according to claim 7, wherein the etching mask having the groove-shaped opening formed thin is formed.   The method for manufacturing a liquid crystal device according to claim 7, wherein in the polishing step, chemical mechanical polishing is performed as the polishing.

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