Polarizing element, method for producing same, liquid crystal device, electronic apparatus, and projection display

A polarizing element includes a substrate; a plurality of protruded threads formed on one of surfaces of the substrate in a rough stripe pattern when viewed two-dimensionally, each of the protruded threads having a side surface forming a slope inclined with respect to the one surface of the substrate; a plurality of metal thin wires each formed on the slope of the each protruded thread so as to be cantilever-supported by the slope and each extended in an extension direction of the protruded thread; and a protection film covering the protruded threads and the metal thin wires.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority from Japanese Patent Application No. 2008-320951, filed on Dec. 17, 2008, the contents of which are incorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to a polarizing element, a method for producing the polarizing element, a liquid crystal device, an electronic apparatus, and a projection display.

2. Related Art

A variety of electro-optical apparatuses use a liquid crystal device as a light modulation device. In widely known liquid crystal devices, a liquid crystal layer is provided between a pair of substrates opposing each other. Additionally, it is common for such a liquid crystal device to include a polarizing element inputting a predetermined polarized light to the liquid crystal layer and an alignment film controlling alignment of liquid crystal molecules when no voltage is applied.

Among known polarizing elements, there are a thin-film polarizing element and a wire-grid polarizing element. The thin-film polarizing element is produced by extending a film made of resin containing iodine or a dichroic dye in a single direction to allow molecules of iodine or the dichroic dye to be aligned in the extension direction. The wire-grid polarizing element is formed by densely laying nano-scale metal thin wires on a substrate made of a transparent material.

The wire-grid polarizing element is made of an inorganic material. Thus, due to its excellent thermal resistance, the wire-grid polarizing element is suitably used particularly as a thermally-resistant constituent member, such as a polarizing element for a light valve of a liquid crystal projector. JP-A-2005-242379 discloses a structural example of the wire-grid polarizing element thus characterized.

As described above, the wire-grid polarizing element is excellent in thermal resistance as compared to a polarizing element made of an organic material, but tends to deteriorate due to oxidization of metal thin wires. For example, when a liquid crystal projector including a wire-grid polarizing element is continuously used for a long hour, the polarizing element continues to intercept light from a light source for the long hour and thus, heat storage occurs in the polarizing element. As a result, the oxidization of the metal thin wires is accelerated, thereby promoting deterioration. In order to prevent the oxidization, there is also proposed a technique for coating the metal thin wires with a different material for protection.

On the other hand, optical characteristics of the polarizing element are influenced by a refractive index of a material provided around the metal thin wires, so that a material with a refractive index of 1 seems to be desirable. In other words, it is desirable to place the metal thin wires in an air (or a vacuum). In this case, however, optical characteristics seem to be reduced when a region between the metal thin wires is completely filled with a protection material to protect the polarizing element.

SUMMARY

An advantage of the invention is to provide a wire-grid polarizing element that prevents deterioration due to the oxidization of metal thin wires and minimizes reduction of optical characteristics, and another advantage of the invention is to provide a method for producing the polarizing element. Additionally, still other advantages of the invention are to provide a liquid crystal device, an electronic apparatus, and a projection display, each of which includes the polarizing element and thereby exhibits high display quality and high reliability.

In order to solve the above problems, a polarizing element according to a first aspect of the invention includes a substrate; a plurality of protruded threads formed on one of surfaces of the substrate in a rough stripe pattern when viewed two-dimensionally, each of the protruded threads having a side surface forming a slope inclined with respect to the one surface of the substrate; a plurality of metal thin wires each formed on the slope of the each protruded thread so as to be cantilever-supported by the slope and each extended in an extension direction of the protruded thread; and a protection film covering the protruded threads and the metal thin wires.

In the structure above, the protection film protects the metal thin wires. Preventing oxidization of the metal thin wires leads to suppression of reduction in optical characteristics of the polarizing element. Consequently, the polarizing element can obtain good optical characteristics.

In the polarizing element of the aspect, preferably, in a region between adjacent pairs of the protruded thread and the metal thin wire is formed a space that is not filled with the protection film.

In the structure above, since the space is formed in the region between the adjacent pairs of the protruded thread and the metal thin wire, a part between the metal thin wires remains unburied in the protection film, so that the polarizing element can have excellent optical characteristics.

In the polarizing element of the aspect, preferably, an upper end surface of the protruded thread is roughly flat, and the each metal thin wire is protruded from the slope toward the upper end surface of the protruded thread in a manner so as to cover at least a part of the upper end surface when viewed two-dimensionally.

In the above structure, a width of the metal thin wires can be set with high flexibility.

In the polarizing element of the aspect, preferably, parts of the protection film covering adjacent pairs of the protruded thread and the metal thin wire contact with each other at an upper portion of the space formed between the adjacent pairs of the protruded thread and the metal thin wire.

In the structure above, the space formed between the adjacent metal thin wires can enclose an air or an atmospheric gas upon formation processing (or a vacuum). Thereby, the polarizing element can have excellent optical characteristics.

In the polarizing element of the aspect, preferably, the protection film is made of a translucent insulation material.

In the structure above, the metal thin wires are insulated from any surrounding members. Accordingly, for example, when the polarizing element is incorporated in an electronic device, no unintended electric current flow occurs between wires of the electronic device and the metal thin wires of the polarizing element. Thus, the electronic device can exhibit stable performance.

In the polarizing element of the aspect, preferably, the metal thin wires are made of a metal selected among silicon, germanium, and molybdenum.

Since the above-mentioned materials are not oxidized, the polarizing element does not deteriorate and thus can be highly reliable. Particularly, when the polarizing element is used for an application purpose under a high temperature condition, oxidization reaction is promoted under the high temperature environment. However, the polarizing element made of any one of the above metals can be highly durable.

A method for producing a polarizing element according to a second aspect of the invention, the polarizing element includes a plurality of protruded threads formed on one of surfaces of a substrate in a rough stripe pattern when viewed two-dimensionally, and a mask formed on an upper portion of each of the protruded threads. The method includes forming a plurality of metal thin wires each extended along the each protruded thread, each of the metal thin wires being made of a metal material deposited both on one of side surfaces of the protruded thread and on one side surface of the mask adjacent to the one side surface of the protruded thread; removing the mask; and forming a protection film covering the metal thin wires by a chemical vapor deposition process in such a manner that a region between adjacent pairs of the protruded thread and the metal thin wire includes a space that is not filled with the protection film.

Upon formation of the metal thin wires, there remains a resist as the mask, which can prevent the metal material from being deposited on an unnecessary part. In addition, since the metal material is deposited both on the protruded thread and on the mask, there can be obtained a wide deposition area, whereby a sufficient amount of the metal material can be deposited. Furthermore, each metal thin wire formed on one side wall surface of each protruded thread is protruded in the region between adjacent ones of the protruded threads.

Furthermore, the CVD process is characterized by that a forming film rapidly grows (film formation proceeds at high speed), thus allowing high-speed film formation. As the formation of the protection film proceeds, a region between adjacent metal thin wires is narrowed by an amount of thickness of the protection film, resulting that a raw material gas can hardly be spread between the adjacent metal thin wires and between the adjacent protruded threads. Thus, the film formation reaction can hardly be caused between the adjacent pairs of the protruded thread and the metal thin wire where the raw material gas can hardly be spread. Then, at an upper end portion of the each metal thin wire exposed to the raw material gas, a formation reaction of the protection film can easily proceed. Accordingly, the formation reaction of the protection film proceeds preferentially at the upper end portion of the each metal thin wire, and the protection film grows in a manner so as to narrow an upper gap between the adjacent metal thin wires.

In this case, the region including the metal thin wires where the protection film is formed has an indented configuration with many concealed portions when viewed two-dimensionally. When the protection film is formed by the CVD process, the raw material gas is hardly spread in the concealed portions, leading to a delayed growth of the protection film. Additionally, when the formation reaction of the protection film proceeds preferentially at the upper end portions of the metal thin wires, the raw material gas cannot be further spread in the region between the adjacent pairs of the protruded thread and the metal thin wire. Accordingly, the film growth in the region therebetween stops and the region remains unburied in the protection film. Thus, while the metal thin wires are effectively protected by the protection film, the region where the growth of the protection film is delayed is not buried in the protection film to form the space. Therefore, the method of the second aspect can easily produce the polarizing element that includes the space in the protection film and thereby exhibits excellent optical characteristics.

In the method of the second aspect, preferably, the one side surface of the mask is a slope that covers at least a part of the upper portion of the each protruded thread when viewed two-dimensionally.

In the method above, the metal thin wire formed on the one side surface of the mask result in two-dimensionally overlapping with the upper portion of the each protruded thread. In short, the metal thin wires covering the upper portions of the protruded threads can be easily formed, and the width of the metal thin wires can be easily controlled.

Preferably, in the method of the second aspect, before the metal thin wire formation step, the protruded thread formation step forms a resist having a predetermined pattern on one of surfaces of a base member forming the substrate and etches the base member via the resist to obtain the substrate having the protruded threads formed in the predetermined pattern, and the mask formation step forms the mask by using a part of the resist left on the upper portion of each of the protruded threads.

In the method above, the mask can be formed simultaneously with formation of the protruded threads. This can simplify a process of producing the polarizing element and can facilitate formation of the resist mask matching a shape of the protruded threads.

A projection display according to a third aspect of the invention includes an illumination optical system that outputs light, a liquid crystal light valve that modulates the light, the polarizing element of the first aspect that receives the light modulated by the liquid crystal light valve, and a projection optical system that projects polarized light transmitted through the polarizing element on a projected surface.

In the structure above, the projection display includes the polarizing element having high thermal resistance, which can suppress heat-induced deterioration of the polarizing element and oxidization-induced deterioration accelerated by heating even when a high power light source is used. Therefore, the obtained projection display can be highly reliable and can have excellent display characteristics.

A liquid crystal device according to a fourth aspect of the invention includes a pair of substrates, a liquid crystal layer provided between the substrates, and the polarizing element of the first aspect formed on a surface of at least one of the substrates, the surface facing the liquid crystal layer.

In the structure above, the liquid crystal device of the fourth aspect includes the polarizing element having excellent optical characteristics and having high reliability achieved by protection of the metal thin wires.

An electronic apparatus according to a fifth aspect of the invention includes the liquid crystal device of the fourth aspect.

In the structure above, the electronic apparatus of the fifth aspect includes a display section and a light modulation unit having high display quality and high reliability.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Embodiments of the invention will be described.

First Embodiment

Hereinafter, descriptions will be given of a polarizing element according to a first embodiment of the invention and a method for producing the polarizing element of the first embodiment by referring to the drawings.FIGS. 1Aand1B are schematic views showing a polarizing element1of the first embodiment.FIG. 1Ais a fragmentary perspective view of the polarizing element1, andFIG. 1Bis a fragmentary sectional view taken along a Y-Z plane of the polarizing element1.

In the descriptions below, an XYZ coordinate system will be set, and based on the XYZ coordinate system, positional relationships between constituent members will be explained. In this case, a predetermined direction within a horizontal plane is referred to as an X-axis direction; a direction orthogonal to the X-axis direction within the horizontal plane is referred to as a Y-axis direction; and a direction orthogonal to each of the X-axis direction and the Y-axis direction is referred to as a Z-axis direction. In the present embodiment, an extension direction of metal thin wires corresponds to the X-axis direction, and an arrangement direction of the metal thin wires corresponds to the Y-axis direction. In addition, in all of the drawings referred to below, film thicknesses of constituent elements, a size ratio among the elements, and the like are changed according to needs.

Polarizing Element

As shown inFIG. 1A, the polarizing element1includes a substrate11, a plurality of metal thin wires14extended in a single direction on the substrate14, and a protection film16covering the metal thin wires14.

The substrate11is made of a transparent material, such as glass, quartz, or plastic. Depending on application purposes of the polarizing element1, heat storage occurs in the polarizing element1, thereby causing a temperature increase in the polarizing element1. Accordingly, preferably, the substrate11is made of a highly thermal resistant material, such as glass or quartz.

On a surface of the substrate11are formed a plurality of grooved portions12extended in the X-axis direction. A portion between adjacent ones of the grooved portions12corresponds to each of a plurality of protruded threads13. The grooved portions12are formed at an equal interval in the Y-axis direction in a cycle shorter than a wavelength of visible light, and the protruded threads13are also formed in the same cycle.

Each of the metal thin wires14is provided on a side surface (a slope)13aof the each protruded thread13to be formed in a manner extending in the X-axis direction, which is same as the extension direction of the protruded thread13. The metal thin wire14transmits linearly polarized light vibrating in a direction orthogonal to the extension direction of the metal thin wire14(namely, in the Y-axis direction) and reflects linearly polarized light vibrating in the extension direction thereof14(namely, in the X-axis direction). The metal thin wire14is made of a metal such as aluminum.

On the substrate11is provided the protection film16covering surfaces of the substrate11and the metal thin wires14. The protection film16is made of a translucent insulation film, such as a silicon oxide film. The protection film16includes a first protection film16acovering a side surface13aof the each protruded thread13and the each metal thin wire14and extended in the X-axis direction, a second protection film16bcovering the upper portion of the each metal thin wire14and extended in the X-axis direction, and a third protection film16ccovering a bottom surface12aof each of the grooved portions12and extended in the X-axis direction.

Adjacent second protection films16bare mutually connected in the Y-axis direction and integrated all together to cover entire upper surfaces of the metal thin wires14. Each region surrounded by the first, the second, and the third protection films16a,16b, and16cforms a space15. An inside of the space15is filled with a vacuum, an air, or a raw material gas used upon formation of the protection film16. A surface of the second protection film16bnot facing the substrate11reflects a pattern of the metal thin wires14to be slightly wavy, where portions two-dimensionally overlapping with the metal thin wires14rise and portions two-dimensionally overlapping with the spaces15fall.

As shown inFIG. 1B, the side surface13aof the protruded thread13is formed so as to be inclined in a tapered manner in a direction receding from the bottom surface12a. A top surface13bof the protruded thread13is a flat surface approximately parallel to the bottom surface12aof the grooved portion12. Regarding sizes of the grooved portion12and the protruded thread13, for example, a height h1and a width L, respectively, of the protruded thread13are 100 nm and 70 nm, respectively, and a width S of the bottom surface12ais 70 nm, and a cycle (a pitch) d including the grooved portion12and the protruded thread13is 140 nm.

In each metal thin wire14, a part of an opposing surface14aopposing the protruded thread13is provided on the side surface13aof the protruded thread13, whereas a remaining part of the opposing surface14ais distant from the protruded thread13. Additionally, an upper end portion of the metal thin wire14(an end portion thereof in the Z-axis direction)14bis formed up to above the top surface13b. The part of the opposing surface14anot in contact with the side surface13atwo-dimensionally overlaps with the top surface13b.

A width of the metal thin wire14is closely related to performance of the polarizing element1. If the width of the metal thin wire14is controlled by a width in a +Y-axis direction from the side surface13a, the width of the metal thin wire14can be increased only by the width of the grooved portion12at maximum. However, in the embodiment, since the metal thin wire14is formed so as to cover the top surface13b, the width of the metal thin wire14can be set more flexibly. For example, the metal thin wire14may have a width b of 30 nm and a height h2of 30 nm.

A height H from the bottom surface12ato the upper surface of the second protection film16b(the upper surface of the protection film16) may be 200 nm, for example. In the present embodiment, the adjacent second protection films16bare connected with each other, but alternatively, may not necessarily be connected with each other. For example, in another possible structure, a small gap may be formed between the adjacent second protection films16b. In this case, the protection film16is formed for each of the metal thin wires16, resulting that the plurality of protection films16extended in the X-axis direction are arranged in a large number of rows in the Y-axis direction at equal intervals.

A thickness of the first protection film16a(a thickness thereof in the Y-axis direction) is set to a thickness in which adjacent first protection films16ado not contact with each other in the Y-axis direction (namely, in which the space15is formed between the first protection films16a). A width of the second protection film16bin the Y-axis direction is made larger than widths of the protruded thread13and the metal thin wire14including the first protection film16ain the Y-axis direction. Additionally, the third protection film16cis formed integrally with the first and the second protection films16aand16b. Then, a void surrounded by the first, the second, and the third protection films16a,16b, and16cis the space15.

In general, optical characteristics of a polarizing element are influenced by a refractive index of a material arranged around metal thin wires and a desirable refractive index seems to be 1.FIGS. 2A,2B, and2C are illustrations showing optical characteristic changes due to the refractive index of a material arranged around metal thin wires included in respective wire-grid polarizing elements.

FIG. 2Ais a graph and a schematic structural view showing optical characteristics (transmittance and contrast) of a wire-grid polarizing element in an air (the refractive index of 1).FIG. 2Bis a graph and a schematic structural view showing optical characteristics of a wire-grid polarizing element in which liquid crystal (a refractive index of 1.6) is filled around the metal thin wires, andFIG. 2Cis a graph and a schematic structural view showing optical characteristics of a wire-grid polarizing element in which a coating film (SiO2) is formed between metal thin wires and liquid crystal in such a manner that the liquid crystal is positioned on the coating film.

The graphs shown inFIGS. 2A,2B, and2C each indicate a calculation result of a transmittance Tp obtained when inputting linearly polarized light having a vibration direction parallel to a transmission axis of the polarizing element in each of the mentioned-above conditions (a vibration direction vertical to the extension direction of the metal thin wire) and a calculation result of a contrast (Tp/Ts) obtained as a ratio between the transmittance Tp and a transmittance Ts of linearly polarized light in a vibration direction parallel to a reflection axis of the polarizing element.

As shown inFIG. 2A, it is found that the polarizing element with the metal thin wires placed in the air exhibits good characteristics in a visible light region. In contrast, in the condition ofFIG. 2Bwhere the liquid crystal is filled in an opening portion between the metal thin wires, a uniformity of transmittance is reduced in the visible light region, and particularly, there is a significant drop in a region of blue color (a region near a wavelength of 440 nm). This indicates that the optical characteristics are reduced when a material having a refractive index higher than 1 is arranged around the metal thin wires.

Additionally, in the polarizing element having the structure shown inFIG. 2C, the coating film (SiO2) prevents the liquid crystal from being filled between the metal thin wires while an air is filled between the metal thin wires (or a vacuum is created between the wires). This structure causes no reduction in transmittance and contrast, as opposed to the structure shown inFIG. 2B, even though the wire-grid polarizing element is placed in the liquid crystal having the high refractive index. Thus, there can be provided good optical characteristics equal to those obtained in the structure ofFIG. 2A.

In the polarizing element1of the embodiment, the region between the metal thin wires14is not filled with the protection film16and has the space15.

Method for Producing Polarizing Element

FIGS. 3A to 3EandFIGS. 4A to 4Dare illustrations of steps for producing the polarizing element1.FIGS. 3A to 3Eillustrate steps for forming the metal thin wires14, andFIGS. 4A to 4Dillustrate steps for forming the protection film16. Each of the drawings corresponds to the sectional view ofFIG. 1B.

First, as shown inFIG. 3A, there is prepared a substrate member11A, such as a glass substrate. Then, a resist material is applied on one of surfaces of the base member11A by spin coating and then pre-baked to form a resist layer20a. For example, the resist material may be a chemical amplification type positive photoresist: TDUR-P338EM (manufactured by Tokyo Ohka Kogyo Co., Ltd.). In the embodiment, the resist layer20ahas a width of 200 nm.

Next, as shown inFIG. 3B, for example, the resist layer20ais exposed by a two-beam interference exposure system using a laser beam having a wavelength of 266 nm as an exposure light beam and then baked (post-exposure baking: PEB) to be developed. Thereby, there is formed a resist layer20having a striped pattern. The resist layer20of the embodiment has a height of 200 nm.

In this case, for example, an exposure apparatus used to perform the two-beam interference exposure system may be an exposure apparatus as shown inFIG. 5. An exposure apparatus120includes a laser light source121applying an exposure light beam, a diffraction beam splitter122, a monitor123, beam expanders124and125, mirrors126and127, and a stage128where the substrate11is to be mounted.

The laser light source121may be an Nd:YVO4 laser apparatus having a fourth-order harmonic wavelength of 266 nm, for example. The diffraction beam splitter122is a splitting unit generating two laser beams by splitting a single laser beam output from the laser light source121. The diffraction beam splitter122is structured to generate two diffracted beams (±first order) having an equal intensity when an incident laser beam is TE polarized light. The monitor123receives light emitted from the diffraction beam splitter122to convert the received light into an electric signal. Based on the converted electric signal, the exposure apparatus120can adjust an intersection angle of the two laser beams and the like.

The beam expander124includes a lens124aand a space filter124band expands a beam diameter of one of the two laser beams split by the diffraction beam splitter122to approximately 200 mm, for example. Similarly, the beam expander125also includes a lens125aand a space filter125band expands a beam diameter of the other one of the two laser beams.

The mirrors126and127, respectively, reflect a laser beam transmitted though the beam expanders124and125, respectively, toward the stage128. The mirrors126and127generate interference light by intersecting the laser beams to apply the interference light to the resist layer20aon the substrate11.

In this manner, the resist layer20acan be exposed at a formation pitch narrower than the wavelength of the laser light source121by the exposure apparatus120applying the interference light onto the resist layer20a.

Next, as shown inFIG. 3C, by performing dry etching via the resist20, the substrate material11A is etched down by approximately 50 to 100 nanometers to perform a patterning of the substrate material11A so as to form the substrate11having the grooved portions12and the protruded threads13. In the present embodiment, the etching is performed to remove approximately 100 nanometers for the grooved portions12. Additionally, in the dry etching, the resist20formed on the substrate material11A is also etched, whereby a remaining resist21used as a mask in a later step remains on the top surface13bof the protruded thread13.

As an etching gas in the embodiment, a mixture gas is used that contains C2F6, CF4, and CHF3. As reaction conditions in etching, for example, a gas flow rate of C2F6:CF4:CHF3is 20:30:30 sccm, discharge power is 300 W, pressure is 5 Pa, and reaction time ranges from 30 to 40 sec.

Next, as shown inFIG. 3D, a known magnetron sputtering apparatus is used to form the metal thin wires14in such a manner that each of the metal thin wires14straddles the side surface31aof the protruded thread13and a side surface21aof the remaining resist21. In the drawing, each of arrows indicates a flying direction of sputtered particles. Due to the presence of the remaining resist21, deposition of a metal film on an unnecessary portion can be prevented, as well as the sputtered particles can be deposited in the manner straddling both the side surfaces13aand21a. Thus, the metal thin wires14can be formed so as to have a large bottom area and a large volume.

The metal thin wires14are formed on an entire part of at least a region where the polarizing element is formed on the substrate11. In order to form the metal thin wires14, there may be used any of known oblique deposition methods, such as ion beam sputtering, other than magnetron sputtering. As reaction conditions in the embodiment, a gas flow rate of Ar is 10 sccm, discharge power is 1000 W, pressure is 0.1 Pa, and reaction time ranges from 2 to 4 min The metal thin wires14are formed on an entire part of at least a region where the polarizing element is formed on the substrate11. In order to form the metal thin wires14, there may be used any of known oblique deposition methods, such as ion beam sputtering, other than magnetron sputtering. As reaction conditions in the embodiment, a gas flow rate of Ar is 10 sccm, discharge power is 1000 W, pressure is 0.1 Pa, and reaction time ranges from 2 to 4 min.

In the embodiment, the metal thin wires14are made of aluminum. However, other than aluminum, silicon, germanium, or molybdenum may be suitable. When aluminum is used for the metal thin wires14, deterioration may occur because aluminum is an easily oxidized metal although processing of aluminum is easy. Accordingly, among the metal materials mentioned above, silicon, germanium, or molybdenum hardly oxidized is preferably used, since those materials can prevent deterioration of the metal thin wires14.

For example, when the polarizing element is used for a purpose in a high temperature state, an oxidization reaction is accelerated under the high temperature environment. However, when the metal thin wires14are made of any of the above materials, the polarizing element can have a high thermal resistance. In addition, according to needs, an alloy mainly containing those materials may be used for the material of the metal thin wires14.

Next, as shown inFIG. 3E, ashing is performed to remove the remaining resist21remaining on the top surface13bof the protruded thread13. The removal of the remaining resist21exposes a part of the opposing surface14ain contact with the side surface of the remaining resist21in the each metal thin wire14, whereby the metal thin wire14contacts only with the side surface13aof the protruded thread13. As reaction conditions, a gas flow rate of O2is 50 sccm, pressure is 10 Pa, reaction time is 30 sec, and ICP/Bias power is 60/30 W.

Next, as shown inFIGS. 4A to 4D, the protection film is formed on the metal thin wires14by a chemical vapor deposition (CVD) process. In this case, as the method for forming the protection film16, besides the CVD process, for example, evaporation or sputtering may be possible among commonly used methods. However, in the case of evaporation, an angle of a film raw material emitted to a forming surface of the protection film from an arrangement position of the film raw material in an evaporation device varies depending on positions on the forming surface, so that a distance between the film raw material and the forming surface is not exactly constant. Accordingly, a thickness of the produced protection film varies and thus, a quality of the polarizing element is not constant. Additionally, a film formation speed in sputtering is extremely slow, and therefore, it is difficult to obtain a film formation speed expected in the embodiment. As a result, the embodiment is possible when the CVD process is used for film formation.

First, as shown inFIG. 4A, the substrate11with the metal thin wires14is placed under a work environment of the CVD process and then a raw material gas16gof the protection film16is supplied. The raw material gas16gspreads down to the bottom surface12a, thereby forming the protection film16. In the embodiment, as the protection film16, a silicon oxide film is formed, and the raw material gas16gused is a mixture gas of tetraethoxysilane (TEOS) and oxygen O2. In the drawing, TEOS and O2are both shown as the raw material gas16g, without showing them distinctively from each other.

Other than silicon oxide, the protection film16may be made of an insulation material, such as silicon nitride (SiN), silicon nitrogen oxide (SiON), alumina (Al2O3), or the like. Then, in accordance with the material of the protection film16selected, the material of the raw material gas16gcan also be selected. In addition, the CVD process may be a thermal CVD process or a plasma CVD process. The present embodiment uses the plasma CVD process. In reaction conditions in the CVD process of the embodiment, for example, a gas flow rate of TEOS:O2is 12:388 sccm, power is 400 W, pressure is 40 Pa, reaction temperature is 110° C., and reaction time is 2 min.

As shown in the drawing, with reaction of the raw material gas16g, the protection film16generated by chemical reaction is deposited on surfaces of the adjacent metal thin wires14and the substrate11. The film formation speed of the protection film16may be 100 nm/min, for example. In an initial stage of the film formation, the protection film16is deposited on the bottom surfaces12a, the side surfaces13a, the top surfaces13b, and outer peripheries of the metal thin wires14. As the reaction proceeds, the protection film16grows in a manner so as to cover the metal thin wires14. Additionally, a distance between adjacent protection films16formed around adjacent metal thin wires14is gradually narrowed by an amount of thickness of the grown protection film16.

Next, as shown inFIG. 4B, when the reaction further proceeds, the distance between the adjacent metal thin wires14is narrowed by the amount of the thickness of the protection film16. This almost hinders entry of the raw material gas16ginto the grooved portions12. Accordingly, reactions of the raw material gas16goccur one after another in the protection film16formed on the metal thin wires14before the raw material gas16genters into the grooved portions12, resulting that formation of the protection film16proceeds preferentially on the metal thin wires14.

In that case, if reaction speed is slow, there is a sufficient time to allow the raw material gas16gto spread into the grooved portions12even when the distance between the metal thin wires14is narrowed by the thickness of the protection film16. Accordingly, the protection film16is not formed preferentially on the metal thin wires14and the reaction proceeds on an entire surface. Thereby, formation of the protection film16allows the grooved portions12to be gradually buried. However, it is not desirable that the grooved portions12are buried, in terms of optical characteristics. Therefore, in the present embodiment, with high reaction speed, the grooved portions12are formed.

Each of the metal thin wires14of the embodiment is protruded like a peaked portion from one of the side surfaces13aof the protruded thread13to the Y-axis direction. On the surface of the metal thin wire14thus formed, in order to allow the protection film16to be deposited near a lower end portion of the metal thin wire14indicated by a reference numeral14c, it is necessary that the raw material gas16genters into the grooved portion12, flows round the metal thin wire14, and then reaches the lower end portion14c. Accordingly, deposition of the protection film16is extremely difficult on the lower end portion14c. Depending on reaction conditions, the metal thin wire14may be exposed out in the space15at the lower end portion14c.

Next, as shown inFIG. 4C, as the reaction further proceeds, adjacent protection films16continuously growing on the adjacent metal thin wires14abut with each other. Thereby, between the adjacent metal thin wires14is formed the space15surrounded by the protection film16.

Next, as shown inFIG. 4D, as the reaction still further proceeds, a front surface of the protection film16is gradually flattened, resulting in formation of the protection film16having a large thickness. In this manner, the polarizing element1of the embodiment is completed.

In the polarizing element1thus formed, the metal thin wires14are protected by the protection film16, so that oxidization of the metal thin wires14can be prevented. Additionally, the space15is formed in the region between the respective portions including the protruded threads13and the metal thin wires14, whereby the polarizing element1can be highly reliable and can have excellent optical characteristics.

In the embodiment, the second protection films16bprovided on the upper end portions14bof the adjacent metal thin wires14contact with each other in a direction parallel to an arrangement axis direction. Accordingly, between the metal thin wires14is formed the space15capable of enclosing the air or an atmospheric gas upon formation processing (or a vacuum), thereby allowing the polarizing element1to have excellent optical characteristics.

Additionally, in the embodiment, the protection film16is made of a translucent insulation material. Since the metal thin wires14are covered with the insulation material to be insulated from surrounding members. Thus, for example, when the polarizing element1is incorporated in an electronic apparatus, no electric current flows between the metal thin wires14and wires of the apparatus.

In the method for producing the polarizing element1thus formed, when forming the metal thin wires14, the presence of the remaining resist21can prevent deposition of a metal material on an unnecessary portion. Additionally, since the metal material is deposited both on the protruded thread13and on the remaining resist21, there can be obtained a wide area for deposition, thereby securing a sufficient amount of deposition. In addition, the protection film16protects and reinforces the metal thin wires14, thus preventing deterioration and damage induced due to oxidization of the metal thin wires14. Consequently, the polarizing element1having excellent optical characteristics can be easily produced.

Furthermore, in the embodiment, the CVD process is used to form the protection film16. The CVD process is characterized by high-speed film formation. Thereby, as the film formation proceeds, film formation reactions occur before the raw material gas16gspreads in the space15, and the protection film grows preferentially on the upper end portion of each of the metal thin wires14. Then, growth of the film between the metal thin wires14stops and thus the region between the metal thin wires14is not buried in the protection film16, thereby facilitating production of the polarizing element1having excellent optical characteristics.

Additionally, in the embodiment, the metal thin wires14are protected only by the protection film16. Alternatively, a plurality of deposition films may be laminated furthermore on the protection film16.

Projection Display

Next, a description will be given of an electronic apparatus according to an embodiment of the invention. A projector800shown inFIG. 6includes a light source810, dichroic mirrors813and814, reflecting mirrors815,816, and817, an incident lens818, a relay lens819, an output lens820, light modulation sections822,823, and824, a cross dichroic prism825, and a projection lens826.

The light source810includes a lamp811such as a metal halide lamp, and a reflector812reflecting light of the lamp. As the light source810, besides the metal halide lamp, there may be mentioned an ultra-high pressure mercury lamp, a flash mercury lamp, a high pressure mercury lamp, a deep UV lamp, a xenon lamp, a xenon flash lamp, or the like.

The dichroic mirror813transmits red light included in white light from the light source810and reflects blue light and green light. The transmitted red light is reflected by the reflecting mirror817to be input to the light modulation section822for red light. Of the blue light and the green light reflected by the dichroic mirror813, the green light is reflected by the dichroic mirror814and input to the light modulation section823for green light. The blue light is transmitted through the dichroic mirror814and input to the light modulation section824for blue light via a relay optical system821including the incident lens818, the relay lens819, and the output lens820provided to prevent optical loss due to a long optical path.

In each of the light modulation sections822to824, on opposite sides of a liquid crystal light valve830are arranged an input polarizing element840and an output polarizing element section850so as to sandwich the light valve830therebetween. The input polarizing element840and the output polarizing element section850are positioned such that transmission axes of the polarizing element840and the polarizing element section850intersect with each other (a cross nicol arrangement).

The input polarizing element840is a reflecting polarizing element that reflects light of a vibration direction orthogonal to the transmission axis.

The output polarizing element section850includes a first polarizing element (a pre-polarization plate or a pre-polarizer)852and a second polarizing element854. The first polarizing element852corresponds to the above-described polarizing element according to the embodiment of the invention. The second polarizing element854is a polarizing element made of an organic material. In the output polarizing element section850, the polarizing elements852and854are both a light-absorbing polarizing element and work together to absorb light.

In general, such a light-absorbing polarizing element made of an organic material tends to deteriorate due to heat and thus cannot be used as a polarization unit for a large power projector requiring a high level of luminance. However, in the projector800of the embodiment, the first polarizing element852made of an inorganic material having high thermal resistance is arranged between the second polarizing element854and the liquid crystal light valve830, and the polarizing elements852and854cooperate to absorb light. Thereby, deterioration of the second polarizing element854made of an organic material is suppressed.

The three color light beams modulated by the respective light modulation sections822to824are input to the cross dichroic prism825. The cross dichroic prism825is formed by adhering together four square prisms. On interfaces of the square prisms are formed a dielectric multilayer reflecting red light and a dielectric multilayer reflecting blue light in an X-letter shape. The three color light beams are synthesized by the dielectric multilayers to generate light representing color images. The synthesized light is projected on a screen827by the projection lens826, whereby color images are enlarged to be displayed.

In the projector800thus formed, the output polarizing element section850includes the polarizing element of the embodiment described above, so that deterioration of the polarizing element can be suppressed even when using a high power light source. Accordingly, the projector800can be highly reliable and can have excellent display characteristics.

Liquid Crystal Device

FIG. 7is a schematic sectional view showing an example of a liquid crystal device300according to an embodiment of the invention. The liquid crystal300includes the polarizing element of the embodiment. The liquid crystal device300of the embodiment is formed by providing a liquid crystal layer350between an element substrate310and an opposing substrate320.

The element substrate310and the opposing substrate320, respectively, include polarizing elements330and340, respectively. The polarizing elements330and340are both the polarizing element of the described-above polarizing element of the embodiment and have a structure in which metal thin wires with the protection film are formed on a substrate made of a transparent material such as glass, quartz, or plastic.

The polarizing element330includes a substrate main body331and a metal thin wire332, and the polarizing element340includes a substrate main body341and a metal thin wire342. In the embodiment, the substrate main bodies331and341correspond to the substrate of each of the polarizing elements and also correspond to a substrate of the liquid crystal device. In addition, the metal thin wire332and the metal thin wire342intersect with each other. In each of the polarizing elements330and340, the metal thin wires are arranged on an inner surface side of the element (a side of the each element facing the liquid crystal layer350).

On the inner surface side of the polarizing element330are provided a pixel electrode314, a not-shown wire, and a TFT element, along with an alignment film316. Similarly, on the inner surface side of the polarizing element340are provided a common electrode324and an alignment film326.

In the liquid crystal device thus formed, the substrate main bodies331and341serve as the substrate for the liquid crystal device and the substrate for the polarizing element, so that a total number of components can be reduced. Thus, a thickness of the liquid crystal device as a whole can be reduced, thereby improving a function of the liquid crystal device300. Furthermore, since the device structure is simplified, the production of the liquid crystal device can be facilitated and cost reduction can be promoted.

Electronic Apparatus

Next, a description will be given of an electronic apparatus according to an embodiment of the invention.FIG. 8is a perspective view showing an example of the electronic apparatus including the liquid crystal device ofFIG. 7. A mobile phone (an electronic apparatus)1300shown inFIG. 8includes the liquid crystal device of the embodiment as a small display section1301, a plurality of operation buttons1302, an earpiece1303, and a mouthpiece1304. Thereby, the mobile phone1300can be highly reliable and can obtain a display section achieving high-quality display.

Furthermore, besides the above mobile phone, the liquid crystal device of the embodiment can be suitably used as an image displaying unit for an electronic book, a personal computer, a digital still camera, a liquid crystal television, a view finder type or direct view type video tape recorder, a car navigation device, a pager, an electronic organizer, an electronic calculator, a word processor, a work station, a TV phone, a point-of-sale (POS) terminal, an apparatus with a touch panel, or the like.

While some preferred embodiments of the invention have been described with reference to the accompanying drawings, it is obvious that the invention is not restricted to the embodiments. The shapes of the constituent members and the combination of the members shown in the embodiments are merely examples, and various modifications and changes can be made based on design requirements or the like without departing from the scope of the invention.