JP2018036670A - Polarizer and manufacturing method of polarizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarizer exhibiting excellent optical characteristics and a manufacturing method of the polarizer.SOLUTION: A polarizer comprises: a translucent substrate 11 transmitting light in a use band; an absorption layer 12 that includes at least a metal-based semiconductor layer containing metal, and that is arranged in one-dimensional grid shape at narrower pitches than wavelength of the light in the use band; and a reflection layer 14 that is arranged in one-dimensional grid shape at narrower pitches than the wavelength of the light in the use band. The absorption layer 12 and the reflection layer 14 are stacked from the translucent substrate 11 side in this order or the reflection layer 14 and the absorption layer 12 are stacked from the translucent substrate 11 side in this order.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polarizing plate that absorbs one of orthogonal polarization components (so-called P-polarized wave and S-polarized wave) and transmits the other, and a method of manufacturing the polarizing plate.

  In the liquid crystal display device, it is indispensable to dispose a polarizing plate on the surface of the liquid crystal panel from the principle of image formation. The function of the polarizing plate is to absorb one of orthogonally polarized components (so-called P-polarized wave and S-polarized wave) and transmit the other.

  Conventionally, as such a polarizing plate, a dichroic polarizing plate in which an iodine-based or dye-based high molecular organic substance is contained in a film is often used. As these general production methods, a method is used in which a polyvinyl alcohol film and a dichroic material such as iodine are dyed, followed by crosslinking using a crosslinking agent and uniaxial stretching. Thus, since the dichroic polarizing plate is produced by stretching, it generally tends to shrink. In addition, since the polyvinyl alcohol film uses a hydrophilic polymer, it is very easily deformed particularly under humidified conditions. Moreover, since a film is fundamentally used, the mechanical strength as a device is weak, and it may be necessary to adhere a transparent protective film.

  In recent years, the use of liquid crystal display devices has been expanded and their functions have been enhanced. Accordingly, high reliability and durability are required for each device constituting the liquid crystal display device. For example, in the case of a liquid crystal display device that uses a light source with a large amount of light, such as a transmissive liquid crystal projector, the polarizing plate receives strong radiation. Therefore, excellent heat resistance is required for the polarizing plate used in these. However, since the film-based polarizing plate as described above is an organic substance, there are naturally limitations in improving these characteristics.

  In the United States, Corning sells a highly heat-resistant inorganic polarizing plate under the name Polarcor. This polarizing plate has a structure in which silver fine particles are diffused in glass, and does not use organic substances such as a film. The principle uses plasma resonance of island-shaped fine particles. That is, light absorption by surface plasma resonance when light is incident on noble metal or transition metal island-like particles is used, and the absorption wavelength is affected by the particle shape and the surrounding dielectric constant. Here, when the shape of the island-shaped fine particles is elliptical, the resonance wavelengths in the major axis direction and the minor axis direction are different, thereby obtaining polarization characteristics. Specifically, a polarization component parallel to the major axis on the longer wavelength side is obtained. A polarization characteristic of absorbing and transmitting a polarization component parallel to the minor axis is obtained. However, in the case of Polarcor, the wavelength range in which the polarization characteristics can be obtained is a region close to the infrared region, and does not cover the visible light range required for a liquid crystal display device. This is due to the physical properties of silver used in the island-shaped fine particles.

Patent Document 1 discloses a UV polarizing plate by applying the above principle to deposit fine particles in glass by thermal reduction, and proposes to use silver as metal fine particles. In this case, it is considered that absorption in the minor axis direction is used contrary to the previous Polarcor. Figure1
As shown in Fig. 4, although it functions as a polarizing plate even in the vicinity of 400 nm, the extinction ratio is small and the band that can be absorbed is very narrow, so even if Polarcor and the technique of Patent Document 1 are combined, It cannot be a polarizing plate that can be covered.

Non-Patent Document 1 describes a theoretical analysis of an inorganic polarizing plate using plasma resonance of metal island-shaped fine particles. According to this document, it is described that aluminum fine particles have a resonance wavelength shorter than that of silver fine particles by about 200 nm, and therefore it is possible to produce a polarizing plate that covers the visible light region by using aluminum fine particles.

  Patent Document 2 discloses several methods for producing a polarizing plate using aluminum fine particles. Among them, it is described that a glass based on silicate is not desirable as a substrate because aluminum and glass react with each other, and calcium aluminoborate glass is suitable (paragraphs 0018 and 0019). However, glass using silicate is widely distributed as optical glass, and it is economically undesirable that a highly reliable product can be obtained at a low cost and this is not suitable. In addition, a method for forming island-shaped particles by etching a resist pattern is described (paragraphs 0037 and 0038). Usually, a polarizing plate used in a projector needs to have a size of several centimeters and a high extinction ratio. Therefore, when the polarizing plate for visible light is aimed, the resist pattern size is sufficiently shorter than the visible light wavelength, that is, a size of several tens of nanometers is necessary, and in order to obtain a high extinction ratio, It is necessary to form a pattern with high density. Further, when used for a projector, it is necessary to form a pattern with a large area. However, in the method of applying high-density fine pattern formation by lithography as described, it is necessary to use electron beam drawing or the like to obtain such a pattern. Electron beam drawing is a method of drawing individual patterns from an electron beam, and is not practical because of poor productivity.

  Further, Patent Document 2 describes that aluminum is removed by chlorine plasma. However, when etching is usually performed, chloride adheres to the sidewall of the aluminum pattern. Chloride can be removed with a commercially available wet etchant (for example, SST-A2 from Tokyo Ohka Kogyo Co., Ltd.), but chemicals that react with aluminum chloride react with aluminum even though the etching rate is slow. It is difficult to realize a desired pattern shape by such a method.

  Furthermore, Patent Document 2 describes another method of depositing aluminum on a patterned photoresist by oblique film formation and removing the photoresist (paragraphs 0045 and 0047). However, in such a method, it is considered that it is necessary to deposit aluminum on the substrate surface to some extent in order to obtain adhesion between the substrate and aluminum. However, this means that the shape of the deposited aluminum film is different from prolate spheres including prolate ellipsoids, which are suitable shapes described in paragraph 0015. In addition, paragraph 0047 describes that the overprecipitation integral is removed by anisotropic etching perpendicular to the surface. In order to function as a polarizing plate, the shape anisotropy of aluminum is extremely important. Therefore, it is considered necessary to adjust the amount of aluminum deposited on the resist portion and the substrate surface so that a desired shape can be obtained by etching. However, as described in paragraph 0047, the submicron is 0.05 μm or less. It is considered very difficult to control these by size, and it is doubtful whether it is suitable as a production method with high productivity. In addition, a high transmittance is required in the direction of the transmission axis as a characteristic of the polarizing plate. Usually, when glass is used for the substrate, reflection of several percent from the glass interface is inevitable, and it is difficult to obtain a high transmittance. .

Patent Document 3 describes a polarizing plate by oblique vapor deposition. This method obtains polarization characteristics by manufacturing a micro-columnar structure by oblique deposition of a transparent and opaque material with respect to the wavelength of the used band. Unlike Patent Document 1, a fine pattern is obtained by a simple method. Therefore, it is considered a highly productive method. However, the aspect ratio of the micro-columnar structure of the material that is opaque to the band used, the interval between the individual micro-columnar structures, and the linearity are important factors for obtaining good polarization characteristics. However, this method uses the phenomenon that the columnar structure is obtained by the fact that the next flying vapor particles do not deposit in the shadowed part of the initial deposition layer of vapor deposition particles. Therefore, it is difficult to intentionally control the above items. As a method for improving this, a method of providing a polishing mark on a substrate by rubbing before vapor deposition is described, but in general, the particle diameter of the vapor deposition film is about several tens of nanometers at maximum. In order to control the anisotropy of such particles, it is necessary to intentionally produce a submicron pitch by polishing. However, in a general polishing sheet or the like, the limit is about submicron, and it is not easy to manufacture such a fine polishing mark. In addition, as described above, the resonance wavelength of the Al fine particles greatly depends on the refractive index of the surroundings. In this case, a combination of transparent and opaque substances is important. However, Patent Document 3 discloses a good polarization in the visible light region. There is no description of combinations for obtaining characteristics. Similarly to Patent Document 1, when glass is used as the substrate, reflection of several percent from the glass interface is inevitable.

Non-Patent Document 2 describes a polarizing plate for infrared communication called Lamipol. This has a laminated structure of Al and SiO ₂ and shows a very high extinction ratio according to this document. Further, Non-Patent Document 3 describes that a high extinction ratio can be realized at a wavelength of 1 μm or less by using Ge instead of Al that is responsible for Lamipol's light absorption. In addition, it is expected that a high extinction ratio can be obtained from FIG. 3 to Te (tellurium) in the same document. As described above, Lamipol is an absorptive polarizing plate that provides a high extinction ratio. However, since the thickness of the light-absorbing material and the transparent material is the size of the light-receiving surface, Lamipol is used for projector applications that require a size of several cm square Not suitable for polarizing plates.

  Patent Document 4 describes a polarizing plate that combines a wire grid structure and an absorption film. When a metal or semiconductor film is used for the absorption film, it is strongly influenced by the optical characteristics of the material. Therefore, the reflectance in a specific area is reduced by adjusting the dielectric film thickness between the material, the wire grid, and the absorption film. It is possible, but it is difficult to realize this in a wide wavelength range.

  In addition, it is possible to widen the band by using highly absorptive Ta, Ge, etc., but the absorption in the transmission axis direction simultaneously increases, and the transmittance in the transmission axis direction, which is an important characteristic of the polarizing plate, is increased. It will decline.

  As an improvement measure for the above problem, there is application of fine particles to the absorption film. However, the method of directly depositing the absorption film using the oblique film formation that has been proposed so far relies on self-organization by shadowing of the absorption film to be deposited, so the physical properties of the material itself, the roughness of the substrate, etc. The absorption characteristics were difficult to control.

US Pat. No. 6,772,608 JP 2000-147253 A JP 2002-372620 A JP 2008-216957 A

J. et al. Opt. Soc. Am. A Vol. 8, no. 4 619-624 Applied Optics Vol. 25 No. 21986 311-314 J. et al. Lightwave Tec. Vol. 15No. 6 1997 1042-1050

  This invention is proposed in view of such a situation, and it aims at providing the manufacturing method of the polarizing plate which has the outstanding optical characteristic, and a polarizing plate.

  As a result of intensive studies, the present inventors have found that by using a metal-containing semiconductor layer containing a metal as the light absorption layer, the reflectance is reduced and excellent optical properties can be obtained, and the present invention is completed. It came.

  That is, the polarizing plate according to the present invention has at least a light-transmitting substrate that transmits light in a use band and a metal-containing semiconductor layer containing a metal, and has a one-dimensional lattice shape with a pitch smaller than the wavelength of light in the use band. And a reflection layer arranged in a one-dimensional lattice pattern with a pitch smaller than the wavelength of light in the use band, and the absorption layer and the reflection layer are arranged in this order from the translucent substrate side. The reflective layer and the absorbing layer are laminated in this order from the side of the transparent substrate.

  The polarizing plate manufacturing method according to the present invention includes an absorbing layer having at least a metal-containing semiconductor layer containing a metal and a reflective layer on a light-transmitting substrate that transmits light in a use band. And a grid structure arranged in a one-dimensional lattice pattern at a pitch smaller than the wavelength of light in the use band is formed by etching.

  According to the present invention, by using a metal-containing semiconductor layer containing a metal having a high extinction coefficient corresponding to light absorption as the light absorption layer, it becomes possible to improve light absorption more than the semiconductor layer. The reflectance can be lowered as compared with the metal layer, and excellent optical characteristics can be obtained.

FIG. 1 is a schematic cross-sectional view showing a first polarizing plate according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a second polarizing plate according to the embodiment of the present invention. FIG. 3 is a schematic sectional view showing a conventional polarizing plate. FIG. 4A is a graph showing the optical characteristics of the polarizing plate of the comparative example, and FIG. 4B is a graph showing the reflectance of the polarizing plate of the comparative example. FIG. 5 is a schematic cross-sectional view showing the polarizing plate of Example 1. 6A is a graph showing the optical characteristics of the polarizing plate of Example 1, and FIG. 6B is a graph showing the reflectance of the polarizing plate of Example 1. FIG. FIG. 7 is a schematic cross-sectional view showing a polarizing plate used for the first simulation. FIG. 8 is a schematic cross-sectional view showing a polarizing plate used for the second simulation. FIG. 9 is a graph showing optical characteristics when Si containing 5 atm% Fe is used as the absorbing layer in the first simulation. FIG. 10 is a graph showing optical characteristics when Si containing 10 atm% Fe is used as the absorption layer in the first simulation. FIG. 11 is a graph showing optical characteristics when Si containing 5 atm% Fe is used as the absorbing layer in the second simulation. FIG. 12 is a graph showing optical characteristics when Si containing 10 atm% Fe is used as the absorbing layer in the second simulation. FIG. 13A is a graph showing the etching depth with respect to the etching time, and FIG. 13B is a table showing the calculation result of the etching rate. FIG. 14 is a schematic cross-sectional view showing a polarizing plate used in the simulation of Example 4. FIG. 15 is a graph showing optical characteristics when the thickness of the dielectric layer is 5 nm. FIG. 16 is a graph showing optical characteristics when the thickness of the dielectric layer is 20 nm. FIG. 17 is a graph showing optical characteristics when the thickness of the dielectric layer is 35 nm. FIG. 18 is a graph showing optical characteristics when the thickness of the dielectric layer is 50 nm. FIG. 19 is a schematic cross-sectional view showing the polarizing plate of Example 5. FIG. 20 is a graph showing optical characteristics when Si is used as the absorption layer. FIG. 21 is a graph showing optical characteristics when Si containing 20 atm% Ta is used as the absorbing layer. FIG. 22 is a graph showing optical characteristics when Si containing 25 atm% Ta is used as the absorbing layer. FIG. 23 is a graph showing optical characteristics when Si containing 33 atm% Ta is used as the absorbing layer. FIG. 24 is a graph showing the absorption axis reflectivity when Si, Si containing 20 atm%, Si containing 25 atm% Ta, Si containing 33 atm% Ta, and Ta are used as the absorbing layer, respectively. is there. FIG. 25 is a graph showing the difference between the maximum value and the minimum value in the measurement wavelength range of the absorption axis reflectivity with respect to the atomic percentage of Ta. FIG. 26 is a graph showing the transmission axis transmittance when Si, Ta containing 20 atm% Si, Ta containing 25 atm% Si, Ta containing 33 atm% Si, and Ta are used as the absorbing layer, respectively. is there. FIG. 27 is a graph showing the average value in the measurement wavelength range of the transmission axis transmittance with respect to the atomic percentage of Ta. FIG. 28 is a schematic cross-sectional view showing the polarizing plate of Example 6. FIG. 29 is a graph showing the absorption axis reflectance when the thickness of the dielectric layer in the polarizing plate of Example 6 is 2.5 nm, 5.0 nm, 7.5 nm, and 10.0 nm, respectively. 30 is a schematic sectional view showing the polarizing plate of Example 7. FIG. FIG. 31 is an SEM image of a cross section of the polarizing element of Example 7. FIG. 32A is a graph showing the optical characteristics of the polarizing plate of Example 7, and FIG. 32B shows the transmission axis in each wavelength band of red (Red), green (Green), and blue (Blue). It is a table | surface which shows the average value of the transmittance | permeability Tp, the absorption-axis transmittance | permeability Ts, contrast CR (Tp / Ts), the transmission-axis reflectance Rp, and the absorption-axis reflectance Rs. FIG. 33 is a schematic sectional view showing the polarizing plate of Example 8. FIG. 34 is an SEM image of a cross section of the polarizing element of Example 8. FIG. 35 (A) is a graph showing the optical characteristics of the polarizing plate of Example 8, and FIG. 35 (B) shows the transmission axis in each wavelength band of red (Red), green (Green), and blue (Blue). It is a table | surface which shows the average value of the transmittance | permeability Tp, the absorption-axis transmittance | permeability Ts, contrast CR (Tp / Ts), the transmission-axis reflectance Rp, and the absorption-axis reflectance Rs.

Hereinafter, embodiments of the present invention will be described in detail in the following order with reference to the drawings.
1. 1. Configuration of polarizing plate 2. Manufacturing method of polarizing plate Example

<1. Configuration of polarizing plate>
The polarizing plate according to the present embodiment has at least a light-transmitting substrate that transmits light in a use band and a metal-containing semiconductor layer containing a metal, and has a one-dimensional lattice shape with a pitch smaller than the wavelength of light in the use band. And a reflecting layer arranged in a one-dimensional lattice pattern with a pitch smaller than the wavelength of light in the use band, and the absorbing layer and the reflecting layer are laminated in this order from the translucent substrate side. Or a reflection layer and an absorption layer are laminated in this order from the light transmitting substrate side. That is, the polarizing plate according to the present embodiment has an absorption layer and a reflection layer formed in this order with respect to incident light. Further, a dielectric layer arranged in a one-dimensional lattice pattern at a pitch smaller than the wavelength of light in the use band may be provided between the absorption layer and the reflection layer.

  FIG. 1 is a schematic cross-sectional view showing a first polarizing plate according to an embodiment of the present invention. As shown in FIG. 1, the first polarizing plate has at least a light-transmitting substrate 11 that transmits light in the use band and a metal-containing semiconductor layer containing metal, and a pitch smaller than the wavelength of light in the use band. The absorption layers 12 arranged in a one-dimensional lattice, the dielectric layers 13 arranged in a one-dimensional lattice at a pitch smaller than the wavelength of light in the use band, and the pitch smaller than the wavelength of light in the use band. The reflective layer 14 is arranged in a one-dimensional lattice pattern, and the absorbing layer 12, the dielectric layer 13, and the reflective layer 14 are laminated in this order from the light transmitting substrate 11 side. That is, in the first polarizing plate 1, convex portions in which the absorption layer 12, the dielectric layer 13, and the reflective layer 14 are laminated in this order from the light transmitting substrate 11 side are arranged on the light transmitting substrate 11 at regular intervals. It has a one-dimensional lattice-like wire grid structure.

  FIG. 2 is a schematic sectional view showing a second polarizing plate according to the embodiment of the present invention. As shown in FIG. 2, the second polarizing plate has at least a light-transmitting substrate 11 that transmits light in the use band and a metal-containing semiconductor layer containing metal, and a pitch smaller than the wavelength of light in the use band. The absorption layers 12 arranged in a one-dimensional lattice, the dielectric layers 13 arranged in a one-dimensional lattice at a pitch smaller than the wavelength of light in the use band, and the pitch smaller than the wavelength of light in the use band. The reflective layer 14 is arranged in a one-dimensional lattice pattern, and the reflective layer 14, the dielectric layer 13, and the absorbing layer 12 are laminated in this order from the light transmitting substrate 11 side. That is, in the second polarizing plate 1, the convex portions in which the reflective layer 14, the dielectric layer 13, and the absorption layer 12 are laminated in this order from the light transmitting substrate 11 side are arranged on the light transmitting substrate 11 at regular intervals. It has a one-dimensional lattice-like wire grid structure.

  In such a first or second polarizing plate, the width of at least a part of the absorption layer 12 or the dielectric layer 13 of the convex portion of the one-dimensional lattice-like wire grid structure is narrower than the width of the reflective layer 14. In particular, it is more preferable that the width of the absorption layer 12 is narrower than the width of the reflection layer 14. Thereby, the transmittance | permeability of a polarizing plate can be increased and a reflectance can be reduced.

  The translucent substrate 11 is made of a material having a refractive index of 1.1 to 2.2, such as glass, sapphire, and quartz, which is transparent to light in the use band. In the present embodiment, it is preferable to use a crystal or sapphire substrate with high thermal conductivity as a constituent material of the light-transmitting substrate 11. Thereby, it has high light resistance with respect to intense light, and becomes useful as a polarizing plate for an optical engine of a projector that generates a large amount of heat.

  Further, when the light-transmitting substrate 11 is made of an optically active crystal such as quartz, excellent optical characteristics can be obtained by arranging the lattice-like convex portions in a direction parallel to or perpendicular to the optical axis of the crystal. it can. Here, the optical axis is a direction axis that minimizes the difference in refractive index between O (ordinary ray) and E (extraordinary ray) of light traveling in that direction.

  Depending on the use of the polarizing plate, glass, particularly quartz (refractive index 1.46) or soda lime glass (refractive index 1.51) may be used. The component composition of the glass material is not particularly limited. For example, an inexpensive glass material such as silicate glass widely distributed as optical glass can be used, and the manufacturing cost can be reduced.

The absorption layer 12 is composed of one or more layers having at least a metal-containing semiconductor layer containing a metal. Since the metal-containing semiconductor layer contains a metal having a high extinction coefficient corresponding to light absorption, the metal-containing semiconductor layer can improve light absorption as compared with the semiconductor layer, and can reduce reflectance as compared with the metal layer.

  As the semiconductor of the metal-containing semiconductor layer, any one of Si, Ge, Te, ZnO, and the like can be used. Since the band gap energy of the semiconductor is involved in the light absorption effect of the semiconductor, it is necessary that the band gap energy is equal to or lower than the use band. For example, when using visible light, it is necessary to use a semiconductor having a wavelength of 400 nm or more, that is, a band gap of 3.1 eV or less. Also, as the metal of the metal-containing semiconductor layer, one or more kinds of pure metals or alloys of Ta, Al, Ag, Cu, Au, Mo, Cr, Ti, W, Ni, Fe, Sn, Nb, etc. should be used. Can do.

  Moreover, it is preferable that the metal content of a metal containing semiconductor layer is 50 atm% or less. If the metal content of the metal-containing semiconductor layer is too high, the transmittance will decrease. The semiconductor of the metal-containing semiconductor layer is preferably Si that can be easily formed. More preferable combinations of the metal-containing semiconductor layer include Si containing Fe, Si containing Ta, and the like.

  The absorbing layer 12 preferably further includes a metal layer in addition to the metal-containing semiconductor layer, and the width of the metal layer is preferably narrower than the width of the reflective layer 14. Thereby, the reflectance of a polarizing plate can be reduced. The width of the absorption layer 12 can be controlled by etching, and the side etching amount can be controlled by the etching gas pressure and the pressure of He gas for cooling the substrate.

  Moreover, it is preferable that the absorption layer 12 further has a metal layer or a semiconductor layer in addition to the metal-containing semiconductor layer. Thereby, reflection can be suppressed, the transmittance can be improved, and the contrast (extinction ratio: transmission axis transmittance / absorption axis transmittance) can be increased.

When Si containing Fe is used as the metal-containing semiconductor layer, the Fe content is preferably 50 atm% or less. When the Fe content is more than 50 atm%, etching becomes difficult even if the gas type is devised. Furthermore, in order to enable etching with CF ₄ widely used in semiconductor etching processes, it is preferably 10 atm% or less.

  Further, when Si containing Fe is used as the metal-containing semiconductor layer, it is preferable to further provide a Ta layer as the absorption layer 12 in order to increase the reflectance reduction effect. When the Ta layer is provided, the absorption layer 12 is preferably formed in the order of the Ta layer and the metal-containing semiconductor layer with respect to the light incident direction. Further, the metal-containing semiconductor layer is preferably thicker than the Ta layer. Thereby, a low reflectance can be obtained and a high transmittance can be obtained. Also, the contrast (extinction ratio: transmission axis transmittance / absorption axis transmittance) can be increased by enhancing the absorption effect and the interference effect.

  Moreover, when Si containing Ta is used as the metal-containing semiconductor layer, the Ta content is preferably 40 atm% or less. In the range where the Ta content is 40 atm% or less, the reflectance is 4% or less equivalent to the glass interface level, and the transmittance is also a high value. Therefore, in practice, the reflectance is reduced and the transmittance is kept high. Can do.

Further, when Si containing Ta is used as the metal-containing semiconductor layer, it is preferable to further provide a Ta layer as the absorption layer 12 in order to enhance the effect of reducing the reflectance. When the Ta layer is provided, the absorption layer 12 is preferably formed in the order of the Ta layer and the metal-containing semiconductor layer with respect to the light incident direction. Further, the metal-containing semiconductor layer is preferably thicker than the Ta layer. Thereby, a low reflectance can be obtained and a high transmittance can be obtained. Also, the contrast (extinction ratio: transmission axis transmittance / absorption axis transmittance) can be increased by enhancing the absorption effect and the interference effect.

  The absorption layer 12 is preferably formed with a high density film by vapor deposition or sputtering. Since the density of the film is high, thermal conductivity can be improved and heat dissipation can be improved.

  The dielectric layer 13 is formed with a film thickness such that the phase of the polarized light transmitted through the absorption layer 12 and reflected by the reflection layer 14 is shifted by a half wavelength with respect to the light incident from the transparent substrate 11 side. The specific film thickness is appropriately set within a range of 1 to 500 nm that can adjust the phase of polarized light and enhance the interference effect. In this embodiment mode, since the light reflected by the absorption layer 12 is absorbed, an improvement in contrast can be realized even if the film thickness is not optimized. In practice, the desired polarization characteristics are balanced with the actual manufacturing process. You can decide on

A general material such as SiO ₂ , Al ₂ O ₃ , or MgF ₂ can be used as the material constituting the dielectric layer 13. In addition, the refractive index of the dielectric layer 13 is preferably greater than 1.0 and 2.5 or less. Note that the optical characteristics of the absorption layer 12 are also affected by the refractive index of the surroundings, and therefore the polarizing plate characteristics may be controlled by the material of the dielectric layer 13.

  The reflective layer 14 is formed by arranging a metal thin film extending in a band shape in the Y direction as an absorption axis on the dielectric layer 13. That is, the reflective layer 14 has a function as a wire grid polarizer, and has an electric field component in a direction parallel to the longitudinal direction of the wire grid (Y-axis direction) out of light incident from the translucent substrate 11 side. A polarized wave (TE wave (S wave)) is attenuated, and a polarized wave (TM wave (P wave)) having an electric field component in a direction (X-axis direction) orthogonal to the longitudinal direction of the wire grid is transmitted.

  The constituent material of the reflective layer 14 is not particularly limited as long as it is a material having reflectivity with respect to light in the use band. For example, Al, Ag, Cu, Mo, Cr, Ti, Ni, W, Fe, Si, A single metal such as Ge or Te, an alloy containing these, or a semiconductor material can be used. In addition to the metal material, for example, it may be composed of an inorganic film or a resin film other than a metal formed with high surface reflectance by coloring or the like.

The pitch, line width / pitch, thin film height (thickness, lattice depth), and thin film length (lattice length) of the reflective layer 14 are preferably in the following ranges, respectively.
0.05μm <pitch <0.8μm
0.1 <(line width / pitch) <0.9
0.01 μm <thin film height <1 μm
0.05μm <thin film length

In addition, it is preferable to provide a protective film that covers the surfaces of the light-transmitting substrate 11 and the grid-shaped convex portions as long as the change in optical characteristics does not affect the practical use. For example, by depositing SiO ₂ or the like, reliability such as moisture resistance can be improved. As a method for forming the protective film, it is preferable to use plasma CVD (Chemical Vapor Deposition). By using plasma CVD, a protective film can be deposited also in the gaps between the lattice-shaped convex portions.

According to the polarizing plate having such a configuration, a polarized wave (TE wave) having an electric field component parallel to the grating of the reflective layer is utilized by utilizing four actions of transmission, reflection, interference, and selective light absorption of the polarized wave. (S wave)) can be attenuated and a polarized wave (TM wave (P wave)) having an electric field component perpendicular to the grating can be transmitted. That is, the TE wave is attenuated by the selective light absorption action of the polarized wave of the absorption layer 12, and the TE wave transmitted through the absorption layer 12 and the dielectric layer 13 is reflected by the grid-like reflection layer 14 functioning as a wire grid. Is done. Here, by appropriately adjusting the thickness and refractive index of the dielectric layer 13, the TE wave reflected by the reflective layer 14 is partially reflected when passing through the absorbing layer 12 and returned to the reflective layer 14. In addition, the light that has passed through the absorption layer 12 can be attenuated by interference. A desired polarization characteristic can be obtained by selectively attenuating the TE wave as described above.

  In addition, the polarizing plate according to the present embodiment uses a metal-containing semiconductor layer containing a metal having a high extinction coefficient corresponding to light absorption as the light absorption layer, thereby improving light absorption more than the semiconductor layer. In addition, the reflectance can be lowered as compared with the metal layer, and excellent optical characteristics can be obtained. Therefore, the design range of the polarizing plate can be expanded more than before, and a polarizing plate having a desired extinction ratio in the visible light region can be provided.

  In addition, since the polarizing plate according to the present embodiment is made of an inorganic material that is more durable than an organic material, the polarizing plate exhibits high light resistance against strong light used in a liquid crystal projector and obtains high reliability. be able to. Further, since the reflectance can be reduced in a wide wavelength range, it can be applied to a general-purpose polarizing plate such as a polarizing filter for a camera or a polarizing plate for a liquid crystal TV.

<2. Manufacturing method of polarizing plate>
Next, the manufacturing method of a polarizing plate is demonstrated. In the manufacturing method of the polarizing plate according to the present embodiment, an absorption layer having at least a metal-containing semiconductor layer containing a metal and a reflective layer are arranged in this order or reverse on a light-transmitting substrate that transmits light in a use band. Are stacked in this order, and a grid structure arranged in a one-dimensional lattice pattern at a pitch smaller than the wavelength of light in the use band is formed by etching.

  Here, the manufacturing method of the 1st polarizing plate shown in FIG. 1 is demonstrated. In the first polarizing plate manufacturing method, first, the absorption layer 12, the dielectric layer 13, and the reflective layer 14 are formed in this order on the translucent substrate 11.

  The absorption layer 12 is formed by vapor deposition or sputtering. Specifically, the translucent substrate 11 is disposed facing the target at the time of film formation, the argon gas particles are made to collide with the target, and the target component that is repelled by the impact is attached onto the substrate, thereby absorbing layer 12. Get. The metal-containing semiconductor layer can be formed by using, for example, a metal-containing semiconductor target such as an Fe-containing silicon target or a Ta-containing silicon target.

  Further, the dielectric layer 13 and the reflective layer 14 are formed by a general vacuum film forming method such as sputtering, vapor phase growth, or vapor deposition, or a sol-gel method (for example, a sol is coated by a spin coating method and gelled by thermosetting. (Method).

On the reflective layer 14 thus formed, a lattice-like mask pattern is formed by nanoimprinting, photolithography, or the like, and then a lattice-like convex portion is formed by dry etching. Examples of the dry etching gas include Ar / O ₂ for the antireflection film (BARC), Cl ₂ / BCl _{3 for} AlSi, SiO ₂ , Si, and Ta for CF ₄ / Ar. Further, by optimizing the etching conditions (gas flow rate, gas pressure, power, substrate cooling temperature), a highly perpendicular lattice shape can be realized. Further, the width (X-axis direction) of the absorption layer 12 can be adjusted depending on the etching conditions.

Further, when etching between the grids forming the grid-like convex portions, in order to suppress redeposition due to etching and to reliably remove the metal at the substrate interface, it is transparent such as SiO ₂ and Ta ₂ O ₅ and CF A material that can be easily etched by ₄ may be formed on the substrate as long as the polarization performance is not affected. The material may be partially or completely removed by etching.

  When Al or AlSi is used for the reflective layer 14, it is desirable to select materials that can be etched with fluorine for the absorbing layer 12 and the dielectric layer 13. By doing so, a high etching selection ratio can be obtained, the width of the designed film thickness of the absorption layer 12 and the dielectric layer 13 can be widened, which is advantageous in process construction.

In addition, a protective film such as SiO ₂ can be deposited on the uppermost portion for the purpose of improving reliability such as moisture resistance, as long as the change in optical characteristics does not affect the application.

<3. Example>
Examples of the present invention will be described below. Here, as the absorption layer, a polarizing plate using a metal-containing semiconductor layer containing a metal was prepared, and optical characteristics were evaluated. The present invention is not limited to these examples.

[Comparative example]
FIG. 3 is a schematic sectional view showing a conventional polarizing plate. A 20 nm Ta layer, 50 nm SiOx, and 60 nm Al were sequentially formed on the light-transmitting substrate by sputtering, and dry etching was performed to form a grid structure having a pitch of 140 nm.

  FIG. 4A is a graph showing the optical characteristics of the polarizing plate of the comparative example, and FIG. 4B is a graph showing the reflectance of the polarizing plate of the comparative example. As shown in FIGS. 4 (A) and 4 (B), Ta works effectively as a light absorbing film, but the absolute value of the reflectance is less than 10%, and is used in a normal liquid crystal TV or liquid crystal monitor. This is much higher than the reflectance of organic polarizing plates. Thus, with the conventional polarizing plate, it is difficult to obtain a low reflectance in a wide visible wavelength range.

[Example 1]
FIG. 5 is a schematic cross-sectional view showing the polarizing plate of Example 1. On the light-transmitting substrate, Ta was formed with a thickness of 10 nm, (Fe5%) Si was formed with 15 nm, SiOx was formed with 30 nm, and Al was formed with a thickness of 60 nm by sputtering, followed by dry etching to form a grid structure with a pitch of 140 nm. (Fe 5%) Si was formed using a silicon target containing 5 atm% Fe.

  6A is a graph showing the optical characteristics of the polarizing plate of Example 1, and FIG. 6B is a graph showing the reflectance of the polarizing plate of Example 1. FIG. As can be seen from a comparison between FIG. 6B and FIG. 4B, the polarizing plate of Example 1 was able to significantly reduce the reflectance. In particular, the reflectance in the green region where the visibility is high can be reduced to 2% or less. Moreover, the polarizing plate of Example 1 was able to reduce a reflectance in the visible wavelength wide range compared with the comparative example. Thus, it has been found that the reflectance can be significantly reduced by using a metal-containing semiconductor layer containing a metal as the absorbing layer.

[Example 2]
Next, the effect of reducing the reflectivity of the metal-containing semiconductor layer was verified by simulation using the RCWA (Rigorous Coupled Wave Analysis) method.

FIG. 7 is a schematic sectional view showing a polarizing plate used for the first simulation, and FIG. 8 is a schematic sectional view showing a polarizing plate used for the second simulation. The polarizing plate used in the first simulation has a structure in which a reflective layer, a dielectric layer, and an absorbing layer are formed from the substrate side, like the second polarizing plate shown in FIG. 2, and contains Fe in the absorbing layer. Si, SiO ₂ was used for the dielectric layer, and Al was used for the reflective layer. The polarizing plate used for the second simulation is a structure in which an absorbing layer, a dielectric layer, and a reflecting layer are formed from the substrate side, like the first polarizing plate shown in FIG. Si contained, SiO ₂ was used for the dielectric layer, and Al was used for the reflective layer.

FIG. 9 is a graph showing optical characteristics when Si containing 5 atm% Fe is used as the absorbing layer in the first simulation. The polarizing plate used in this simulation had a grid structure with a pitch of 140 nm and was laminated from the substrate side with 100 nm of Al, 20 nm of SiO ₂ and 25 nm of Si containing 5% Fe.

FIG. 10 is a graph showing optical characteristics when Si containing 10 atm% Fe is used as the absorption layer in the first simulation. The polarizing plate used for this simulation had a grid structure with a pitch of 140 nm, and was laminated with 15 nm of Si containing 100 nm of Al, 50 nm of SiO ₂ and 10% of Fe from the substrate side.

FIG. 11 is a graph showing optical characteristics when Si containing 5 atm% Fe is used as the absorbing layer in the second simulation. The polarizing plate used in this simulation had a grid structure with a pitch of 140 nm and was laminated with 25 nm of Si containing 5 atm% Fe, 20 nm of SiO ₂ and 100 nm of Al from the substrate side.

FIG. 12 is a graph showing optical characteristics when Si containing 10 atm% Fe is used as the absorbing layer in the second simulation. The polarizing plate used in this simulation had a grid structure with a pitch of 140 nm, and was formed by laminating 15 nm of Si containing 10 atm% Fe, 50 nm of SiO ₂ and 100 nm of Al from the substrate side.

  As shown in FIGS. 9 and 11, when Si having an Fe content of 5 atm% is used for the absorption layer, the reflectance in a wide wavelength region is not sufficiently reduced, but the wavelength of 500 nm which is important as a polarizing plate for visible light is used. The reduction of the reflectance in the green area is sufficient, and it can be used for a channel polarizing plate for a liquid crystal projector. In order to reduce the reflectance in a wide wavelength region, it is effective to stack Ta as in the first embodiment.

  Further, as shown in FIGS. 10 and 12, when Si having an Fe content of 10 atm% is used for the absorption layer, the reflectance is reduced in a wide wavelength region without stacking Ta as in Example 1. It is possible to make it. Thus, it was found that the reflectance can be adjusted by the Fe content, and the effect of reducing the reflectance in a wide wavelength region is enhanced by increasing the Fe content.

[Example 3]
Next, the influence of the Fe content in the actual manufacturing process was verified. Here, the etching rate of Fe-containing Si was measured when CF ₄ was used as the etching gas. The CF-based etching gas is a gas that is widely used for fine etching of MEMS, semiconductors, and the like. (Fe5%) Si, (Fe10%) Si, and (Fe15%) Si were formed on the individual glass substrates, respectively, and these were subjected to etching treatment collectively.

  FIG. 13A is a graph showing the etching depth with respect to the etching time, and FIG. 13B is a table showing the calculation result of the etching rate. As shown in FIG. 13B, (Fe5%) Si has an etching rate of 0.973 nm / sec, (Fe10%) Si has an etching rate of 0.234 nm / sec, and (Fe15%) Si was not etched. In other words, it was found that the etching rate decreases and the etching becomes difficult when the Fe content increases.

  Although there is a report that Fe can be etched if ammonia is used as the etching gas, this structure is not a Fe-containing Si single layer, but a plurality of layers are laminated, so it affects other layers (corrosion during etching). In view of etching anisotropy), it is not suitable for use. Also, there is a method of physical removal with argon gas, but this structure has a fine pitch, so that re-adhesion is likely to occur, causing deterioration of characteristics.

For the reasons described above, it is considered that an Fe content of more than 50 atm% is difficult even if the gas type is devised. Therefore, the Fe content is preferably 50 atm% or less, more practically 10 atm% or less that can be etched with CF ₄ widely used in semiconductor etching processes. When the Fe content is 10 atm% or less, it is preferable to stack Ta in order to increase the reflectance reduction effect.

[Example 4]
Even in the structure using Si containing Fe in the absorption layer, there is an interference effect between the reflection layer, the dielectric layer, and the absorption layer, and therefore the reflectance varies depending on the thickness of the dielectric layer. Therefore, in Example 4, the reflectivity due to the film thickness of the dielectric layer was verified by simulation using the RCWA method.

FIG. 14 is a schematic cross-sectional view showing a polarizing plate used in the simulation of Example 4. The polarizing plate of Example 4 had a grid structure with a pitch of 140 nm, and was obtained by laminating 25 nm of Si containing 100 nm of Al, SiO ₂ , and 5% of Fe from the substrate side.

  15 to 18 are graphs showing optical characteristics when the thickness of the dielectric layer is 5 nm, 20 nm, 35 nm, and 50 nm, respectively. As can be seen from FIGS. 15 to 18, the reflectance can be reduced by controlling the film thickness of the dielectric layer. When the film thickness of the dielectric is 5 nm, 20 nm, 35 nm, and 50 nm, the reflectivity is high, but the reflectivity can be lowered by stacking Ta as in Example 1.

  15 to 18, it can be seen that increasing the film thickness of the dielectric layer increases the absorption effect and interference effect, and increases CR (extinction ratio: transmission axis transmittance / absorption axis transmittance). It was.

  In addition, the thickness of the dielectric layer is preferably thin because etching time is shortened and the manufacturing process is advantageous. For example, the polarizing plate of the simulation result shown in FIG. 10 requires a long etching time because the dielectric layer has a thickness of 50 nm and Si containing 10 atm% Fe is used as the absorbing layer.

[Example 5]
Next, a sample was actually produced and verified for the Ta content of a polarizing plate using Ta-containing Si as an absorption layer.

FIG. 19 is a schematic cross-sectional view showing the polarizing plate of Example 5. The polarizing plate of Example 5 had a grid structure with a pitch of 140 nm, and was laminated from the substrate side with an absorption layer of 30 nm, SiO ₂ of 30 nm, and Al of 40 nm.

  20 to 23 are graphs showing optical characteristics when Si, Si containing 20 atm%, Si containing 25 atm%, and Si containing 33 atm% Ta are used as the absorption layer, respectively. .

FIG. 24 shows Si and T containing 20 atm% of Si and Ta as the absorption layer, respectively.
It is a graph which shows the absorption-axis reflectance when Si containing 25 atm% of a, Si containing 33 atm% of Ta, and Ta are used. FIG. 25 is a graph showing the difference between the maximum value and the minimum value in the measurement wavelength range of the absorption axis reflectance with respect to the atomic percentage of Ta.

  Moreover, FIG. 26 shows the transmission axis transmittance when Si, Ta containing 20 atm% Si, Ta containing 25 atm% Si, Ta containing 33 atm% Si, and Ta are used as the absorbing layer, respectively. It is a graph. FIG. 27 is a graph showing the average value in the measurement wavelength range of the transmission axis transmittance with respect to the atomic percentage of Ta.

  As shown in FIG. 25, the difference between the maximum value and the minimum value in the measurement wavelength range of the absorption axis reflectance becomes smaller as the Ta content increases, and it is preferable that the Ta content is larger as the absorption type polarizing plate. Become. On the other hand, as shown in FIG. 27, the average value of the transmission axis transmittance in the measurement wavelength range becomes smaller as the Ta content increases, and it is preferable that the Ta content is smaller.

  25 and 27 that the Ta content is preferably 40 atm% or less. While the reflectivity of a general float glass is 8%, in the range where the Ta content is 40 atm% or less, the reflectivity is equal to or less than that of glass, and the transmittance is also high. , Reduction in reflectance and high transmittance can be maintained.

  In Example 4, the structure of the first polarizing plate shown in FIG. 1 was used, but the same effect can be obtained even if the structure of the second polarizing plate shown in FIG. 2 is used.

[Example 6]
In Example 3, the reflectance according to the film thickness of the dielectric layer was described. In Example 6, a sample was actually manufactured and verified for the wavelength of the minimum value of the reflectance due to the film thickness of the dielectric layer.

FIG. 28 is a schematic cross-sectional view showing the polarizing plate of Example 6. The polarizing plate of Example 5 had a grid structure with a pitch of 140 nm and was laminated with 35 nm of Si containing 220 nm of Al, SiO ₂ , and 5 atm% of Fe from the substrate side.

  FIG. 29 is a graph showing the absorption axis reflectance when the thickness of the dielectric layer in the polarizing plate of Example 6 is 2.5 nm, 5.0 nm, 7.5 nm, and 10.0 nm, respectively. As shown in FIG. 29, it was found that the wavelength of the minimum value of the absorption axis reflectance can be controlled by the thickness of the dielectric layer. Further, since the reflectivity is reduced even when the thickness of the dielectric layer is as thin as 2.5 nm, it has been found that there is no need for the dielectric layer depending on the wavelength for which low reflectivity is desired.

30 is a schematic cross-sectional view showing the polarizing plate of Example 7, and FIG. 31 is an SEM image of the cross section of the polarizing element of Example 7. The polarizing plate of Example 7 was produced as follows. First, on a light-transmitting substrate having a thickness of 0.7 mm (product name: Eagle 2000, manufactured by Corning), SiO ₂ is 15 nm as a base film, Ta is 15 nm as an absorption layer A, and Si is 10 nm as an absorption layer B (Fe 5%). The dielectric layer was formed by sputtering with SiOx of 40 nm and the reflective layer with Al of 170 nm in this order. (Fe 5%) Si was formed using a silicon target containing 5 atm% Fe.

Moreover, BARC (Bottom Anti-Reflective Coat) was formed on the reflective layer, and a lattice-like mask pattern was formed with a resist. Next, BARC was removed by scum treatment with Ar / O ₂ gas, and Al was etched with Cl ₂ / BCl ₃ . Thereafter, the corrosive layer (chlorinated compound) was removed by H ₂ O plasma, and the resist and BARC were removed by O ₂ ashing. Then, the absorption layer was etched with CF ₄ / Ar gas to form lattice-shaped convex portions, and a polarizing plate having a grid structure with a pitch of 140 nm was produced. The etching conditions of the absorption layer were CF ₄ gas flow rate: 20 sccm, Ar gas flow rate: 4 sccm, CF ₄ / Ar gas pressure: 0.5 Pa, He gas pressure for cooling: 400 Pa, etching time: 80 sec. The width of the Ta layer of the polarizing plate of Example 7 was almost the same as the width W of the Al layer.

  FIG. 32A is a graph showing the optical characteristics of the polarizing plate of Example 7, and FIG. 32B shows the transmission axis in each wavelength band of red (Red), green (Green), and blue (Blue). It is a table | surface which shows the average value of the transmittance | permeability Tp, the absorption-axis transmittance | permeability Ts, contrast CR (Tp / Ts), the transmission-axis reflectance Rp, and the absorption-axis reflectance Rs. As in Example 1, the polarizing plate of Example 7 was able to reduce the reflectance over a wide visible wavelength range as compared with the comparative example. Moreover, the polarizing plate of Example 7 was able to obtain high contrast CR.

FIG. 33 is a schematic cross-sectional view showing the polarizing plate of Example 8, and FIG. 34 is an SEM image of the cross section of the polarizing element of Example 8. The polarizing plate of Example 8 was produced in the same manner as the polarizing plate of Example 7 except for the etching conditions of the absorption layer. The etching conditions of the absorption layer were CF ₄ gas flow rate: 20 sccm, Ar gas flow rate: 4 sccm, CF ₄ / Ar gas pressure: 2.0 Pa, cooling He gas pressure: 1000 Pa, and etching time: 80 sec. The width of the Ta layer of the polarizing plate of Example 8 was formed narrower than the width W of the Al layer.

  FIG. 35 (A) is a graph showing the optical characteristics of the polarizing plate of Example 8, and FIG. 35 (B) shows the transmission axis in each wavelength band of red (Red), green (Green), and blue (Blue). It is a table | surface which shows the average value of the transmittance | permeability Tp, the absorption-axis transmittance | permeability Ts, contrast CR (Tp / Ts), the transmission-axis reflectance Rp, and the absorption-axis reflectance Rs. In the polarizing plate of Example 8, the contrast CR was substantially the same as that of Example 7, but the reflectance could be lowered as compared with Example 7. This was particularly noticeable in the blue wavelength band (430 nm-510 nm).

  11 translucent substrate, 12 absorbing layer, 13 dielectric layer, 14 reflecting layer

That is, the polarizing plate according to the present invention has at least a light-transmitting substrate that transmits light in the use band and a metal-containing semiconductor layer containing Fe, and has a one-dimensional lattice shape with a pitch smaller than the wavelength of light in the use band. And a reflection layer arranged in a one-dimensional lattice pattern with a pitch smaller than the wavelength of light in the use band, and the absorption layer and the reflection layer are arranged in this order from the translucent substrate side. laminated comprising, or from said light transmitting substrate side and the reflective layer and the absorbing layer is Ri Na are laminated in this order, the semiconductor of the metal-containing semiconductor layer is a Si, Fe-containing the metal-containing semiconductor layer the amount, characterized in der Rukoto following 10 atm%.

Moreover, the manufacturing method of the polarizing plate which concerns on this invention is the absorption layer which has at least the metal containing semiconductor layer whose Fe content is 10 atm% or less and whose semiconductor is Si on the transparent substrate which permeate | transmits the light of a use zone | band. And a reflective layer are laminated in this order or in the reverse order, and a grid structure arranged in a one-dimensional lattice pattern at a pitch smaller than the wavelength of light in the use band is formed by etching.

Claims (21)

A light-transmitting substrate that transmits light in the use band;
An absorption layer having at least a metal-containing semiconductor layer containing a metal and arranged in a one-dimensional lattice pattern at a pitch smaller than the wavelength of light in a use band;
A reflective layer arranged in a one-dimensional lattice at a pitch smaller than the wavelength of light in the use band,
The polarizing plate in which the absorption layer and the reflection layer are laminated in this order from the light transmitting substrate side, or the reflection layer and the absorption layer are laminated in this order from the light transmission substrate side.   The polarizing plate according to claim 1, further comprising a dielectric layer arranged in a one-dimensional lattice pattern at a pitch smaller than a wavelength of light in a use band between the absorption layer and the reflection layer. The semiconductor of the metal-containing semiconductor layer is any one of Si, Ge, Te, ZnO,
The metal of the metal-containing semiconductor layer is Ta, Al, Ag, Cu, Au, Mo, Cr, Ti, W, Ni, Fe, Sn, Nb, one or more pure metals or alloys,
The polarizing plate according to claim 1, wherein the metal content of the metal-containing semiconductor layer is 50 atm% or less.   The polarizing plate according to any one of claims 1 to 3, wherein a width of at least a part of the absorbing layer or the dielectric layer is narrower than a width of the reflective layer.   The polarizing plate according to claim 4, wherein the absorption layer further includes a metal layer, and the width of the metal layer is narrower than the width of the reflective layer.   The polarizing plate according to claim 5, wherein the absorption layer is formed in the order of the metal layer and the metal-containing semiconductor layer with respect to a light incident direction.   The polarizing plate according to claim 5 or 6, wherein the metal layer is a Ta layer.   The polarizing plate according to claim 5, wherein the metal of the metal-containing semiconductor layer is Fe.   The polarizing plate according to claim 1, wherein the absorption layer further includes a metal layer or a semiconductor layer.   The polarizing plate according to claim 1, wherein the semiconductor of the metal-containing semiconductor layer is Si.   The polarizing plate according to claim 10, wherein the metal of the metal-containing semiconductor layer is Fe.   The polarizing plate according to claim 11, wherein the metal-containing semiconductor layer has an Fe content of 50 atm% or less.   The polarizing plate according to claim 11 or 12, wherein the absorption layer further comprises a Ta layer.   The polarizing plate according to claim 13, wherein the absorption layer is formed in the order of the Ta layer and the metal-containing semiconductor layer with respect to a light incident direction.   The polarizing plate according to claim 14, wherein the metal-containing semiconductor layer is thicker than the Ta layer.   The polarizing plate according to claim 9, wherein the metal of the metal-containing semiconductor layer is Ta.   The polarizing plate according to claim 16, wherein a Ta content of the metal-containing semiconductor layer is 40 atm% or less.   The polarizing plate according to claim 16 or 17, wherein the absorption layer further comprises a Ta layer.   The polarizing plate according to claim 18, wherein the absorption layer is formed in the order of the Ta layer and the metal-containing semiconductor layer with respect to a light incident direction.   The polarizing plate according to claim 19, wherein the metal-containing semiconductor layer is thicker than the Ta layer. On the light-transmitting substrate that transmits light in the use band, an absorption layer having at least a metal-containing semiconductor layer containing a metal and a reflective layer are laminated in this order or reverse order,
A method of manufacturing a polarizing plate, which forms a grid structure arranged in a one-dimensional lattice pattern at a pitch smaller than the wavelength of light in a use band by etching.