JPS5842003A - Polarizing plate - Google Patents

Abstract

PURPOSE:To obtain a transmissive or reflective polaring plate for display, by forming a minute conductive grating pattern on a transparent or semitransparent substrate through an insulating layer and setting grating intervals of the conductive grating pattern to <=1.4mum. CONSTITUTION:Cr is vacuum-deposited onto a silicon substrate 2 whose surface is coated with a silicon oxide, and Au is vapor-deposited onto Cr. A resist film is provided on this substrate 2, and a pattern is exposed, and a conductive grating 1 is obtained by sputter etching. The line width of the grating is 0.15mum, and the pitch is 0.4mum. Thus, a reflective polarizing plate having 1/10 extinction ratio is obtained. If an Au grating pattern 1 is provided on the glass substrate 2 and the grating intervals are set to 0.63m and 1.4m, a transmissive polaring plate having 1/10 and 1/30 extinction ratios are obtained. If an Si2N3 film is stuck to one face by the CVD method, a reflective polarizing plate having ruggedness is obtained. A transparent protection film 3 may be formed by providing the conductive grating 1 on the thin film substrate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polarizing plate that can be used in, for example, a liquid crystal display device, and can be of a transmissive type as well as a reflective type, has flat wavelength characteristics, and can be made into a thin film.

Conventionally, polarizing plates have been used such as Nicol prisms and Durham-Thomson prisms that use zero-order refraction crystals, or stretched films of polyvinyl alcohol (PVA') containing iodine, and stretched films of Norastik and PVA' that contain a dichroic color purple. and so on were used.

However, in method (2), the polarization characteristics are highly dependent on the angle of incidence, making it difficult to miniaturize, and being less economical.
In the case of ■ and ■, the weft loss was large and the wavelength band was limited, and in the case of ■, the moisture resistance was poor.

In order to solve these drawbacks, the present invention attempts to manufacture a polarizing plate by using a fine conductive grating, and will be described in detail below with reference to Examples.

The principle of polarization by the iodine-PVA stretched film is as follows. Iodine forms a complex in PVA, forming a linear conductive part parallel to the stretching direction. When light is incident perpendicularly to this film, the light with an electric field component that coincides with the stretching direction is generated within the film. It is absorbed to induce an electric current and generate Zeel heat. On the other hand, light having a polarization component perpendicular to the stretching direction cannot induce an electric current and is therefore transmitted without being absorbed.

In the case of dichroic dyes as well, the molecules are generally elongated and a microscopic current flows in the direction of this long axis, so the principle of polarization is the same as in the case of iodine-PVA film.

Therefore, the tiny conductive grating 9Tan is considered to be a model of the polarizing film described above, and is expected to have a similar polarizing effect.

The width and pitch of the grating, especially the pitch, must be as small as the wavelength band of the light used.

When the pitch is larger than the wavelength, its action as a diffraction grating becomes stronger. Therefore, for a polarizing plate used in the visible light region, the grating pitch should be 0.4 μm or less, preferably 0.2-μm or less.
Hereinafter, it is more preferable that Fio is less than o4 μmυ. In the field of optical communication, which has become popular in recent years, the wavelength band used is the 1.4 μm band, but for use in the field, it is less than 1.4 μm, preferably less than 0.7 μm, and more preferably IM or less. 0. j It is necessary that it is 4 μm or less.

Polarizing plates with metal gratings can already be used in the far-infrared region as diffraction gratings! This is achieved by diagonally depositing metal onto a plastic replica. However, since this method uses a diffraction grating for the substrate, the wavefront of transmitted light is disturbed, and the pitch cannot be made sufficiently small, so it cannot be used in the near-infrared or visible light region.

Gratings with a pitch of 1 .mu.ml or finer can be produced by electron or X-ray lithography, or, as a special method, by phosphorography using interferometry using extremely short wavelength light.

Conductive grid materials include ordinary gold, gold, aluminum,
In addition to silver, chromium, etc., carbon vapor deposited films can be used.

Substrates can be made of ordinary transparent materials such as glass plates, quartz plates, NaCl plates, KCl plates, etc.; opaque substrates can be made of metal plates such as gold, silver/copper, iron, graphite plates, silicon, or dalmanium. Semiconductor substrates such as

Since opaque substrates, particularly metal and graphite plates, are conductive themselves, it is necessary to create a conductive grid through an insulating film.

When using a transparent substrate, it can be used for both transmissive and reflective types, and when using an opaque substrate, it can be used for reflective type.

FIG. 1 shows an example of a conductive grating fabricated on a substrate with a flat surface. Ft, s#i conductive grating, 2 is the substrate. To make this, a metal thin film or a Kahn thin film is deposited on the substrate 2, or made using a method such as a metal or a metal, coated with a resist, and exposed to ultraviolet light, X#, or extreme ultraviolet light. Develop and save this resist pattern as
process, etch, and finally remove the resist.
A highly conductive grid l is produced. In the case of an electron beam, exposure can be performed by scanning a narrowly focused I-m, but X1! ! In this case, exposure is performed through a mask made using an electron beam. In the case of extreme ultraviolet rays, it is possible to produce minute armpits by using laser light as a light source and side-lighting by interferometry. As extreme ultraviolet lasers have not yet been developed,
Uses harmonics such as YAG laser.

FIG. 2 is an example of a conductive grid pattern with unevenness. 1 is a conductive grid and 2/ri substrate. To make this, apply a resist onto the substrate and use the same method as the example shown in Figure 1.
Either expose and develop and then vapor-deposit metal on top of it, or
This can be achieved by preparing a substrate with an uneven cross-sectional shape, heating it, and then transferring the surface shape using a grating or a sheet of paper that is pressed onto the substrate. If a resist is used, then use the solvent Kfi! L, if you remove the resist,
It is also possible to use the so-called lift-off method to form the same shape as in FIG.

If the vapor deposition is performed from directly above, the shape shown in Figure 2 will be obtained, but if the vapor deposition is performed from an angle, the convex portions will be strangely deposited.

The conductive portion may be provided in either the convex portion or the concave portion, or both, but it is necessary that the adhesive is not continuous and is KM standing. If the convex portion of the substrate 2 is undercut as shown in Fig. 3, the conductive grid 1 may be formed by vapor deposition from directly above, but if there is no undercut as shown in Fig. 2, or the conductive grid 1 is If the base is swollen, oblique deposition is preferred.

When X-rays or extreme ultraviolet rays are used as a light source when exposing the resist F, the substrate should be thicker. However, when an electron beam is used, the electron beam is scattered from the KFi and the substrate and reenters the resist, making it difficult to process with high resolution.

In order to avoid this problem, it is possible to use a thin film substrate. When an iI film substrate is used, there is no back scattering t of the electron beam, and a grating with an extremely narrow pitch interval can be produced. Thin film substrate materials that can be used include ordinary organic thin films or silicon nitride fabricated on a silicon wafer and the silicon removed by etching. , 1 μm or less, preferably 0.5 μm or less. At present, electron beam processing is about 0.4 beams for thick film substrates, but it is possible to process thin film substrates about one order of magnitude finer.

The polarizing plate produced as described above has poor mechanical strength up to the trenches, and its properties change due to dirt and deterioration, so as shown in Figure 4, transparent plastic or inorganic thin film capes are used to protect the polarizing plate. @6! Preferably, it is coated with aluminum. The effect of the coating is not only to protect the skin, but also to prevent disturbances in the wavefront of transmitted light. Furthermore, since the strength is weak when a thin film substrate is used, this has the effect of reinforcing this.

The extinction ratio of the polarizing plate described above can be improved by multilayering it. Further, in this case, even if the pitch of each layer is widened, the pitch as a whole can be narrowed as shown in FIG. 5, so that the difficulties in manufacturing technology are reduced. In particular, when substrate processing is performed using electron beam phosphorography, it is easy to create isolated patterns, but it has the disadvantage that it is difficult to create thin-pitch Al layers, so multilayer methods are not effective. be. The pitch of each layer can be multiplied by the number of layers compared to a single layer. In contrast, the width of the grid cannot be made wider than in the case of a single layer, and the width of the grid pattern of each layer is less than 0.7 μmυ.

(Example 1) Approximately 1
00X thick chromium was vacuum deposited followed by 1500X thick gold. Chromium spin-coded the substrate and gold lolomethylated poly-a-methylstyrene (abbreviated as aM-CN3);
After baking at 135° C. for 30 minutes and exposing it to an electron beam, it was rinsed with acetone and isopropyl alcohol. After this, argon gas sputter etching was performed at 10-'Torr for 10 minutes with an output of 50W.
Perform gold etching, line width 0.15-, pitch 0.4
I made an interesting grid. The slippage is the wavelength of H・-N・Rede (
0,634 m), resulting in a reflective polarizing plate with an extinction ratio of 1/10.

(Example 2) Same as Example 1, 1
AZ-2415 (Sibley #)
The sample was spin-coded as 0001 and baked at 95°C for 30 liters.

The 9th harmonic of the YAG laser was divided into two beams, and the substrate was irradiated at different angles to generate interference waves and exposed. Development was carried out by diluting AZ2401 developer (manufactured by Shifure 4 Co., Ltd.) to 175% with deionized water, followed by rinsing with deionized water. After that, as in Example 1, Ardens I4
I processed it using ivy etching to create a solid gold lattice plate. The lattice spacing is 0.16 .mu.m, and one pitch is 0.33 .mu.m, with 10 squares in each direction. An extinction ratio of 11/10 was obtained at a wavelength of 0.63 srs.

(Example 3) A gold lattice plate was produced on a glass substrate in the same manner as in Example 1. The extinction ratio was the same for the transmission type.

(Example 4) A film having a thickness of 100018102 mm was deposited on the polarizing plate of Example 3, and a similar conductive grid pattern was also produced. The extinction ratio was 1/100 in the transmission type.

(Example 5) 100 μm was deposited on a silicon substrate with a thickness of 400 μm using a low pressure CVD method.
A silicon nitride film of 001 was attached to one side, and a 5 m square window was made using photoresist from the opposite side.
H! Etching was performed at 70°C for 4 hours to produce a silicon substrate with a silicon nitride thin film window.The groove was coated with chromium 100X.

After evaporating gold 500X, electron beam resist PMM was applied.
0001- was coated, and an electron beam having an aperture of 50X was applied without light at an accelerating voltage of 50 kV.

Methyl isobutyl ketone-isoglobil alcohol 1:
After developing with 1 solution, the gold was processed and etched using Inglobil alcohol solution and aluminum spatuta etch. The dimensions of the obtained grid are width 200X and pitch 400
Nine met by X.

This polarizing plate had an extinction ratio of 1/30 at a wavelength of 4000X.

As explained above, the polarizing plate frame according to the present invention can be made into a thin film, can be made into a reflective type as well as a transmission type, and has the advantage of being excellent in moisture resistance and heat resistance.
Suitable for use in biomedical measurements or optical communication parts.

[Brief explanation of the drawing]

1M to 5 each show an embodiment of the present invention.
The figure shows a polarizing plate fabricated on a substrate with a flat surface, FIG. Figure 4 shows a polarizing plate provided with a protection layer, and Figure 5 shows a multilayered polarizing plate. DESCRIPTION OF SYMBOLS 1... Conductive grid, 2... Substrate, 3... Transparent protective film. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Scope of Claims] (1) A polarizing plate characterized by a fine conductive lattice/matrix formed on a substrate. (2. The polarizing plate according to claim 1, which is a transmissive type polarizing plate, characterized in that a transparent substrate is used as the substrate. (3) The polarizing plate according to claim 1, in which the substrate is A reflective polarizing plate characterized in that an opaque substrate is used as the polarizing plate.
A polarizing plate characterized by using a thin film substrate as a substrate. (5) The polarizing plate according to claim 4, wherein the thin film substrate has a thickness of 1 μm or less. (6) In the polarizing plate according to claim 1, a substrate having an uneven portion is used as the substrate, and a metal matrix is formed on either or both of the recesses and the projections of the substrate. Features: Polarizing plate. (7) An i-polarizing plate according to claim 1, characterized in that the fine conductive lattice/phosphorescent lattice spacing is 1.4 μm or less. (8) The polarizing plate according to claim 1, further comprising a transparent protective film on the fine conductive grid. (9) A fine conductive grid pattern is formed on the substrate, and a transparent protective film is formed on the polarizing plate, and a fine conductive grid pattern and a transparent protective film are layered many times on top of the polarizing plate. A polarizing plate characterized by: (g) In the polarizing plate according to claim 9, the width of each layer of fine conductive grid pattern is 0.7 μm or less, and the pitch is 1.4×number of layers or less. Board.