JPH0784282A - Production of spatial optical modulator - Google Patents

Abstract

PURPOSE:To relatively easily form a light shielding layer capable of maintaining the electrical insulation between pixel electrodes without degrading the degree of light shielding. CONSTITUTION:A photoconductive layer 103 between the pixel electrodes 104, 104 is partly removed by isotropic etching and further the metallic light shielding layer 113 is formed over the entire surface in the process for production of the spatial optical modulation element which has the photoconductive layer 103 and a layer of a ferroelectric liquid crystal 106 between two sheets of transparent conductive electrodes 102 and 107, having the plural island-shaped pixel electrodes 104 between these two layers and further inserting the light shielding layer 112 in the groove-shaped spacing parts between the pixel electrodes 104 and 104. A carbon particle-contg. photopolymer 114 is packed into the spacing parts and is then thermally shrunk. A poolyimide which is the material of an oriented film 105 is packed into the spaces freshly generated by the thermal shrinkage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a projection display,
The present invention relates to a method for manufacturing a spatial light modulator used in a holographic television or an optical arithmetic unit.

[0002]

2. Description of the Related Art An optical writing type spatial light modulator (hereinafter, simply referred to as "spatial light modulator") composed of a liquid crystal layer and a photoconductive layer is compared with a TFT drive type liquid crystal panel or the like. It has the advantages that the structure is simple and the aperture ratio can be increased. Therefore, it is considered to be promising as the core of image display devices such as projection displays and holographic televisions, and various structures have been developed.

6 shows an example of the spatial light modulator having the most basic structure (for example, C. Gomez et al., Japanese Journal of Applied Physics Vol. 30 ( 1991
Year) L386 to L388 (Jap. J. Ap.
pl. Phys. 30 (1991) pp. L386-L
388)). This consists of two transparent conductive electrodes 602, 6
The photoconductive layer 603 and the liquid crystal layer 606 are sandwiched between 07,
Further, a plurality of pixel electrodes 604 made of metal are provided between them.
Is arranged. In FIG. 6, 601 and 608 are transparent insulating substrates, 605 is an alignment film, 610 is writing light, and 611 is reading light.

However, in the case of this structure, the photoconductive layer 6 between the pixel electrodes 604 and 604 where the readout light 611 is adjacent is read.
No. 03 is directly irradiated, so that there is a problem that a malfunction occurs.

As another structure having another basic structure, there is a structure in which a dielectric reflection film is formed on the entire surface instead of the metal pixel electrode, and a light shielding layer is further formed on the entire surface (see, for example, Japanese Patent Laid-Open Publication No. Sho. 63-109422, FIG. 7).

However, in the case of this structure, there is a problem that the resolution is deteriorated unless the electric resistance in the sheet direction of the dielectric reflection film or the light shielding layer is sufficiently increased. As a method of substantially suppressing the electric resistance in the sheet direction while maintaining the light shielding degree, as shown in FIG.
A possible method is to fill the gap between 04 and 704 with a light-shielding layer 712 having an insulating property. Incidentally, 70 in FIG.
1, 708 are transparent insulating substrates, 702 and 707 are transparent conductive electrodes, 703 is a photoconductive layer, 705 is an alignment film, and 706.
Is a liquid crystal layer, 710 is writing light, and 711 is reading light.

Further, in order to further reduce the crosstalk between adjacent pixel electrodes and at the same time improve the light blocking degree, a part or all of the photoconductive layer between the pixel electrodes is removed, and the photoconductive layer has an insulating property. A method of filling with a light-shielding material has been proposed (for example, JP-A-3-2836).

Further, the present inventors have proposed a structure in which a metal light shielding film 813 is added in addition to the light shielding layer 812 as shown in FIG. 8 in order to further increase the light shielding degree.
The method of forming the groove portion in the photoconductive layer 803 is particularly effective when the photoconductive layer 803 has a rectifying property. That is, when the photoconductive layer 803 has a p / i / n photodiode structure, the uppermost layer of the photoconductive layer 803 is an n layer having a relatively low resistance, but by providing a groove portion, the pixel electrode The n layer in between is removed and the electrical insulation between the adjacent pixel electrodes is maintained, so that deterioration of resolution can be suppressed. In FIG. 8, reference numerals 801 and 808 are transparent insulating substrates, 802 and 807 are transparent conductive electrodes, 804 is a pixel electrode, 805 is an alignment film, 806 is a liquid crystal layer, 810 is writing light, and 811 is reading light. .

[0009]

As described above, the light-shielding material for forming the light-shielding layer between the pixel electrodes has a sufficient light-shielding degree even if it is thin, and is sufficient to maintain the resolution. It is required to have electric resistance. Further, particularly in the case of the structure in which the groove portion is provided between the pixels as described above, if the light shielding material filled between the pixels has a low resistance, the pixel electrode and the metal light shielding film (or the transparent conductive electrode on the writing side) There is a problem in that a leak current is generated between the first and the second), which causes a pixel defect or the like. Further, there is a manufacturing requirement that the space between the pixel electrodes should be easily filled.

However, in general, very few materials satisfy all of these requirements. For example, a polymer having a high light-shielding degree capable of blocking 99% or more of incident light with a thickness of about 1 μm and easy to fill is a polymer containing particles of a light-absorbing substance such as carbon. Although a medium may be considered, it is difficult to completely suppress crosstalk between pixels and pixel defects because the carbon particles themselves have electrical conductivity.

The present invention has been made in view of the above circumstances, and it is possible to relatively easily form a light-shielding layer capable of maintaining electrical insulation between pixel electrodes without lowering the light-shielding degree. It is an object to provide a method for manufacturing a spatial light modulator.

[0012]

In order to achieve the above object, a method of manufacturing a spatial light modulator according to the present invention comprises a first electrode and a second electrode arranged in parallel to the first electrode.
The electrode, a photoconductive layer in electrical contact with the first electrode, and a liquid crystal layer inserted between the second electrode and the photoconductive layer, the liquid crystal layer of the photoconductive layer. A method for manufacturing a spatial light modulation element, comprising: a plurality of island-shaped pixel electrodes that are in electrical contact with a side interface; and a light-shielding layer inserted in a groove-shaped gap between the pixel electrodes. Characterized in that the light-shielding layer is formed by filling the gap portion with a heat-shrinkable medium containing conductive particles, and then performing heat shrinkage, and filling the gap newly generated by the heat shrinkage with an insulating medium. And

Further, in the constitution of the method of the present invention,
The photoconductive layer preferably has a rectifying property. Further, in the constitution of the method of the present invention, it is preferable that the light absorbing particles are particles containing carbon as a main component.

Further, in the constitution of the method of the present invention,
The insulating medium is preferably the material of the alignment film that aligns the liquid crystal molecules. Further, in the configuration of the method of the present invention, the heat-shrinkable medium remaining on the upper surface of the pixel electrode between the step of filling the heat-shrinkable medium into the gap and the step of heat-shrinking the heat-shrinkable medium. Is preferably inserted.

Further, in the constitution of the method of the present invention,
It is preferable to include a step of expanding the groove-shaped gap portion between the pixel electrodes by performing isotropic etching on the photoconductive layer using the pixel electrodes as an etching mask. In the groove-shaped gap part,
It is preferable to include a step of forming a metal light-shielding film that substantially covers the bottom surface of the gap portion, is in electrical contact with the photoconductive layer, and is electrically separated from the pixel electrode.

[0016]

When the light-absorbing particles such as carbon are contained in the heat-shrinkable medium and filled in the gaps between the pixel electrodes, the light-shielding layer can be formed. However, in this state, the insulating property cannot be secured due to the conductivity of the carbon particles themselves. Therefore, this medium is contracted by heat treatment. Then, a new gap is created at the interface between the photoconductive layer, the pixel electrode, or the like and this medium, or inside the medium itself. When this gap is filled with an insulating medium such as polyimide, it electrically insulates between adjacent pixel electrodes or between the pixel electrode and the metal light-shielding film or the transparent conductive electrode at the bottom of the gap.
Accordingly, it is possible to relatively easily form the light shielding layer that can maintain the electrical insulation between the pixel electrodes without lowering the light shielding degree.

[0017]

EXAMPLES The present invention will be described in more detail below with reference to examples. (Embodiment 1) First, the spatial light modulator of FIG. 7 having the most basic structure to which the present invention is applied will be described.

As shown in FIG. 7, a transparent insulating substrate 701.
A transparent conductive electrode on (eg glass, quartz, etc.)
702 (for example, ITO (indium-tin oxide),
ZnO, SnO₂Etc.) and the photoconductive layer 703 are sequentially stacked.
Layered. In addition, on the photoconductive layer 703, a fine pattern is formed.
Align the pixel electrode 704 and the liquid crystal layer 706, which are separated like a circle
Alignment film 705 (for example, a thin polymer film such as polyimide)
Film) are sequentially arranged, and a gap portion of the pixel electrode 704.
A light-blocking layer 712 having an insulating property is filled in the portion.
In addition, the transparent conductive electrode 707 on the opposite side (for example, IT
O, ZnO, SnO ₂Etc.) the alignment film 705 is uniform
It has been formed into a film. In FIG. 7, 708 is a transparent insulating substrate.
(Eg, glass, quartz, etc.).

As the material used for the photoconductive layer 703,
For example, CdS, CdTe, CdSe, ZnS, ZnS
e, GaAs, GaN, GaP, GaAlAs, InP
Such as compound semiconductor, amorphous such as Se, SeTe, AsSe
Quality semiconductors, Si, Ge, Si _1-xC_x, Si_1-xG
e_x, Ge_1-xC_x(0 <x <1) polycrystal or amorphous
Semiconductor, and (1) Phthalocyanine pigment (hereinafter referred to as Pc
Abbreviated), for example, metal-free Pc, XPc (X = Cu, N
i, Co, TiO, Mg, Si (OH)₂Etc.), Al
ClPcCl, TiOClPcCl, InClPcC
1, InClPc, InBrPcBr, etc. (2) Mono
Azo dyes such as azo dyes and disazo dyes, (3) penis
Penylene type such as rheic anhydride and penenylene imide
Pigment, (4) Indigoid dye, (5) Quinacridone face
(6) Anthraquinones, pyrenequinones, etc.
Ring quinones, (7) cyanine dyes, (8) xanthene dyes
Materials, (9) charge transfer complexes such as PVK / TNF, (1
0) Made from pyrrolium salt dye and polycarbonate resin
Eutectic complex, (11) azurenium salt compound, etc.
There is a semiconductor.

Amorphous Si, Ge, Si
_{1-x Cx} , Si _1-x Ge _x , Ge _1-x C _x (hereinafter a-
Si, a-Ge, a-Si _1-x C _x , a-Si _1-x Ge
_x , a-Ge _1-x C _x ) is abbreviated as a photoconductive layer 703.
In the case of being used in the above, hydrogen or a halogen element may be included, and oxygen or nitrogen may be included in order to reduce the dielectric constant or increase the resistivity. Further, in order to control the resistivity, elements such as B, Al, and Ga, which are p-type impurities,
Alternatively, an element such as P, As, or Sb which is an n-type impurity may be added. In this way, the amorphous materials to which impurities are added are stacked to form junctions of p / n type, p / i type, i / n type, p / i / n type, etc., and the photoconductive layer 703 is depleted. Layers can be formed to control dielectric constant and dark resistance or operating voltage polarity. Further, not only such an amorphous material but also two or more kinds of the above materials may be stacked to form a heterojunction, and a depletion layer may be formed in the photoconductive layer 703.

The thickness of the photoconductive layer 703 is 0.1-1.
It is preferably in the range of 0 μm. In the first embodiment, amorphous silicon, which has a characteristic that dark resistance is relatively high, is used. Further, a p / i / n structure having a rectifying property is used because erasing light is not required when actually driving.

As the pixel electrode 704, for example, Al, T
Metals such as i, Cr, Ag, Au, Ta and Pt, or a laminate of two or more kinds of these metals can be used. The thickness of the pixel electrode 704 is 0.1 to 10
It is preferably in the range of μm.

As the liquid crystal layer 706, a liquid crystal having a TN (twisted nematic) structure may be used, but it is preferable to use a ferroelectric liquid crystal capable of higher speed response. Alternatively, antiferroelectric liquid crystal may be used. The thickness of the liquid crystal layer 706 is preferably in the range of 0.1 to 50 μm.

Next, a method of manufacturing the spatial light modulator having the above structure will be described with reference to FIG. First, 40m
On a glass substrate 201 of m × 40 mm × 0.3 mm,
ITO was formed into a film having a thickness of 0.1 μm by a sputter deposition method to form a transparent conductive electrode 202. Then, amorphous silicon (hereinafter abbreviated as a-Si: H) having a p / i / n photodiode structure is formed by plasma CVD.
The films were laminated in a thickness of 1.8 μm to form a photoconductive layer 203 (the above is FIG. 2A). Here, the p layer is doped with 400 ppm of B (boron), and the n layer is doped with 40 ppm of P (phosphorus). The p-layer has a thickness of 0.1 μm and the i-layer has a thickness of 1.25 μm.
The film thickness of the m and n layers is 0.45 μm.

Then, an Al film having a film thickness of 0.3 μm is formed on the surface of the photoconductive layer 203 by a vacuum vapor deposition method, and by photolithography, a pixel having a size of 20 μm × 20 μm, a pitch of 5 μm, and 1000 × 1000 pixels is formed. Electrode 204
Was formed (FIG. 2 (b)). A mixed acid etching solution containing nitric acid, phosphoric acid, acetic acid and the like was used for etching the Al film.

Next, a liquid carbon particle-containing photopolymer 214 (CK-manufactured by Fuji Hunt Electronics Technology Co., Ltd.) is coated on the entire surface by spin coating.
2000) and then prebaked at a temperature of 90 ° C. for 5 minutes. Further, an overcoat film (CP-2000 manufactured by Fuji Hunt Electronics Co., Ltd.) for preventing deterioration during exposure was applied and prebaked at a temperature of 90 ° C. for 5 minutes. Then 30
Exposed to UV light for seconds. At this time, the carbon particle-containing photopolymer 214 is removed from the pixel electrodes 204, 204.
It was confirmed by an electron microscope that the gap was formed thicker than that on the pixel electrode 204. Also, 90 ℃
It was also confirmed that the shrinkage hardly occurs even when the heat treatment of 1. The thickness of the carbon particle-containing photopolymer 214 on the pixel electrode 204 was 1.0 μm (above,
FIG. 2C).

Then, reactive ion etching using O ₂ plasma 215 was performed to remove the upper layer portion of the carbon particle-containing photopolymer 214. The flow rate of O ₂ gas was 5.0 ccm, the gas pressure was 4.0 Pa, and the input power for generating plasma was 300 W. By adopting this method, the pixel electrode 20 can be formed in about 3 minutes.
It was possible to etch up to where the upper surface of No. 4 appeared. The debris slightly left on the pixel electrode 204 (those left without being etched due to lumps of carbon particles or the like) was removed by rubbing and washing with cotton fiber in running water. As a result, the light shielding layer 212 was formed between the pixel electrodes 204, 204 (above, FIG. 2D).

Then, a heat treatment (post-baking) was performed at a temperature of 200 to 250 ° C. for 10 minutes. As a result, it was confirmed by an electron microscope that the carbon particle-containing photopolymer 214 (light-shielding layer 212) between the pixel electrodes 204 and 204 was thermally contracted and a gap was formed between the pixel electrode 204 and the pixel electrode 204. Further, the carbon particle-containing photopolymer 2
It was also confirmed that a hollow portion was formed also in 14 itself (above, FIG. 2 (e)).

Next, polyamic acid was applied to the entire surface by spin coating. At this time, the polyamic acid completely penetrated into the gaps and cavities generated in the step (e). By heating in this state at a temperature of 200 ° C. for 1 hour (imidization treatment), the film thickness becomes 100.
An Angstrom polyimide alignment film 205 was formed (above, FIG. 2 (f)). The orientation treatment (rubbing treatment) was performed by rubbing the surface in a certain direction with a nylon cloth.
It was confirmed that between the pixel electrodes 204, 204, polyimide was certainly completely infiltrated in the gap portion generated in the step (e).

On the other hand, IT is also formed on the glass substrate 208 of 40 mm × 40 mm × 0.3 mm by the sputter deposition method.
O is formed into a film having a thickness of 0.1 μm, and the transparent conductive electrode 207 is formed.
Was formed. Then, a polyimide alignment film 205 was formed and an alignment treatment was performed. Next, resin beads 216 having a diameter of 1 μm were distributed on this glass substrate 208 and bonded to the other glass substrate 201 to form a gap of 1 μm between the two substrates. Finally, a ferroelectric liquid crystal (CS-1029 manufactured by Chisso Corp.) is placed in this gap.
Was injected and heat-treated. As a result, between both boards,
A ferroelectric liquid crystal layer 206 having a thickness of 1 μm was formed (above,
FIG. 2 (g)).

As described above, the spatial light modulator having the structure of FIG. 7 was obtained. As the light-absorbing particles contained in the light-shielding layer 212, carbon particles having a large absorption coefficient over the entire wavelength range of visible light (that is, black) are preferable, but in addition to this, only light in a specific wavelength range is used. It is also possible to use particles that absorb (such as pigments). Further, the matrix containing these particles is not necessarily limited to the photopolymer, and a medium that shrinks by heating can be used.

Further, the medium for permeating the gap portion newly formed in the step (e) is not limited to polyamic acid, and may be, for example, photoresist.
When an alignment film material such as polyamic acid is used, the alignment film 205 is formed on the pixel electrode 204 and the pixel electrode 20.
There is an advantage that the insulation treatment between 4 and 204 can be performed at the same time.

In step (d), the pixel electrode 2
The debris left on the surface of No. 04 is removed by rubbing and washing, but this can also be performed after the heat shrinkage of step (e). However, in general, when a heat-shrinkable medium is heat-shrinked,
Since the medium itself hardens as the volume decreases, the pixel electrode 2
04 It is difficult to completely remove the debris on the upper surface. Therefore, it is preferable to remove the debris in the soft state before the heat shrinkage. Next, a driving method and an operating principle of the spatial light modulator manufactured as described above will be briefly described.

As an example of a drive pulse waveform applied between both transparent conductive electrodes 202 and 207, an erase pulse 301 (voltage V _e , time T _e ) and a writing period 302 (voltage V _w , time) as shown in FIG. T _w ) and the continuous one are used.

When the erasing pulse 301 is applied to the spatial light modulator in which the photoconductive layer 203 having a rectifying property and the ferroelectric liquid crystal layer 206 are connected in series, a forward voltage is applied to the photoconductive layer 203. The ferroelectric liquid crystal layer 206 is forcibly turned off. Next, in the low voltage writing period 302, the photoconductive layer 203 is in the reverse bias state, but a photocurrent proportional to the intensity of the writing light is generated, and the ferroelectric liquid crystal layer 206 and the photoconductive layer 203 are exposed. The charge Q is accumulated in the pixel electrode 204 on the interface. Then, the ferroelectric liquid crystal layer 206 is kept in a polarization inversion state P (−P _s <P <+ P _s ; P _s is the magnitude of spontaneous polarization) that balances with the charge Q. In this state, the ferroelectric liquid crystal layer 2
It is considered that the + P _s and −P _s states are distributed in area within 06 or that the liquid crystal molecules are in a transitional transition state. Here, since the polarization state of the liquid crystal, that is, the intensity of the reading light can be controlled by the amount of the photocurrent, that is, the intensity of the writing light, a halftone can be realized.

In addition to the unipolar pulse of FIG. 3, for example,
C. Gomez and others Japanese Journal of Applied Physics Volume 30 (1991) L386
Pages L388 (Jap. J. Appl. Phy
s. 30 (1991) pp. It is also possible to drive with bipolar pulses as shown in L386-L388)).

Using the above spatial light modulator,
I tried to configure a spray device. The system at this time is shown in Fig. 4.
You This is the writing information of the spatial light modulator 402.
Using the image presented on the CRT 401,
The read input light 408 from the metal halide lamp is polarized.
Spatial light change through photon 405 and beam splitter 404.
The read output light 409 is irradiated onto the adjustment element 402 and the analyzer
406, the screen 4 taken out through the lens 410
It is what was projected on 11. In FIG. 4, 403 is a drive
A power source 407 is a writing light. Spatial light modulator 40
The effective area of 2 is 2.5 cm x 2.5 cm,
Is enlarged to 100 cm x 100 cm on the screen 411
did. As the driving pulse, the unipolar pulse shown in FIG. 3 is used.
Used, V _e= 15V, T_e= 100 μsec, V_w=-
1.35V, T_w= 1100 μsec.

As a result, an image was observed on the screen 411, but the input CRT 401 image was faithfully reproduced. At this time, the brightness on the screen 411 was 80 lx, and the contrast ratio on the screen 411 was 100: 1. In addition, there are almost no defective pixels that show different movement from normal pixels, and 1000 × 100
There were only a few of 0 pixels. Screen 4
On Pixel 11, one pixel was enlarged to 1 mm × 1 mm, but at this time, a slight crosstalk between the adjacent pixel electrodes 204 and 204 was observed. This is because the adjacent pixel electrodes 20
The reason for this is that the 4, 204 are in electrical contact with each other through the low resistance n layer. Moreover, when the output of the metal halide lamp of the light source was increased more than this, the contrast ratio of the output image decreased. This is the pixel electrode 204,
This means that the light shielding layer 212 alone is insufficient in light shielding degree.

The same results were obtained when writing was performed using a TFT liquid crystal panel instead of the CRT 401. For comparison, the spatial light modulator was manufactured by omitting the heat treatment in step (e) and similarly incorporated into the projection display device. At this time, the crosstalk between the pixels observed on the screen 411 was larger than that in the previous case. This means that the resistance between pixels is smaller than in the previous case.

(Embodiment 2) FIG. 8 is a sectional view showing another embodiment of the spatial light modulator. The spatial light modulator shown in FIG. 8 is basically the same as the spatial light modulator shown in FIG. 7, but different in the following points. (1) Photoconductive layer 80 between adjacent pixel electrodes 804, 804
A groove is formed by removing a part of 3 by etching. As a result, the adjacent pixel electrodes 80
4 and 804 are electrically separated to improve the resolution. (2) At the bottom of the groove formed in (1), for example, Al, Ti,
A metal light shielding film 813 made of a metal such as Cr, Ag, Au, Ta or Pt is formed. Thereby, the malfunction of switching due to the read output light 811 sneaking into the photoconductive layer 803 side is eliminated, and the read light intensity can be increased.

Next, a method of manufacturing the spatial light modulator having the above structure will be described with reference to FIG. The procedure is almost the same as that of the first embodiment, but the different points from the first embodiment will be mainly described.

First, in the same manner as in the first embodiment,
An ITO thin film is deposited on the glass substrate 101 as a transparent conductive electrode 102, and a p-type photoconductive layer 103 is formed.
/ I / n photodiode structure amorphous silicon was deposited by the plasma CVD method. Then, as in the case of Example 1, the pixel electrode 1 is formed on the surface of the photoconductive layer 103.
04 was formed. However, the material is C instead of Al.
The film thickness was set to 0.2 μm by using r (see FIG.
(A)).

Next, by the chemical dry etching method using CF ₄ + O ₂ gas, the adjacent pixel electrodes 104,
A groove having a depth of 1.3 μm was provided in the photoconductive layer 103 between the layers 104. As a result, the n layer between the pixel electrodes 104 and 104 was completely removed, and the i layer was partially etched. In this case, the flow rates of CF ₄ and O ₂ are each 1000 ccm.
And 300 ccm, input power for generating plasma was 400 W, and etching time was 195 seconds. still,
Since this method is isotropic etching, the pixel electrode 10
4 was etched to the lower part. The depth of the wraparound etching in the lateral direction was about 1.0 μm (above, FIG. 1B).

Next, Al is vapor-deposited with a film thickness of 0.3 μm on the entire surface to form an Al reflection film 116 on the pixel electrode 104 (hereinafter, the Cr pixel electrode 104 and the reflection film 116 are grouped together. And a metal light-shielding film 113 is formed on the bottom of the groove between the pixel electrodes (FIG. 1C).

Then, a carbon particle-containing photopolymer 114 was formed in exactly the same manner as in step (c) in Example 1. In this case, the pixel electrode 10 is provided between the pixel electrodes.
It was confirmed by an electron microscope that the layer was formed thicker than that on No. 4. It was also confirmed that shrinkage hardly occurred even when heat treatment was performed at 90 ° C. The thickness of the carbon particle-containing photopolymer 114 on the pixel electrode is 1.0.
μm (above, FIG. 1 (d)).

Then, in the same manner as in step (d) of Example 1, reactive ion etching using O ₂ plasma 115 was performed to remove the upper layer portion of the carbon particle-containing photopolymer 114. In about 3 minutes, etching could be performed up to where the upper surface of the pixel electrode 104 appears. The debris slightly left on the pixel electrode 104 was removed by rubbing and washing with cotton fiber in running water. As a result, the light shielding layer 112 was formed between the pixel electrodes (above, FIG. 1E).

Then, a heat treatment (post-baking) was performed at a temperature of 200 to 250 ° C. for 10 minutes. As a result, the carbon particle-containing photopolymer 114 between the pixel electrodes is
The (light-shielding layer 112) is thermally contracted, and the pixel electrode and the photoconductive layer 1
It was confirmed by an electron microscope that a gap was formed between the sample No. 03 and the sample No. 03. Further, the photopolymer containing carbon particles 11
It was also confirmed that a hollow portion was formed also in 4 itself (above, FIG. 1 (f)).

Next, polyamic acid was applied to the entire surface by spin coating. At this time, the polyamic acid completely penetrated into the gaps and cavities generated in the step (f). In this state, heat cure the polyamic acid,
A polyimide alignment film 105 was formed. The thickness of the alignment film 105 on the pixel electrode was 100 angstrom. It was confirmed that, between the pixel electrodes, the polyimide was certainly completely infiltrated into the gap portion generated in the step (f) (above, FIG. 1 (g)).

Then, in the same manner as in step (g) of Example 1, alignment treatment, bonding of both transparent insulating substrates 101 and 108, and injection of ferroelectric liquid crystal were performed. As a result, the ferroelectric liquid crystal layer 106 having a thickness of 1 μm was formed between both substrates, and the spatial light modulator having the structure of FIG. 8 was obtained (the above is FIG. 1 (h)).

The grooves can be formed by using anisotropic etching such as reactive ion etching instead of chemical dry etching, and electrical insulation between the pixel electrodes 104, 104 can be obtained.
However, in the case of anisotropic etching, the amount of the light-shielding layer 112 that can be filled is reduced because there is no wraparound under the pixel electrode 104, and the light-shielding degree is reduced. Therefore, it is preferable to use isotropic etching for reading with brighter light. As the isotropic etching, in addition to the above chemical dry etching, for example, HF and HN are used.
Wet etching using a mixed solution of O ₃ can also be used.

A projection display device shown in FIG. 4 was constructed by using the above spatial light modulator. The effective area of the spatial light modulator 402 is 2.5 cm × 2.5 cm, which is 100 cm × 100 c on the screen 411.
Expanded to m. As the drive pulse, the unipolar pulse shown in FIG. 3 is used, V _e = 15 V, T _e = 100 μsec,
V _w = −1.35 V and T _w = 1100 μsec.

As a result, an image was observed on the screen 411, but the input CRT 401 image was faithfully reproduced. Brightness on the screen 411 is 80l
x, the contrast ratio on the screen 411 is 100:
It was 1. Also, there are almost no defective pixels that show different movement from normal pixels, and 4 to 5 out of 1000 × 1000 pixels
It was about an individual. One pixel is 1 m on the screen 411
It is enlarged to mx 1 mm, but at this time the adjacent pixel electrodes 1
Almost no crosstalk between 04 and 104 was observed. This means that the adjacent pixel electrodes 104 and 104 are completely electrically insulated. Further, as the output of the metal halide lamp of the light source was increased, the contrast ratio of 100: 1 was maintained until the brightness on the screen 411 reached 1000 lx. This indicates that the light-shielding degree was improved due to the large filling amount of the light-shielding layer 112 between pixels.

For comparison, the spatial light modulator was manufactured by omitting the heat treatment in the step (f) and similarly incorporated in the projection display device. The image observed on the screen 411 was difficult to see because many pixel defects occurred (a few% of the whole). The defect at this time always looks bright regardless of the presence or absence of writing light, and deteriorates the contrast of the image. This means that the pixel electrode 104 and the metal light shielding film 113 are short-circuited, and the on / off of the liquid crystal is not controlled by the photocurrent generated in the photoconductive layer 103.

Example 3 A supplementary experiment was conducted on the photopolymers containing carbon particles used in Examples 1 and 2.

First, the carbon particle-containing photopolymer was applied to the entire surface of the glass substrate and heat-treated under various conditions. When the change in thickness before and after the heat treatment was measured, the following results (Table 1) were obtained.

[0056]

[Table 1]

Here, the change in thickness is the ratio of the thickness after heat treatment to the thickness before heat treatment. According to this, 90
It can be seen that heat shrinkage does not occur at 0 ° C, but heat shrinkage occurs when heated at 200 ° C, and the volume decreases by about 10%.

Next, the change in resistivity of the carbon particle-containing photopolymer before and after heat treatment at 200 ° C. for 10 minutes was measured. For the measurement, a glass / ITO substrate was coated with this medium, and an Al electrode was formed thereon by vapor deposition. According to this, 6 × 10 ⁷ before heat treatment
Ω · cm, 8 × 10 ⁷ Ω · cm after heat treatment.

From the above, the reduction of crosstalk and the reduction of pixel defects due to the heat treatment are not due to the effect of increasing the electric resistance of the carbon particle-containing photopolymer itself, but rather due to the reduction of the volume and the polyimide (resistivity Is 10 ¹⁰ Ω
It can be said that it is more due to the effect of permeating (about cm) and causing an insulating effect.

Even when the heat treatment in the step (f) is omitted in Example 2, for example, the carbon particle-containing photopolymer itself is surely obtained at the same time as the heat curing treatment of the polyamic acid in the step (g) (200 ° C., 1 hour). Heat shrinks. But,
In this case, since the polyamic acid does not permeate, a gap portion 517 as shown in FIG. 5 is generated after the heat shrinkage, and the pixel electrode 504 is bent due to the pressure of the resin beads 518 for forming the gap and the light shielding layer 512, for example. May come into contact with and cause a short circuit. Therefore, step (f) cannot be omitted.

[0061]

As described above, according to the method for manufacturing a spatial light modulator of the present invention, it is relatively easy to form a light-shielding layer that can maintain electrical insulation between pixel electrodes without lowering the light-shielding degree. Can be formed. Therefore, it is possible to realize a spatial light modulator which has good characteristics without pixel defects and which can be read with bright light.

[Brief description of drawings]

FIG. 1 is a process drawing showing an embodiment of a method of manufacturing a spatial light modulator according to the present invention.

FIG. 2 is a process drawing showing another embodiment of the method for manufacturing the spatial light modulator according to the present invention.

FIG. 3 is a drive pulse waveform diagram for driving a spatial light modulator.

FIG. 4 is a schematic diagram of a projection display device manufactured using a spatial light modulator.

FIG. 5 is a structural cross-sectional view of the spatial light modulation element when the heat treatment step of the carbon particle-containing photopolymer is omitted in the method for manufacturing a spatial light modulation element according to the present invention.

FIG. 6 is a structural cross-sectional view showing a conventional spatial light modulator.

FIG. 7 is a structural cross-sectional view showing a conventional spatial light modulator.

FIG. 8 is a structural cross-sectional view showing a conventional spatial light modulator.

[Explanation of symbols]

101, 108 Transparent Insulating Substrate 102, 107 Transparent Conductive Electrode 103 Photoconductive Layer 104 Pixel Electrode 105 Alignment Film 106 Ferroelectric Liquid Crystal Layer 112 Light Shielding Layer 113 Metal Light Shielding Film 114 Carbon Particle-Containing Photopolymer 115 O ₂ Plasma 116 Reflective Film 117 resin beads

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasunori Zutomi, 1006 Kadoma, Kadoma City, Osaka Prefecture, Matsushita Electric Industrial Co., Ltd. (72) Junko Asayama, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 72) Inventor, Kuni Ogawa, 1006, Kadoma, Kadoma, Osaka Prefecture, Matsushita Electric Industrial Co., Ltd.

Claims (7)

[Claims] 1. A first electrode, a second electrode arranged in parallel with the first electrode, a photoconductive layer in electrical contact with the first electrode, and the second electrode. And a liquid crystal layer inserted between the photoconductive layer and a plurality of island-shaped pixel electrodes electrically contacting the liquid crystal layer side interface of the photoconductive layer, and between the pixel electrodes. A method of manufacturing a spatial light modulator in which a light-shielding layer is inserted in a groove-shaped gap portion, wherein a heat-shrinkable medium containing light-absorbing particles is filled in the gap portion, and then heat shrinkage is performed, A method for manufacturing a spatial light modulation element, characterized in that the light-shielding layer is formed by filling an insulating medium in a gap newly generated by contraction. 2. The method for manufacturing a spatial light modulator according to claim 1, wherein the photoconductive layer has a rectifying property. 3. The method for producing a spatial light modulator according to claim 1, wherein the light absorbing particles are particles containing carbon as a main component. 4. The method of manufacturing a spatial light modulator according to claim 1, wherein the insulating medium is a material of an alignment film that aligns liquid crystal molecules. 5. The step of removing the heat-shrinkable medium remaining on the upper surface of the pixel electrode is inserted between the step of filling the gap part with the heat-shrinkable medium and the step of heat-shrinking the heat-shrinkable medium. The method for manufacturing a spatial light modulator according to claim 1. 6. The spatial light modulator according to claim 1, further comprising the step of expanding the groove-shaped gap portion between the pixel electrodes by performing isotropic etching on the photoconductive layer using the pixel electrodes as an etching mask. Manufacturing method. 7. An expanded groove-shaped gap portion between the pixel electrodes, which substantially covers the bottom surface of the gap portion, is in electrical contact with the photoconductive layer, and is electrically separated from the pixel electrode. The method for manufacturing a spatial light modulator according to claim 6, including a step of forming a metal light-shielding film.