JP2647780B2 - Spatial light modulator and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spatial light modulator used for a projection type display and a method of manufacturing the same.

[0002]

2. Description of the Related Art At present, three types of projection type display are being developed.
There are different approaches. Among them, a projection type display using a cathode ray tube has a limitation in the brightness of the cathode ray tube and has a drawback that the device becomes large, so that there is a limit in increasing the area of the display. In addition, in the case of a liquid crystal projection display comprising a liquid crystal panel having a thin film transistor array, the resolution of the liquid crystal panel is insufficient, the aperture ratio of the liquid crystal panel is low, and the light resistance of the thin film transistor array made of an amorphous silicon thin film. Is low.

[0003] For this reason, a projection display in which a spatial light modulator, a small display, and a light source are incorporated in an enlarged projection optical system is expected to be promising. In this method, a weak image is once written on a spatial light modulator, another read light is modulated according to this write information, and projected on a screen.

In such a type of display, a so-called liquid crystal light valve using a nematic liquid crystal for a light modulation layer is generally used. However, in this system, one of the P and S polarized light components of the read light phase-modulated by the liquid crystal layer passes through the polarizing beam splitter and is projected on the screen. For this reason, when the reading light is in a random polarization state, 50% or more of the light is absorbed by the polarizing beam splitter. For this reason, the utilization rate of the reading light decreases, and the beam splitter generates heat.

As a method for solving this problem, a polymer-dispersed liquid crystal (PDLC) has recently been proposed.
A new liquid crystal light valve using the light scattering phenomenon of uid Crystal) has been proposed. PDLC is a liquid crystal material obtained by dispersing liquid crystal particles in a transparent polymer such as acrylic, and only a few years have passed since research began. In such a new type of liquid crystal light valve, transmission or scattering of the readout light is selected by the applied voltage applied to the PDLC, so that a polarizing beam splitter is unnecessary and the light utilization is high. Further, since it is not necessary to provide alignment layers on both side surfaces of the liquid crystal layer, it is easy to manufacture a large-area spatial light modulator. In addition, since birefringence is not used for light modulation, even if the thickness of the liquid crystal layer is uneven, the spatial uniformity of the readout light is not significantly affected.

[0006]

However, even when such a spatial light modulator is used, the readout light is still transmitted to the PD.
Irradiation is performed on the light modulation layer made of LC. Further, from the side opposite to the read light, write light is irradiated to the photoconductive layer. Therefore, the readout light must be reflected between the light modulation layer and the photoconductive layer so that the readout light does not leak to the photoconductive layer side.

For this purpose, it is known to provide a dielectric multilayer mirror between the photoconductive layer and the light modulation layer made of PDLC. However, the dielectric multilayer film is formed by stacking a large number of dielectric films having different refractive indices, and the reflectance is at most about ninety-nine to ninety-nine percent. Since the reading light has a much higher light intensity than the writing light, if even a small part of the reading light leaks to the photoconductive layer side, the resistivity decreases due to the photoconductive effect. Therefore, in order to improve the intensity ratio (amplification rate) of the read light to the write light, the read light transmitted through the dielectric multilayer film must be effectively blocked between the photoconductive layer and the light modulation layer. .

An object of the present invention is to provide a spatial light modulation device having a transparent electrode, a light modulation layer made of a liquid crystal material for modulating the intensity, phase or traveling direction of readout light according to an applied voltage, and a dielectric multilayer film. Another object of the present invention is to effectively block read light between the photoconductive layer and the light modulation layer.

[0009]

The present invention comprises a photoconductive layer,
One transparent electrode film provided on one surface of the photoconductive layer, a light shielding layer provided on the other surface of the photoconductive layer, and a dielectric multilayer film provided on the light shielding layer; A spatial light modulator including at least a light modulation layer provided on a dielectric multilayer film and another transparent electrode film provided on a surface of the light modulation layer, and a read-out light beam according to an applied voltage. The light modulation layer is formed of a liquid crystal material that modulates intensity, phase or traveling direction, and has a resistivity of 10 ⁸ Ωcm to ^{10 10} Ωcm and a light of a wavelength of 600 nm of 10 ⁴ cm ⁻¹ to 10 ⁵ cm ⁻¹ . The present invention relates to a spatial light modulator in which the light-shielding layer is constituted by a hydrogenated amorphous silicon film having a light absorption coefficient.

As a liquid crystal material, a nematic liquid crystal, a cholesteric liquid crystal, a smectic liquid crystal, and PDLC are preferable. The photoconductive layer is preferably formed of a Bi ₁₂ SiO ₂₀ single crystal, a Bi ₁₂ GeO ₂₀ single crystal, or a GaAs single crystal. Or
Photoconductive layer, GaAs film, hydrogenated amorphous silicon film,
It is preferable to use a hydrogenated amorphous silicon carbide film or an amorphous selenium film.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A manufacturing process of a spatial light modulator 12A according to an embodiment of the present invention will be described step by step with reference to FIGS. In this embodiment, as the photoconductive layer 1A, Bi ₁₂ SiO ₂₀
A single crystal or a Bi ₁₂ GeO ₂₀ single crystal is used.

First, the photoconductive layer 1A made of these single crystals
Is cut out from a single crystal wafer, and one transparent electrode film 2A is provided on one surface of the photoconductive layer 1A (FIG. 1). Then
As shown in FIG. 2, a light shielding layer 3 is provided on the other surface of the photoconductive layer 1A according to the present invention. The configuration and manufacturing method of the light shielding layer 3 will be described later. Next, as shown in FIG. 3, a dielectric multilayer film 4 is provided on the surface of the light shielding layer 3 by vapor deposition.

On the other hand, as shown in FIG. 4, the other transparent electrode film 2B is formed on the surface of the glass substrate 7. The dielectric multilayer film 4 and the transparent electrode film 2B are opposed to each other with a sealing material 5 including a spacer interposed therebetween. Dielectric multilayer film 4, transparent electrode film 2B
A flat space 6 is formed between the sealing material 5.

In this embodiment, a polymer dispersed liquid crystal (PDLC), which is a liquid crystal material obtained by dispersing liquid crystal particles in a transparent polymer, is used. As a specific manufacturing method, a mixture of an uncured nematic liquid crystal and a resin matrix is injected from an injection port, and the injection port is sealed and then cured as in the case of a conventional ordinary twisted nematic liquid crystal. As a result, a light modulation layer 8 made of PDLC is formed in the space 6 as shown in FIG.

There is also a manufacturing method that does not use a sealing material. That is, for example, a mixture of an uncured nematic liquid crystal and a resin matrix is supplied on a substrate provided with a transparent electrode, and then, a dielectric multilayer film and a photoconductive layer to which a transparent electrode is attached are superimposed, and irradiated with light or the like. It can also be cured. Of course, after that, a sealing material may be applied to the periphery to seal the periphery. According to this manufacturing method, the mixture of the uncured nematic liquid crystal and the resin matrix may be simply supplied by roll coating, spin coating, printing, coating with a dispenser, or the like, so that the injection step is simple and the productivity is extremely high. . In addition, the mixture of these uncured nematic liquid crystals and the resin matrix may have adverse effects on the performance of the liquid crystal, such as ceramic particles for controlling the substrate gap, plastic particles, spacers such as glass fibers, pigments, dyes, viscosity modifiers, etc. May be added.

Next, the operation of such a spatial light modulator will be described with reference to the configuration example of FIG. The writing light emitted from the weak writing light source 10A passes through the liquid crystal television 11 and becomes input image light. The input image light is condensed by the lens 13A and is irradiated on the spatial light modulator 12A. This input image light passes through the transparent electrode film 2A and enters the photoconductive layer 1A. On the other hand, a high-luminance readout light source 10
The reading light emitted from B is collected by the lens 13B,
The light is reflected by the mirror, adjusted by the lens 13C, and enters the light modulation layer 8.

Next, the incident light is mainly reflected by the dielectric multilayer film 4, passes through the light modulation layer 8 once again, is condensed by the lens 13C, and is projected on the screen 14 through the lens 13D.

The writing light is illuminated by the liquid crystal television 11. In a portion of the photoconductive layer 1A that is not exposed to light, the voltage applied between the pair of transparent electrode films 2A and 2B is mostly concentrated on the photoconductive layer 1A. Therefore, the voltage applied to the light modulation layer 8 does not reach the threshold voltage of the light modulation layer 8. On the other hand, when the light shines on the photoconductive layer 1A, the electric resistance of the photoconductive layer 1A is greatly reduced at that portion, and the voltage distributed to the light modulating layer 8 is increased and exceeds the threshold value.

Inside the light modulation layer 8 made of PDLC,
When no voltage is applied to the light modulation layer 8, the liquid crystal molecules are arranged along the interface between the polymer and the liquid crystal. The shape of the liquid crystal particles is random. When the voltage applied to the light modulation layer 8 is low, the refractive indices of the liquid crystal molecules and the polymer are significantly different.
The reading light changes its traveling direction many times in the light modulation layer 8 and is scattered. On the other hand, when the voltage applied to the light modulation layer 8 exceeds the threshold voltage and the liquid crystal molecules are oriented in the direction of the electric field, the read light passes through the light modulation layer 8 without being scattered.

With such a mechanism, the two-dimensional intensity distribution in the input image light is converted into the two-dimensional intensity distribution in the readout light. If the intensity of the reading light is made higher than the intensity of the writing light, the signal amplification factor becomes higher accordingly.

As described above, the dielectric multilayer film 4 reflects only 90 to 99% of read light. For this reason,
Part of the reading light passes through the dielectric multilayer film 4 and the photoconductive layer 1A.
Leaks towards you. The more the intensity of the read light is higher than the intensity of the write light, the more the photoconductive layer 1A as described above
The light leaking to the direction becomes stronger, and the photoconductive layer 1A is exposed.

Therefore, in order to increase the signal amplification factor, it is necessary to provide a light-shielding layer 3 for blocking readout light passing through the dielectric multilayer film 4 between the photoconductive layer 1A and the dielectric multilayer film 4. However, the light shielding layer 3 is required to have contradictory characteristics. That is, the light-shielding layer 3 must have a high ability to absorb the read light, and this can increase the intensity of the read light. However, the light-shielding layer having a high readout light absorbing ability usually remarkably lowers its specific resistance when light is absorbed. In such a case, the resolution of the spatial light modulator rapidly deteriorates, and the projected image becomes unclear.

Here, the present inventor has solved the above two trade-offs, and has found a new light-shielding layer that can prevent the deterioration of the resolution of the element while increasing the intensity of the reading light. As a result, a bright, clear, and high-resolution projected image can be obtained. The light-shielding layer used in the present invention has a resistivity of 10 ⁸ Ωcm to ^{10 10} Ωcm regardless of the presence or absence of irradiation light, and has a light absorption coefficient of 10 ⁴ cm ^-1 to 10 ⁵ cm ^-1 at a wavelength of 600 mm. Amorphous silicon film.

If the resistivity of the hydrogenated amorphous silicon film in a light place is lower than 10 ⁸ Ωcm, the resolution of the device is degraded. Also, if the light absorption coefficient of this film is lower than 10 ⁴ cm ^-1 ,
Since the amount of light transmitted through the light shielding layer 3 increases, the projected image cannot be brightened. Further, from the viewpoint of the characteristics of the projected image, the higher the light absorption coefficient of the hydrogenated amorphous silicon film and the specific resistivity in a bright place, the better. However, in an amorphous film, it is common that the greater the amount of light absorption, the lower the resistivity in a light place. Also, films with high resistivity in the light typically have low light absorption. As described above, since the light absorption coefficient and the resistivity in a light place are in an opposite relationship to each other, it is impossible to increase both of them. In the conventional hydrogenated amorphous silicon film, when the light absorption coefficient is set in the above range, the resistivity is limited to 10 ⁵ Ωcm in terms of manufacturing properties. The absorption coefficient was 10 ⁴ cm ^-1 at the manufacturing limit. If the resistivity in the light exceeds 10 ¹⁰ Ωcm, the light absorption coefficient will be 10 ⁴ cm
It is difficult to keep it above ^-1 and if the light absorption coefficient is 1
When it exceeds 0 ⁵ cm ⁻¹ , it was difficult to maintain the resistivity in a light place at 10 ⁸ Ωcm or more.

Next, a method for providing the hydrogenated amorphous silicon film on the surface of the photoconductive layer will be described. For this purpose, a monosilane gas is used as a material gas, and a film is formed by plasma enhanced chemical vapor deposition (plasma CVD) while maintaining the temperature of the substrate at 120 ° C. or lower. Usually, the hydrogenated amorphous silicon film is used as a photoconductive layer or a photoconductor. In such a photoconductive layer, it is necessary to increase the light absorption coefficient, that is, the light sensitivity. At the same time, when light is absorbed, the specific resistance must be reduced as quickly as possible. For this purpose, it is necessary to reduce the defects of the film and to provide a film as dense as possible. Due to such requirements, hydrogenated amorphous silicon films are formed at a temperature of 200 ° C. or higher.

When such a conventional hydrogenated amorphous silicon film is used for the light-shielding layer of the spatial light modulator, the resistance at the time of light absorption is sharply reduced, so that the resolution of the device is greatly deteriorated. Therefore, in the present invention, based on a completely opposite idea, a suitable defect was introduced into the hydrogenated amorphous silicon film to form a hydrogenated amorphous silicon film having a suitable light absorption rate and a suitable resistivity. . That is,
In the present invention, the hydrogenated amorphous silicon film was successfully provided on the surface of the photoconductive layer by a plasma CVD method while maintaining the temperature of the substrate at 120 ° C. or lower.

Further, while maintaining the temperature of the substrate at 100 ° C. or lower, the hydrogenated amorphous silicon film is formed by plasma CVD.
Film formation using monosilane gas by the method
It has been found that the light-shielding layer of the present invention can be obtained even when the film is heat-treated at a temperature of 100 ° C. or lower and 100 ° C. or higher. According to this method, not only the characteristics of the hydrogenated amorphous silicon film are not deteriorated by the above heat treatment, but also the surface of the film becomes smooth by the heat treatment, and the dielectric multilayer film easily adheres to the surface of the light shielding layer. When the heat treatment temperature exceeds 120 ° C., the densification of the hydrogenated amorphous silicon film proceeds,
The specific resistivity becomes too low during light absorption.

Next, an embodiment in which the photoconductive layer is a hydrogenated amorphous silicon film or a hydrogenated amorphous silicon carbide film will be described with reference to FIGS.
First, as shown in FIG. 7, one transparent electrode film 2A is provided on a glass substrate 17 whose surface is optically polished.

Next, as shown in FIG. 8, a photoconductive layer 1B made of a hydrogenated amorphous silicon film is provided on the surface of one transparent electrode film 2A, and a light shielding layer 3 is provided on the surface of the photoconductive layer 1B. After that, the dielectric multilayer film 4, the light modulation layer 8, the other transparent electrode film 2B, and the glass substrate 7 are provided according to the procedure described with reference to FIGS. Thus, the spatial light modulator 12B shown in FIG. 9 is obtained.

The photoconductive layer 1B made of a hydrogenated amorphous silicon film is preferably formed by plasma CVD. At this time, as described above, if the light shielding layer 3 is also formed by plasma CVD, the transparent electrode film 2A
The photoconductive layer 1B and the light-shielding layer 3 can be continuously formed on the same device by plasma CVD in the same device. Of course, at this time, it is necessary to appropriately change the material gas. The operation of the spatial light modulator 12B is the same as the operation of the element 12A described above.

Next, actual experimental results will be described. First, the spatial light modulator is operated in a procedure as shown in FIGS.
12A was prepared.

However, the photoconductive layer 1A was formed of a single crystal of Bi ₁₂ SiO ₂₀ and its size was 35 mm × 35 mm × 0.5 mm. The transparent electrode films 2A and 2B were formed by a vacuum evaporation method. The light shielding layer 3 was formed by a plasma CVD method.
This condition is as follows. Equipment used: Shimadzu PCVD-25 type Material gas: SiH ₄ material gas flow rate 5 sccm Material gas pressure 25 m torr Discharge energy 100 W Substrate temperature 50 ° C Film formation time 2 hours Film thickness 6000 angstrom

The amorphous film thus obtained (light-shielding layer 3)
About, the light absorption coefficient was measured, 4.3 × 10 ⁴ cm
^-1 (wavelength 600 nm). The resistivity was measured by a two-terminal method, and the following values were obtained. 3.8 × 10 ⁹ Ω · cm (resistivity in dark) 3.0 × 10 ⁸ Ω · cm (resistivity in light) The dielectric multilayer film 4 was formed by a vacuum evaporation method. The dielectric multilayer film 4 is a laminate of a TiO ₂ thin film and a SiO ₂ thin film, and a total of 20 alternately stacked. And PDLC by the following materials
And a light modulation layer 8 having a thickness of 18 μm was obtained. (Nematic liquid crystal) dielectric of the long axis and vertical mixing liquid crystal ordinary refractive index n _o = 1.525 extraordinary refractive index n _e = 1.748 in the long axis parallel to the direction of the liquid crystal molecules relative permittivity = 17.6 liquid crystal molecules of cyanobiphenyl Rate = 5.1 (ultraviolet curable polymer) Urethane polymer Refractive index _np = 1.524 Curing wavelength region ... 350 to 380 nm (spherical spacer agent) Hard resin Diameter ... 18 μm

Then, evaluation was performed by incorporating the spatial light modulator 12A into the optical system as shown in FIG. In order to confirm whether or not a color moving image can be realized, a total of three elements 12A were prepared and incorporated into the optical system shown in FIG. That is, the same spatial light modulation elements 20B, 20R, and
20G were fabricated and incorporated into the optical system of FIG. 10, respectively. Figure
In the ten optical systems, blue light is modulated by the liquid crystal panels 21B, 21R, and 21G, respectively, to obtain respective readout lights.
Each of these readout lights is transmitted through lenses 22B, 22R,
The light passes through 22G and enters the spatial light modulators 20B, 20R, and 20G. Thereby, writing to each element is performed. On the other hand, white light emitted from the white light source 23 is focused on the mirror 25 by the lens 24A. Of this reflected light, blue light is reflected by the dichroic mirror 26B, and the element 20B
Incident on. Visible light other than blue light passes through the dichroic mirror 26B. Next, the red light is reflected by the dichroic mirror 26R and enters the element 20R. The green light passes through the dichroic mirror 26R, and the element 20G
Incident on. These primary color lights pass through the light modulation layer 8, are mainly reflected by the dielectric multilayer film 4, pass through the light modulation layer 8 again, and are projected on the screen 27 through the lenses 24B and 24C. Thereby, a full-color image is formed.

As a result, the writing light intensity was 300 μW / cm
^{2. A} readout light intensity of 0.3 W / cm ² was achieved. Therefore, this intensity ratio became 1000 times, and a large signal amplification factor was obtained. As a result, the image was projected on a 110-inch diagonal screen and could be fully viewed even in a bright room. The resolution at this time was 1000 × 1000 pixels when the number of pixels was 301 p / mm on the spatial light modulator, which was sufficient.

In the above experiment, a hydrogenated amorphous silicon film was formed on the surface of the photoconductive layer, and then heat-treated in a vacuum furnace under the following conditions. Temperature 120 ° C: Atmospheric pressure: 8.7 × 10 ^-7 torr: Time: 2 hours

The light absorption coefficient, resistivity in a dark place, and resistivity in a bright place of this hydrogenated amorphous silicon film are respectively
4.3 × 10 ⁴ cm ^-1 , 1.5 × 10 ¹⁰ Ωcm, 3.8 × 10 ⁸ Ωcm
Met. In addition, when a spatial light modulator was manufactured in the same manner as above, a resolution equal to or higher than the above example was obtained. The read light intensity was slightly lower than the above example, and was 0.1 W / cm ² .

In the above experimental example, the substrate temperature was
A hydrogenated amorphous silicon film was formed in the same manner as above except at 200 ° C., and a film having the following characteristics was obtained. Light absorption coefficient: 4.0 × 10 ⁴ cm ⁻¹ , resistivity in dark place 5.0 × 10 ⁹
Ω · cm, resistivity in the light: 3.0 × 10 ⁶ Ω · cm, film thickness: 80
00 angstroms. Except for this, when a spatial light modulator was manufactured in the same manner as above, the writing light intensity was 300 μW /
to cm ^2, the read light intensity became 0.1 W / cm ^2.
The resolution was 10 lp / mm on the spatial light modulator.

In the above experimental example, a comparative experiment was performed in which the material gas for forming the light shielding layer and the flow rate thereof were changed to change the characteristics of the light shielding layer 3. Table 1 below shows the film forming conditions and the characteristic values of each sample. Except for the light-shielding layer 3, the spatial light modulators of Comparative Samples 1 and 2 were manufactured in the same manner as described above.

[0040]

[Table 1]

In sample 1 shown in Table 1, a-SiGe:
An H film was prepared. The resistivity of the film is lowered by the addition of germanium. In Sample 2, an a-SiC: H film was formed. The addition of carbon lowers the light absorption coefficient for 600 mm light. When a projection experiment was performed on Sample 1, only an image with a resolution of about 10 lp / mm was obtained. (Optical amplification factor in this case is 10 ⁵ times.) When it was projected experiments on sample 2, the optical amplification factor
Only about 100 times the device was obtained.

[0042]

According to the present invention, a light-shielding layer is provided between a photoconductive layer and a dielectric multilayer film, and the light-shielding layer is formed of an amorphous film having the above characteristics. The read light that has passed can be effectively absorbed. Therefore, even if the intensity of the readout light is increased, the readout light hardly leaks to the photoconductive layer side, so that the photoconductive layer is less likely to be exposed to the readout light. This makes it possible to increase the magnification of the read light intensity with respect to the write light intensity. Moreover, when an amorphous film having the above characteristics is used,
Even if a part of the reading light is absorbed, the resolution of the spatial light modulation element does not deteriorate, so that the resolution of the reading light can be increased while increasing the intensity of the reading light.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state in which one transparent electrode film 2A is formed on the surface of a photoconductive layer 1A.

FIG. 2 is a cross-sectional view showing a state in which a light shielding layer 3 is provided on a photoconductive layer 1A.

FIG. 3 is a cross-sectional view showing a state in which a dielectric multilayer film 4 is provided on the surface of a light shielding layer 3.

FIG. 4 is a cross-sectional view showing a state in which a sealing material 5 is provided between a dielectric multilayer film 4 and another transparent electrode film 2B.

FIG. 5 is a sectional view showing a spatial light modulator 12A.

FIG. 6 is a schematic diagram illustrating an example of a projection optical system.

FIG. 7 is a cross-sectional view showing a state in which one transparent electrode film 2A is provided on the surface of a glass substrate 17.

FIG. 8 shows a photoconductive layer 1B and a light shielding layer 3 on the surface of a transparent electrode film 2A.
Is a cross-sectional view showing a state in which are sequentially provided.

FIG. 9 is a sectional view showing a spatial light modulator 12B.

FIG. 10 is a schematic diagram illustrating an example of a full-color projection optical system.

[Explanation of symbols]

 1A, 1B Photoconductive layer 2A One transparent electrode film 2B The other transparent electrode film 3 Light shielding layer 4 Dielectric multilayer film 7, 17 Glass substrate 8 Light modulation layer made of liquid crystal material 12A, 12B, 20B, 20R, 20G Spatial light Modulator 14, 27 Screen 21B, 21R, 21G LCD panel 23 White light source 26B, 26R Dichroic mirror

Continued on the front page (72) Inventor Yukihisa Osugi 3-9 Takeda-cho, Mizuho-ku, Nagoya-shi, Aichi Prefecture No. 13, NGK Takeda-Kita Company House (72) Inventor Shoji Tange 2-chome, Okamachi, Mizuho-ku, Nagoya-shi, Aichi 38-2, Hill Residence, Gaishi City, Japan (56) References JP-A-59-81627 (JP, A)

Claims (5)

(57) [Claims] 1. A photoconductive layer, one transparent electrode film provided on one surface of the photoconductive layer, a light shielding layer provided on the other surface of the photoconductive layer, and A spatial light modulator comprising at least a provided dielectric multilayer film, a light modulation layer provided on the dielectric multilayer film, and another transparent electrode film provided on the surface of the light modulation layer. Te, the intensity of the reading light in accordance with an applied voltage, the light modulation layer by the liquid crystal material to modulate the phase or direction of travel is formed, 10 ⁸
Ωcm to ^{10 10} Ωcm and 10 ⁴ for light with a wavelength of 600 nm
A spatial light modulator, wherein the light-shielding layer is constituted by a hydrogenated amorphous silicon film having a light absorption coefficient of cm ^-1 to 10 ⁵ cm ^-1 . 2. The spatial light modulator according to claim 1, wherein the photoconductive layer is a hydrogenated amorphous silicon film or a hydrogenated amorphous silicon carbide film. 3. The method of manufacturing a spatial light modulator according to claim 1, wherein a monosilane gas is used as a material gas, and the temperature of the substrate is kept at 120 ° C. or less, and the hydrogenated amorphous silicon is formed by plasma enhanced chemical vapor deposition. A method for manufacturing a spatial light modulator, which forms a film. 4. The hydrogenated amorphous silicon film is
4. The method according to claim 3, wherein said hydrogenated amorphous silicon film is heat-treated at a temperature of not less than 100 ° C. and not more than 120 ° C.
A method for manufacturing the spatial light modulation device according to the above. 5. The method of manufacturing a spatial light modulator according to claim 2, wherein the light shielding layer and the photoconductive layer are continuously formed in the same device by a plasma enhanced chemical vapor deposition method. To manufacture a spatial light modulator.