JP2857274B2 - 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 projection display,
The present invention relates to a spatial light modulator used for an image display device such as a holographic television and an optical arithmetic device and an image arithmetic device, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Hitherto, high-definition televisions having a large screen and high-density pixels have been developed in various systems, and some of them have been put to practical use. Above all, development of a projection type display using liquid crystal technology as an alternative to the conventional cathode ray tube method has been active. The conventional cathode ray tube method has a problem that the brightness of the screen tends to decrease and the entire image tends to be dark when the density of pixels is increased, and it is difficult to increase the size of the cathode ray tube itself.

A projection display device using a liquid crystal element driven by a thin film transistor is an effective method in terms of weight and size reduction and low power consumption. However, the aperture ratio is not large, and the element itself is complicated and expensive. Is mentioned as a problem to be solved.

On the other hand, in combination with a photo-writing type liquid crystal element using a CRT as an input, a device structure is simpler and a CR
Attention has been paid to a device combining the advantages of T and a liquid crystal element (JP-A-63-109422, etc.). In recent years, a liquid crystal element having an amorphous silicon thin film as a high-sensitivity light-receiving layer has been used to form a device of 100 inches or more. It is now possible to project moving images on a large screen. As for the liquid crystal material, a high-resolution liquid crystal light valve can be realized by using a ferroelectric liquid crystal capable of high-speed response. Further, such an optical writing type liquid crystal element is expected to be a core of a next-generation parallel operation device and an optical computing device by utilizing a memory characteristic and a binarization characteristic of a ferroelectric liquid crystal. .

On the other hand, holographic televisions have been attracting attention as apparatuses capable of viewing three-dimensional stereoscopic moving picture images without glasses, and liquid crystal elements are particularly expected as rewritable hologram recording media. The resolution of the current transistor-driven liquid crystal element is 12 to 25 (lp / m
m), and realization of a high resolution of 200 (lp / mm) or more is desired in the future.

A spatial light modulator used in such an image display device or an image processing device includes a liquid crystal layer, a photoconductive layer, a reflective layer, an alignment film for aligning liquid crystal, and the like. In a modulation device, a photoconductor having a rectifying property is generally formed in the photoconductive layer uniformly over the entire device, and the presence of such a photoconductive layer enables high-speed response. At the same time, the state of each pixel or the entire surface of the element can be returned to the initial state only by an electric signal (Japanese Patent Application Laid-Open No. 64-18130).

On the other hand, in a conventional spatial light modulator, in order to read out a modulated optical output after optical writing, an element structure in which a metal reflection layer is provided separately between a liquid crystal layer and a photoconductive layer (see FIG. 1). Japanese Patent Application Laid-Open No. Sho 62-169120) and an element structure in which a dielectric reflection thin film layer is provided instead of a metal reflection layer have been proposed. In such an element structure, the limit resolution for writing a high-density image input is given by, for example, the following equation.

[0008]

(Equation 1)

In equation (1), f is the resolution, ρ is the volume resistivity of the light receiving layer, C is the sum of the capacitance of the light receiving layer and the liquid crystal layer, and τ is the response time of the liquid crystal. As a typical numerical example, ρ = 10 ¹⁰
From Ω · cm, C = 10 nF / cm ² and τ = 100 μs, f = 100 (lp / mm) is obtained. At present, when a dielectric reflective film is provided, a resolution of 125 (lp / mm) at the maximum has been confirmed (Abstract Collection of the Japan Society of Applied Physics, 1990, 26a-H-9).

On the other hand, when the output image is a metal reflective film having clear pixels, it is required to form fine pixels of 100 (lp / mm) or more. As a fine processing technology in the current silicon semiconductor technology, a photolithography technology capable of processing a pattern line width on the order of μm or less has been developed. By using this technology, one pixel is 10 μm square and the width between pixels is 10 μm. A pattern of 1 μm or less can be formed.

Particularly, the latter spatial light modulator has a sharp pixel shape, and is an optical writing type element applied to a large-screen and high-density display such as a high-definition television.
The realization of a spatial light modulator having a large aperture ratio and capable of displaying a high-luminance screen is expected. In addition, the optical operation element using the binarization processing capability based on the threshold characteristic of the ferroelectric liquid crystal has a distinct threshold value and pixel shape for each element (corresponding to a pixel). It has been proposed as a main element (Japanese Patent Application No. 3-1145, Japanese Patent Application No.
-1146).

[0012]

As an image display device having a high resolution or an optical operation device for performing two-dimensional information processing having high-density information, there is a spatial light modulation device using a ferroelectric liquid crystal. The factors that limit the
(1) In-plane diffusion length of optical carriers generated in the light-receiving layer,
(2) Drift of electric charge at each junction interface inside the light receiving layer due to rectification, (3) Crosstalk due to electric field strength leakage between adjacent pixels, (4) Size of minimum domain of ferroelectric liquid crystal, etc. Can be considered.

In particular, in the element structure provided with the separated metal reflection layer, the resolution is greatly deteriorated due to the influence of the factors (1) and (2), and the resolution is limited by the resolution limit determined by these factors. The pixel density of a spatial light modulator having a reflective surface is determined.

FIG. 7 is a sectional view of an example of a conventional spatial light modulator. In the conventional spatial light modulation device, a photoconductive layer 13 having a pin structure is formed uniformly over the entire surface of the device.
Due to a potential difference and an electric field generated between adjacent pixels, electrons move in the n-layer and holes move in the p-layer in the lateral direction of the device, and crosstalk occurs between pixels.
There is a problem that resolution is deteriorated due to (1) and factor (2).

According to the present invention, there is provided a spatial light modulation device having a liquid crystal layer, a photoconductive layer, an alignment film, and the like, in which a resolution deterioration caused in the photoconductive layer as described above is prevented. The object of the present invention is to provide a spatial light modulator capable of faithfully displaying information with a high density by providing a spatial light modulator capable of easily obtaining the spatial light modulator according to the present invention. An object of the present invention is to provide a method for manufacturing a light modulation element.

[0016]

To achieve the above object, a spatial light modulator according to the present invention comprises a first electrode, a second electrode facing the first electrode, and a first electrode. A plurality of pixel portions and an inter-pixel portion formed between the plurality of pixel portions, wherein each of the pixel portions is electrically substantially separated by the inter-pixel portion. A photoconductive layer, a plurality of reflective layers connected to a pixel portion of the photoconductive layer, a liquid crystal layer provided between the reflective layer and the second electrode, and a photoconductive layer between pixels of the photoconductive layer. An input light-shielding layer for preventing writing light from entering the portion, and each pixel portion has a diode structure between one of the reflection layers corresponding thereto and the first electrode.
A, thereby characterized in that it has a rectifying property. Up
In the above configuration, each of the pixel portions of the photoconductive layer includes a p-type semiconductor layer, an i-type semiconductor layer formed on the p-type semiconductor layer, and an n-type semiconductor formed on the i-type semiconductor layer. Layer, which provides rectification. Preferably, the inter-pixel portion of the photoconductive layer has an i-type semiconductor layer, and the i-type semiconductor layer does not diffuse the charge generated in each of the pixel portions of the photoconductive layer to other pixel portions. . Further, it is preferable that the upper surface of the inter-pixel portion of the photoconductive layer is lower than the upper surface of the pixel portion of the photoconductive layer to form a groove. Further, it is preferable that the i-type semiconductor layer is exposed on the upper surface of the portion between the pixels of the photoconductive layer.

Further, another spatial light modulation element of the present invention comprises a first electrode, a second electrode facing the first electrode,
A plurality of pixel portions and an inter-pixel portion formed between the plurality of pixel portions, each of the pixel portions being substantially electrically connected to the first electrode; A photoconductive layer, a reflective film connected to a pixel portion and an inter-pixel portion of the photoconductive layer, a liquid crystal layer provided between the reflective film and the second electrode, An input light-shielding layer for preventing writing light from entering the inter-pixel portion of the photoconductive layer, wherein each pixel portion includes a diode structure between the reflective film and the first electrode;
Has a concrete, to characterized this by having a rectifying property
You .

Further, still another spatial light modulator according to the present invention includes a first electrode, a second electrode facing the first electrode, and a plurality of electrodes electrically connected to the first electrode. A photoconductive layer having a pixel portion and an inter-pixel portion formed between the plurality of pixel portions, wherein each of the pixel portions is substantially substantially electrically separated by the inter-pixel portion; A plurality of reflective layers connected to the pixel portion of the conductive layer or a reflective film connected to the pixel portion and the inter-pixel portion of the photoconductive layer,
A liquid crystal layer provided between the reflective layer or the reflective film and the second electrode, wherein each pixel portion corresponds to one of the reflective layers or the reflective film and the first electrode; has a diode structure between the, thereby having a rectifying property, the upper surface of the inter-pixel portion of the photoconductive layer, and characterized by being lowered than the upper surface of the pixel portion of the photoconductive layer
I do . In the above structure, it is preferable that the i-type semiconductor layer is exposed on the upper surface of the portion between the pixels of the photoconductive layer. Further, it is preferable that an alignment film is formed on at least the upper surface of the photoconductive layer at a portion between pixels.

In the method of manufacturing a spatial light modulator according to the present invention , a diode structure is formed by stacking a plurality of layers.
Forming a photoconductive layer having a plurality of layers;
At least a predetermined area of at least one layer is selectively etched, and
As a result, a plurality of pixel portions that have not been etched
And this pixel portion can be substantially electrically separated.
Forming a pixel-to-pixel portion, and the writing light
An input for preventing the light from entering the portion between the pixels of the conductive layer.
Forming a light shielding layer. Smell the above method
After the step of forming the photoconductive layer,
Before, further comprising a step of forming a reflective film on the photoconductive layer
It is preferred to include.

[0020]

According to the above arrangement, each pixel portion of the photoconductive layer is aligned.
Since a photoconductor having fluidity is formed, its switching speed can be significantly improved. Further, in the absence of bias light, a large electric field is applied to the ferroelectric liquid crystal layer by applying a voltage in the forward direction to the photoconductor having a rectifying property, forcing the image memory state to the initial state. You can go back. On the other hand, if a voltage is applied in the opposite direction to the rectifying photoconductor while some image pattern is received, the pixel with light input will be in a low resistance state, and the liquid crystal will be coordinated in that part. Is reversed, and the pixel portion without light input remains at a high resistance and the configuration of the liquid crystal is not reversed.

In the photoconductive layer, a photoconductor having a rectifying property is formed for each pixel, so that the photocarriers generated in the light receiving layer are diffused in the in-plane direction, and the light receiving due to the rectifying property is provided. Since drift of electric charges at each junction interface inside the layer can be prevented, resolution degradation due to these effects can be suppressed.

In the above structure, the rectifying photoconductor is made of , for example , an amorphous silicon semiconductor having a diode structure, so that it is easy to form a film over a large area and to generate a photocurrent. A light-receiving layer having good quantum efficiency can be easily formed.

In the above structure, the reflection layer is divided in units of pixels on the photoconductor having rectifying properties, so that light reflection in a region between pixels can be suppressed, and contrast between pixels can be suppressed. And blurring and blurring of an image can be improved. Also, the input light shielding layer
Therefore, light does not enter between pixels when writing an image.
And the portion of the photoconductive layer located between the pixels is always high.
It becomes a resistance area, and electrons and holes generated in pixel units
The load is prevented from moving to the next pixel, and the
Crosstalk is eliminated. Also, the pixel portion of the photoconductive layer
And the use of a reflective film connected between the pixels
High reflectance can be achieved and readout image with high brightness
Obtainable. Also, the upper surface of the portion between pixels of the photoconductive layer
Is lower than the upper surface of the pixel portion of the photoconductive layer,
By doing so, the portion between the pixels of the photoconductive layer and the pixel portion
A step is formed between the layers, causing stress relaxation in the entire photoconductive layer.
Be sent. As a result, the effect of increasing the assembly accuracy of the glass substrate is improved.
The result is.

Further, according to the method of manufacturing a spatial light modulator of the present invention, after forming a diode structure, it is formed in pixel units.
Accordingly , a photoconductor having a rectifying property in the photoconductive layer can be easily formed for each pixel.

According to the method of manufacturing a spatial light modulator of the present invention , a reflection layer is formed after a diode structure is formed.
And a reflective layer and a rectifying photoconductor are formed in pixel units.
Accordingly, the reflection layer and the photoconductor having a rectifying property can be easily formed for each pixel. Also write light
To prevent light from entering the inter-pixel portion of the photoconductive layer.
For forming an input light-shielding layer for
An input to prevent light from entering between pixels when writing images
A light shielding layer is easily obtained.

Hereinafter, the operation of the present invention will be specifically described with reference to the drawings. FIG. 1 is a cross-sectional view of one embodiment of the spatial light modulator of the present invention, and the manner in which the above-described resolution degradation is improved will be described with reference to FIG. Photoconductive layer 13
Constitutes a rectifying pin diode for each pixel unit, on which a metal reflective layer 14 is formed separately for each pixel unit. Note that the photoconductive layer 13 is preferably an amorphous silicon layer that can be easily formed over a large area and has a quantum efficiency of photocurrent generation that is close to an ideal value of 1. On the other hand, the photoconductive layer 13 located between the pixels forms only the i-layer 13b of the amorphous silicon layer. With such an element structure, the pin structure corresponding to a pixel is two-dimensionally distributed in a plane in a columnar manner, and a region between the pixels has a pattern shape surrounded by the i-layer 13b.

[0027] When irradiated with light while a reverse bias voltage is sign pressurized to such a spatial light modulator 1, photocurrent i layer 13
b, of which electrons drift toward the n-layer 13c and holes drift toward the p-layer 13a. The area between pixels is p
Since only the i-layer 13b is formed without the layer and the n-layer, the photoconductive layer 13 located between the pixels is formed due to the absence of the channel layer at the low-resistance interface and the existence of the light-shielding layer 27.
Is always a high resistance region, and the movement of charges such as electrons and holes generated in pixel units to adjacent pixels is suppressed, and crosstalk between pixels is eliminated.

In particular, when the photoconductive layer 13 is made of amorphous silicon, the main carrier having a long running length is an electron. Therefore, p of the charge pair generated by light absorption is moved from the substrate side so that the electron can travel in the layer. The layer 13a, the i-layer 13b, and the n-layer 13c are formed in this order. At this time, it is most effective to limit the lateral drift of electrons as carriers on the n-layer 13c side.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an embodiment of the spatial light modulator of the present invention. Transparent insulating substrate 1 such as glass
A light-shielding film 27 made of chromium or the like is formed on a portion between the pixels 1 to prevent light from entering between the pixels during image writing. On the surface, ITO or SnO _x
A transparent conductive electrode 12 made of an amorphous silicon semiconductor or the like is further formed thereon, and a p-layer 13a, an i-layer 13b, and an n-layer 13c are laminated in a diode structure in this order. Photoconductive layer 13 corresponding to
In this part, only the i-layer 13b is laminated.

The material used for the photoconductive layer 13 is, for example, CdS, CdTe, CdSe, ZnS, ZnSe, Ga
Compound semiconductors such as As, GaN, GaP, GaAlAs, InP, amorphous semiconductors such as Se, SeTe, AsSe, Si, Ge, Si _1-x C _x , Si _1-x Ge _x , G
e _1-x C _x (0 <x <1) a semiconductor such as a polycrystalline or amorphous semiconductor, or (1) a phthalocyanine pigment (hereinafter referred to as “P
c "), for example, non-metallic Pc, XPc (X = Cu,
Ni, Co, TiO, Mg, Si (OH) ₂ etc.), Al
ClPcCl, TiOClPcCl, InClPcC
1, InClPc, InBrPcBr, etc., (2) monoazo dyes, azo dyes such as disazo dyes, (3) penylene anhydrides, penylene pigments such as penyleneimide, (4) indigoid dyes, (5) quinacridone pigments, (6) Polycyclic quinones such as anthraquinones and pyrenequinones, (7) cyanine dyes, (8) xanthene dyes, (9) charge transfer complexes such as PVK / TNF, (10) formed from a beryllium salt dye and a polycarbonate resin Eutectic complexes, and (11) organic semiconductors such as azurenium salt compounds.

Further, amorphous Si, Ge, Si
_1-xC_x, Si_1-xGe_x, Ge_1-xC_x(Hereinafter a-
Si, a-Ge, a-Si_1-xC_x, A-Si_1-xGe
_x, A-Ge _1-xC_xTo the photoconductive layer 13
When used, hydrogen or halogen elements may be included.
Oxygen or nitrogen to reduce the dielectric constant or increase the resistivity.
You may include it. In addition, a p-type impurity is used for controlling the resistivity.
Elements such as B, Al, and Ga, or n-type impurities.
Alternatively, an element such as P, As, or Sb may be added.

The amorphous material to which the impurity is added is laminated to form a junction such as p / n, p / i, i / n, p / i / n, etc., and a depletion layer is formed in the photoconductive layer 13. May be formed to control the dielectric constant, dark resistivity or operating voltage polarity. In addition to such an amorphous material, a heterojunction is formed by laminating two or more kinds of the above materials to form a photoconductive layer 13.
A depletion layer may be formed therein. Also, the photoconductive layer 13
Is preferably in the range of 0.1 μm to 10 μm.

On the surface of the n-layer 13c of the photoconductive layer 13, a reflective layer 14 made of a metal thin film of aluminum, chromium, titanium or the like is formed. Therefore, the p layer 13a and the n layer 13c
The reflection layer 14 is formed as a pixel pattern separated on a pixel-by-pixel basis.

On this surface, an alignment film 15 made of a polymer thin film such as nylon or polyimide, an obliquely deposited SiO ₂ film, etc. for aligning the liquid crystal is formed uniformly over the entire surface of the device. The orientation film 15 is formed so that the orientation of the ferroelectric liquid crystal molecules is parallel to the layer direction, and the thickness thereof is 1000 Å or less, particularly preferably 100 Å or less.

The cell thickness of the ferroelectric liquid crystal layer 16 is determined by spacers 17 such as resin beads. In particular, in order to increase the contrast of output light, in the case of a transmissive spatial light modulator, the thickness of the ferroelectric liquid crystal layer 16 is reduced to about 2 μm.
In the case of a reflective spatial light modulator, it is preferable to set the thickness to about 1 μm. The material of the ferroelectric liquid crystal layer 16 is preferably a chiral smectic C liquid crystal which is a ferroelectric liquid crystal.

[0036] Similarly, also on the transparent insulating substrate 20 such as glass, ITO and the transparent conductive electrode 19 such as SnO _x is formed, also on the alignment film 15 and the same orientation layer 18 is the element It is formed uniformly over the entire surface.

Next, the operation of the spatial light modulator 1 will be described. The incident light 2 from the substrate side on which the photoconductive layer 13 is laminated
1 records pattern information. On the opposite side of the element, read light 22 is irradiated via a polarizer 23, and output light 24 modulated according to the recorded pattern information is output via an analyzer 25. The polarization directions of the polarizer 23 and the analyzer 25 are orthogonal.

FIG. 2 is a sectional view of another embodiment of the spatial light modulator of the present invention. The spatial light modulator 1 of this embodiment is
1 is substantially the same as that shown in FIG. 1, except that a uniform multilayer dielectric reflective film 26 is formed over the entire surface of the element instead of the reflective layer 14 formed separately for each pixel. . Therefore, by using a multilayer dielectric reflection film as compared with a metal thin film, a reflectance of 90% or more can be achieved, and a read image with high luminance can be obtained.

FIG. 3 is a sectional view of another embodiment of the spatial light modulator of the present invention. The spatial light modulator 1 of this embodiment is
1 is substantially the same as that shown in FIG. 1, except that a corresponding portion of the photoconductive layer 13 between the pixels includes a p-layer 13a and an i-layer 13b.
Are laminated. Accordingly, resolution degradation is prevented by suppressing the lateral drift of photocarriers, particularly electrons, in the n-layer 13c.

FIG. 4 is a cross-sectional view for explaining the steps of one embodiment of the method for manufacturing a spatial light modulator according to the present invention. In the step (a), a chromium film is formed on the glass substrate 11 by a sputtering method to form a light-shielding film 27. Then, a portion corresponding to each pixel is removed by photolithography, and an ITO is formed thereon. The electrode 12 was formed by a sputtering method.

In step (b), a p-layer 13a of an amorphous silicon photoconductive layer is formed over the entire surface by a plasma CVD method, and then a resist film is formed on portions other than the light-shielding film by photolithography, ie, on each pixel portion. 30
To form

In the step (c), p corresponding to the distance between pixels
After the layer 13a is removed by etching or the like, the resist film 30 is removed, and then the i-layer 13b and the n-layer 13c of the amorphous silicon photoconductive layer are successively formed so that the pixel portion has a pin diode structure. I do. Further, an aluminum thin film is formed thereon as a reflective layer 14 by, for example, electron beam evaporation. Next, a resist film 31 is formed on each pixel using photolithography.

In the step (d), after removing the reflective layer 14 and the n-layer 13c of the amorphous silicon photoconductive layer between the pixels by etching, the resist film 31 is removed. Next, as an alignment film 15 for aligning the ferroelectric liquid crystal, a polyimide film is formed by, for example, coating. When performing the alignment treatment, in order to obtain a uniform alignment,
It is preferable to perform a rubbing treatment in which the surface of the polymer film is rubbed with a cloth such as nylon. Further, when a SiO ₂ film formed by the oblique deposition method is used as the alignment film 15, rubbing treatment is not required.

After the step (d), the spatial light modulator shown in FIG. 1 can be manufactured by laminating together with the glass substrate 20 on the opposite side in which the spacers 17 are dispersed.

Hereinafter, specific examples of the spatial light modulator according to the present invention and the method of manufacturing the same will be described in detail. Embodiment 1 In this embodiment, the manufacture of the spatial light modulator shown in FIG. 1 will be described with reference to FIG.
55 mm × 45 mm × 1.
Using a 1 mm glass substrate, a chromium film having a thickness of 1000 Å is formed thereon by a sputtering method, and a light-shielding film is formed over the entire surface. Next, using photolithography, a light-shielding film 27 was formed with a 40 μm square window corresponding to one pixel in a pixel pattern of 45 μm pitch in the vertical and horizontal directions. Next, a film of ITO having a thickness of 0.05 μm to 0.5 μm was formed thereon by a sputtering method, and a transparent conductive electrode 12 was formed over the entire surface (step a).

In order to form amorphous silicon of a p-layer, after forming amorphous silicon by a plasma CVD method, 1000 ppm of boron is added to an effective area of 35 mm × 35 mm to form a 500 angstrom thick p-layer 13a. Formed. Next, the substrate is taken out of the film forming apparatus, and a resist film 30 is pattern-formed at a portion corresponding to between pixels by using photolithography (step b).

After the p layer 13a corresponding to between pixels is removed by etching or the like, the resist film 30 is removed and the p layer 13a is removed.
The substrate on which the layer 13a is patterned is again subjected to plasma C
A 2 μm-thick non-added i-layer 13 b in a VD apparatus;
P-doped n-layer 13c with a thickness of 2000 Å
Is continuously formed. Next, an aluminum thin film having a thickness of 1500 angstroms was formed as a reflective layer 14 on the entire surface of the n-layer 13c by electron beam evaporation. Then, using a photolithography, a resist film 31 is formed in a pattern in a portion corresponding to between the pixels (step c).

The reflection layer 14 made of an aluminum film is wet-etched with an acidic solution, so that a portion of the resist film 31 remains. Further, an amorphous silicon n-layer 13c is wet etching using a hydrofluoric acid based solution, or by reactive ion etching with CF ₄ and oxygen pixel pattern is formed. On this, as an alignment film 14,
Polyamic acid, which is a precursor of polyimide, is applied with a spinner to a thickness of 200 Å or less, and the entire substrate is placed in a heat treatment furnace and subjected to a heat treatment at 230 ° C. for 1 hour. It is formed (d step).

On the other hand, one side of the transparent insulating substrate 2 shown in FIG.
After a transparent conductive electrode 19 of ITO was formed on the entire surface by sputtering, a polyimide alignment film 18 was laminated on the entire surface in the same manner as described above. Then, the alignment film 15,
By rubbing the surface of 18 with a nylon cloth in a certain direction,
An alignment process is performed on the alignment film.

Next, the formation of the ferroelectric liquid crystal layer 16 will be described. In order to realize a ferroelectric liquid crystal layer having a thickness of about 1 μm, a spacer 17 made of beads having a diameter of 1 μm dispersed in isopropyl alcohol is sprayed on the surface of the alignment film 15 on one side of the substrate, and then sprayed. A liquid crystal cell was manufactured by applying a UV curable resin around the transparent insulating substrates 11 and 20 and bonding them together. In this liquid crystal cell, a ferroelectric liquid crystal (trade name "ZLI-36") is placed in a vacuum.
54) (manufactured by Merck & Co., Inc.), and then heated to a temperature higher than the phase transition temperature (62 ° C.) of the ferroelectric liquid crystal and returned to room temperature at a slow cooling rate of 1 ° C./min or less in order to obtain uniform alignment. Oriented.

Thus, the spatial light modulator 1 according to the present invention was obtained. Next, the evaluation of the characteristics of the obtained spatial light modulator 1 will be described. FIG. 5 is a schematic configuration diagram of a projection display device used for evaluating the spatial light modulator. A CRT display 43 having a resolution of 480 pixels vertically and 650 pixels horizontally was used as a means for performing optical writing on the spatial light modulator 1. The readout light is emitted from the light source 40 of the metal halide lamp, is condensed by the condenser lens 41, and is irradiated on the spatial light modulator 1 via the polarization beam splitter 42. The output image is reflected by the polarizing beam splitter 42 and
The image is enlarged at 4 and imaged on a screen 45. When each pixel on the screen of the CRT display 43 is written in the divided pixel of the spatial light modulator 1, it is converted into a square pixel on the screen 45.

As a result, an image having an aperture ratio as large as 80% and enlarged to a size equivalent to 100 inches is displayed on the screen 4.
5, a bright image with an illuminance of 2000 lumens is obtained. Further, the contrast of the image was 250: 1, and the resolution was 650 TV lines in the vertical direction.

Further, when a moving image was output, a clear high-brightness image was obtained without any afterimage with respect to the movement at the video rate. Also, a color image could be obtained by preparing three sets of combinations of the CRT display 43 and the spatial light modulator 1 corresponding to the three primary colors of RGB and combining them on the screen.

On the other hand, for comparison of the characteristic evaluation, when the spatial light modulator having the structure shown in FIG. 7 was incorporated in the projection display shown in FIG.
A result of zero TV lines was obtained.

(Embodiment 2) By the same manufacturing method as shown in Embodiment 1, the pixel shape is 8 μm square and the pixel pitch is 1
A spatial light modulator having a pixel pattern of 0 μm and having a pixel pattern of 3200 pixels × 3200 pixels was manufactured. Therefore, the total number of pixels is 10 ⁷ or more. Regarding the characteristics of the obtained spatial light modulator, a recorded image was read out after recording a photographic image for evaluating the resolution, and a resolution of 100 (lp / mm) could be confirmed.

(Embodiment 3) According to the same manufacturing method and pixel pattern as in Embodiment 2, an element structure similar to that of the spatial light modulator shown in FIG.
A dielectric reflection film 26 composed of an alternately laminated film of S and MgF ₂ was formed by electron beam evaporation. The obtained spatial light modulating element is 90%
Since the above reflectance can be achieved, the brightness of the image is increased and the resolution of 100 (lp / mm) is achieved.

(Example 4) In order to obtain the spatial light modulator shown in FIG. 3, it is the same as the manufacturing method shown in Example 1, but in the step (b) shown in FIG. The difference is that the p-layer 13a, the i-layer 13b, and the n-layer 13c are successively laminated. Therefore, the portion of the light-shielding film 27, that is, the portion of the photoconductive layer 13 corresponding to between pixels is p
/ I structure. The shape of the pixel is 8 μm as in the second embodiment.
When formed at the corners, the resolution of the obtained spatial light modulator was 100 (lp / mm). Therefore, as compared with the element structure shown in FIG. 1, the step of forming the pattern of the p-layer 13a can be omitted, and it has been confirmed that a high-resolution spatial light modulation element can be obtained by a simpler manufacturing method. From this result, it is expected that in the spatial light modulator using the amorphous silicon layer as the light-receiving layer, the drift of electrons in the n-layer 13c in the horizontal direction is the largest factor causing the deterioration of resolution.

Next, the result of characteristic evaluation of the spatial light modulator of this embodiment as a holographic television device will be described. FIG. 6 is a schematic configuration diagram of a holographic television device used for evaluating the spatial light modulator. As means for performing optical writing on the spatial light modulation element, coherent light from a He-Ne laser 51 is split by a half mirror 52 and one light beam is
Through the lens 58 and the other light beam is
The beam passes through a beam expander composed of 4 and 55 and is irradiated as a reference beam onto a CCD 58 via a half mirror 57.
An interference fringe pattern is formed on the imaging surface of the CCD 58.
The image data of the interference fringe pattern is converted into an electric signal,
It is transferred to RT65 and reproduced.

The image data of the interference fringe pattern reproduced on the screen of the CRT 65 is optically written to the spatial light modulator 1 by the lens 66 and recorded. The pixel pattern of the spatial light modulator 1 used was a pixel pattern of 8 μm square having a pitch of 10 μm and 3200 × 3200 = approximately 10 ⁷ pixels.

The image is read out using a He-Ne laser 61.
Is passed through a beam expander composed of lenses 62 and 63, is applied to the spatial light modulator 1 via a polarization beam splitter 64, and the modulated output light passes through the polarization beam splitter 64 and passes through a lens 67. The stereoscopic image in the reflection mode is observed with the naked eye 68.

As a result, a stereoscopic image displayed in real time could be reproduced, and the movement of the subject 50 could be observed with a real time hologram. The aperture ratio is 64%,
It was confirmed that the image had a contrast of 200: 1 and a resolution of 100 lines / mm.

[0062]

As described above , the spatial light modulator of the present invention
Indicates that a rectifying photoconductor is formed for each pixel.
Therefore, in addition to improving the switching speed of the photoconductive layer and facilitating the initialization of the memory state, the in-plane diffusion of photocarriers and the drift at each junction interface are prevented, so that spatial light having high resolution can be obtained. A modulation element can be obtained. In particular, by using, for example, an amorphous silicon semiconductor as the photoconductor, it is possible to increase the light receiving area of the spatial light modulator, and to obtain a highly sensitive spatial light modulator to exhibit high quantum efficiency. Can be. In addition, since the reflection layer is divided in pixel units above the photoconductor, light reflection in a region between pixels is suppressed, and a high-resolution spatial light modulator can be obtained. Also, enter
The portion of the photoconductive layer located between the pixels due to the power light-shielding layer
Is always a high resistance area, and electrons generated in pixel units and
The movement of charges such as holes to adjacent pixels is suppressed.
Thus, crosstalk between pixels is eliminated. Also, photoconductive
Use reflective film connected to pixel part and inter-pixel part of layer
High reflectance can be achieved by
A protruding image can be obtained. Also, the pixels of the photoconductive layer
The upper surface of the intervening portion is higher than the upper surface of the pixel portion of the photoconductive layer.
Due to the lowered configuration, the portion between pixels of the photoconductive layer and the pixel portion
A step is formed between the photoconductive layer and the entire surface of the photoconductive layer to relieve stress.
Is brought. As a result, the accuracy of glass substrate assembly is improved.
This produces the effect of

Further, a method of manufacturing a spatial light modulator according to the present invention.
According to this, it is easy to form a reflective layer or a reflective layer and a photoconductor having a rectifying property in pixel units, and writing light enters the inter-pixel portion of the photoconductive layer by a simple manufacturing process.
An input light-shielding layer for preventing light from being emitted can be formed, so that a high-resolution spatial light modulator with low manufacturing cost can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of a spatial light modulator according to the present invention.

FIG. 2 is a sectional view of another embodiment of the spatial light modulator of the present invention.

FIG. 3 is a sectional view of another embodiment of the spatial light modulator of the present invention.

FIG. 4 is a cross-sectional view for explaining a step in one embodiment of a method for manufacturing a spatial light modulator according to the present invention.

FIG. 5 is a schematic configuration diagram of a projection display device used for evaluating a spatial light modulator.

FIG. 6 is a schematic configuration diagram of a holographic television device used for evaluating a spatial light modulator.

FIG. 7 is a sectional view of an example of a conventional spatial light modulator.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 transparent insulating substrate 12 transparent conductive electrode 13 photoconductive layer 13 a p layer 13 bi layer 13 c n layer 14 reflective layer 15 alignment film 16 ferroelectric liquid crystal layer 17 spacer 18 alignment layer 19 transparent conductive electrode 20 transparent insulating substrate Reference Signs List 21 incident light 22 readout light 23 polarizer 24 output light 25 analyzer 26 multilayer dielectric reflection film 27 light shielding film 30, 31 resist film 40 light source 41 condenser lens 42 polarization beam splitter 43 CRT display 44 lens 45 screen 51, 61 He− Ne laser 52, 57 Half mirror 53 Mirror 54, 55, 56, 62, 63, 66, 67 Lens 58 CCD 64 Polarizing beam splitter 65 CRT 68

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuki Kuratomi 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Hisato Ogawa 1006 Odaka Kadoma Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (56) References JP-A-62-169120 (JP, A) JP-A-3-192332 (JP, A) JP-A-4-356023 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02F 1/135

Claims (11)

(57) [Claims] A first electrode, a second electrode facing the first electrode, and electrically connected to the first electrode;
A photoconductive layer having a plurality of pixel portions and an inter-pixel portion formed between the plurality of pixel portions, wherein each of the pixel portions is substantially substantially electrically separated by the inter-pixel portion; A plurality of reflective layers connected to a pixel portion of the photoconductive layer, a liquid crystal layer provided between the reflective layer and the second electrode, and writing light is incident on a portion of the photoconductive layer between pixels. An input light-blocking layer for preventing the occurrence of the light-shielding layer.
Has a diode structure between the electrodes .
Spatial light modulation element having a rectifying property Ri. 2. Each of the pixel portions of the photoconductive layer has a p-type semiconductor layer, an i-type semiconductor layer formed on the p-type semiconductor layer, and an n-type semiconductor formed on the i-type semiconductor layer. and a layer, thereby spatial light modulator according to claim 1, wherein the rectifying is provided. 3. An inter-pixel portion of the photoconductive layer has an i-type semiconductor layer, and the i-type semiconductor layer does not diffuse electric charges generated in each of the pixel portions of the photoconductive layer to other pixel portions. The spatial light modulator according to claim 2 . 4. The spatial light modulation device according to claim 1, wherein the upper surface of the inter-pixel portion of the photoconductive layer is lower than the upper surface of the pixel portion of the photoconductive layer to form a groove. 5. The spatial light modulator according to claim 4 , wherein the i-type semiconductor layer is exposed on the upper surface of the portion between the pixels of the photoconductive layer. 6. A first electrode, a second electrode facing the first electrode, and electrically connected to the first electrode,
A photoconductive layer having a plurality of pixel portions and an inter-pixel portion formed between the plurality of pixel portions, wherein each of the pixel portions is substantially substantially electrically separated by the inter-pixel portion; A reflective film connected to a pixel portion and an inter-pixel portion of the photoconductive layer; a liquid crystal layer provided between the reflective film and the second electrode; and writing light to the inter-pixel portion of the photoconductive layer. A spatial light modulation element having an input light-blocking layer for preventing incidence, and each pixel portion having a diode structure between the reflection film and the first electrode , thereby having a rectifying property. 7. A first electrode, a second electrode facing the first electrode, and electrically connected to the first electrode,
A photoconductive layer having a plurality of pixel portions and an inter-pixel portion formed between the plurality of pixel portions, wherein each of the pixel portions is substantially substantially electrically separated by the inter-pixel portion; A plurality of reflective layers connected to the pixel portion of the photoconductive layer or a reflective film connected to the pixel portion and the inter-pixel portion of the photoconductive layer, between the reflective layer or the reflective film and the second electrode; A liquid crystal layer provided, wherein each of the pixel portions has a diode structure between one of the reflective layers or the reflective film and the first electrode corresponding thereto , and
A spatial light modulator having more rectifying properties, wherein an upper surface of a portion between pixels of the photoconductive layer is lower than an upper surface of a pixel portion of the photoconductive layer. 8. The spatial light modulator according to claim 7 , wherein the i-type semiconductor layer is exposed on the upper surface of the portion between the pixels of the photoconductive layer. 9. The spatial light modulator according to claim 1 or 7, wherein the alignment film on at least the upper surface of the inter-pixel portion of the photoconductive layer is formed. 10. A step of forming a photoconductive layer having a diode structure by laminating a plurality of layers, and selectively etching a predetermined region of at least one of the plurality of layers, thereby performing etching. Forming a plurality of unexposed pixel portions and an inter-pixel portion capable of substantially electrically separating the pixel portion, and preventing writing light from being incident on the inter-pixel portion of the photoconductive layer. Forming an input light-shielding layer for performing the method. 11. The method of manufacturing a spatial light modulator according to claim 10 , further comprising a step of forming a reflective film on the photoconductive layer after the step of forming the photoconductive layer and before the etching.