JPH05303352A - Optical valve device - Google Patents

Abstract

PURPOSE:To realise the high-speed operation by using a substrate of two-layered structure consisting of an electrically insulating carrier layer and a semiconductor single crystal thin film layer on this carrier layer to form a thin film switching element and using high-polymer disperse liquid crystal as electrooptic materials. CONSTITUTION:This device consists of a driving substrate 1, a counter plate 8, and a high-polymer disperse liquid crystal layer 9 arranged between them, and a driving electrode 12 and a driving circuit are formed on the driving substrate 1 and has the two-layered structure consisting of a carrier layer 2 and a single crystal silicon semiconductor thin layer 3. The driving circuit consists of an integrated circuit and includes a field-effect metal insulator transistor TR 13. The source electrode of the TR 13 is connected to scanning lines 15, and the integrated circuit includes an X driver 6 and a Y driver 7, and they are connected to signal lines 14 on columns and scanning lines 15 on rows respectively. The response speed of high-polymer disperse liquid crystal is higher than 1msec, and an image is formed quickly in accordance with the switching speed of the single crystal silicon TR.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat type light valve device used for a direct view type display device, a projection type display device and the like. More specifically, the present invention relates to a light valve device, such as an active matrix device, in which an integrated circuit substrate having a drive circuit formed on a semiconductor thin film is integrally incorporated as a liquid crystal panel.

2. Description of the Related Art The principle of an active matrix device is very simple. Each pixel is provided with a switch element, and when a specific pixel is selected, the corresponding switch element is made conductive, and when it is not selected, the switch element is turned off. It is to be in a conductive state. This switch element is formed on a glass substrate that constitutes a liquid crystal panel. Therefore, the thinning technology of the switch element is important. A thin film transistor is usually used as this element. Conventionally, in an active matrix device, a thin film transistor has been formed on the surface of an amorphous silicon thin film or a polycrystalline silicon thin film deposited on a glass substrate. Since these amorphous silicon thin film and polycrystalline silicon thin film can be easily deposited on the glass substrate by using the chemical vapor deposition method, they are suitable for manufacturing an active matrix device having a relatively large screen. A transistor element formed on an amorphous or polycrystalline silicon thin film is generally of the field effect insulated gate type. Currently, active matrix liquid crystal devices using an amorphous silicon thin film are commercially produced with an area of about 3 inches to 10 inches. 35 for amorphous silicon thin film
Since it can be formed at a low temperature of 0 ° C. or less, it is suitable for a large area liquid crystal panel. Further, in the active matrix liquid crystal device using the polycrystalline silicon thin film, a small liquid crystal panel of about 2 inches is currently commercially produced.

A conventional active matrix device using an amorphous silicon thin film or a polycrystalline silicon thin film is suitable for a direct-view type display device which requires a relatively large area image plane, while the device is used. It is not always suitable for the miniaturization and the high density of pixels. Recently, in addition to the direct-view type display device, there is an increasing demand for a microminiaturized display device or a light valve device having miniaturized and high-density pixels. Such a micro light valve device is used as, for example, a primary image forming surface of a transmissive image device, and can be applied as a transmissive high-definition television. By using a fine semiconductor manufacturing technique, a micro light valve device having a pixel size on the order of 1 μm and a size of about several cm as a whole becomes possible. However, when a conventional amorphous or polycrystalline silicon thin film is used, there is a problem that the image forming speed is very slow. Further, since the formation temperature is 600 ° C. or lower, it is not possible to apply a fine semiconductor processing technique to form a submicron-order transistor element. For example, in the case of an amorphous silicon thin film, the film forming temperature is 30
Since the temperature is about 0 ° C., the high temperature treatment required for the miniaturization technique cannot be performed. Further, in the case of a polycrystalline silicon thin film, the size of the crystal grains is about several μm, so that miniaturization of the thin film element is necessarily limited. Further, the film forming temperature of the polycrystalline silicon thin film is about 600 ° C., and it is impossible to sufficiently apply the miniaturization technique requiring a high temperature treatment of 1000 ° C. or more. As described above, in the conventional active matrix display device using the amorphous or polycrystalline silicon thin film, it is necessary to realize the information processing speed, the integration density, and the chip size which are similar to those of the normal semiconductor integrated circuit element. There was a problem that was extremely difficult. In view of the above-mentioned problems of the conventional technique, it is a first object of the present invention to provide a miniaturized light valve device such as an active matrix liquid crystal device that operates at high speed. In order to achieve this object, in the present invention to form a thin film switching element using a substrate having a two-layer structure consisting of an electrically insulating carrier layer and a semiconductor single crystal thin film layer formed thereon, By using a polymer dispersed liquid crystal capable of high-speed operation as the electro-optical material, the high-speed operation of the light valve device is realized by directly utilizing the high-speed operation of the transistor formed of single crystal silicon. By the way, conventionally, various types of semiconductor laminated substrates having such a two-layer structure have been known. This is a so-called SOI substrate. The SOI substrate has a single crystal structure in which a polycrystalline silicon thin film is deposited on the surface of a carrier made of an insulating material by chemical vapor deposition or the like, and then heat treatment is performed by laser beam irradiation to recrystallize the polycrystalline film. It was obtained by converting to. However, generally, a single crystal obtained by recrystallization of a polycrystal does not always have a uniform crystal orientation and has a large lattice defect density. For these reasons,
It was difficult to apply the miniaturization technique to the SOI substrate manufactured by the conventional method as in the case of the silicon single crystal wafer. In view of this point, the present invention uses a semiconductor single crystal thin film having crystal orientation uniformity and a low density of lattice defects that are comparable to those of a silicon single crystal wafer that is widely used in semiconductor manufacturing processes, and has a fine and high resolution. It is a second object of the present invention to provide a light valve device of the above.

Means for achieving the above first and second objects will be described with reference to FIG. FIG. 1 (A) shows the planar shape of the substrate 1 used in the present invention, and FIG. 1 (B) shows the same sectional structure. As shown, the substrate 1 has a wafer shape with a diameter of 6 inches, for example. The substrate 1 includes a carrier layer 2 made of quartz, for example.
It has a two-layer structure composed of a single crystal thin film layer 3 made of, for example, silicon formed thereon. The miniaturized semiconductor manufacturing technique is applied to the single crystal thin film layer 3 of the substrate 1, for example, a drive circuit and a pixel electrode of an active matrix device are formed for each chip section. FIG. 1C is an enlarged plan view of the integrated circuit chip thus obtained. As shown in the figure, the integrated circuit chip 4 has a length of 1.5 cm per piece, for example, and is significantly smaller than a conventional active matrix device. The integrated circuit chip 4 has a pixel region 5 in which a matrix of fine pixel electrodes and insulated gate field effect transistors corresponding to the individual pixel electrodes are formed, and a pixel signal for supplying each pixel with a pixel signal. It has an X driver area 6 in which a driving circuit, that is, an X driver is formed, and a Y driver area 7 in which a scanning circuit, that is, a Y driver is formed to scan each transistor element line-sequentially. According to the present invention, since a single crystal thin film having a charge mobility extremely higher than that of an amorphous thin film or a polycrystalline thin film is used, the X and Y drivers that require high-speed response are formed on the same plane as the pixel region. can do. FIG. 2 is a sectional view showing an ultra-compact and ultra-high-density active matrix light valve device assembled by using the integrated circuit chip 4 described above with reference to FIG. As shown in the figure, the light valve device includes a counter substrate 8 facing the integrated circuit chip 4 with a predetermined gap, and a polymer dispersed liquid crystal layer 9 as an electro-optical material layer filled in the gap. Consists of. Each pixel electrode formed in the pixel region 5 of the integrated circuit chip 4 is selectively excited by conduction of the corresponding transistor element and acts on the polymer dispersed liquid crystal layer 9 to control its light transmission characteristics at high speed. Functions as a valve. Since the size of each pixel electrode is about 1 μm, an extremely high-definition active matrix liquid crystal device can be obtained. Figure 1
FIG. 1E is a partially enlarged plan view of the pixel region 5 shown in FIG. 1C, showing one pixel. FIG. 1F is a schematic sectional view of one pixel similarly. As shown, pixel 1
Reference numeral 1 denotes a pixel electrode 12, a transistor 13 for exciting the pixel electrode 12 in response to a signal, and the transistor 13
And a scanning line 15 for scanning the transistor 13. The signal line 14 is connected to the X driver, and the scanning line 15 is connected to the Y driver 7. Transistor 1
3 comprises a drain region formed in the single crystal thin film layer 3, a source region, a channel region formed between the two, and a gate electrode 16 formed on the channel region via a gate insulating film. There is. That is, the transistor 13
Is an insulated gate field effect type. The gate electrode 16 is composed of a part of the scanning line 15, the pixel electrode 12 is connected to the source region, and the drain electrode 17 is connected to the drain region. The drain electrode 17 constitutes a part of the signal line 14.

As described above, according to the present invention, a substrate having a two-layer structure comprising an insulating carrier layer and a semiconductor single crystal thin film layer formed thereon is used, and the semiconductor single crystal thin film is used. The layer has the same quality as a wafer made of a semiconductor single crystal bulk. Therefore, pixel electrodes and switching elements for driving pixels at high speed can be formed in an integrated manner on such a semiconductor single crystal thin film layer by using miniaturization technology, and at the same time, a polymer dispersion that responds at high speed as an electro-optical material. Since the liquid crystal is used, a light valve device that operates at high speed can be realized. The resulting integrated circuit chip has an extremely high pixel density and an extremely small pixel size, so that an ultra-small, high-speed and high-definition light valve device such as an active matrix liquid crystal device can be constructed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a schematic exploded perspective view showing an embodiment of the light valve device according to the present invention. As shown,
The light valve device includes a driving substrate 1, a counter substrate 8 arranged to face the driving substrate, and a polymer dispersed liquid crystal layer 9 which is an electro-optical material layer arranged between the driving substrate 1 and the counter substrate 8. It consists of A pixel electrode or a drive electrode 12 that defines a pixel and a drive circuit for exciting the drive electrode 12 in response to a predetermined signal are formed on the drive substrate 1. The drive substrate 1 has a two-layer structure including a carrier layer 2 made of quartz glass and a single crystal silicon semiconductor film layer 3. In addition, a polarizing plate 18 is adhered to the back surface side of the quartz glass carrier layer 2. The drive circuit is composed of an integrated circuit formed on the single crystal silicon semiconductor film layer 3. This integrated circuit includes a plurality of field effect insulated gate transistors 13 arranged in a matrix. Transistor 1
The source electrode of No. 3 is connected to the corresponding pixel electrode 12, and the drain electrode of No. 3 is also connected to the scanning line 14. The integrated circuit further includes an X driver 6 and is connected to a signal 14 in a column. Furthermore, the Y-driver 7 is connected to the row-shaped scanning lines 15. The counter substrate 8 is composed of a glass carrier 19 and a counter electrode or a common electrode 21 formed on the inner surface of the glass carrier 19.
In this embodiment, PDL is used as the polymer dispersed liquid crystal layer 9.
C (polymer-dispersed liquid)
d crystals) or PN-LC (polymer)
r network liquid crystal)
Etc. are used. These materials are conventional TN (twi
liquid crystal or STN (super)
There is no need for a polarizing plate as in a twisted nematic liquid crystal. The polymer-dispersed liquid crystal is a composite material in which a liquid crystal and a polymer are combined, and when a voltage is not applied, it becomes a white turbid state due to light scattering and becomes transparent when a voltage is applied. This material has a response speed faster than 1 msec. Therefore, the switching speed of the single crystal silicon transistor and the light valve device with this polymer dispersed liquid crystal enable very fast image formation. Further, although the present invention allows pixels to be formed at a very high density, it does not require a polarizing plate, so that the amount of light required is small and changes in transistor characteristics due to heat generation can be prevented. Further, the polymer-dispersed liquid crystal used in the present invention is most suitable for a small light valve device. That is, in the structure of the light valve device shown in FIG. 10, after the integrated circuit substrate 4 is formed, the polymer dispersed liquid crystal 9 is formed on the entire surface by a spin coating method or the like, and then the counter substrate 8 is sequentially formed thereon. A small panel can be formed by scribing in a chip shape as in (A). In the conventional TN liquid crystal, the integrated circuit substrate 4 is first scribed into a chip shape, then the counter substrate 8 is formed with a sealant, and the liquid crystal is poured into the space between the integrated circuit substrate 4 and the counter substrate 8. .. In this case, it is not suitable for a small light valve device because a sealant area is required. In the case of the light valve device of the present invention, since the polymer dispersion circuit is used as the electro-optical material, a small light valve device can be realized without the need for a sealant. FIG. 3 is a graph showing the relationship between the voltage applied to the polymer-dispersed liquid crystal forming the pixel shown in FIG. 2 and the transmittance of the liquid crystal layer. As shown in the figure, by applying a voltage equal to or higher than the threshold voltage (4 V) between the counter electrode and the pixel electrode, the transmittance of the liquid crystal layer is extremely changed, and the shielded state transits to the transmissive state. The voltage applied to the pixel is controlled by controlling the conduction of the transistor element connected to the pixel electrode. Next, the operation of the above-described embodiment will be described in detail with reference to FIGS. The gate electrode of each transistor element 13 is connected to the scanning line 15, and Y
A scanning signal is applied by the driver 7 to control conduction and interruption of the individual transistor elements 13 in a line sequential manner. The display signal output from the X driver 6 is applied to the selected transistor 13 in the conductive state via the signal line 14. The applied display signal is transmitted to the corresponding pixel electrode 12, excites the pixel electrode and acts on the liquid crystal layer 9 to make its transmittance substantially 100%. On the other hand, when the transistor element 12 is not selected, the transistor element 12 is turned off and the display signal written in the pixel electrode is maintained as an electric charge. The liquid crystal layer 9
Has a high specific resistance and normally operates as capacitive. The on / off current ratio is used to represent the switching performance of these drive transistor elements 13. The current ratio required for liquid crystal operation can be easily obtained from the writing time and the holding time. For example, when the display signal is a television signal, 90% or more of the display signal must be written in about 60 μsec of the scanning line period. On the other hand, 90% or more of the charges must be retained in about 16 msec which is one field period. As a result, a current ratio of 5 digits or more is required. At this time, the drive transistor element is formed on the single crystal silicon semiconductor film layer 3 having an extremely high charge mobility, so that an on / off ratio of 6 digits or more can be secured. Therefore, an active matrix type light valve device having an extremely high speed signal response can be obtained by the high speed transistor and the high speed response liquid crystal. Further, the peripheral driver circuits 6 and 7 can be simultaneously formed on the same silicon single crystal semiconductor thin film by utilizing the high mobility characteristic of the single crystal thin film. Next, a method of manufacturing a semiconductor chip type light valve device substrate in which the pixel electrode and the driving circuit are integrated will be described in detail with reference to FIGS. First, in the step shown in FIG. 4A, the quartz glass substrate 2 and the single crystal silicon semiconductor substrate 22 are prepared. As the single crystal silicon semiconductor substrate 22, it is preferable to use a high quality silicon wafer used in LSI manufacturing, and the crystal orientation thereof has uniformity in the range of <100> 0.0 ± 1.0. Lattice defect density is 500 /
It is not more than cm ² . First, the surfaces of the prepared quartz glass substrate 2 and the surface of the single crystal silicon semiconductor substrate 22 are precisely smoothed. Subsequently, the both surfaces that have been smoothed are overlapped and heated to thermocompress the two substrates. By this thermocompression bonding process, both substrates 2 and 22 are firmly fixed to each other. In the step shown in FIG. 4B, the surface of the single crystal silicon semiconductor substrate is polished. As a result, the single crystal silicon semiconductor film layer 3 polished to a desired thickness is formed on the surface of the quartz glass substrate 2. A driving substrate 1 having a two-layer structure composed of a carrier layer 2 made of a quartz glass substrate and a single crystal silicon semiconductor film layer 3 is obtained. In addition,
An etching process may be used instead of the polishing process for thinning the single crystal silicon semiconductor substrate 22. In the single crystal silicon semiconductor film layer 3 thus obtained, the quality of the silicon wafer 22 is preserved substantially as it is, so that it is possible to obtain a substrate material extremely excellent in the uniformity of crystal orientation and the lattice defect density. .. On the other hand, as has been conventionally done, the single crystal thin film obtained by recrystallization of the deposited amorphous or polycrystalline silicon thin film has many lattice defects and the crystal orientation is not uniform, so Not suitable for. In the step shown in FIG. 4C, the surface of the single crystal silicon semiconductor film layer 3 is thermally oxidized to form a silicon oxide film 23 on the entire surface. A silicon nitride film 24 is deposited thereon by using the chemical vapor deposition method. Further, the resist 25 is covered. The resist 25 is patterned by photolithography to remove only the element region 26. In this state, an etching process is performed to remove the silicon oxide film 23 and the silicon nitride film 24 in the portions not covered with the resist 25. FIG. 4C shows a processed state of the driving substrate 1 thus obtained. Figure 4 (D)
In the step shown in (1), after removing the resist 25, the silicon oxide film 23 and the silicon nitride film 24 covering the element region 26 are used as a mask to perform thermal oxidation treatment of the single crystal silicon semiconductor film layer 3 to form a field oxide film 27. .. In the region surrounded by the field oxide film 27, the single crystal silicon film layer 3 is left and the element region 26 is formed. In this state, the silicon oxide film 23 and the silicon nitride film 24 used as the mask are removed. In the step shown in FIG. 5E, thermal oxidation treatment is performed again to form the gate oxide film 28 on the surface of the single crystal silicon film layer 3.
In the step shown in FIG. 5F, a polycrystalline silicon film is deposited by the chemical vapor deposition method. The polycrystalline silicon film is selectively etched using a resist 29 patterned into a predetermined shape to form a gate electrode 16 made of the polycrystalline silicon film on the gate oxide film 28. Figure 5
In the step shown in (G), after removing the resist 29, ion implantation of arsenic impurity is performed through the gate oxide film 28 using the gate electrode 16 as a mask to form the drain region 30 and the source region 31 in the silicon single crystal film 3. Form. As a result, below the gate electrode 16, a transistor channel formation region 32 in which arsenic impurity is not implanted is provided between the drain region 30 and the source region 31. Finally, in a step shown in FIG. 5H, a part of the gate oxide film 28 on the drain region 30 is removed to form a contact hole, and the drain electrode 17 is connected thereto. Similarly, a part of the gate oxide film 28 on the source region 31 is removed to form a contact hole, and the drive electrode 12 is formed so as to cover this part. The drive electrode or the pixel electrode 12 is composed of a transparent electrode made of ITO or the like. In addition, the field oxide film 27 arranged below the pixel electrode 12 is transparent, and the quartz glass substrate 2 arranged below it is also transparent.
Therefore, the three-layer structure composed of the drive electrode 12, the field oxide film 27 and the quartz glass substrate 2 is optically transparent, and a light valve device of transmission type can be obtained. As mentioned above,
In the manufacturing method shown in FIGS. 4 to 5, a high-quality single crystal silicon film is subjected to a film forming process using high temperature, a high-resolution photolithography etching, an ion implantation process, and the like to obtain a micron-order or sub-micron-order process. It is possible to form a field effect insulated gate transistor having a size. Since the silicon single crystal film used has extremely high quality, the electric characteristics of the obtained insulated gate transistor are also excellent. At the same time, the pixel electrodes can be formed in a size of micron order by the miniaturization technique, so that a semiconductor integrated circuit chip substrate for an active matrix liquid crystal device having a high density and a fine structure can be formed. FIG. 6 is a schematic sectional view showing another embodiment of the semiconductor integrated circuit chip for a light valve device according to the present invention. As shown, the integrated circuit chip has a pixel region 5 and driver regions 6 and 7 on a substrate 2. In the pixel region 5, a pixel electrode (not shown) and an insulated gate transistor element 13 connected to the pixel electrode are formed. The transistor 13 has a source region 3 formed in the silicon single crystal film 3.
0 and the drain region 31 and the gate electrode 16 disposed on the silicon single crystal film via the gate insulating film. The region where the transistor 13 is formed is surrounded by the field oxide film 27. On the other hand, the driver regions 6 and 7 are arranged at positions separated from the pixel region 5, and have an insulated gate type transistor 13 'as a component thereof. The transistor 13 'is composed of a source region 30' and a drain 31 'formed on a common silicon single crystal 3 and a gate electrode 16' arranged via a gate insulating film. Similarly, the region where the transistor 13 'is formed is the field oxide film 2
Surrounded by 7 '. As is apparent from the figure, the insulated gate transistor 13 in the pixel region 5 and the insulated gate transistor 13 ′ in the driver regions 6 and 7 are shown.
Can be simultaneously formed in the common silicon single crystal film 3. By the way, in the light transmission type light valve device,
The transmission and blocking of the light incident on the pixel region 5 is controlled.
Therefore, the pixel region 5 must be transparent to the incident light, so that the silicon single crystal film 3 is completely thermally oxidized and converted into the field oxide film 27. That is, the field oxide film 27 made of silicon dioxide is transparent, and the single crystal silicon film 3 left only in the element region is opaque. On the other hand, the driver regions 6 and 7 are not related to the light valve function and are preferably shielded from incident light as much as possible. This is because normal operation of the insulated gate transistor 13 'is hindered by the influence of incident light. Therefore, in the embodiment shown in FIG. 5, the field oxide film 27 ′ formed in the driver regions 6 and 7 is obtained by partially thermally oxidizing only the upper portion of the silicon single crystal film 3. The silicon single crystal film 3 is left under the oxide film 27 '. As described above, the silicon single crystal film 3
Since it is opaque, it can effectively block incident light. FIG. 7 is a graph showing the relationship between drain current and drain voltage of an insulated gate transistor formed on a silicon single crystal film. The solid line shows the case where the semiconductor under the channel forming region is grounded, and the dotted line shows the case where the semiconductor under the channel forming region is open. As is clear from the figure, when the semiconductor is grounded below the channel formation region and its potential is stabilized, ideal drain current saturation characteristics with respect to the drain voltage are obtained, and stable operation of the transistor can be secured. On the other hand, when the semiconductor is open below the channel formation region, the potential is unstable, so that the drain current fluctuates with respect to the drain voltage. Therefore, in the embodiment shown in FIG. 6, the semiconductor is grounded below the channel formation region. As described above, according to the preferred embodiment of the present invention, since the silicon single crystal film is obtained by polishing, a desired film thickness can be secured and the semiconductor grounding under the channel formation region can be easily performed. Such grounding may be performed only on the insulated gate transistors formed in the driver region, or may be performed on the transistors formed in both the driver region and the pixel region. FIG. 8 is a graph showing the relationship between the drain leakage current of the insulated gate transistor formed in the silicon single crystal film and the film thickness of the silicon single crystal layer. The drain leak current indicates the magnitude of the leak current flowing in the channel region when the drain voltage is applied to the non-conductive transistor. As shown in the figure, there is no dependency of the drain leakage current on the thickness of the silicon single crystal layer when the incident light is not irradiated. However, for example, when the incident light of 3000 lux is irradiated, the drain leak current increases with the increase of the film thickness. Since the drain leak current deteriorates the on / off current ratio of the transistor, it must be suppressed as much as possible. In particular, the transistor formed in the pixel region is irradiated with incident light, so that countermeasures are necessary. Therefore, it is preferable to set the film thickness of the silicon single crystal layer existing in the pixel region smaller than the film thickness of the silicon single crystal layer existing in the driver region. The film thickness can be easily controlled by selective etching or the like. In particular, it is practically important that the silicon single crystal layer has a larger drain leakage current value than the silicon amorphous layer or the silicon single crystal layer. 9A and 9B are schematic cross-sectional views showing another embodiment of the integrated circuit chip substrate according to the present invention. FIG. 9A shows a cross section of the raw material substrate and FIG. 9B shows an insulated gate type substrate. It is a cross section of a completed product in which a transistor is formed. The raw material substrate has a structure in which a low resistance film layer 33 is interposed in the middle of the laminated structure of the quartz carrier layer 2 and the single crystal silicon film layer 3. The low resistance thin film layer 33 is composed of, for example, an impurity-doped silicon polycrystalline thin film. To manufacture, a low resistance thin film layer 33 is first deposited on the quartz carrier layer 2 and a single crystal silicon wafer is thermocompression bonded thereto. Then, by polishing this single crystal silicon wafer, a single crystal silicon film layer 3 having a desired film thickness can be obtained. An insulated gate transistor is formed on the two-layer structure film of the single crystal silicon film layer 3 and the low resistance thin film layer 33 by the same method as the steps shown in FIGS. This transistor has a source region 30 and a drain region 31 formed in a single crystal silicon film layer, a channel region 32 formed between them, and a gate disposed on the channel region 32 via a gate oxide film 28. Electrode 16
It consists of and. This element region is surrounded by the field oxide film 27. Below the channel region 32 is a low resistance region 34. The low resistance region 34 is obtained from the low resistance thin film layer 33. With this structure, the potential of the insulated gate transistor can be set and its operation is stabilized. FIG. 10 is a schematic sectional view showing another embodiment of the active matrix type light valve device according to the present invention. This light valve device is constructed using an integrated circuit chip substrate 4. As described above, the integrated circuit chip substrate 4 incorporates finely divided pixel electrodes and drive circuit elements such as switching transistors in the silicon single crystal thin film layer. A counter substrate 8 is formed on the surface of the integrated circuit chip substrate 4 with a polymer dispersed liquid crystal 9 interposed therebetween. The polymer dispersed liquid crystal 9 is formed by spin coating or the like, and its film thickness can be easily controlled. In the case of spin coating, the film thickness can be controlled by the rotation speed during formation and its viscosity. FIG. 11 is a schematic plan view showing still another embodiment of the light valve integrated circuit chip substrate according to the present invention. The integrated circuit chip 4 has a pixel area 5, an X driver area 6 and a Y driver area 7 as in the above-described embodiment. In addition, the video signal processing circuit area 36
have. The video signal processing circuit formed in this area 36 is for processing an image signal or a video signal input from an external signal source and transferring it to the X driver area 6. As described above, since the present invention uses the silicon single crystal thin film, in addition to the signal circuit or the scanning circuit formed in the transistor for driving the pixel electrode or the driver region, the video signal processing circuit is also used for the semiconductor fine processing at the same time. It can be formed using a technique. That is, LS
It is possible to freely install an additional circuit having an I-scale function on the integrated circuit chip substrate 4. When a light valve device or a display device is configured by using the integrated circuit chip 4 shown in FIG. 11, since it can be directly connected to an external image signal source, a compact image device having extremely excellent versatility can be obtained. You can As a circuit additionally incorporated, in addition to the video signal processing circuit, for example, a memory circuit, an IC
Examples include an inspection circuit and a sensor circuit. Finally, an application example of the active matrix type light valve device according to the present invention will be briefly described with reference to the drawings. FIG. 12 shows an example applied as a video projector. Video projector 3
7 has a built-in ultra-compact light valve device configured by using the integrated circuit chip substrate shown in FIG. 11, which displays a primary image according to a video signal and uses this magnifying optical system. The secondary image 38 of high magnification is projected and displayed on the screen. The illustrated example is a small ceiling type. As described above, since the active matrix type light valve device according to the present invention has an ultra-small size on the order of centimeters, the video projector itself can be extremely downsized as compared with the conventional one. Even if the size of the light valve device itself is extremely small, the formed pixel area contains minute pixels of extremely high density, so even in the case of magnified projection, so-called high definition class high quality The next projected image can be obtained. FIG. 13 shows FIG.
It is a typical expanded sectional view of the video projector 37 shown in FIG. The video projector 37 incorporates three active matrix transmissive light valve devices 39 to 41.
The white light emitted from the white light source lamp 42 is reflected by the reflecting mirror M1.
After being reflected by, the light is separated into red light, blue light, and green light by the three-color separation filter 43. The red light selectively reflected by the dichroic mirror DM1 is reflected by the reflecting mirror M.
After being reflected by 2, the light is condensed by the condenser lens C1 and is incident on the first light valve device 39. Light valve device 39
After passing through the dichroic mirrors DM3 and DM4, the red light modulated in accordance with the video signal is magnified and projected forward through the magnifying lens 44. Similarly, the blue light passing through the dichroic mirror DM1 is selectively reflected by the dichroic mirror DM2 and condensed by the condenser lens C2, and then the second light valve device 4
It is incident on 0. Here, after being modulated according to the video signal, it is incident on the common magnifying lens 44 via the dichroic mirrors DM3 and DM4. Further, the green light passes through the dichroic mirrors DM1 and DM2, is then condensed by the condenser lens C3, and is incident on the third light valve device 41. Here, after being modulated in accordance with the video signal, the light is reflected by the reflecting mirror M3 and the dichroic mirror DM4 and goes to the magnifying lens 44. In this way, the three primary color lights respectively modulated by the three light valve devices are finally combined by the magnifying lens 44 to project the secondary image magnified forward. The dimensions of the light valve device used are on the order of centimeters, and the dimensions of the various optical components and the white light lamp can be correspondingly reduced. Therefore, the overall shape and size of the video projector 37 can be made significantly smaller than that of the conventional one. Further, since the present invention can form an image at a very high speed, a color image can be easily formed by the following method. That is, the red, blue, and green lights are not separately projected onto the three panels to be combined, but the red, blue, and green lights are sequentially projected through the one panel for a short time. The projected image is synthesized by the afterimage effect of the eyes. In the case of colorization by this method, it is necessary to shorten the display time for one color at high speed, but this can be easily performed in the present invention. Conventional a-
In the case of a TN liquid crystal light valve device using SiTFT, a-Si
Is 0.1 cn ² / sec and the response speed of the TN liquid crystal is as slow as several tens of nsec, which is not possible. FIG. 14 shows
FIG. 14 is a schematic perspective view showing an example in which the video projector 37 shown in FIG. 13 is applied to a projection CRT. In this projection CRT, a screen constituting a television screen is illuminated from behind by a video projector 37, and a secondary enlarged image 38 is projected on the television screen. Such a projection CRT has ultrahigh resolution and high brightness. Further, it is possible to form a completely flat screen and is extremely lightweight.

As described above, according to the present invention, the pixel electrode and the driving circuit are integratedly formed on the semiconductor single crystal thin film layer formed on the carrier layer by using the semiconductor miniaturization technique. A light valve device is constructed by using the obtained integrated circuit chip substrate and polymer dispersed liquid crystal. Therefore, there is an effect that a small-sized high-speed light valve device having an extremely high pixel density can be obtained. Further, the size of the integrated circuit chip substrate can be made approximately the same as that of a normal semiconductor IC chip by using polymer dispersed liquid crystal as the electro-optical material, so that there is an effect that an extremely small high speed light valve device can be obtained.
Since the pixels are manufactured by using the semiconductor miniaturization technology, there is an effect that an extremely high-precision light valve device can be obtained. Since each element can be formed on the single crystal thin film layer by using the integrated circuit technology, there is an effect that a circuit having various functions comparable to an LSI can be easily added. Since integrated circuit chips are obtained by dividing the wafer, local defects on the wafer only cause some of the chips to be defective, and as a whole, the yield can be increased and the cost can be reduced. .. Further, since the single crystal thin film layer is used, there is an effect that a high temperature process can be applied and miniaturization of each circuit element can be promoted. Finally, there is an effect that not only the switching transistor but also the driver circuit and its protection circuit can be built in simultaneously by using the single crystal thin film, and the reliability can be improved. In addition, there is an effect that a system that can be easily colorized can be realized by high speed operation.

[Brief description of drawings]

1A is a plan view of a substrate, FIG. 1B is a schematic sectional view of the substrate, FIG. 1C is an enlarged plan view of an integrated circuit chip formed on the substrate, and FIG. FIG. 3 is a schematic cross-sectional view of a light valve device used for a substrate, (E) is an enlarged plan view of a pixel formed in a pixel region of an integrated circuit chip, and (F) is a schematic enlarged cross-sectional view of the pixel region.

FIG. 2 is a schematic exploded perspective view showing an embodiment of a light valve device.

FIG. 3 is a graph showing the relationship between liquid crystal applied voltage and transmittance.

4A to 4D are first half process diagrams showing an embodiment of a method for manufacturing a semiconductor integrated circuit chip.

5 (E) to (H) are process diagrams of the latter half of FIG. 4.

FIG. 6 is a schematic cross-sectional view showing another embodiment of a semiconductor integrated circuit chip substrate.

FIG. 7 is a graph showing the relationship between drain voltage and drain current of an insulated gate transistor.

FIG. 8 is a graph showing the relationship between the drain leak current of an insulated gate transistor formed in a silicon single crystal layer and the film thickness of the silicon single crystal layer.

9A and 9B are schematic cross-sectional views showing still another embodiment of the integrated circuit chip substrate.

FIG. 10 is a schematic cross-sectional view showing another embodiment of the light valve device.

FIG. 11 is a schematic plan view showing still another embodiment of the integrated circuit chip substrate.

FIG. 12 is a schematic perspective view of a video projector to which the light valve device is applied.

FIG. 13 is a schematic cross-sectional view showing the detailed structure of the VIZIO projector.

FIG. 14 is a schematic perspective view of a projection CRT incorporating a video projector.

[Explanation of symbols]

1 substrate 2 carrier layer 3 semiconductor single crystal thin film layer 4 integrated circuit chip substrate 5 pixel region 6 X driver 7 Y driver 8 counter substrate 9 polymer dispersed liquid crystal layer 11 pixel 12 pixel electrode 13 transistor 14 signal line 15 scanning line 16 gate electrode 17 Drain Electrode 21 Common Electrode 22 Single Crystal Silicon Semiconductor Substrate 26 Element Area 27 Field Oxide Film 28 Gate Oxide Film 30 Drain Area 31 Source Area 32 Transistor Channel Forming Area 33 Low Resistance Thin Film Layer 34 Low Resistance Area 36 Video Signal Processing Circuit Area 37 Video projector 39 Light valve device 40 Light valve device 41 Light valve device 45 Color filter

Claims (1)

[Claims] 1. A drive substrate on which a drive electrode and a drive circuit for exciting the drive electrode in response to a predetermined signal are formed, an opposite substrate arranged to face the drive substrate, the drive substrate, and In a light valve device comprising an electro-optical material layer arranged between opposed substrates, the electro-optical material layer is a polymer dispersed liquid crystal layer, and the driving substrate is a two-layer structure comprising a carrier layer and a semiconductor single crystal thin film layer. The drive circuit is formed of an integrated circuit formed on the semiconductor single crystal thin film layer, the drive electrode is integratedly arranged on the semiconductor single crystal thin film layer, and is formed on the high-dispersion liquid crystal layer excited by the drive circuit. A light valve device characterized in that the light valve device acts to control the light transmittance thereof.