JPH04128717A - Light valve device - Google Patents

Abstract

PURPOSE:To make the device subminiature and very fine by forming a photoelectromotive force element which detects a light signal and generates electric power with incident light on a semiconductor single-crystal layer, formed on a carrier layer together with a driving circuit. CONSTITUTION:A substrate 1 in a wafer shape has two-layered structure consisting of the carrier layer 2 made of, for example, quartz and the single- crystal semiconductor layer 3 formed of, for example, silicon, on the carrier layer. Refining semiconductor manufacture technology is applied to the single crystal semiconductor layer 3 of this substrate 1 to form the driving circuits, photoelectromotive force element, and picture element electrodes of, for example, an active matrix display device by chip sections. Therefore, X and Y drivers 6 and 7 which need to have fast response, a solar battery 8 with high photoelectric conversion efficiency, and a fast light signal detecting element 9 which has high photodetection sensitivity can be formed in a picture element area 5 on the same plane. Consequently, a light valve device with high picture element density is obtained and a small-sized light valve device is also obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flat plate light valve device used in direct-view display devices, projection display devices, and the like. More specifically, the present invention relates to a light valve device, such as an active matrix liquid crystal display device, in which an integrated circuit in which a drive circuit is formed in a semiconductor thin film is integrally incorporated as a liquid crystal panel.

[Conventional technology]

The principle of active matrix liquid crystal display devices is very simple. Each pixel is provided with a switch element. When a specific pixel is selected, the corresponding switch element is made conductive, and when not selected, the switch element is made non-conductive. It is something to keep. This 7-inch element is formed on a glass substrate that constitutes a liquid crystal panel. Therefore, technology to reduce the thickness of switch elements is important. A thin film transistor is usually used as this element.

In conventional active matrix devices, thin film transistors have been formed on the surface of an amorphous silicon thin film or polycrystalline silicon deposited on a glass substrate. Since these amorphous silicon thin films and polycrystalline silicon thin films can be easily deposited on glass substrates using chemical vapor deposition, they are suitable for manufacturing relatively large-screen active matrix liquid crystal display devices. Transistor elements formed in amorphous or polycrystalline silicon thin films are generally of the field effect insulated gate type. Currently, active matrix liquid crystal display devices using amorphous silicon with an area of about 3 inches to 10 inches are commercially produced. Amorphous silicon thin films can be formed at low temperatures of 350° C. or lower, so they are suitable for large-area liquid crystal panels. Furthermore, as for active matrix liquid crystal display devices using polycrystalline silicon films, small liquid crystal display panels of about 2 inches are currently being commercially produced.

[Problem to be solved by the invention]

While active matrix liquid crystal display devices using conventional amorphous silicon thin films or polycrystalline silicon thin films are suitable for direct-view display devices that require a relatively large image surface, they are also suitable for device miniaturization and pixel height. Not necessarily suitable for densification. In addition to direct-view display devices, there has recently been an increasing demand for ultra-compact display devices or light valve devices having miniaturized, high-density pixels. Such a micro display device is used, for example, as a primary image forming surface of a projection type image device, and can be applied as a projection type high-visibility television. By using the WL narrow groove conductor manufacturing technology, it is possible to create an ultra-small light valve device having a pixel size on the order of 10 square meters and a total size on the order of several tens of thousands.

However, when conventional amorphous or polycrystalline silicon thin films are used, submicron-order transistor elements cannot be formed by applying fine semiconductor processing technology. For example, in the case of an amorphous silicon thin film, its mobility is about 1 d/Vsec, so a drive circuit that requires high-speed operation cannot be formed on the same substrate, and in the case of a polycrystalline silicon thin film, the mobility of crystal particles is The size is a number
Therefore, miniaturization of active elements is inevitably limited.

Furthermore, even if the drive circuit is formed using thin film transistors, a small number of electrical connections (more than 10 terminals in total) are required from the outside for control signals or power sources for image signals, clocks, synchronization, etc. This is an ultra-compact light valve device. In addition, the power supply circuit provided outside the light valve device increases the weight and volume of the entire system.As mentioned above, in the conventional active matrix display device,
There are limits to ultra-miniaturization when considering electrical connections.

In view of the problems of the conventional techniques described above, a first object of the present invention is to provide a light valve device such as an active matrix liquid crystal display device that is ultra-compact and miniaturized.

To achieve this objective, the present invention includes forming a photovoltaic element capable of detecting an optical signal and generating electric power from incident light together with a driving circuit in a semiconductor single crystal layer formed on a carrier layer. I made it.

By the way, various types of semiconductor laminated substrates in which a semiconductor layer is formed on such a carrier layer are conventionally known. This is what is called a So■ substrate. For example, an SOI substrate is produced by depositing a polycrystalline silicon thin film on the surface of a carrier made of an insulating material using chemical vapor deposition, etc., and then recrystallizing the polycrystalline film using laser beam irradiation or the like to convert it into a single crystal structure. was obtained. However, in general, single crystals obtained by recrystallization of polycrystals do not necessarily have a −-like crystal orientation and have a large lattice defect density. For these reasons, it has been difficult to apply the same miniaturization technology as silicon single crystal wafers to SOI substrates manufactured by conventional methods or to incorporate high-performance photovoltaic elements therein. In view of this, the present invention aims to produce fine, high-resolution and photovoltaic power by using a semiconductor thin film having crystal orientation uniformity and low density of lattice defects comparable to that of silicon single crystals widely used in semiconductor processes. A second object is to provide a light valve device incorporating an element.

[Means to solve the problem]

The means taken to achieve the objects shown in FIGS. 1 and 2 above will be explained based on FIG. 1.

FIG. 1F shows a planar shape of a substrate 1 used in the present invention, and FIG. 1 [F] also shows a cross-sectional structure.As shown in FIG. The substrate 1 has a two-layer structure consisting of a carrier layer 2 made of, for example, quartz and a single crystal semiconductor layer 3 made of, for example, silicon formed thereon. A miniaturized semiconductor manufacturing technique is applied to the single crystal semiconductor layer 3 of this substrate 1, and, for example, a drive circuit of an active matrix display device, a photovoltaic element, and a pixel electrode are formed in each chip section.

FIG. 10 is an enlarged plan view of the integrated circuit chip thus obtained. As shown in FIG. It is significantly smaller than other devices. The integrated circuit chip 4 includes a pixel region 5 in which fine pixel electrodes arranged in a matrix and insulated gate field effect transistors corresponding to the individual pixel electrodes are formed, and a pixel region 5 for supplying image signals to each transistor. An X driver region 6 in which a drive circuit, that is, an According to the present invention, an amorphous thin film or a polycrystalline El film has Compared to single crystal Fi!, which has extremely high charge mobility and few crystal defects! 1, the X and Y drivers that require high-speed response, the thick PIII battery that has high charging conversion efficiency, and the optical signal structure element that is fast and has high photodetection sensitivity can be formed on the same plane as the pixel area. I can do it. The output from the solar cell is connected to the power supply of the X and Y drivers, the image signal from the optical signal detector is connected to the X driver, and the control signals such as clock and synchronization are connected to the X and Y drivers.

FIG. 10 is a sectional view showing an active matrix light valve device that is ultra-compact and ultra-high-density and is assembled using the above-mentioned integrated circuit chip 4 and inputs signals and IIA using light. As shown, the light valve device is connected to an integrated circuit chip 4.
A counter substrate 1 is disposed opposite to the substrate with a predetermined gap therebetween.
0, and an electro-optical material layer such as a liquid crystal layer 11 filled in the gap. Note that an alignment film 1 for aligning liquid crystal molecules included in the liquid crystal layer 11 is provided on the surface of the integrated circuit chip 4.
2 is coated. The individual pixel electrodes formed in the pixel region 5 of the integrated circuit chip 4 are selectively excited by conduction of the corresponding transistor elements and act on the liquid crystal layer 11.
It controls its light transmission properties and functions as a light valve. Since the size of each pixel is about 104, it is possible to obtain an extremely high-definition active matrix liquid crystal light valve device.

FIG. 1e is a partially enlarged plan view of the pixel area 5 shown in FIG. 10, showing one pixel. FIG. 1F is also a schematic cross-sectional view of one pixel. As shown, pixel 13
is a pixel electrode 14, a transistor 15 for exciting the pixel electrode 14 according to a signal, and a signal for supplying a signal to the transistor 15! 16 and a scan vA17 for scanning the transistor. The signal line 16 is connected to the X driver and scans! 17 is connected to Y Drino 1. The transistor 15 has a drain region 1. formed in the single crystal thin film layer 3. It consists of a source region and a gate electrode 18 formed on a channel region with a gate insulating film interposed therebetween. That is, the transistor 15 is of an insulated gate field effect type. The gate electrode 18 is formed from a part of the scan 1!17, and the pixel electrode 14 is connected to the source region, and the drain electrode 19 is connected to the drain region.

The drain electrode 19 constitutes a part of the signal \a16.

[Function] As described above, according to the present invention, a substrate having a two-layer structure consisting of an insulating carrier layer and a semiconductor single crystal thin film layer formed thereon is used, and the semiconductor single crystal thin film The layer has the same quality as a wafer consisting of a semiconductor single crystal bulk. Therefore, pixel electrodes, switching elements for driving pixels, thick transistors, optical signal detection elements, etc. can be integrally formed in such a semiconductor single crystal thin film layer by making full use of miniaturization technology. The resulting integrated circuit chip has extremely high pixel density and extremely small pixel dimensions, and can be used to construct ultra-compact light valve devices, such as active matrix liquid crystal displays, with no or very few externally connected Vt terminals. .

〔Example〕

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 one embodiment of the light valve device according to the present invention. As shown in FIG. and an electro-optic material layer, such as a liquid crystal layer 11, disposed between the drive substrate l and the counter substrate 10. The drive substrate l includes a pixel electrode or drive electrode 14 that defines a pixel, a drive circuit for exciting the drive electrode 14 according to a predetermined signal, a solar cell 8 that supplies power to the drive circuit, and an incident light signal. An optical signal detection element 9 is formed which converts the signal into an electrical signal and supplies the electrical signal to the drive circuit.

The driving substrate 1 has a two-layer structure consisting of a carrier layer 2 made of quartz glass and a single crystal silicon semiconductor film layer 3. In addition, a polarizing plate 20 is adhered to the back side of the quartz glass carrier layer 2. The drive circuit and photovoltaic elements such as solar cells and optical signal detection elements are comprised of integrated circuits formed on this single crystal silicon semiconductor film layer 3. This integrated circuit includes a plurality of field effect insulated gate transistors 15 arranged in a matrix. The source electrode of the transistor 15 is connected to the corresponding pixel electrode 14, and the gate electrode is also connected to the scanning! Similarly, the drain electrode is connected to the signal line 16.

The integrated circuit further includes an X driver 6 and a column-shaped signal line]
6. Furthermore, it includes a Y dry half and is connected to a row scanning line 17. The counter substrate 10 is composed of a glass carrier 21, a polarizing plate 22 formed on the outer surface of the glass carrier 21, and a counter electrode or common electrode 23 formed on the inner surface of the glass carrier 21.

Next, the operation of the above embodiment will be explained in detail with reference to FIG. The gate electrode of each transistor element 15 is scanned! 17, and a scanning signal is applied by the Y dry huff to control conduction and cut-off of each transistor element 15 line sequentially.

The display signal output from the X-dry halo is applied via a signal line 16 to a selected transistor 15 in the conductive body. The applied display signal is transmitted to the corresponding pixel electrode 14, which acts on the excited display liquid crystal layer 11 to make its transmittance substantially 100%.

On the other hand, when not selected, the transistor element 15 becomes a non-conducting body and maintains the display signal written to the pixel electrode as a charge. Note that the liquid crystal layer 11 has a high specific resistance and normally operates as a capacitor. The on/off it current ratio is used to represent the switching performance of these drive transistor elements 15. The current ratio required for liquid crystal operation can be easily determined from the write time and retention time. For example, if the display signal is a television broadcast signal, one scanning period of approximately 60 μsec
90% or more of the display signal must be written during this period.

On the other hand, more than 90% of the charge must be held in one field period of about 15 m5ec, and as a result, the current ratio needs to be five orders of magnitude or more. At this time, since the drive transistor element is formed on the single crystal silicon semiconductor thin film layer 3 having extremely high charge mobility, an on/off ratio of 6 digits or more can be ensured. Therefore, an active matrix type light valve device having extremely high-speed signal response can be obtained. Further, by utilizing the high mobility of the single crystal thin film, it is possible to simultaneously form the peripheral circuits 6 and 7 on the same silicon single crystal semiconductor thin film. Furthermore, since a single crystal silicon semiconductor thin film has very few crystal defects, it is possible to form a highly efficient solar cell 8 and an optical signal detection element 9 with excellent response speed and detection intensity on the same silicon single crystal thin film. I can do it. As shown in FIG. 3, the solar cell 8 is constructed by connecting a plurality of PN junction diodes 24 in series according to the required voltage, increasing the area or connecting them in parallel according to the required current. . The power taken out from the PN junction diode 24 is stabilized through the constant voltage circuit 25 and then supplied to the drive circuit 6.7. Optical signal detection element 9
The photocurrent detected using the PN junction diode 26 is passed through the resistive element 27 as a load, and the generated voltage is sent to the amplifier 28.
After amplifying the signal, the signal is supplied to drive circuits 6 and 7. Normally, the minimum signals required by the drive circuit include an image signal, a synchronization signal for each of the X driver and Y driver, and a clock signal, so a corresponding number of photodetecting elements are provided. Since a light valve device is normally used in a state where light is incident, if a solar cell is provided in an area excluding pixels or drive circuits, a portion of the light incident on the light valve device will be used as an incident light source for the solar cell. can be used.

The input optical signal to the optical signal detection element is a laser diode,
Alternatively, the light modulated by a photodiode or the like is narrowed down by an optical system using a lens or the like, or is introduced into each photodetector element by passing it through an optical fiber. By providing an optical filter suitable for the incident light on the photodetection element, excess light due to disturbances such as stray light can be removed, and the photodetection ability can also be improved. To minimize the number of optical inputs, only the image signal should be input, and the image signal should be passed through an image signal processing circuit to generate synchronization signals, clocks, etc. to the X driver and Y driver. I can do it. In this case, only one image signal is sufficient as an optical input.

〔Effect of the invention〕

As described above, according to the present invention, a pixel electrode, a drive circuit, a power supply circuit using a solar cell, and an incident light signal detection are made using semiconductor miniaturization technology for a semiconductor single crystal thin film formed on a carrier layer. A light valve device is formed using an integrated circuit chip substrate obtained by integrally forming elements. Therefore, it is possible to obtain a light valve device having an extremely high pixel density. Furthermore, since it can be made to the same level as an integrated circuit chip, it is possible to obtain an extremely compact light valve device. Since integrated circuit technology can be used for the single crystal thin film layer, there is an effect that circuits having various functions comparable to LSI can be easily added. Furthermore, by using a single crystal thin film, it is possible to simultaneously incorporate not only a switching transistor but also a drive circuit, a thick gate electrode for t5, and a photodetector element for signal input. Finally, there is the advantage that the light valve arrangement can be driven with no or very few electrical connections to the light valve arrangement.

[Brief explanation of drawings]

Figure 1-5 is a plan view of the board, Figure 1-6 is a schematic cross-sectional view of the board, Figure 1-0 is an enlarged plan view of an integrated circuit chip formed on the board, and Figure 1-0 is an enlarged plan view of the integrated circuit chip. A schematic cross-sectional view of the light valve device used in the substrate, Fig. 1 is a partially enlarged plan view of the pixel area of the integrated circuit chip, the first drawing is a schematic cross-sectional view of the pixel, and Fig. 2 is a schematic cross-sectional view of the light valve device. FIG. 3 is a schematic exploded perspective view showing an embodiment of the present invention, and FIG. 3 is an embodiment of the solar cell circuit and the detection circuit. 1 ・ ・ ・ 21; Hand side 2...Carrier layer 3...Semiconductor single crystal thin film 4...Integrated circuit thousand knob substrate 5...Pixel area 6...X driver buffer...Y driver 8 ... Solar cell 9 ... Optical signal detection element 10 ... Counter substrate 11 ... Liquid crystal layer 13 ... Pixel 15 ... Transistor 16 ... Signal line 17 ... Scanning line FIG. is better than Mitsunobu

Claims (12)

[Claims] (1) A drive substrate on which a drive electrode and a drive circuit for exciting the drive electrode according to a predetermined signal are formed, a counter substrate disposed opposite to the drive substrate, and the drive substrate and the counter substrate. In a light valve device consisting of an electro-optical material layer and a photovoltaic element arranged between, the drive substrate has a two-layer structure consisting of a carrier layer and a semiconductor single crystal thin film layer, and the drive circuit is a semiconductor layer. It consists of an integrated circuit formed on a single crystal thin film layer, and the driving electrode is arranged integrally on the semiconductor single crystal thin film layer and acts on the electro-optic material layer to control its optical transparency when excited by the driving circuit. The light valve device is characterized in that the photovoltaic element is formed on the semiconductor single crystal thin film layer, and the electric power generated by the light incident on the photovoltaic element is supplied as a power source to the drive circuit. (2) The light valve device according to claim 1, wherein the photovoltaic element supplies an electric signal generated by incident light to the drive circuit as a control or input signal. (3) The integrated circuit includes a plurality of drive elements arranged in a matrix, and the drive electrode is made up of a plurality of pixel electrodes arranged in a matrix, and is selectively excited by each drive element. The light valve device according to claim 1 or 2, characterized in that: (4) Claim 3, characterized in that the integrated circuit includes a scanning circuit for scanning the matrix-shaped driving elements.
The light valve device described in. (5) The light valve device according to claim 4, wherein the integrated circuit includes an image signal processing circuit for processing an image signal input from the outside and transmitting the processed image signal to the scanning circuit. (6) Claim 1 characterized in that the drive substrate is formed with a spacer for maintaining a predetermined gap with respect to the counter substrate, and the gap is filled with an electro-optical material layer made of liquid crystal. 2. The light valve device according to item 2. (7) The light valve device according to any one of claims 1 to 2, wherein a subdivided color filter formed corresponding to the matrix pixel electrode or the photovoltaic element is arranged on the drive substrate. (8) A substrate having a two-layer structure consisting of a carrier layer and a semiconductor single crystal thin film layer formed on the carrier layer, an integrated pixel electrode formed on the semiconductor single crystal thin film layer, and the semiconductor single crystal thin film layer. an integrated drive circuit formed integrally on the semiconductor single crystal thin film layer for exciting the integrated pixel electrode; and a photovoltaic element formed on the semiconductor single crystal thin film layer for supplying power, control signals, or image signals to the integrated drive circuit. A semiconductor device consisting of. (9) The semiconductor device according to claim 8, wherein the carrier layer is made of quartz and the semiconductor single crystal thin film layer is made of silicon. (10) The silicon semiconductor single crystal thin film layer has uniformity in the range of <100>0.0±1.0 with respect to crystal orientation,
10. The semiconductor device according to claim 9, wherein the single crystal lattice defect density is 500 defects/cm^3 or less. (11) The semiconductor device according to claim 8, wherein the integrated circuit includes an insulated gate transistor formed on the surface of the semiconductor single crystal thin film layer, and a region below the channel formation region is grounded to the semiconductor single crystal thin film layer. . (12) The semiconductor device according to claim 8, wherein the photovoltaic element is a PN junction diode formed on the surface of the semiconductor single crystal thin film layer, or a plurality of diodes connected in series or in parallel. .