JP2000075808A - Semiconductor single crystal thin-film substrate light valve device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light valve device which has a high pixel density and prevents latch-up. SOLUTION: A composite substrate consisting of a silicon single crystal thin-film layer 2 and quartz glass 3, pixel electrodes 4 on the surface of this composite substrate, an integrated driving circuit in the silicon single crystal thin-film layer 2 for driving the pixel electrodes 4, a light shielding means for shielding this integrated driving circuit from incident light, a counter substrate 11 arranged to face the composite substrate and a liquid crystal layer 14 between the composite substrate and the counter substrate 11 are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat light valve device used for a direct-view display device, a projection display device and the like, and a method of manufacturing the same. More specifically, the present invention relates to an active matrix type light valve device formed by using a semiconductor thin film substrate on which driving recirculation and a pixel electrode group are integrally formed, and a method of manufacturing the same.

[0002]

2. Description of the Related Art The principle of an active matrix device is relatively simple: a switching element is provided for each pixel, the corresponding switching element is turned on when a specific pixel is selected, and the switching element is turned off when not selected. It is to be kept in a non-conductive state. This switch element is formed on a semiconductor thin film substrate constituting an active matrix device. The switching element is usually formed of a thin film type insulated gate field effect transistor.

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 films and polycrystalline silicon thin films can be easily deposited on a glass substrate using physical vapor deposition or chemical vapor deposition, they are suitable for manufacturing an active matrix device having a relatively large screen. I have.

[0004]

However, a conventional active matrix device using an amorphous silicon thin film or a polycrystalline silicon thin film is not always suitable for miniaturization of thin film switch elements and high density of pixel electrodes. . In recent years, apart from a direct-view type display device that requires a relatively large area image surface, there is an increasing demand for a microminiature display device or light valve device having miniaturized high-density pixels. Such a micro light valve 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 vision television. If the fine semiconductor manufacturing technology or the LSI manufacturing technology can be used, it has a pixel size of the order of 1 μm and has a total size of several cm.
It is believed that a very small light valve device having a comparable size can be realized.

However, when a conventional amorphous or polycrystalline silicon thin film is used, it is difficult to form a thin film transistor switching element on the order of μm or sub-μm by making full use of LSI manufacturing technology. For example, in the case of an amorphous silicon thin film, the deposition temperature is 30
Since the temperature is about 0 ° C., high-temperature processing required for LSI manufacturing technology cannot be performed. In the case of a polycrystalline silicon thin film, since the size of the crystal is about several μm, miniaturization of the thin film transistor is necessarily limited. In addition, the deposition temperature of the polycrystalline silicon thin film is about 600 ° C.
Miniaturization technology or LS that requires high temperature processing of 00 ° C or higher
It is difficult to make full use of I manufacturing technology.

As described above, in an active matrix device using a conventional amorphous silicon thin film or polycrystalline silicon thin film, it is not possible to realize the same integration density and chip size as a normal semiconductor integrated circuit. There was a problem that it was extremely difficult. SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, it is a general object of the present invention to provide a light valve device such as an active matrix liquid crystal device having finer and finer pixels. To achieve this goal,
In the present invention, a thin film transistor switch element group and its periphery are formed by using a composite substrate having a two-layer structure including an electrically insulating carrier layer and a high-quality semiconductor single crystal thin film layer formed thereon, such as a silicon single crystal thin film layer. A drive circuit was formed.

Meanwhile, a silicon single crystal thin film transistor is superior to a silicon amorphous thin film transistor or a silicon polycrystal thin film transistor in terms of high-speed response and miniaturization of an element, but has a large leak current due to incident light. Has a defect. This light leakage current deteriorates the on / off current ratio of the switching element composed of a transistor, and therefore needs to be suppressed as much as possible. For this reason, it is particularly necessary to take measures against light blocking of the thin film transistor switching element formed in the pixel array region.

Further, in the present invention, not only a switch element group but also a peripheral drive circuit are integrally formed on a semiconductor single crystal thin film, for example, a silicon single crystal thin film, in order to enable high-speed response of the element and achieve miniaturization. ing. In particular, when a silicon single crystal thin film is used, a CMOS transistor can be formed, so that power consumption can be reduced. However, when CMOS transistors are integratedly formed, latch-up or the like occurs between the N-type transistor and the P-type transistor due to irradiation of incident light, and there is a risk of malfunction or runaway in the worst case. Therefore, it is necessary to take measures against light blocking even for the peripheral driving circuits arranged outside the pixel array region.

Accordingly, it is a primary object of the present invention to provide an effective light-shielding means for a switch element group and a peripheral circuit element group integrated on a semiconductor single crystal thin film formed on the surface of a composite substrate.

[0010]

In order to achieve the above-mentioned general and main objects of the present invention, a light valve device according to the present invention comprises a composite substrate having a semiconductor single crystal thin film layer and an insulating carrier layer. I use. Pixel electrode groups defining pixels are formed on the surface of the composite substrate with high density and high definition.
Further, an integrated drive circuit for driving the pixel electrode group is formed at high density in the semiconductor single crystal thin film layer. In addition, the light valve device includes a light shielding means for shielding the integrated driving circuit from incident light. An opposing substrate is arranged to face the composite substrate with a predetermined gap therebetween. The predetermined gap is filled with an electro-optical material layer, and optical modulation of incident light is performed for each pixel.

The integrated driving circuit formed on the semiconductor single crystal thin film layer includes a switch element group arranged corresponding to the pixel electrode group, and selectively supplies power to each pixel electrode. The light-shielding means includes a light-shielding film for shielding each switch element from light. The light-shielding film is disposed immediately below the semiconductor single-crystal thin-film region in which each switch element is formed, and blocks light incident from the back surface of the light valve device.
This light-shielding film has conductivity and is electrically separated from the corresponding switch element by an insulating layer. This insulating layer is interposed between the semiconductor single crystal thin film layer and the insulating carrier layer.

According to another aspect, the light-shielding film is located immediately above the switch element on the opposite side of the semiconductor single crystal thin film layer with respect to each switch element, and blocks light from the front side of the light valve device. I have. In this case, each switch element is constituted by an insulated gate field effect transistor including a source region and a drain region formed in the semiconductor single crystal thin film layer and a gate electrode accumulated and arranged via a gate insulating film, The light-shielding film is laminated on the surface of the gate electrode, and at least blocks light incident on the channel region of the insulated gate field-effect transistor. Alternatively, the light-shielding film may be an electrode film extending from the drain electrode connected to the drain region and disposed above the gate electrode so as to cover the switch element.

As described above, the integrated drive circuit includes, in addition to a switch element group for selectively picking up a pixel electrode group, a driver circuit arranged around the pixel electrode group for driving the switch element group. It also contains The light-shielding means also includes a light-shielding layer for shielding the entire driver circuit from light. This light-shielding layer may be composed of, for example, a light-shielding sealer for bonding the composite substrate and the counter substrate to each other. Alternatively, this suitable light layer may be constituted by a light-shielding resin layer applied to the peripheral surface of the composite substrate. Further, the light-shielding layer may be constituted by a metal frame member arranged on the periphery of the composite substrate.

The light valve device having the above-described structure is manufactured by the method described below. First, a pair of semiconductor single crystal plate members and an insulating carrier plate member are prepared. Next, a light-shielding film is formed on the surface of one of the plate members. Subsequently, a pair of plate members is bonded with the light-shielding film interposed therebetween, and the semiconductor single crystal plate member is polished to form a semiconductor single crystal thin film layer. As this semiconductor single crystal plate member, for example, a high-quality silicon wafer used for LSI manufacturing is used. By polishing this silicon wafer, a silicon single crystal thin film layer having substantially the same quality as that of the silicon wafer can be obtained. Further, a pixel electrode group is formed on the semiconductor single crystal thin film layer so as not to overlap the light-shielding film, and a switch element group is formed integrally so as to overlap the light-shielding film. Finally, the opposing substrate is bonded to the carrier plate member via a predetermined gap, and the gap is filled with an electro-optical material to complete the light valve device. According to this manufacturing method, the light shielding means including the light shielding film is formed immediately below the semiconductor single crystal thin film layer region where each switch element is formed.

As described above, according to the present invention, a composite substrate having a two-layer structure including 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, a pixel electrode group and a driving circuit for driving the pixel electrode group can be integrally formed on the semiconductor single crystal thin film layer by making full use of a miniaturization technique or an LSI manufacturing technique. This integrated drive circuit includes a switch element group for selectively supplying power to the pixel electrode group and a peripheral circuit for line-sequentially scanning these switch element groups. The resulting light valve device has a very high pixel density and a very small pixel size and can constitute a very small and high definition light valve device, for example an active matrix device.

In particular, in accordance with the present invention, the light valve device includes suitable light means to protect the integrated drive circuit from incident light.
For example, the light-shielding means includes a light-shielding film that shields the channel region of the insulated gate field-effect transistor constituting each switch element from incident light. For this reason, it is possible to prevent a light leakage current from being generated in the insulated gate field effect transistor formed on the semiconductor single crystal thin film. The light-shielding means also includes a light-shielding layer, and shields the CMOS transistors constituting the peripheral driver recovery from external incident light.
Therefore, it is possible to effectively prevent a latch-up or the like which causes a malfunction.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic sectional view showing one embodiment of a light valve device according to the present invention, and shows an example in which a light shielding film is provided as light shielding means. For easy understanding, FIG. 1 shows only one pixel portion. As shown, the light valve device utilizes a composite substrate 1. The composite substrate 1 is composed of a semiconductor single crystal thin film layer, for example, a silicon monolithic thin film layer 2 and an insulating carrier layer, for example, a quartz glass layer 3
And On the composite substrate 1, a pixel electrode 4 for defining a pixel is formed. Further, an integrated drive circuit for driving the pixel electrode 4 is formed in the silicon single crystal thin film layer 2. This integrated drive circuit includes a switch element 5 for selectively supplying power to a corresponding pixel electrode 4. The switch element 5 is composed of an insulated gate field effect transistor, and has a pair of a drain region D and a source region S formed in the silicon single crystal thin film layer 2 and a gate insulating film 6.
, And a gate electrode G having a predetermined shape, which is stacked and disposed via the gate electrode G. Source region S of transistor
Are electrically connected to the pixel electrode 4 and the drain region D is electrically connected to the metal pattern 7.
These pixel electrodes 4 and metal butter 7 are deposited on the field oxide film 8. The field oxide film 8 is obtained by subjecting the silicon single crystal thin film layer 2 to a selective thermal oxidation treatment. The switch element 5 is entirely covered with a protective film 15.

Light shielding means for shielding the individual switch elements 5 from incident light is provided. In this embodiment, the light shielding means is constituted by a light shielding film 9. The light-shielding film 9 is disposed immediately below the semiconductor single-crystal thin-film layer region in which the switch elements 5 are formed, and blocks light incident from the back side of the light valve device. The light incident from the front side can be effectively blocked by the gate electrode C of the switch element 5. The light-shielding film 9 is made of, for example, polysilicon doped with impurities, has light-shielding properties and conductivity, is embedded in the insulating layer 10, and is electrically separated from the corresponding switch element 5. This light shielding film 9
By providing conductivity to the switch element 5, the switch element 5 can be used as a back gate electrode. The insulating layer 10
Is interposed between the silicon single crystal thin film layer 2 and the quartz glass layer 3.

An opposing substrate 11 is arranged to face the composite substrate 1 with a predetermined gap therebetween. The opposing substrate 11 includes a glass plate 12 and a common electrode 13 formed on an inner surface thereof.
Consists of An electro-optical material layer, for example, a liquid crystal layer 14 is filled between the composite substrate 1 and the counter substrate 11, and performs optical modulation of incident light for each pixel. That is, the transmittance for the incident light changes according to the magnitude of the voltage applied between the pixel electrode 4 and the common electrode 13, and a light valve function is achieved.

In the above-described embodiment, the light-shielding film 9 is formed of a polysilicon film patterned in a predetermined shape. However, the material of the light-shielding film is not limited to this, and may be made of, for example, a refractory metal or a silicide made of a compound of a refractory metal and silicon. Examples of the high melting point metal include tungsten, tankle, and platinum. The gate electrode G of the transistor constituting the switch element 5 is usually made of polysilicon. However, the present invention is not limited to this, and silicide may be used instead of polysilicon.

Next, an example of a method of manufacturing the light valve device shown in FIG. 1 will be described with reference to FIGS. 2 (A) to 2 (G).
First, in the step shown in FIG. 2A, a silicon single crystal plate 21 and a quartz glass plate 22 are prepared. For example, the silicon single crystal plate 21 is preferably a high quality silicon wafer used for LSI manufacturing, and has a crystal orientation in the range of 100> 0.0 ± 1.0. The lattice defect density is 500 / cm 2 or less. The back surface of silicon single crystal plate 21 is covered with insulating layer 23.
This insulating layer 23 is made of, for example, a silicon oxide film or a silicon nitride film, and its surface is planarized. On the other hand, a light shielding film 24 is formed on the surface of the quartz glass plate 22. The light shielding film 24 is made of polysilicon or refractory metal silicide patterned in a predetermined shape. Further, the entire surface of the quartz glass plate 22 is covered with the insulating layer 25. This insulating layer 2
5 is also made of a silicon oxide film or silicon nitride and its surface is flattened.

Next, in the step shown in FIG. 2 (B), the two plate members 21 and 22 which have been flattened are superimposed on each other and heated so that both plate members are thermocompression-bonded to each other. By this thermocompression bonding, both plate members are firmly fixed. As a result, the insulating layer 26 that has been fused into a single layer is
Will intervene. The light shielding film 24 is embedded in the insulating layer 26.

Next, in the step shown in FIG. 2C, the surface of the silicon single crystal plate 21 is polished. As a result, a silicon single crystal thin film layer 27 polished to a desired thickness is formed on the surface of the insulating layer 26. Therefore, the quartz glass plate 22
A composite substrate having a carrier layer made of and a single crystal silicon thin film layer 27 is obtained. Note that an etching process may be used instead of the polishing process to make the single crystal silicon plate 21 thinner. The single-crystal silicon thin film 27 thus obtained
Since the quality of the silicon wafer 21 is substantially preserved as it is, it is possible to obtain a semiconductor substrate material having extremely excellent crystal orientation uniformity and lattice defect density.

Incidentally, various types of semiconductor substrates having a silicon single crystal thin film are conventionally known. This is a so-called SOI substrate. For example, an SOI substrate is formed by depositing a polycrystalline silicon thin film on a carrier surface made of an insulating material by a chemical vapor deposition method or the like, and then performing a heat treatment by laser beam irradiation or the like to recrystallize the polycrystalline film to obtain a single crystal It was obtained by converting to a structure. However,
In general, 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 has been difficult to apply a miniaturization technique or an LSI manufacturing technique to an SOI substrate manufactured by a conventional method, similarly to a silicon wafer. In view of this point, the present invention provides fine and high-resolution light using a silicon single crystal thin film having crystal orientation uniformity and low density lattice defects equivalent to those of a silicon wafer widely used in a semiconductor manufacturing process. It constitutes a valve device.

Next, a process of forming a switch element and a pixel electrode on the composite substrate manufactured as described above will be described below. First, in the step shown in FIG.
Performing selective thermal oxidation of the silicon single crystal thin film 27;
A field oxide film 28 is formed. This selective thermal oxidation is performed on the entire thickness of the silicon single crystal thin film 27 and is completely converted into a silicon oxide film.
8 is substantially transparent. As a result of the selective thermal oxidation, an element region is formed by the silicon single crystal thin film 27 left in the portion served by the field oxide film 28. At this time, the light shielding film 2 is formed immediately below the formed element region.
Mask alignment of the selective thermal oxidation process is performed so that 4 is located.

Next, in the step shown in FIG. 2E, only the surface portion of the silicon single crystal thin film 27 left in the element region is subjected to selective thermal oxidation to form a gate insulating film 29. Subsequently, a gate electrode 30 patterned in a predetermined shape is provided on the gate insulating film 29. The gate electrode 30 is made of polysilicon or silicide and is optically opaque.

Further, in the step shown in FIG. 2F, impurity doping is performed on the silicon single crystal thin film 27 to form a drain region 31 and a source region 32. This impurity doping is performed, for example, by implanting impurities such as arsenic through the gate insulating film 29 using the gate electrode 30 as a mask. As a result,
In the element region, a switch element 33 having an insulated gate field effect transistor structure including a pair of a drain region and a source region, a gate electrode and the like is formed. Since the switch element 33 is formed on the high-quality silicon single crystal thin film 27 having a large charge mobility, the switch element 33 has a high-speed response.
It has micro dimensions on the order of m or sub-μm.
The transistor channel region formed between the drain region 31 and the source region 32 is shielded from below by the light shielding film 24 and shielded from above by the gate electrode 30. Therefore, even when the pixel is irradiated with the incident light, a light leakage current is not induced in the single crystal thin film transistor.

Finally, in the step shown in FIG. 2G, a transparent electrode material such as ITO
Is formed by patterning. Since the pixel electrode 34 is disposed so as not to overlap the light-shielding film 24, incident light can pass through a laminated structure including the transparent electrode 34, the field oxide film 28, the insulating layer 26 and the quartz glass plate 22, A transmission type light valve device can be configured. The transparent electrode 34 is electrically connected to the source region 32 of the transistor via a contact hole opened in the gate insulating film 29. On the other hand, a metal pattern 35 is also formed, and is electrically connected to the drain region 31 of the transistor via another contact hole opened in the gate insulating film 29. Finally, the switch element 33 is covered with a protective film 36. Thus, a semiconductor substrate chip for a light valve device is completed. Although not shown, in order to assemble the light valve device,
An opposing substrate is overlaid on the composite substrate via a predetermined gap, and an electro-optical material such as a liquid crystal is sealed in the gap.

FIGS. 3A to 3C are process diagrams showing an example of another method for manufacturing a composite substrate according to the present invention.
Unlike the example described above, in this example, the light shielding film is formed in advance on the surface of the silicon single crystal plate. First,
In the step shown in FIG. 3A, a quartz glass plate 41 and a silicon single crystal plate 42 are prepared. Quartz glass plate 41
Finish the back of the machine smoothly. On the other hand, the silicon single crystal plate 42
After a base layer 43 made of a silicon oxide film is formed on the surface of the substrate, a light shielding film 44 is formed thereon by patterning. Then, an insulating layer 45 made of a silicon oxide film is deposited so as to cover the light shielding film 44. This deposition is performed using, for example, a chemical vapor deposition method. After performing the deposition process, the surface of the insulating layer 45 is polished and flattened.

Next, in the step shown in FIG. 3B, the flattened back surface of the quartz glass plate 41 and the silicon single crystal plate 4
The two planarized surfaces are thermocompressed together. As a result, the insulating layer 45 made of a silicon oxide film and the quartz glass plate 41 are thermally fused and integrated with each other. Finally, FIG. 3 (C)
In the step shown in (1), the silicon single crystal plate 42 is polished to a desired thickness to form a silicon single crystal thin film layer 46. The silicon single crystal thin film layer 46 is electrically separated from the light shielding film 44 via the underlayer 43. Thus, the composite substrate according to the present invention is manufactured. On the silicon single crystal thin film layer 46 laminated on the surface of the composite substrate, a fine and high-density switch element group and a pixel electrode group can be integratedly formed by making full use of LSI manufacturing technology.

Next, another example of the method of manufacturing a composite substrate according to the present invention will be described with reference to FIGS. 4 (A) to 4 (G). In this example, the element isolation region is formed simultaneously with the formation of the light shielding film. First, in the step shown in FIG. 4A, a silicon single crystal plate 51 made of a silicon wafer or the like is prepared. The surface of the silicon single crystal plate 51 is etched to form a step or a groove 52. An insulating layer 53 made of a silicon oxide film is provided on the surface where the groove is formed. As a result, the groove 52 is filled with the insulating layer 53. The insulating layer 53 is formed by depositing silicon dioxide by a chemical vapor deposition method or by thermally oxidizing the surface of the silicon single crystal plate 51. Further, a semiconductor polycrystalline layer 54 made of polysilicon is formed on the surface of the insulating layer 53. This process is performed by depositing polysilicon by chemical vapor deposition. Subsequently, the surface of the deposited polysilicon is polished and planarized.

Next, in the step shown in FIG. 4B, an insulating carrier plate member, for example, a quartz glass plate 55, also having a flattened back surface, is thermocompression-bonded to the flattened semiconductor polycrystalline layer 54. Join. Subsequently, in a step shown in FIG. 4C, the semiconductor single crystal plate 51 is removed by etching using the insulating layer 53 as a stopper to form a silicon single crystal thin film 56. This removal treatment may use a polishing technique instead of etching. As a result, the portion of the insulating layer 53 existing at the bottom of the step or the groove 52 is exposed. The exposed portion of the insulating layer 53 separates the silicon single crystal thin film 56 into individual elements to provide an element region where a switch element is formed. Then, a semiconductor polycrystalline layer 54 or a polysilicon layer is laminated above the element region via an insulating layer 53. This polysilicon layer forms a light shielding film later.

In the step shown in FIG. 4D, a mask 57 made of a silicon nitride film is formed so as to cover only the silicon single crystal thin film 56. Note that FIG. 4D shows the layout of the substrates upside down for easy understanding. As apparent from the figure, the mask 57 obtained by patterning the silicon nitride film exposes only the insulating layer 53.

In the step shown in FIG.
The insulating layer 53 is selectively etched through 7 to remove the exposed silicon oxide film to form a window 58.
The polysilicon layer or the semiconductor polycrystalline layer 54 is exposed in the window 58. In the step shown in FIG. 4F, the LO of the polysilicon layer 54 is
COS oxidation or selective thermal oxidation is performed to convert to an oxide film layer 59. Therefore, the window 58 is buried by the oxide film layer 59. Subsequently, the surface of the buried oxide film layer 59 is planarized by polishing or etching.

Finally, in the step shown in FIG. 4G, the remaining mask 57 is removed. As a result, the silicon single crystal thin films 56 are individually electrically separated by the oxide film layer 59. In other words, the oxide film layer 59 forms an element isolation region. On the other hand, the polysilicon layer 54 is disposed directly below the individual silicon single crystal thin film 56 via the insulating layer 53. This polysilicon layer 54 forms a light shielding film. According to the above-described method, a composite substrate in which element isolation regions are formed in advance can be obtained, and the surface of the composite substrate is completely flattened, and an ideal surface state for applying an LSI manufacturing technique can be obtained. Have.

In the various examples described above, the light-shielding film constituting the light-shielding means is disposed immediately below each switch element, and shields the switch element from light incident from the back side of the light valve device. I have. On the other hand, in the example described below, a light-shielding film is formed immediately above each switch element, and the switch element is shielded from light incident from the front side of the light valve device. An example will be described with reference to FIG.

In this embodiment, the light-shielding film is constituted by a part of the metal wiring which is extended. As shown in the figure, a silicon single crystal thin film layer 62 is formed on the surface of the quartz glass layer 61. This silicon single crystal thin film layer 62
Is formed by bonding and polishing a silicon wafer in the same manner as in the above-described example, and has the same high quality as the silicon wafer in terms of uniform crystal orientation and lattice defect density. The silicon single crystal thin film layer 62 is surrounded by a field oxide film 63 to form an element region. In this element region, LS
A switching element 64 composed of a high-speed and fine insulated gate field effect transistor is formed by using the I manufacturing technique. The transistor switch element 64 is composed of a drain region 65, a source region 66, and a gate electrode 67 having a predetermined shape stacked and arranged via a gate insulating film. On the other hand, a pixel electrode 68 is formed on the field oxide film 63.

In this embodiment, the gate electrode 67 and the pixel electrode 68 are formed simultaneously by patterning a common polysilicon thin film. In order to maintain the transparency of the pixel electrode 68, the polysilicon thin film has a very small thickness. Therefore, the light shielding property of the gate electrode 67 itself cannot be expected, and some light shielding means must be provided. Pixel electrode 6
8 is electrically connected to the source region 66 of the transistor, and its surface is covered with an interlayer insulating film 69. The interlayer insulating film 69 also covers the switch element 64 at the same time. On the interlayer insulating film 69, a metal pattern or a metal wiring 70 is formed. The metal wiring 70 is connected to the drain region 65 of the transistor via a contact hole opened in the interlayer insulating film 69. The metal pattern 70 has a portion extended so as to cover the gate electrode 67 above the element region. This extended portion constitutes the light shielding film 71. Metal wiring 7
Since 0 is made of a metal electrode material such as aluminum, it is naturally opaque. As described above, in the present example, the structure is such that the drain electrode and the light shielding film are also used. Finally, the switching element 64 and the pixel electrode 68
Is covered with a protective film 72. This protective film 72
Is flattened, and an electro-optical material layer and a counter substrate (not shown) are stacked thereon.

FIG. 5B is an enlarged plan view showing a part of the structure shown in FIG. 5A. As shown, the switch element 64 is arranged at the intersection of the scanning line 73 and the signal line 74. The scanning line 73 supplies a scanning signal for line-sequentially selecting the switch element 64 and is electrically connected to the gate electrode 67. On the other hand, the signal line 74 is made of the above-described metal wiring 70, is electrically connected to the drain region 65 of the transistor switching element 64 via a contact hole, and has a predetermined image signal. To selectively supply the pixel electrode 68. This pixel electrode 68 is electrically connected to the source region 66 of the transistor switch element 64 via a contact hole. A part of the metal wiring 70 or the drain electrode is extended so as to cover the entire switch element 64 and forms a light shielding film 71.
In this example, since the switching element 64 is located locally at the intersection of the scanning line 73 and the signal line 74, the surface contact of the pixel electrode 68 can be extremely large. As a result, the aperture ratio for each pixel can be made large, and the light valve device can have high luminance.

In the above-described example, the light-shielding film is also used as the drain electrode. On the other hand, in the following embodiment, the light-shielding film is overlaid on the surface of the gate electrode and formed by so-called self-alignment. As shown in FIG. 6, a silicon single crystal thin film layer 82 is disposed on the surface of a quartz glass layer 81. Silicon single crystal thin film layer 82
Are surrounded by a field oxide film 83 and define an element region. A switch element 84 formed of an insulated gate field effect transistor is formed in the element region. This transistor is formed by applying the LSI manufacturing technique to the high-quality silicon single crystal thin film layer 82, has a fine size, and has excellent high-speed switching characteristics. The transistor includes a pair of a drain region 85 and a source region 86, and a gate electrode 88 having a predetermined shape stacked and arranged via a gate insulating film 87. The gate electrode 88 is disposed so as to cover a channel region formed between the drain region 85 and the source region 86, and controls electrical conduction and cutoff of the channel region. In this example, the gate electrode 88 is made of polysilicon. This polysilicon is an opaque material by nature, but its transmittance does not become 0% when its thickness is small. Therefore, it is not always possible to obtain a complete light shielding effect only by the gate electrode 88.

Therefore, in this embodiment, the gate electrode 88
A light-shielding film 89 is formed on the substrate. This light-shielding film 89 is made of, for example, a metal such as aluminum or a silicide which is a compound of a high-melting-point metal and silicon, and can completely block incident light. Accordingly, there is no fear that the channel region existing below the gate electrode is irradiated with incident light, and no light leakage current occurs. As a result,
The supply charge accumulated in the pixel electrode does not leak even during the non-selection period of the switch element, and a stable operation can be guaranteed. The gate electrode 88 and the light shielding film 89 have the same planar shape and can be processed by self-alignment. The pixel electrode 90 is connected to the source region 86 of the transistor switch element 84. The pixel electrode 90 can be made of polysilicon similarly to the gate electrode, and is deposited on the field oxide film 83. A transparent conductive material such as ITO may be used instead of polysilicon. On the other hand, a metal wiring 91 is connected to the drain region 85 of the transistor switch element 84. The metal wiring 91 can be simultaneously patterned by using the same film as the light shielding film 89.

FIG. 7A is a schematic sectional view showing an example in which the embodiment shown in FIG. 6 is further improved. As shown, a silicon single crystal thin film layer 102 is formed on a quartz glass layer 101.
Is arranged. The silicon single crystal thin film layer 102 is selectively thermally oxidized except for the element region, and is converted into a field oxide film 103. In this element region, a switching element 10 comprising an insulated gate field effect transistor
4 is formed using a fine processing technique or an LSI manufacturing technique.

This insulated gate field effect transistor has a so-called LDD structure and is of a high withstand voltage type. That is,
A first drain region 105 composed of a high concentration impurity region and a first drain region
The source region 106 is formed apart from the source region 106.
Furthermore, a second drain region 1 made of a low concentration impurity region
07 is formed adjacent to the first drain region 105, and a second source region 108 also formed of a low-concentration impurity region is formed adjacent to the first source region 106. The difference between the pair of the second drain region 107 and the second source region 108 is that
09 is arranged. Thus, in the LDD structure,
Since the transistor channel formation region 109 is continuous with the second drain region 107 and the second source region 108, which are low-concentration impurity regions located at both ends of the transistor channel formation region 109, punch-through and a short channel effect can be effectively prevented. A pressure resistance structure can be realized. In particular, since a high voltage is applied to a switch element for driving a pixel electrode, a high breakdown voltage structure significantly contributes to improvement in reliability.

A gate electrode 111 is overlaid on the transistor channel formation region 109 via a gate insulating film 110. A light-shielding film 112 is further disposed on the gate electrode 111 to shield the transistor channel formation region 109 from incident light. In this example, the planar shape of the light shielding film 112 is set to be larger than the planar shape of the gate electrode 111. The reason for adopting such dimensions is to realize an LDD structure by self-alignment using the light shielding film 112 as described later.

A pixel electrode 113 is provided on the field oxide film 103, and one end of the pixel electrode 113 is electrically connected to the first source region 106 of the transistor switch element 104. On the other hand, a metal wiring 114 is also formed,
One end is electrically connected to the first drain region 105 of the transistor switching element 104. Finally, a protective film 115 is deposited so as to cover the switch element 104 and the pixel electrode 113. The surface has been subjected to a flattening process, and although not shown, a liquid crystal layer and a counter substrate are arranged on top of this to complete the light valve device.

FIG. 7B is a schematic cross-sectional view of a semi-finished product showing a process for manufacturing the switch element having the LDD structure shown in FIG. 7A. FIG. 7B shows an impurity doping process by ion implantation using the light shielding film 112 as a mask. As shown, since doping of impurity ions, for example, arsenic ions, is not performed immediately below the gate electrode 111, the transistor channel formation region 109 maintains the original conductivity type of the silicon single crystal thin film layer 102, for example, P type. On the other hand, impurity arsenic ions are directly implanted into portions not covered by the light-shielding film 112 used as a mask, so that the first drain region 105 and the first source region 106 made of a high-concentration N + type impurity region are formed. It is formed. Further, a low-concentration impurity region is formed in the silicon single crystal thin film layer 102 which does not overlap with the gate electrode 111 but overlaps with the light-shielding film 112 by sneaking of impurity arsenic ions or diffusion of impurity arsenic. That is, the N − -type impurity regions are formed on both sides of the gate electrode 111 to form the second drain region 107 and the second source region 108. As a result, by using the light-shielding film 112 which is slightly larger than the gate electrode 111 as a mask for ion implantation, an LDD structure can be formed at a time by self-alignment.

In the various embodiments described above, the light shielding means is constituted by a light shielding film for shielding each switch element from the front side or the back side. On the other hand, in the embodiment described below, the light shielding means is provided to shield the peripheral circuit. As described above, according to the present invention, since a high-quality silicon single crystal thin film having a high charge mobility is used, not only the switch element group but also the peripheral drive circuit element group for driving these switch element groups are used at the same time. It can be formed in an integrated manner using LSI manufacturing technology. Generally, it is advantageous to use CMOS transistors as the peripheral circuit element group. A CMOS transistor is composed of a set of N-type and P-type insulated gate field effect transistors, and is characterized by low power consumption. However, when N-type and P-type transistors are arranged adjacent to each other, a parasitic silicide composed of an NPNP junction is necessarily formed, and when irradiated with incident light, latch-up occurs and normal operation cannot be maintained. As a result, in the worst case, runaway occurs and the function of the light valve is destroyed. For this,
It is extremely important to shield the peripheral circuit element group in addition to the individual switch elements.

FIG. 8A shows an example of a light shielding structure for the above-described peripheral circuit. FIG. 8A shows a planar shape of the light valve device. A composite substrate 121 having a silicon single crystal thin film layer formed on the surface thereof has a pixel array area 12 at the center.
2 and a peripheral circuit area 123 existing in the peripheral portion. In the silicon single crystal thin film layer located on the surface of the pixel array area 122, pixel electrode groups 124 arranged in a matrix and corresponding switch element groups 125 are formed at a high density in an integrated manner. Each switch element 125 is constituted by an insulated gate field effect transistor.
The gate electrodes of the transistors are scanning lines 1 arranged in rows.
26, the drain electrode thereof is connected to the signal lines 127 arranged in a column, and the source electrode thereof is connected to the corresponding pixel electrode 124.

On the other hand, on the surface of the silicon single crystal thin film layer existing in the peripheral circuit area 123, peripheral circuits including an X driver 128 and a Y driver 129 are similarly formed in an integrated manner using LSI manufacturing technology. The X driver 128 is connected to the column-shaped signal line 127 to supply an image signal to each pixel, and the Y driver 129 is connected to the row-shaped scanning line 12.
6 and supplies a line-sequential scanning signal to each pixel. These peripheral circuits 128 and 129 correspond to the light shielding layer 13.
0. The light shielding layer 130 is arranged so as to surround the pixel array area 122, and selectively shields only the peripheral sealing path. On the other hand, the switch element groups 125 formed in the pixel array area are individually provided with the light shielding films as described above.

FIG. 8B is a schematic view showing a sectional structure of the light valve device shown in FIG. As shown in the figure, a counter substrate 131 is disposed on the composite substrate 121 with a predetermined gap therebetween, and an electro-optical material such as a liquid crystal 132 is sealed in the gap. The liquid crystal 132 is the sealer 1
It is sealed by 33. Not enclosed, sealer 1
An image search array is arranged in an inner portion surrounded by 33, and a Y driver 129 is arranged outside the sealer 133.
And other peripheral circuits. The pixel array and peripheral circuits are formed on a common silicon single crystal thin film layer. Peripheral circuits including the Y driver 129 are shielded from above and below by the light shielding layer 130. In this example, the light-shielding layer 130 is formed of a metal frame member arranged on the periphery of the composite substrate 121. This metal frame member has a light-shielding function and also has a function of cooling the light valve device because of its excellent thermal conductivity. Furthermore, since it is made of a metal material, it also has an electromagnetic shielding function. In the present example, the metal frame member or the metal frame is disposed apart from the surface of the composite substrate 121, but is not necessarily limited to this, and the metal frame may be bonded to the surface of the composite substrate 121. With such a configuration, malfunction of peripheral circuits due to latch-up or the like can be effectively prevented.

In order to clarify the structure, operation and effect of the present invention, the overall operation of the light valve device will be briefly described with reference to FIGS. 8 (A) and 8 (B). The gate electrode of each transistor switch element 124 is connected to a scanning line 126, and a scanning signal is applied by a Y driver 129 to control the application and cutoff of each transistor switch element 125 in line order.

The image signal output from the X driver circuit 128 is applied via a signal line 127 to a selected transistor switch element 125 which is conductive. The applied image signal is transmitted to the corresponding pixel electrode 124.
As a result, charges corresponding to the magnitude of the image signal are supplied to and accumulated in each pixel electrode 124. The pixel electrode 124 is excited by the accumulated charges and acts on the liquid crystal layer 132 to locally change the transmittance, thereby exhibiting a light valve function. on the other hand,
At the time of non-selection, the transistor switch element 125 becomes non-conductive, and maintains the image signal written to the pixel electrode 124 as electric charge. Note that the liquid crystal layer 132 has a high specific resistance and normally operates as a capacitive element. Since the transistor switch element is shielded by the light-shielding film, no light leakage current occurs in the non-conductive state, and the electric charge maintained in the pixel electrode does not leak. Therefore, an extremely stable light valve function can be exhibited.

Incidentally, the on / off current ratio is used to represent the switching performance of these transistor switching elements. The current ratio required for the liquid crystal operation can be easily obtained from the writing time and the holding time. For example, when the image signal is a television signal, about 60 .mu.
90% or more of the image signal must be written during msec. On the other hand, about 16 msec, which is one field period
Must hold at least 90% of the charge. As a result, the current ratio needs to be 5 digits or more. At this time, since the transistor switch element is formed on a silicon single crystal thin film having extremely high charge mobility, an on / off ratio of six digits or more can be secured. Therefore, it is possible to obtain an active matrix type light valve device having an extremely high-speed signal response. Further, the X driver circuit 128 and the Y driver circuit 1 are simultaneously used by utilizing the high mobility characteristic of the silicon single crystal thin film.
It is possible to form a peripheral circuit including 29 on the same silicon single crystal thin film. At this time, the driver circuit is also in the light shielding layer 1.
Since the light valve device 30 is effectively closed, malfunction of the light valve device can be prevented.

In the above-described example, the light-shielding layer for shielding the peripheral circuit is constituted by a metal frame. On the other hand, in the embodiments described below, the light-shielding layer is formed of a light-shielding resin layer applied to the peripheral surface and the back surface of the composite substrate. As shown in FIG. 9A, the composite substrate 1
An opposing substrate 142 is mounted on 41. A pixel array is formed in a portion of the composite substrate 141 covered by the opposing substrate 142, and peripheral circuits including driver circuits are integrally formed in a peripheral portion of the composite substrate 141 not covered by the opposing substrate 142. I have. A light-shielding resin layer 143 is applied so as to cover the driver circuit.

FIG. 9B is a schematic view showing a sectional structure of the light valve device shown in FIG. 9A. As shown in the figure, the opposing substrate 142 is bonded and fixed to the composite substrate 141 by a sealer or a seal member 144 via a predetermined gap.
The gap between both substrates is filled with a liquid crystal layer 145. A driver circuit 146 is formed around the composite substrate 141. The light-shielding resin layer 143 is applied so as to cover the driver circuit 146. The light-shielding resin layer 143 is made of, for example, an epoxy resin in which a black pigment is dispersed.

By the way, the composite substrate 141 usually uses quartz glass as a carrier. Therefore, light may enter the driver circuit 146 through the quartz glass carrier not only from the front side but also from the back side of the light valve device. Therefore, in this example, the light-shielding resin layer 143 is applied to not only the front surface but also the back surface of the display substrate 141. Finally, FIG. 10 is a schematic sectional view showing another configuration example of the light shielding layer. As shown, a silicon single crystal thin film 152 is formed on the surface of the composite substrate 151. The silicon single crystal thin film 152 has a peripheral drive circuit 15 in addition to the pixel array.
3 is also formed in high density and integrated. Composite substrate 151
A counter substrate 154 is mounted on the substrate with a predetermined gap therebetween. A liquid crystal 155 is filled and sealed in the gap between the two substrates. The two substrates are joined to each other by a sealer 156 made of an adhesive. In this example, this sealer 15
6 constitutes a light shielding layer. That is, the peripheral driving circuit 153
A sealer 156 made of a black resin is disposed so as to cover. According to this structure, the sealer can also be used as the light-shielding layer without providing an additional light-shielding layer, and the manufacturing process can be rationalized. The black resin 157 is used to more completely shield the driving circuit 153 from light.
Is applied to the side surface and the back surface of the light valve device. Since both the composite substrate 151 and the counter substrate 154 are made of a transparent material, light incident from the substrate end face may be refracted or the like and irradiated to the drive circuit 153. For this purpose, the side and back surfaces of each substrate are also covered with a light-shielding black resin.

[0057]

As described above, according to the present invention, a pixel electrode group and a driving circuit are integrated using a semiconductor miniaturization technique or an LSI manufacturing technique for a semiconductor single crystal thin film formed on a carrier layer. The light valve device is configured by using an integrated circuit chip substrate obtained by forming the light valve device. Therefore, there is an effect that a light valve device having an extremely high pixel density can be obtained. In addition, the dimensions of the integrated circuit chip substrate are
Since it can be made approximately the same as the C chip, there is an effect that an extremely small light valve device can be obtained. Since the pixel is manufactured using the semiconductor miniaturization technology, there is an effect that an extremely accurate light valve device can be obtained.

In particular, since the light shielding means for shielding the drive circuit from the incident light is used, there is an effect that the light valve device can be normally operated without being affected by the incident light. By arranging a light shielding film from the front side and the back side for each of the switch element groups included in the driving circuit, it is possible to suppress the light leak current of the switch element and to assure a stable light valve function. There is. In addition, by providing a light-shielding layer that closes the peripheral driver circuit and the like included in the drive circuit quickly from external incident light, it is possible to prevent latch-up from occurring in the driver circuit and prevent malfunction of the light valve device.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one embodiment of a semiconductor single crystal thin film substrate light valve device of the present invention.

FIG. 2 is a process chart for explaining a method of manufacturing a light valve device of the present invention.

FIG. 3 is a process chart showing a method for manufacturing a composite substrate used in the light valve device of the present invention.

FIG. 4 is a process chart showing another example of a method for manufacturing a composite substrate used in the light valve device of the present invention.

FIG. 5 is a schematic sectional view showing another embodiment of the semiconductor single crystal thin film substrate light valve device of the present invention.

FIG. 6 is a schematic cross section showing another embodiment of the semiconductor single crystal thin film substrate light valve device of the present invention.

FIG. 7 is a schematic sectional view showing another embodiment of the semiconductor single crystal thin film substrate light valve device of the present invention.

FIG. 8 is a schematic plan view showing another embodiment of the semiconductor single crystal thin film substrate light valve device of the present invention.

FIG. 9 is a perspective view showing another embodiment of the semiconductor single crystal thin film substrate light valve device of the present invention.

FIG. 10 is a schematic sectional view showing another embodiment of the semiconductor single crystal thin film substrate light valve device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Composite substrate 2 Silicon single crystal thin film layer 3 Quartz glass layer 4 Pixel electrode 5 Switching element 6 Gate insulating film 7 Metal pattern 8 Field oxide film 9 Light shielding film 10 Insulating layer 11 Opposite substrate 12 Glass plate 13 Common electrode 14 Liquid crystal layer 15 Protection Film D Drain region G Gate electrode S Source region

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[Procedure amendment]

[Submission date] September 13, 1999 (1999.9.1)
3)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 29/786 H01L 29/78 612B 619B (72) Inventor Tsuneo Yamazaki 1-8 Nakase Nakase, Mihama-ku, Chiba-shi, Chiba Address Seiko Instruments Inc. (72) Inventor Masaaki Taguchi 1-8-8 Nakase, Mihama-ku, Chiba Chiba Prefecture Inside Seiko Instruments Inc. (72) Inventor Satoru Yabe 1-8-1, Nakase, Mihama-ku, Chiba Pref. (72) Inventor Yoshikazu Kojima 1-8-1, Nakase, Mihama-ku, Chiba City, Chiba Prefecture Inside of Iko Instruments Co., Ltd. (72) Hiroaki Takasu 1-8-1, Nakase, Nakase, Mihama-ku, Chiba City, Chiba Prefecture Seiko Instruments (72) Inventor High Ryuichi No No 1-8-8 Nakase, Mihama-ku, Chiba-shi, Chiba Prefecture Inside Seiko Instruments Inc. (72) Inventor Hiroshi Suzuki 1-8-8 Nakase, Mihama-ku, Chiba-shi, Chiba Seiko Instruments Inc. Inside (72) Masaaki Kamiya Inventor Inside Seiko Instruments Inc., 1-8 Nakase, Mihama-ku, Chiba-shi, Chiba

Claims (11)

[Claims] 1. A composite substrate having a semiconductor single crystal thin film layer and an insulating carrier layer, a pixel electrode group formed on a surface of the composite substrate and defining a pixel, and a pixel electrode formed integrally on the semiconductor single crystal thin film layer An integrated drive circuit for driving the electrode group; a light-blocking means for shielding the integrated drive circuit from incident light; a counter substrate disposed to face the composite substrate via a predetermined gap; A light valve device comprising an electro-optic material layer for optically modulating incident light for each cord. 2. The integrated driving circuit includes a switch element group formed to correspond to the pixel electrode group and selectively supplying power to each pixel electrode, and the light shielding unit is configured to shield each switch element from light. The light valve device according to claim 1, further comprising a light shielding film. 3. The light valve device according to claim 2, wherein the light-shielding film is disposed immediately below a semiconductor single-crystal thin-film layer region in which individual switch elements are formed. 4. The light valve device according to claim 2, wherein the light-shielding film is located immediately above the switch element on a side opposite to the semiconductor single crystal thin film layer with respect to each switch element. 5. Each switch element is constituted by an insulated gate field effect transistor comprising a source region and a drain region formed in the semiconductor single crystal thin film layer, and a gate electrode laminated with a gate insulating film interposed therebetween. 5. The light valve device according to claim 4, wherein the light shielding film is laminated on a surface of the gate electrode. 6. The light valve device according to claim 5, wherein the light shielding film has a plane size larger than a plane size of a gate electrode, and the insulated gate field effect transistor has an LDD structure. 7. Each switch element is constituted by an insulated gate field effect transistor including a source region connected to a corresponding pixel electrode, a drain region, and a gate electrode, and the light shielding film is formed in the drain region. 5. The light valve device according to claim 4, wherein the light valve device is an electrode film extending from the connected drain electrode and covering the switch element above the gate electrode. 8. The integrated drive circuit includes a switch element group for selectively supplying power to the pixel electrode group, and a driver circuit disposed around the pixel electrode group for driving the switch element group. The light valve device according to claim 1, wherein the light shielding means includes a light shielding layer that shields the entire driver circuit. 9. The light valve device according to claim 8, wherein the light shielding layer comprises a light shielding sealer for bonding the composite substrate and the counter substrate to each other. 10. The light valve device according to claim 8, wherein the light-shielding layer comprises a light-shielding resin layer applied to a peripheral surface of the composite substrate. 11. The light valve device according to claim 8, wherein the light-shielding layer is formed of a metal frame member disposed around a composite substrate.