JPH07294959A - Semiconductor device for light valve - Google Patents

Abstract

PURPOSE:To realize fine pixel sizes on single crystal silicon device forming layers of pixel regions by three-dimensionally forming auxiliary capacitors of pixels on these single crystal silicon device forming layers. CONSTITUTION:An auxiliary capacitor forming material 109 forms the auxiliary capacitors 112 by utilizing the inside of plural grooves 110 formed in the single crystal silicon device forming layers 301 completely electrically separated from the regions where MOS type transistors(TRs) 101 are formed and the front surface parts and side surface parts of the single crystal silicon device forming layers 301. In such a case, the purpose of electrically separating the single crystal silicon device forming layers 301 forming the auxiliary capacitors 112 from the regions formed with the MOS type TRs 101 is to prevent an increase in the leak current of the MOS type TRs 101 by turning of the single crystal silicon device forming layers 301 to the carrier generating regions by photoirradiation. As a result, the plane area occupied by the auxiliary capacitor region is made small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light valve semiconductor device, and more particularly to a light valve semiconductor device in which a pixel region formed on a single crystal silicon device forming layer and a driving circuit are built in the same chip.

[0002]

2. Description of the Related Art Conventionally, there has been known a light valve semiconductor substrate having a switch transistor formed on a polycrystalline silicon film formed on a glass substrate or an amorphous silicon film.

[0003]

However, in many cases, the conventional light valve semiconductor device does not have a built-in drive circuit, and it is necessary to externally connect to a separately manufactured drive IC. Further, a semiconductor device for a light valve having a drive circuit built-in, which is partially made of polycrystalline silicon, is also known. It was extremely difficult to form a large-capacity drive circuit. Further, recently, it has been devised to form a switch transistor of a pixel by single crystal silicon by a recrystallization method or the like, aiming at a finer and faster pixel switch. However, in order to realize a fine pixel size while ensuring a practical aperture ratio, there is a problem that the conventional planar pixel auxiliary capacitance structure cannot cope with the problem.

It is an object of the present invention to solve the above problems and provide a semiconductor device for a light valve having an auxiliary capacitance structure for realizing a fine pixel size on a single crystal silicon device forming layer.

[0005]

The main means adopted by the semiconductor device for a light valve according to the present invention to achieve the above object is that the pixel region formed on the single crystal silicon device forming layer and the driving circuit are the same. In a semiconductor device for a light valve built in a chip, a groove is formed in a single crystal silicon device forming layer in a pixel region, or a multi-layer auxiliary capacitance forming material laminated via an insulating film is used to form a three-dimensional pixel. It is characterized in that the auxiliary capacitance of is formed.

[0006]

In the semiconductor device for a light valve according to the present invention, the auxiliary capacitance of the pixel is three-dimensionally formed on the single crystal silicon device forming layer in the pixel region. The plane area occupied by the auxiliary capacitance region can be made smaller than that of the structure of FIG. Therefore, the aperture ratio of the pixel is improved,
It is possible to realize a light valve device having a finer pixel size while ensuring a practical aperture ratio.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view showing an embodiment of a pixel region of a light valve semiconductor device of the present invention.

A MOS type transistor 1 having a pair of source region 103 and drain region 104 and a gate electrode 102 made of polysilicon or the like on a buried insulating film 114.
01 is formed. The data line 1 made of aluminum or the like is formed in the source region 103 and the drain region 104.
05 and the drain line 107 are connected, and although not shown, the data line 105 is connected to a drive circuit portion formed in the periphery of the pixel region. Further, the drain line 107 is connected to an auxiliary capacitance forming material 109 made of the same material as the gate electrode 102 such as polysilicon. Forming the auxiliary capacitance forming material 109 and the gate electrode 102 with the same material is effective in simplifying the manufacturing process, but they may be formed with different materials if necessary. The auxiliary capacitance forming material 109 is in the plurality of trenches 110 formed in the single crystal silicon device forming layer 301 which is electrically completely separated from the region in which the MOS transistor 101 is formed, and the surface portion of the single crystal silicon device forming layer 301. ,
The auxiliary capacitance 112 is formed using the side surface portion. The single crystal silicon device forming layer 301 forming the auxiliary capacitance 112 is electrically completely separated from the region where the MOS transistor 101 is formed because the single crystal silicon device forming layer 301 is irradiated with light to generate a carrier generation region. This is to prevent the increase of the leak current of the MOS transistor 101.

In the example shown in FIG. 1, the single crystal silicon device forming layer 301 is removed by etching to separate the single crystal silicon device forming layer 301 forming the auxiliary capacitance 112 from the region where the MOS transistor 101 is formed. However, a method of thermally oxidizing the single crystal silicon device forming layer 301 for the entire thickness and separating it may be used. A silicon thermal oxide film obtained by thermally oxidizing the single crystal silicon device forming layer 301 is used as the material of the insulating film 111 of the auxiliary capacitor 112, and since it is commonly used as the gate insulating film of the MOS transistor 101, the manufacturing process Is effective for simplification, but optimization processing such as changing the film thickness may be performed as necessary. The thermal oxide film of single crystal silicon is significantly denser than the thermal oxide film of polysilicon and the deposition oxide film by the CVD method and has very few pinholes, and it is easy to form a thin film. Is one of the most suitable materials for forming. Further, in order to further improve reliability, it is effective that the insulating film 111 has a multi-layer structure with a silicon nitride film.

FIG. 1 shows a structure in which the auxiliary capacitance forming material 109 is extended and also serves as a pixel electrode.
The pixel electrode may be formed using a transparent material such as O.
A protective film 108 is formed on the MOS transistor 101, and a transparent substrate 115 such as glass is fixed on the protective film 108 via a transparent adhesive layer 113 that also serves as a flattening film. Although not shown, the MOS transistor 1
A light-shielding film is formed on the upper surface, lower surface, or both surfaces of 01,
It is desirable to have a structure that prevents light from entering the MOS transistor 101.

FIG. 2 is a schematic sectional view showing another embodiment of the pixel region of the light valve semiconductor device of the present invention. A MOS transistor 101 having a pair of source regions 103, drain regions 104 and a gate electrode 102 made of polysilicon or the like is formed on a transparent insulating substrate 201 such as quartz. A data line 105 and a drain line 107 made of aluminum or the like are connected to the source region 103 and the drain region 104, and although not shown, the data line 105 is connected to a drive circuit portion formed around the pixel region. Further, the drain line 107 is connected to an auxiliary capacitance forming material 109 made of the same material as the gate electrode 102 such as polysilicon. Forming the auxiliary capacitance forming material 109 and the gate electrode 102 with the same material is effective in simplifying the manufacturing process, but they may be formed with different materials if necessary. The auxiliary capacitance forming material 109 is in the plurality of trenches 110 formed in the single crystal silicon device forming layer 301 which is electrically completely separated from the region in which the MOS transistor 101 is formed, and the surface portion of the single crystal silicon device forming layer 301. The auxiliary capacitance 112 is formed using the side surface portion. The single crystal silicon device formation layer 301 forming the auxiliary capacitance 112 is
The reason why the region where the S-type transistor 101 is formed is completely electrically separated will be omitted in the description of the example shown in FIG.

As the material of the insulating film 111 of the auxiliary capacitance 112, a silicon thermal oxide film obtained by thermally oxidizing the single crystal silicon device forming layer 301 is used. The effectiveness of the thermal oxide film of single crystal silicon will also be omitted from the description of the example shown in FIG. In the example of FIG. 2, the pixel electrode 203 made of a transparent material such as ITO is formed on the second intermediate insulating film 202 and connected to the drain line 107 via the contact hole 401. Although not shown, a protective film may be formed on the pixel electrode 203 as needed. Also, MO
It is desirable to form a light-shielding film on the upper surface, lower surface, or both surfaces of the S-type transistor 101 so as to prevent light from entering the MOS-type transistor 101.

According to the embodiments of FIGS. 1 and 2, the auxiliary capacitance 112 of the pixel is formed in the single crystal silicon device forming layer 301 which is electrically completely separated from the region in which the MOS transistor 101 is formed. It is formed by utilizing the inside of the plurality of trenches 110 and the surface portion and the side surface portion of the single crystal silicon device forming layer 301. As a result, the auxiliary capacitance 11
The effective area of 2 can be significantly increased as compared with the conventional planar structure.

FIG. 3 is a schematic sectional view showing an embodiment of the pixel region of the light valve semiconductor device of the present invention. A pair of source region 103 and drain region 1 on the embedded insulating film 114.
A MOS transistor 101 having a gate electrode 102 made of polysilicon and the like is formed. A data line 105 and a drain line 10 made of aluminum or the like are provided in the source region 103 and the drain region 104.
Although not shown, the data line 105 is connected to a drive circuit portion formed around the pixel region. Further, the drain line 107 is made of the same material as the gate electrode 102 such as polysilicon, and the first auxiliary capacitance forming material 50.
Connected to 1. Forming the first auxiliary capacitance forming material 501 and the gate electrode 102 with the same material is effective in simplifying the manufacturing process, but they may be formed with different materials if necessary.

The first auxiliary capacitance forming material 501 utilizes the surface portion and the side surface portion of the single crystal silicon device forming layer 301 which is electrically completely separated from the region where the MOS transistor 101 is formed. A capacitor is formed with the insulating film 503 interposed. Further, the first auxiliary capacitance forming material 501
A second auxiliary capacitance forming material 506 made of polysilicon or the like is formed on the upper part of the substrate via a second insulating film 502. Although not shown, the second auxiliary capacitance forming material 506 is a single crystal silicon device forming layer. They are connected so as to have the same potential as 301. Therefore, the first auxiliary capacitance forming material 5
01 forms a capacitance between the lower surface and the single crystal silicon device forming layer 301 via the first insulating film 503, and the second auxiliary capacitance forming material 5 on the upper surface via the second insulating film 502.
A capacitor is formed between the capacitor and the capacitor 06, and the upper and lower capacitors are combined to form the auxiliary capacitor 112 as a whole. The single crystal silicon device formation layer 301 forming a part of the auxiliary capacitance 112 is replaced with the MOS transistor 101.
Electrically completely separating from the region where the MOS transistor 1 is formed is that the single crystal silicon device forming layer 301 becomes a carrier generation region due to light irradiation, and the MOS transistor 1
This is to prevent an increase in the leak current of 01.

In the example of FIG. 3, the MO of the single crystal silicon device forming layer 301 forming a part of the auxiliary capacitance 112 is formed.
An example is shown in which the single crystal silicon device forming layer 301 is removed by etching for separation from the region where the S-type transistor 101 is formed. However, the single crystal silicon device forming layer 301 is thermally oxidized by the entire thickness. You may use the method of separating by. A silicon thermal oxide film obtained by thermally oxidizing the single crystal silicon device forming layer 301 is used as the material of the first insulating film 503 of the auxiliary capacitance 112, and is commonly used as the gate insulating film of the MOS transistor 101. Therefore, it is effective in simplifying the manufacturing process, but optimization processing such as changing the film thickness may be performed as necessary. The thermal oxide film of single crystal silicon is extremely dense and has very few pinholes as compared with the deposition oxide film by the CVD method, and it is easy to form a thin film. Therefore, it is suitable for forming a large capacity in a small area. Is one of the ingredients. Also,
The second insulating film 502 has a first auxiliary capacitance forming material 50 made of the same material as the gate electrode 102 such as polysilicon.
A thermal oxide film obtained by thermally oxidizing the surface of No. 1 is used. further,
In order to further improve reliability, it is effective that the first insulating film 503 and the second insulating film 502 have a multilayer structure with a silicon nitride film.

Although the pixel electrode is omitted in FIG.
A pixel electrode is formed using a transparent material such as O and connected to the drain line 107. A protective film 108 is formed on the MOS transistor 101, and a transparent substrate 115 such as glass is fixed on the protective film 108 via a transparent adhesive layer 113 that also serves as a flattening film. Although not shown, M
It is desirable to form a light-shielding film on the upper surface, the lower surface, or both surfaces of the OS type transistor 101 so as to prevent light from entering the MOS type transistor 101.
Further, in the example of FIG. 3, the case where the first auxiliary capacitance forming material 501 and the material of the gate electrode 102 are the same material has been described, but the second auxiliary capacitance forming material 506 and the gate electrode 102 may be different depending on the manufacturing process. In some cases, the same material may be used as the above material.

FIG. 4 is a schematic sectional view showing another embodiment of the pixel region of the light valve semiconductor device of the present invention. A MOS transistor 101 having a pair of source regions 103, drain regions 104 and a gate electrode 102 made of polysilicon or the like is formed on a transparent insulating substrate 201 such as quartz. A data line 105 and a drain line 107 made of aluminum or the like are connected to the source region 103 and the drain region 104, and although not shown, the data line 105 is connected to a drive circuit portion formed around the pixel region. The drain line 107 is connected to a first auxiliary capacitance forming material 501 made of the same material as the gate electrode 102 such as polysilicon. Forming the first auxiliary capacitance forming material 501 and the gate electrode 102 with the same material is effective in simplifying the manufacturing process, but they may be formed with different materials if necessary. The first auxiliary capacitance forming material 501 is the MOS transistor 10.
A capacitor is formed by sandwiching the first insulating film 503 by utilizing the surface portion and the side surface portion of the single crystal silicon device forming layer 301 which is electrically completely separated from the region where 1 is formed.
Further, a second auxiliary capacitance forming material 506 made of polysilicon or the like is formed on the first auxiliary capacitance forming material 501 via the second insulating film 502, and although not shown, the second auxiliary capacitance forming material 506 is formed. The material 506 is connected so as to have the same potential as the single crystal silicon device formation layer 301. Accordingly, the first auxiliary capacitance forming material 501 forms a capacitance between the lower surface of the first auxiliary capacitance forming material 501 and the single crystal silicon device forming layer 301 via the first insulating film 503, and the upper surface of the second insulating film 5 is formed.
A capacitor is formed between the second capacitor and the second auxiliary capacitor forming material 506 via 02, and the upper and lower capacitors are combined to form the auxiliary capacitor 112 as a whole. Auxiliary capacity 11
The reason why the single crystal silicon device forming layer 301 forming a part of 2 is completely electrically separated from the region where the MOS transistor 101 is formed is omitted in the description of the example shown in FIG. To do. A silicon thermal oxide film obtained by thermally oxidizing the single crystal silicon device forming layer 301 is used as a material of the first insulating film 503 of the auxiliary capacitance 112. The effectiveness of the thermal oxide film of single crystal silicon will also be omitted in the description of the example shown in FIG. Other parts will be replaced with the description by adding the same reference numerals as those in FIG.

In the embodiment shown in FIGS. 3 and 4, the auxiliary capacitor 112 is composed of two capacitors formed on the upper and lower surfaces of the first auxiliary capacitor forming material 501, and further includes an insulating film and an auxiliary capacitor forming material. It is also possible to three-dimensionally form a large number of capacitors by stacking them. According to the embodiments of FIGS. 3 and 4, the first auxiliary capacitance forming material 501 is formed on the lower surface of the single crystal silicon device forming layer 301 via the first insulating film 503.
And a capacitor is formed between the capacitor and the second auxiliary capacitor forming material 506 via the second insulating film 502 on the upper surface. The auxiliary capacitance 112 is formed. As a result, the effective area of the auxiliary capacitor 112 can be significantly increased as compared with the case of the conventional planar structure. Further, although not shown, it is possible to increase the surface area by forming irregularities on the surface portion, the side surface portion, etc. of the single crystal silicon device forming layer 301 in the auxiliary capacitor 112.

Therefore, since a predetermined capacity can be secured within a small plane area, the aperture ratio of the pixel is improved, and a light valve device having a finer pixel size is secured while securing a practical aperture ratio. Can be realized. In addition, the auxiliary capacity 11
2. Single crystal silicon device forming layer 301 forming 2
Of the MOS transistor 101 is completely electrically separated from the region where the MOS transistor 101 is formed, the single crystal silicon device forming layer 301 becomes a carrier generation region even under light irradiation, and the leak current of the MOS transistor 101 is reduced. The problem of causing an increase does not occur.

Further, in the embodiment shown in FIGS. 1 and 2, a silicon thermal oxide film obtained by thermally oxidizing the single crystal silicon device forming layer 301 is used as the material of the insulating film 111 of the auxiliary capacitor 112. Therefore, it has high reliability, thinning is easy, and a large capacitance can be obtained in a small area, which is effective for miniaturization of pixels. . Further, the insulating film 111 is shared with the gate insulating film of the MOS transistor 101, and the pixel capacitance forming material 109 is used as the gate electrode 1.
Since it is formed of the same material as 02, it is effective in simplifying the manufacturing process.

In the embodiment shown in FIGS. 3 and 4, the material of the first insulating film 503 of the auxiliary capacitor 112 is a silicon thermal oxide film obtained by thermally oxidizing the single crystal silicon device forming layer 301. Since it has high reliability, it can be easily thinned, and a large capacitance can be obtained in a small area, which is effective for miniaturization of pixels. . In addition, the first insulating film 503 is formed on the MOS transistor 101.
Common to the gate insulating film of the first pixel capacitance forming material 5
Since 01 is formed of the same material as the gate electrode 102, it is effective in simplifying the manufacturing process.

[0023]

As described above, according to the present invention, the auxiliary capacitance of the pixel is formed in the plurality of trenches formed in the single crystal silicon device forming layer electrically completely separated from the region where the MOS transistor is formed. And a surface portion and a side surface portion of the single crystal silicon device forming layer. As a result, the effective area of the auxiliary capacitance can be significantly increased as compared with the case of the conventional planar structure, so that the predetermined capacitance can be secured within a small plane area. Alternatively, the supplement of the pixel is formed by a multi-layer auxiliary capacitance forming material laminated via an insulating film. Therefore, the aperture ratio of the pixel is improved, and a light valve device having a finer pixel size can be realized while ensuring a practical aperture ratio.

Further, since the single crystal silicon device forming layer forming the auxiliary capacitor is electrically completely separated from the region in which the MOS type transistor is formed, the single crystal silicon device forming layer is also exposed to light. Does not become a carrier generation region, which does not cause the problem of increasing the leak current of the MOS transistor.
Furthermore, since a silicon thermal oxide film obtained by thermally oxidizing the single crystal silicon device forming layer is used as the material of the insulating film of the auxiliary capacitance, it has high reliability, can be easily thinned, and has a large capacitance. Because it can be obtained in a small area,
This is effective for miniaturization of pixels. . Further, since the insulating film of the auxiliary capacitance is shared with the gate insulating film of the MOS transistor and the pixel capacitance forming material is formed of the same material as the gate electrode, it is effective in simplifying the manufacturing process.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an embodiment of a pixel region of a light valve semiconductor device of the present invention.

FIG. 2 is a schematic cross-sectional view showing another embodiment of the pixel region of the light valve semiconductor device of the present invention.

FIG. 3 is a schematic cross-sectional view showing another embodiment of the pixel region of the light valve semiconductor device of the present invention.

FIG. 4 is a schematic cross-sectional view showing another embodiment of the pixel region of the light valve semiconductor device of the present invention.

[Explanation of symbols]

 101 MOS transistor 102 gate electrode 103 source region 104 drain region 105 data line 106 intermediate insulating film 107 drain line 108 protective film 109 auxiliary capacitance forming material 110 groove 111 insulating film 112 auxiliary capacitance 113 adhesive layer 114 embedded insulating film 115 transparent substrate 201 Transparent Insulating Substrate 202 Second Intermediate Insulating Film 203 Pixel Electrode 301 Single Crystal Silicon Device Forming Layer 401 Contact Hole 501 First Auxiliary Capacitance Forming Material 502 Second Insulating Film 503 First Insulating Film 506 Second Auxiliary Capacitance Forming material

Claims (9)

[Claims] 1. A light valve semiconductor device having a drive circuit formed on a single crystal silicon device forming layer and a pixel region in the same chip, wherein an auxiliary capacitor is formed in the pixel region. Semiconductor device. 2. A groove is formed in the single crystal silicon device forming layer, an insulating film is formed on an inner wall of the groove, and an electrode made of a storage capacitor forming material is formed on the insulating film to form an inside of the insulating film. 2. The semiconductor device for a light valve according to claim 1, wherein the auxiliary capacitance is formed in the. 3. The semiconductor device for a light valve according to claim 1, wherein the auxiliary capacitance has a multi-layer structure in which insulating films are provided above and below an electrode made of an auxiliary capacitance forming material. 4. A single crystal silicon device forming layer in which a MOS transistor for driving a pixel is formed in the pixel region and the auxiliary capacitance is formed, and a single crystal silicon device forming layer in which the MOS transistor is formed. 4. The semiconductor device for a light valve according to claim 1, wherein is electrically isolated. 5. The light valve according to claim 2, wherein a part or all of the insulating film of the auxiliary capacitor is a silicon thermal oxide film obtained by thermally oxidizing the single crystal silicon device forming layer. Semiconductor device. 6. The semiconductor device for a light valve according to claim 2, wherein a part or all of the insulating film of the auxiliary capacitance is made of the same material as the gate insulating film of the MOS transistor. 7. The semiconductor device for a light valve according to claim 4, wherein the auxiliary capacitance forming material is made of the same material as the gate electrode of the MOS transistor. 8. The light valve according to claim 2, wherein the insulating film has a multilayer structure of a thermal oxide film obtained by thermally oxidizing the surface of the single crystal silicon device forming layer and a silicon nitride film. Semiconductor device. 9. The auxiliary capacitance forming material is made of polysilicon, and the insulating film below the auxiliary capacitance forming material is a silicon thermal oxide film and a silicon nitride film obtained by thermally oxidizing the surface of the single crystal silicon device formation. A multi-layered film, wherein the insulating film on the auxiliary capacitance forming material is a multi-layered film of a silicon thermal oxide film and a nitride film obtained by thermally oxidizing the surface of the polysilicon. Item 2. The light valve semiconductor device according to item 2.