JPH06242469A - Semiconductor device for light valve and its manufacture - Google Patents

Abstract

PURPOSE:To form the small-sized light valve device in which a driving circuit capable of high-speed operation is incorporated by removing a single-crystal silicon substrate below a pixel area and making optical transmission possible. CONSTITUTION:On the single-crystal silicon substrate 101, the driving circuit 103 and pixel area 104 are formed and in the pixel area 104, an etching strip layer 102 is formed of a silicon oxide film. Further, the single-crystal silicon substrate 101 below the pixel area 104 is removed, an orienting film 201 is formed below the etching stripe layer 102, and a liquid crystal layer 203 is sandwiched with a counter substrate 205 which has a counter electrode 204 and an orienting film 201 by using a seal 202. The driving circuit 103 is therefore formed on the single crystal silicon substrate 101, so the circuit can operate at a high speed. The driving circuit 103 and pixel area 104 are wired during an IC process, so they can be connected at a several p m pitch and the connection can be made much finer than a conventional connection, thereby improving the reliability because of no connection part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light valve device, and more particularly to an active matrix type and simple matrix type light valve semiconductor device and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as a light valve device, a switch transistor made of polysilicon or amorphous silicon has been known.

[0003]

However, the above-mentioned light valve device does not have a built-in drive circuit, and it is necessary to externally connect it to a separately manufactured drive IC. For this reason, there is a problem in that the mounting cost is increased as a system and the connecting portions have to be formed with the pad portions at a pitch of 100 μm or more, so that the device cannot be downsized.

There is also known a light valve device in which a driving circuit is built in with a part of polysilicon as a material, but since the driving circuit is also formed of polysilicon, a high speed and high driving force circuit cannot be formed. There was a point. SUMMARY OF THE INVENTION It is an object of the present invention to provide a semiconductor device for a light valve, which can solve the above problems and can form a small light valve device having a built-in drive circuit capable of high-speed operation, and a manufacturing method thereof.

[0005]

The main means adopted by the semiconductor device of the present invention in order to achieve the above object is that a pixel region formed on a single crystal silicon substrate and a driving circuit are built in the same chip. The light valve semiconductor device is characterized in that only the single crystal silicon substrate under the pixel region is formed after the drive circuit and the pixel region are formed by the IC process, and then removed to allow light transmission.

As a manufacturing method, a step of forming a drive circuit and a pixel region on a single crystal silicon substrate by an IC process, and then adhering the drive circuit and the pixel region to a transparent support substrate, and forming a single crystal silicon substrate under the pixel region in advance. And a step of etching away the etching stop layer.

[0007]

The semiconductor device of the present invention is a semiconductor device for a light valve capable of forming a small-sized light valve device having a built-in drive circuit capable of high-speed operation as compared with a conventional light valve device using polysilicon or amorphous silicon as a switch transistor. Can be obtained.

[0008]

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 light valve device according to the semiconductor device for a light valve of the present invention. A driving circuit 103 and a pixel region 104 are formed on a single crystal silicon substrate 101.
And the etching stop layer 102 made of a silicon oxide film is formed in the pixel region 104. Further, the single crystal silicon substrate 101 is fixed to the supporting substrate 106 via the protective insulating film 108 and the transparent adhesive layer 105. The support substrate 106 is made of a transparent insulating material such as glass quartz sapphire, the single crystal silicon substrate 101 under the pixel region 104 is removed, and the alignment film 201 is formed under the etching stop layer 102. The counter substrate 2 having the counter electrode 204 and the alignment film 201
The liquid crystal layer 203 is sandwiched between the liquid crystal display panel 05 and the liquid crystal display panel 05 by a seal 202.

In this embodiment, the active matrix type is taken as an example, and each pixel has a switch transistor 501 made of amorphous silicon, polysilicon or single crystal silicon, and is connected to the drain region of the switch transistor 501 continuously. Pixel electrode 5 made of the same material
02 is formed. The wiring 302 is connected to the driving circuit 103 and turns on / off the switch transistor 501 in accordance with the supplied signal. Although not shown, the simple matrix type has a structure having no switch element.

According to the embodiment shown in FIG. 1, since the drive circuit 103 is formed on the single crystal silicon substrate 101, high speed operation is possible. Further, the drive circuit 103 and the pixel region 10
Since 4 and 4 are wired together during the IC process, they can be connected at a pitch of several μm. Conventionally, 100 is used for externally connecting the light valve device and a separately manufactured drive IC.
Compared to the need for a pitch of μm or more, it is possible to make the structure extremely fine, and the reliability is improved because there is no connecting portion.

The etching stop layer 102 may be a silicon nitride film or a composite film thereof instead of the silicon oxide film. 2A to 2C are cross-sectional views in order of the steps of the method for manufacturing a semiconductor device for a light valve according to the present invention. For simplification, the structures inside the driving circuit 103 and the pixel region 104 will be omitted with reference to the detailed FIG.

As shown in FIG. 2A, the drive circuit 103 and the pixel region 104 are formed on the single crystal silicon substrate 101 by using a normal IC process. Pixel area 104
An etching stop layer 102 made of a silicon oxide film, a silicon nitride film or a composite film thereof is formed on the surface. Further, during the IC process, a silicon nitride film 107 is formed on the back surface of the single crystal silicon substrate 101 at an appropriate step and patterned by using a double-sided aligner or the like, and the silicon nitride film 107 in a portion corresponding to the pixel region 104 is removed by etching. Keep it. Although not shown, the active matrix type pixel region 104 has a switch transistor for each pixel, and the simple matrix type has no switch element.

Further, the single crystal silicon substrate 101 has an SOI
When a (Silicon On Insulator) substrate is used, an active matrix type light valve semiconductor device in which a switch transistor of a pixel is formed of single crystal silicon can be obtained. At this time, the drive circuit
It may be formed on the same SOI single crystal silicon thin film as the switch transistor in the pixel region, or the SOI single crystal silicon thin film and the embedded insulating film made of SiO ₂ or the like may be removed only in the drive circuit portion to support the SOI substrate. It may be formed on the thick single crystal silicon substrate on the side. An SOI substrate is obtained by bonding two single crystal silicon substrates with an insulating layer in between and firmly bonding them by heat treatment, and then thinning one of the single crystal silicon substrates to a desired film thickness, a so-called bonded substrate. It is desirable because the laminated wafer has the same high quality (low crystal defects) as a normal single crystal.

Next, as shown in FIG. 2B, the support substrate 106 is bonded to the single crystal silicon substrate 101 via the adhesive layer 105. Here, since the adhesive layer 105 and the supporting substrate 106 are transparent materials, a light transmission type device, for example, a light valve substrate can be manufactured. Next, as shown in FIG. 2C, the pixel region 10 is formed using the silicon nitride film 107 as a mask.
The single crystal silicon substrate 101 under 4 is removed by etching. This etching is performed by using a KOH solution or a hydrazine solution as an etchant, and stops when the etching stop layer 102 made of a silicon oxide film, a silicon nitride film, or a composite film thereof is exposed. Instead of the silicon nitride film, KOH is formed on the back surface of the single crystal silicon substrate 101 after the step shown in FIG.
A resin such as a solution that serves as an etchant mask may be applied, and only a portion corresponding to the pixel region 104 may be patterned and removed by using a double-sided aligner or the like.
Single crystal silicon substrate 1 during the IC process in (a)
01 It is not necessary to form a silicon nitride film on the back surface.

The light valve semiconductor device of the present invention is thus completed. When the liquid crystal cell assembling step is further added, the light valve device shown in FIG. 1 can be formed. Further, for the purpose of facilitating the liquid crystal cell assembling step, after the step of FIG. 2C, the remaining single crystal silicon substrate may be thinned to the extent that the characteristics of the drive circuit are not impaired by back lap (polishing) or the like. .

FIG. 3 is an enlarged schematic sectional view of the vicinity of a connection terminal portion with the outside of the light valve semiconductor device of the present invention shown in FIG. The concave portion of the support substrate 106 is aligned on the connection terminal 301 made of aluminum or the like, and the void 401 is formed on the connection terminal 301. The other portion of the single crystal silicon substrate 101 is bonded to the supporting substrate 106 via the adhesive layer 105.

According to the embodiment shown in FIG. 3, when the wafer is cut into chips, the support substrate 106 is connected to the connection terminals 301.
It is possible to repel the support substrate 106 on the connection terminal 301 by half-cutting so as not to reach the above. This makes it easy to electrically connect the semiconductor device for a light valve of the present invention to the outside. Further, in the manufacturing process shown in FIG. 2C, when the KOH solution or the hydrazine solution is used as an etchant and the single crystal silicon substrate 101 under the pixel region 104 is removed by etching, the surface side of the single crystal silicon substrate 101 is removed. The connection terminal 301 is the support substrate 1
Since it can be completely covered with 06, damage on the surface side due to the etching process can be completely prevented.

[0018]

As described above, according to the present invention, since the drive circuit is formed on the high quality single crystal silicon substrate used for a normal IC, high speed operation is possible. Further, since the driving circuit and the pixel region are wired to each other during the IC process, they can be connected at a pitch of several μm, and conventionally, in order to externally connect the light valve device and a separately manufactured driving IC. Compared with the need for a pitch of 100 μm or more, it is possible to make the structure extremely fine, and since there is no connecting portion, the reliability is also improved. As described above, compared with the conventional active matrix type light valve device using polysilicon or amorphous silicon as a switch transistor and the simple matrix type light valve device without a switch element, a small optical device with a built-in drive circuit that can operate at high speed is provided. A light valve semiconductor device capable of forming a valve device can be obtained.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view in order of the steps of a method for manufacturing a semiconductor device for a light valve according to the present invention.

FIG. 3 is a schematic cross-sectional view of the vicinity of a connection terminal portion with the outside of the light valve semiconductor device of the present invention.

[Explanation of symbols]

 101 Single Crystal Silicon Substrate 102 Etching Stop Layer 103 Driving Circuit 104 Pixel Region 105 Adhesive Layer 106 Supporting Substrate 107 Silicon Nitride Film 108 Protective Insulating Film 201 Alignment Film 202 Seal 203 Liquid Crystal Layer 204 Counter Electrode 205 Counter Substrate 301 Connection Terminal 401 Void

Claims (7)

[Claims] 1. In a light valve semiconductor device in which a pixel region formed on a single crystal silicon substrate and a drive circuit are built in the same chip, the single crystal silicon substrate under the pixel region is removed to allow light transmission. A semiconductor device for a light valve, characterized in that 2. The semiconductor device for a light valve according to claim 1, wherein the pixel region is an active matrix type having a switch transistor for each pixel. 3. The light valve semiconductor device according to claim 1, wherein the pixel region is of a simple matrix type having no switch element. 4. The etching stop layer is made of any one of a silicon oxide film, a silicon nitride film, and a composite film of a silicon oxide film and a silicon nitride film. Light valve semiconductor device. 5. A connection terminal portion for electrically connecting to the outside is formed on the single crystal silicon substrate close to the drive circuit, and a support substrate is bonded on the single crystal silicon substrate. 2. The semiconductor device for a light valve according to claim 1, wherein the connection terminal portion on the single crystal silicon substrate is not bonded to the supporting substrate. 6. A step of forming a drive circuit and a pixel region on a single crystal silicon substrate on which an etching stop layer is formed, a step of adhering a transparent support substrate on the drive circuit and the pixel region, and the pixel region. And a step of etching away the single crystal silicon substrate below the substrate, leaving the etching stop layer. 7. The light valve according to claim 6, wherein the etching stop layer is made of any one of a silicon oxide film, a silicon nitride film, and a composite film of a silicon oxide film and a silicon nitride film. Of manufacturing semiconductor device for automobile.