JPH04299317A - Semiconductor device for light valve and production thereof - Google Patents

Abstract

PURPOSE:To provide the semiconductor device for a light valve of a small size and high speed. CONSTITUTION:A picture element region 108 having switching transistors 104 consisting of polysilicon or amorphous silicon on a field oxide film 102 and a driving circuit element 103 on a single crystal silicon substrate 101 are formed on the same substrate and the single crystal silicon substrate 101 on the rear surface of the picture element region 108 is removed. A transparent material 109 is packed as reinforcement.

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, particularly a semiconductor device for an active matrix type light valve device, and a method for manufacturing the same.

0002

2. Description of the Related Art Conventionally, light valve devices using polysilicon or amorphous silicon as switch transistors have been known.

0003

[Problems to be Solved by the Invention] However, the above-mentioned light valve device does not have a built-in drive circuit, and needs to be externally connected to a separately manufactured drive IC. This increases the mounting cost for the system, and the pads must be formed at a pitch of 100 .mu.m or more, making it impossible to miniaturize the device.

[0004]Also, a light valve device with a built-in drive circuit made partially of polysilicon is known, but since the drive circuit is also made of polysilicon, there is a problem that a high-speed circuit cannot be formed. Ta. SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor device for a light valve and a method for manufacturing the same, which can solve the above-mentioned problems and form a small-sized light valve device incorporating a drive circuit capable of high-speed operation.

[0005]

[Means for Solving the Problems] The main means adopted by the semiconductor device of the present invention to achieve the above object is to form the switch transistor of the pixel using polysilicon or amorphous silicon, and to use single crystal silicon on the same substrate. It is characterized by forming a drive circuit consisting of:

The manufacturing method is characterized in that a pixel region and a drive circuit region are formed on a single-crystal silicon substrate, and the single-crystal silicon substrate below the pixel region is removed to enable light transmission.

[0007]

[Operation] As described above, the present invention provides a semiconductor device for a light valve that can form a light valve device that is smaller and faster than a conventional light valve device using polysilicon or amorphous silicon. be able to.

[0008]

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 cross-sectional view showing an embodiment of the semiconductor device of the present invention. A drive circuit element 103 is formed on a single crystal silicon substrate 101, and a switch transistor 104 is formed on a field oxide film 102 in a pixel region 108. Although not shown, the drive circuit element 103 and the switch transistor 104 are connected to each other by a wiring 105. Furthermore, the single crystal silicon substrate 101 on the lower surface of the pixel region 108 is removed and filled with a transparent material 109 for reinforcement.

According to the embodiment of FIG. 1, the drive circuit element 10
3 is formed on single crystal silicon and is capable of high-speed operation. Furthermore, since the switch transistor 104 and the drive circuit element 103 are wired to each other during the IC process, it is possible to connect them at a pitch of several μm. Compared to the fact that a certain pitch is required, significant miniaturization is possible, and since there are no connecting parts, reliability is also improved.

FIGS. 2(a) to 2(c) are cross-sectional views showing the method of manufacturing the semiconductor device for a light valve according to the embodiment of FIG. 1 in the order of steps. As shown in FIG. 2A, a drive circuit element 103 and a switch transistor 104 are formed on a single crystal silicon substrate 101 using a normal IC process. Specifically, after forming the field oxide film 102, polysilicon or amorphous silicon is deposited, patterned and left only in the pixel region 108 to form the switch transistor 104, and then an IC is formed according to the drive circuit element 103.
Through the process, a MOS transistor having a gate electrode and a pair of source/drain regions is formed. Also, I
During the C process, the single crystal silicon substrate 101 is removed at an appropriate step.
A silicon nitride film 107 is formed on the back surface of the substrate, patterned using a double-sided aligner, etc., and a portion corresponding to the pixel region 108 is removed by etching.

Next, as shown in FIG. 2B, the single crystal silicon substrate 101 is etched away using a KOH solution using the silicon nitride film 107 as a mask. The progress of this etching stops when the field oxide film 102 is exposed. In addition to KOH, a hydrazine solution may be used as the etchant. If the pixel region 108 becomes thinner due to etching and its strength cannot be maintained, it is preferable to fix a supporting substrate on the protective film 106 in advance using an adhesive or the like.

Next, as shown in FIG. 2(c), the pixel area 1
A transparent material 109 is filled into the concave portion of the lower surface of 08. The transparent material 109 is made of, for example, resin or inorganic SiO2 as its main material, and is applied by a spin-on method or a potting method. After coating, it is completely cured by heat treatment or ultraviolet treatment. Through the above steps, the semiconductor device for a light valve shown in FIG. 1 is completed.

[0013]

Effects of the Invention As described above, according to the present invention, a light valve device can be formed which is smaller and can operate at higher speed than light valve devices using conventional amorphous silicon or polysilicon. A semiconductor device can be manufactured at low cost.

[Brief explanation of drawings]

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

FIG. 2 is a schematic partial cross-sectional view showing the manufacturing method of the present invention.

[Explanation of symbols]

101 Single crystal silicon substrate 102 Field oxide film 103 Drive circuit element 104 Switch transistor 105 Wiring 106 Protective film 107 Silicon nitride film 108 pixel area 109 Transparent material

Claims (3)

[Claims] 1. A semiconductor device for a light valve, characterized in that a driving circuit is built into the same chip, a switch transistor of a pixel is made of polysilicon, and the driving circuit is formed of single crystal silicon. 2. The semiconductor device for a light valve according to claim 1, wherein the switch transistor of the pixel is made of amorphous silicon. 3. A step of selectively oxidizing a silicon single crystal substrate to provide a pixel region, a step of forming a drive circuit by an IC process, and simultaneously forming a pixel switch transistor and a pixel electrode, and a step of forming a pixel region on the lower surface of the pixel region. A method for manufacturing a semiconductor device for a light valve, comprising the steps of: removing a silicon single crystal substrate; and filling a reinforcing transparent material into the lower surface of an exposed pixel region.