JP2815249B2 - Method for manufacturing substrate for monolithic liquid crystal display element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a substrate used for a monolithic liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, a color liquid crystal display element has conventionally been formed by forming a polysilicon film or an amorphous silicon film on a quartz or glass substrate.
A substrate on which an i-film is deposited is used, and a pixel portion and a drive circuit portion are formed on the substrate to produce a monolithic type.

However, in recent years, the development of a color liquid crystal display element for high vision has been promoted, and for that purpose, instead of the above-mentioned polysilicon film and amorphous Si film,
A substrate in which a Si single crystal substrate is bonded to a quartz or glass substrate is being adopted. This is because a polysilicon film or an amorphous Si film channel portion mobility of the transistor, each ^{50cm 2 V -1 sec -1, 1cm} 2 V -1 se
Although it is as low as c ^{−1, the} mobility is remarkably large in the Si single crystal.

[0004]

However, in the case of a substrate in which a Si single crystal substrate is bonded as it is, the S
The thickness unevenness of the i-single-crystal substrate is large, for example, about 30 to 40% of the thickness of 1 μm for a 4-inch diameter substrate
This is a major obstacle in manufacturing a display element. For this reason, a single crystal silicon substrate having a thickness of 500 to 600 μm is bonded to a quartz substrate or the like and then polished to, for example, 1 μm by mechanical polishing or chemical polishing. However, this method cannot reduce thickness unevenness to 5% or less. Therefore, it has not been possible to cope with the realization of a high-vision display device.

The present invention has been made in order to solve such problems of the prior art, and it is possible to suppress the occurrence of thickness unevenness by devising etching of a Si single crystal substrate.
It is an object of the present invention to provide a method for manufacturing a substrate for a monolithic liquid crystal display element that can enhance the feasibility of a monolithic liquid crystal display element for high definition television.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a method of manufacturing a substrate for a monolithic liquid crystal display device by etching a Si single crystal substrate bonded to a quartz or glass substrate. Directs light to one light emitting part
From each zone of the Si single crystal substrate
Reflected light is detected by each light receiving element corresponding to each zone
Then, according to the output of these light receiving elements, each zone is
Each corresponding dry etching electrode as control means
Therefore, the individual control is performed, and thereby, the etching of each zone is performed.
The individual objects are controlled individually, thereby achieving the above object.

[0007]

According to the present invention, the thickness of each zone is detected by optical means while etching is performed on the Si single crystal substrate bonded to the quartz or glass substrate while being divided into a plurality of zones. The amount of etching in each zone is controlled based on the detection result. For this reason, by increasing the etching amount for the thick zone and decreasing the etching amount for the thin zone, the Si single crystal substrate is etched with a substantially uniform thickness distribution in each zone.

[0008]

An embodiment of the present invention will be described below.

FIG. 1 is a schematic diagram showing a dry etcher used in this embodiment. The dry etcher was provided on both sides of the stage 4 for holding the substrate 1 to be etched, the parallel plate electrode 5 for reactive ion etching disposed in parallel and opposed to the substrate 1, and the parallel plate electrode 5. For example, an optical interferometer including a light emitting section 6 and a light receiving section 7 for generating a laser beam, and a signal detected by the light receiving section 7 are input, and the output of the parallel plate electrode 5 is controlled based on the input signal. The apparatus includes a CPU 8 and an AC power supply 9 for applying a voltage between the stage 4 and the parallel plate electrode 5. In the present embodiment, the stage 4 has a quartz substrate 2 as the substrate 1 and an S
An i-single-crystal substrate 3 is attached.

The parallel plate electrodes 5 are provided for reactive ion etching, and a large number of divided electrodes 5a are vertically and horizontally arranged on the surface (the bottom surface in this example) on the substrate 1 side in a mesh shape. . Each of the divided electrodes 5a can be etched by using a portion of the substrate 1 thereunder as an etching zone, and the amount of etching is adjusted by adjusting the voltage applied to each of the divided electrodes 5a by the CPU 8.

The light emitting section 6 is provided so that the light irradiation direction is directed to the upper surface of the substrate 1 held on the stage 4 so as to irradiate the entire upper surface of the substrate 1. The light receiving section 7 includes a large number of light receiving elements arranged vertically and horizontally, and directs a detection visual field of each element toward the upper surface of the substrate 1. The detection visual field of each element is made to correspond one-to-one with the etching zone of the substrate 1 which is individually etched by the divided electrode 5a.

Each light receiving element adjusts the light intensity in the light emitting section 6 to a constant value, so that the light reflected from the upper surface of the Si single crystal substrate 3 on the upper side of the substrate 1 and the lower surface thereof The thickness of each etching zone of Si single crystal substrate 3 can be detected based on the interference light with the reflected light from. The detected thickness signal is given to the CPU 8. The CPU 8 detects the flatness based on the input signal, and performs feedback control of the parallel plate electrode 5. This control is performed for the divided electrodes 5 corresponding to the etching zones where the etching amount is excessive.
The applied voltage is reduced for a, and the applied voltage is increased for the divided electrode 5a corresponding to the etching zone that is too small.

The etching by the dry etcher is performed as follows. First, the substrate 1 in which the Si single crystal substrate 3 is bonded to the quartz substrate 2 is set on the stage 4 with the Si single crystal substrate 3 to be etched facing the parallel plate electrode 5. The quartz substrate 2 has a thickness of about 500 μm, for example.
The diameter is 6 inches, and one Si single crystal substrate 3 has the same thickness and diameter. Note that the Si single crystal substrate 3 may have a smaller thickness.

Next, the AC power supply 9 is turned on, the light emitting unit 6, the light receiving unit 7, and the CPU 8 are operated to start etching. At this time, the intensity of the laser light emitted from the light emitting unit 6 is determined so that a part of the laser light reaches the upper surface of the quartz substrate 2 below the substrate 1.

Thus, the Si single crystal substrate 3 is etched for each etching zone by the divided electrode 5a.
At the time of this etching, the etching amount of each etching zone of the substrate 1 is detected by each corresponding light receiving element of the light receiving section 7, and based on this detection signal, the CPU 8 applies the voltage applied to the divided electrode 5a as described above. Control. For example, based on the light intensity detected by the light receiving element b of the light receiving section 7 which detects the portion of the substrate 1 etched at the second B from the left of the split electrode 5a, the second from the left of the split electrode 5a Of the divided electrode 5a of the B
Is controlled in the etching zone corresponding to. In each of the divided electrodes 5a indicated by A to H, similar control is performed based on the signals detected by the corresponding light receiving elements indicated by a to h.

Therefore, in this embodiment, the quartz substrate 2
Can be etched with a uniform thickness distribution, and finally etched to a desired thickness, for example, 1 μm, to suppress thickness unevenness to 5% or less. It has become possible.

In the above embodiment, a substrate in which a Si single crystal substrate is bonded to a quartz substrate is described as an example. However, the present invention is not limited to this, and a substrate in which a Si single crystal substrate is bonded to a glass substrate is described. Of course, it can also be applied to

Further, in the above embodiment, the Si single crystal substrate is etched by reactive ion etching. However, the present invention is not limited to this, and other etching methods can be used.

[0019]

As described in detail above, according to the present invention, thickness unevenness can be suppressed to 5% or less.
In place of the polysilicon and amorphous silicon used up to that point, the feasibility of a future HDTV monolithic liquid crystal display device will be realized by integrating the pixel portion for the liquid crystal display device and the drive circuit into single-crystal Si. Can be enhanced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a state in which a Si single crystal substrate bonded to a quartz substrate is etched with a uniform thickness distribution according to the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Quartz substrate 3 Si single crystal substrate 5 Parallel plate electrode 5a Split electrode 6 Light emitting part 7 Light receiving part 8 CPU 9 AC power supply

Claims (1)

(57) [Claims] 1. S bonded to a quartz or glass substrate
A method for manufacturing a substrate for a monolithic liquid crystal display element by etching an i-single-crystal substrate, wherein light is emitted from one light-emitting portion toward the Si-single-crystal substrate.
And each reflection from each zone of the Si single crystal substrate
Light is detected by each light receiving element corresponding to each zone,
According to the outputs of these light receiving elements,
Control each dry etching electrode.
And individually control the etching of each zone.
A method of manufacturing a substrate for a monolithic liquid crystal display element that is individually controlled .