JPH0517294A - Production of substrate for monolithic liquid crystal display element - Google Patents

Abstract

PURPOSE:To suppress the generation of unequal thicknesses in the Si single crystal substrate constituting a substrate for a monolithic liquid crystal display element by etching this substrate. CONSTITUTION:While the Si single crystal substrate 3 stuck to a quartz substrate 2 or glass substrate are subjected to etching dividedly in plural zones, the thicknesses of the respective zones are detected by optical means consisting of a light emitting section 6 and a light receiving section 7 and the etching rates of the respective zones to be executed by parallel flat plate electrodes 5 are controlled in accordance with the results of the detection. The etching rate to the thick zones are, therefore, increased and the etching rates to the thin zones are decreased, by which the Si single crystal substrate 3 is eventually etched at nearly the uniform thickness distribution.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a color liquid crystal display device has a polysilicon film or amorphous S on a quartz or glass substrate.
A substrate on which an i film is deposited is used, and a pixel portion and a driving circuit portion are formed on the substrate to produce a monolithic type.

However, in recent years, development of a color liquid crystal display device for high-definition has been advanced, and therefore, instead of the above polysilicon film or amorphous Si film,
Substrates in which a Si single crystal substrate is bonded to a quartz or glass substrate are being adopted. This is because the mobility of the channel portion of the transistor is 50 cm ² V ^-1 sec ^-1 and 1 cm ² V ^-1 se for the polysilicon film and the amorphous Si film, respectively.
This is because it is as low as about c ⁻¹ , but the mobility is extremely large in a Si single crystal.

[0004]

However, in the case of a substrate obtained by directly bonding Si single crystal substrates, the S
The thickness of the i single crystal substrate is large, for example, a substrate having a diameter of 4 inches has a thickness of about 30 to 40% for a thickness of 1 μm.
This is a major obstacle in manufacturing a display element. Therefore, a Si single crystal substrate having a thickness of 500 to 600 μm is bonded to a quartz substrate or the like, and then mechanically polished or chemically polished to, for example, 1 μm. However, the thickness unevenness cannot be reduced to 5% or less by this method. Therefore, it was not possible to support the realization of high-definition display devices.

The present invention has been made to solve the above-mentioned problems of the prior art, and suppresses the occurrence of thickness unevenness by devising etching of a Si single crystal substrate.
An object of the present invention is to provide a method for manufacturing a substrate for a monolithic liquid crystal display device, which can enhance the feasibility of a monolithic liquid crystal display device for high definition.

[0006]

The present invention is a method for producing a substrate for a monolithic liquid crystal display device by etching a Si single crystal substrate bonded to a quartz or glass substrate. On the other hand, while performing the etching divided into a plurality of zones, the thickness of each zone is detected by an optical means, and the etching amount of each zone is controlled based on the detection result. Therefore, the above object can be achieved. .

[0007]

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

[0008]

EXAMPLE An example of the present invention will be described below.

FIG. 1 is a schematic diagram showing a dry etcher used in this embodiment. This dry etcher is provided on a stage 4 for holding the substrate 1 to be etched, a parallel plate electrode 5 for reactive ion etching which is arranged in parallel and opposite to the substrate 1, and both sides of the parallel plate electrode 5. For example, an optical interferometer including a light emitting section 6 for generating a laser beam and its light receiving section 7 and a signal detected by the light receiving section 7 are input, and output control of the parallel plate electrode 5 is performed based on the input signal. A CPU 8 and an AC power supply 9 for applying a voltage between the stage 4 and the parallel plate electrode 5 are provided. In the present embodiment, the stage 4 is provided with a quartz substrate 2 and an S
The i-single crystal substrate 3 bonded together is set.

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

The light emitting section 6 is provided so that its light irradiation direction is directed to the upper surface of the substrate 1 held by the stage 4, and the entire upper surface of the substrate 1 is irradiated. The light receiving section 7 includes a large number of light receiving elements arranged vertically and horizontally, and the detection field of view of each element is directed to the upper surface of the substrate 1. The detection visual field of each element has a one-to-one correspondence with the etching zone of the substrate 1 that is individually etched by the divided electrodes 5a.

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

Etching with such a 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 side of the Si single crystal substrate 3 to be etched facing the parallel plate electrode 5. The quartz substrate 2 has, for example, a thickness of about 500 μm,
The diameter is 6 inches, and one Si single crystal substrate 3 has the same thickness and diameter. The Si single crystal substrate 3 may be thinner.

Then, the AC power supply 9 is turned on, and the light emitting section 6, the light receiving section 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 set so that a part of the laser light reaches the upper surface of the quartz substrate 2 below the substrate 1.

As a result, the Si single crystal substrate 3 is etched by the divided electrodes 5a in each etching zone.
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 unit 7, and the voltage applied to the divided electrode 5a by the CPU 8 as described above based on this detection signal. To control. For example, based on the light intensity detected by the light receiving element b of the light receiving unit 7 that detects the portion of the substrate 1 that is etched at the second B from the left of the divided electrode 5a, the second from the left of the divided electrode 5a is detected. To the B of the divided electrode 5a of the B
To control the etching rate of the etching zone corresponding to. Similar control is performed on each of the divided electrodes 5a indicated by A to H based on the signal detected by the corresponding light receiving element indicated by ah.

Therefore, in this embodiment, the quartz substrate 2 is used.
The Si single crystal substrate 3 bonded to the substrate can be etched with a uniform thickness distribution, and when finally etched to a desired thickness, for example, 1 μm, thickness unevenness can be suppressed to 5% or less. It has become possible.

In the above embodiments, the substrate in which the Si single crystal substrate is bonded to the quartz substrate has been described as an example, but the present invention is not limited to this, and the substrate in which the Si single crystal substrate is bonded to the glass substrate is used. Of course, it can be applied to.

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

[0019]

As described above in detail, in the case of the present invention, the thickness unevenness can be suppressed to 5% or less.
In place of the polysilicon and amorphous silicon that have been used up to that point, the feasibility of future monolithic liquid crystal display devices for high-definition television will be realized by incorporating the liquid crystal display element pixel unit and the drive circuit into single crystal Si. Can be increased.

[Brief description of drawings]

FIG. 1 is a schematic view showing a state where 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]

1 substrate 2 Quartz substrate 3 Si single crystal substrate 5 parallel plate electrodes 5a split electrode 6 light emitting part 7 Light receiving part 8 CPU 9 AC power supply

Claims (2)

[Claims] 1. Si bonded to a quartz or glass substrate
A method of manufacturing a substrate for a monolithic liquid crystal display element by etching a single crystal substrate, which comprises dividing the Si single crystal substrate into a plurality of zones and performing etching while using the thickness of each zone as an optical means. And a method for manufacturing a substrate for a monolithic liquid crystal display element, which controls the etching amount of each zone based on the detection result. 2. The optical means comprises a light emitting portion which emits light toward the Si single crystal substrate and a light receiving portion which catches reflected light from the Si single crystal substrate, and the light receiving portion is etched S
The light-receiving element is provided in the number corresponding to each zone on the i single crystal substrate, and the means for performing the etching is provided with the number of dry etching electrodes corresponding to each zone, and the etching electrode is provided in the light-receiving element. The method for manufacturing a substrate for a monolithic liquid crystal display element according to claim 1, wherein the method is controlled in accordance with the intensity of the light captured by.