JPH02199822A - High-frequency cvd - Google Patents

Abstract

PURPOSE:To deposit a good-quality film by a method wherein a semiconductor layer is formed on an insulating substrate, the substrate is placed in a thermoreactive gas and is heated at a heat-resisting temperature or lower of the insulating substrate, high-frequency radio waves are radiated additionally, the semiconductor layer is heated selectively and a deposition film is generated. CONSTITUTION:An insulating substrate 1 on which a semiconductor layer 2 has been deposited is heated at a heat-resisting temperature or lower of the insulating substrate by using a heating part 3 in order to obtain a state that sufficient carriers exist in the semiconductor layer 2. In this state, a thermoreactive gas 5 is introduced and high-frequency radio waves 4 are radiated. Since a large difference in an absorption coefficient of the high-frequency radio waves exists between the insulating substrate 1 and the semiconductor layer 2, the radio waves are absorbed mostly into the semiconductor layer 2 and only the semiconductor layer 2 is heated selectively. As a result, the thermoreactive gas coming into contact with the semiconductor layer 2 is pyrolyzed only on the surface of the semiconductor layer 2; it is possible to deposit a generation film only there. Thereby, the film generated selectively by a pyrolytic operation can be deposited on the semiconductor layer on a low-heat-resisting insulating substrate without damaging the layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for chemical vapor deposition of various films used in manufacturing thin film transistors, etc.
Vapor Deposition).

[Conventional technology]

When manufacturing thin film transistors and the like, a step of depositing and processing 5i02, a silicon layer, etc. is essential. In that case, CVD method is often used. The conventional CVD method involves thermally decomposing the reaction gas, which is the raw material for the produced film, in an electric furnace (
Thermal decomposition CVD method), high-frequency power is applied to a reaction gas at low pressure to generate plasma to cause a reaction and produce a film on the substrate (plasma CVD method).

However, in order to deposit a high-quality product film by the pyrolytic CVD method, it is necessary to heat the entire substrate to a high temperature of about 1000 degrees.

For this reason, it is necessary to use a substrate such as glass with low heat resistance.
It is not possible to deposit a high-quality film on a substrate such as I (5ilicon on in5ulator). Plasma CVD allows a high-quality film to be deposited at a relatively low temperature, but since the substrate is exposed to plasma, the surface is receive damage.

[Problem to be solved by the invention]

The present invention solves the problems of the conventional CVD method described above, and makes it possible to selectively deposit a film produced by thermal decomposition on a semiconductor layer of a low heat-resistant insulating substrate without causing damage. The objective is to provide a high-frequency CVD method.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a semiconductor layer on an insulating substrate, places the substrate in a thermally reactive gas, and heats it to a temperature below the heat resistance temperature of the insulating substrate. By selectively heating the semiconductor layer by irradiating high-frequency radio waves, the thermally reactive gas is selectively subjected to a thermochemical reaction on the surface of the semiconductor layer, thereby producing a deposited film.

[Effect]

FIG. 1 is a schematic diagram explaining the principle of the main components of the present invention, in which 1 is an insulating substrate, 2 is a semiconductor layer, 3 is a heating section, and 4 is a schematic diagram explaining the principle of the main components of the present invention.
is a high frequency radio wave, and 5 is a thermally reactive gas. Take advantage of the properties that First, the insulating substrate 1 on which the semiconductor layer 2 has been deposited is heated by the heating unit 3 to a temperature below the allowable temperature limit of the insulating substrate, and by utilizing the property that the carrier concentration of the semiconductor increases exponentially with temperature, A state is created in which sufficient carriers exist in the semiconductor layer 2.

In this case, if a sufficient amount of carriers exist in the semiconductor layer at room temperature, heating is not even necessary. In this state, the thermally reactive gas 5 is introduced and the high frequency radio waves 4 are irradiated. . Since there is a large difference in the absorption coefficient of high-frequency radio waves between the insulating substrate 1 and the semiconductor layer 2, most of the radio waves are absorbed in the semiconductor NA3, and only the semiconductor layer 2 is selectively heated. Since the carrier concentration of a semiconductor increases exponentially with temperature, positive feedback occurs, which further increases the radio wave absorption coefficient and heats the semiconductor. As a result, the thermally reactive gas in contact with the semiconductor 12 is thermally decomposed only on the surface of the semiconductor layer 2, so that the produced film can be deposited only there.

The configuration of the present invention has some similarities to a plasma CVD method using a high frequency power source. However, plasma C
The VD method is capable of causing a reaction only in a low-pressure gas plasma, whereas the CVD method according to the present invention differs greatly in that there is no restriction on the pressure of the thermally reactive gas. Therefore, it is possible to deposit a high quality film without being damaged by plasma.

〔Example〕

FIG. 2 is a sectional view showing a specific embodiment of the present invention.
A heating section 3 is installed on the outside of the reaction vessel 11 made of quartz glass or the like.
, and a high frequency coil 9 is provided, and the high frequency coil 9
A reaction vessel 11 to which a high frequency power source 1o is connected is provided with a gas inlet 12 and a gas outlet 13. Further, a base body on which a CVD 5i02 layer 7 and a silicon layer 8 are deposited is placed on a low heat-resistant glass substrate 6. By the heating section 3,
The substrate is heated to the allowable temperature limit of the low heat resistant glass substrate 6.

In this state, the thermally reactive gas 5 is introduced into the reaction vessel 11,
Furthermore, a high frequency radio wave is generated inside the high frequency coil 9 by the high frequency power source 1o, and the substrate is scanned so that the entire silicon layer on the substrate is heated and a generated film is deposited on the entire surface.

FIG. 3 is a sectional view showing another example I11gIII of the present invention. Empty j1M with impedance matching device 15
A reaction vessel 11 made of quartz glass or the like is provided within the resonator 14 . The reaction vessel 11 is provided with a gas inlet 12 and a gas outlet 13. Furthermore, a waveguide 16 and a high frequency power source 10
A heating unit 3 that can be scanned inside the reaction vessel 11 is installed with the substrate described in FIG. 2 placed thereon. CVD5i on low heat resistant glass substrate 5
A substrate on which an O□ layer 7 and a silicon layer 8 are deposited is placed on the heating section 3. Thereafter, the heating unit 3 heats the substrate up to the allowable temperature limit of the low heat-resistant glass substrate 6, as in the above-described embodiment. In this state, the thermally reactive gas 5 is introduced into the reaction vessel 11, and then the high frequency power source 10 is used to generate the cavity resonator 14.
A high-frequency radio wave is generated inside the substrate, and the substrate is scanned so that the entire silicon layer on the substrate is heated and a generated film is deposited on the entire surface.

〔Effect of the invention〕

According to the present invention, S OI (5ilicon On In5
Since a high-quality CVD film can be deposited on the substrate (U-lat, or), it becomes possible to manufacture high-performance, large-area SO2 devices at low cost.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram explaining the invention in detail, Figures 2 and 3 are
The figure is a sectional view showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Insulating substrate, 2... Semiconductor layer, 3... Heating part, 4... High frequency radio wave, 5... Heat-reactive gas, 6...
・・Low heat resistant glass substrate, 7...CVD S i0
2 film, 8... silicon layer, 9... high frequency coil, 1
0... High frequency power supply, 11... Reaction container, 12...
Gas inlet, 13... Gas outlet, 14... Cavity resonator, 15... Impedance matching device, 16... Waveguide.

Claims (1)

[Claims] A semiconductor layer is provided on an insulating substrate, the substrate is placed in a thermally reactive gas, heated to a temperature below the heat resistance temperature of the insulating substrate, and then high-frequency radio waves are irradiated to remove the semiconductor layer. A high frequency CVD method characterized by selectively heating the thermally reactive gas to selectively cause a thermochemical reaction on the surface of the semiconductor layer to generate a deposited film.