JPS63115327A - Formation of semiconductor thin film - Google Patents

Abstract

PURPOSE:To unnecessitate the time required for temperature rise and temperature drop in association with the heating of a substrate which is necessary for the formation of a film as well as to contrive improvement in the productivity of the title semiconductor thin film by a method wherein, after silicon has been formed by deposition without heating the substrate, a heat treatment is performed at a temperature higher than the temperature of formation of the above-mentioned silicon. CONSTITUTION:A vacuum chamber 11 is evacuated through an exhaust hole 12. Microwaves are introduced into a plasma generating chamber 15 from a microwave oscillator 14 through a waveguide 13. An electric field is applied to the plasma generating chamber 15 from an electromagnet 16. The raw gas such as SiH4 and the like is introduced from a gas introducing hole 17. The plasma having a high degree of dissociation is generated by providing the intensity of magnetic field in such a manner that the resonant condition of electronic cyclotron is satisfied. The generated plasma passes through a plasma lead-out window 18, reaches a substrate holder 19, and amorphous silicon is formed on a substrate. Even when the characteristics of the film are not satisfied immediately after its formation, excellent film characteristics can be obtained by performing a heat treatment at 200-300 deg.C, for example.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of forming a semiconductor thin film made of amorphous silicon.

BACKGROUND OF THE INVENTION Conventionally, amorphous silicon has been widely applied to solar cells, thin-film transistors, transistors, photosensitive drums, optical sensors, etc., and is expected to continue to be used in a wide variety of fields in the future. However, the amorphous silicon used for these is S
i H4: It is formed by a gas glow discharge decomposition method, and a formation temperature of about 2°C to 350°C is required.

Problems to be Solved by the Invention In conventional technology, amorphous silicon is formed at a temperature of 20°C.
Since it is necessary to raise the temperature above 300° C., it has basically been possible to form the film only on a substrate that has heat resistance of 300° C. or higher or on a thin film formed on a substrate.

In addition, the substrate to be deposited during formation is uniformly heated to 2Q○℃~350℃.
Since it is necessary to maintain the temperature at 0.degree. C., it takes a considerable amount of time to raise the temperature, and at the same time, the heating equipment in the deposition apparatus is complicated and expensive, causing high manufacturing costs.

The present invention aims to solve these problems in the prior art.

Means for Solving the Problems In order to solve the above problems, the present invention has a half-31-
- The method for forming a conductive thin film is a method for forming amorphous silicon by plasma decomposition using microwave electron cyclotron resonance absorption, in which the silicon is deposited without heating the substrate, and then heat treated at a temperature higher than the formation temperature. This is a method of doing this.

More preferably, in the formation of a semiconductor thin film, the amount of raw material gas introduced from the outside is controlled at a pressure of 6×10
-4Torr to 2x10'''Torr.

Function: Using this method, it is possible to form amorphous silicon with good film quality even at room temperature. Moreover, even if the characteristics are not satisfied immediately after film formation,
By performing the heat treatment, good film characteristics can be exhibited.

Furthermore, in the present invention, preferably μ plasma CV
When the high-density and highly excited plasma caused by D is transported to the substrate, the pressure of the vacuum device in which the plasma is generated is adjusted so that the plasma is in a certain appropriate state and contributes to deposition.

That is, the pressure is 5XIC)"'X5X10-'To
In rr, a high-quality film is formed when the decomposition products involved in deposition and the charged particles that give energy to the arrangement of atoms on the surface of the substrate or deposited film are in an appropriate ratio. If the pressure is low, the charged particles will damage the membrane, and if the pressure is high, an appropriate amount of energy will not be supplied by the charged particles, making it difficult to obtain good membrane properties.

Example Hereinafter, typical embodiments of the present invention will be shown based on the drawings.

Figure 1 shows the μ-wave ECR plasma CVD used in this example.
FIG. 2 is a schematic diagram of the device. Reference numeral 11 denotes a vacuum chamber, which is evacuated to a vacuum through an exhaust hole 12.

Microwaves are introduced from a microwave oscillator 14 into a plasma generation chamber 16 through a waveguide 13 . A magnetic field is applied to the plasma generation chamber 16 by the electromagnet 16 . Reference numeral 17 denotes a gas introduction port through which a raw material gas such as S I H4 is introduced. Plasma with a high degree of dissociation is generated by setting the strength of the magnetic field to satisfy electron cyclotron resonance conditions. The generated plasma passes through the plasma extraction window 18 and reaches the substrate holder 19.
Amorphous silicon is formed on the substrate on the holder 19.

Figure 2 shows the changes in photoelectric conductivity and thermal conductivity of an amorphous silicon thin film formed at room temperature by varying the pressure in the vacuum chamber from 6XIC)'' to 2x10-3 Torr depending on the amount of SiH4 introduced. Yes.1×10-4~5
It shows good characteristics at a pressure of X10-'Torr.

FIG. 3 shows changes in photoelectric conductivity and conductivity when amorphous silicon formed at 2×10 −3 Torr is heat-treated to 300° C. Through heat treatment, amorphous silicon has been obtained that exhibits good properties and poses no practical problems.

Figure 4 shows the rate of formation of amorphous silicon when changing the pressure. At pressure with good characteristics, the rate of formation is slow;
The higher the pressure, the faster the speed. Therefore, from an industrial point of view, the number of heat treatment steps increases, but if the pressure is high, C1X
IC)"~2x10-'Torr is useful.

6,,,-7 Effect of the invention The effects of the present invention are as follows.

First, productivity is improved because the time required for heating and cooling the substrate, which was conventionally required during formation, is not required.

Second, by selecting the pressure as described above, although a heat treatment step is added, conditions can be selected that provide a high deposition rate, and the film formation time can be shortened, allowing effective use of the apparatus.

Heat treatment does not require complicated equipment and takes only a short time, so productivity does not decrease.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the μ-wave ECR plasma CVD apparatus used in the present invention, and Figure 2 is a diagram showing the results of this example when amorphous silicon was formed by changing the amount of S I H4 introduced and changing the pressure. Diagram showing changes in optical and dark electrical conductivity of amorphous silicon, Figure 3 shows no photoconductivity 2 x 10
FIG. 4 is a diagram showing the heat treatment characteristics of optical and dark electrical conductivity of amorphous silicon prepared at a pressure of 3 Torr, and FIG. 4 is a diagram showing changes in the formation rate when the pressure is changed. 7.7 11... Vacuum chamber, 12... Exhaust hole, 13... Waveguide, 14... Microwave oscillator, 15... Plasma generation chamber, 16...
...Electromagnet, 17...Gas inlet, 18.
...Plasma drawer window, 19...Substrate holder. Name of agent: Patent attorney Toshio Nakao and one other person
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Claims (2)

[Claims] (1) In a method for forming amorphous silicon by plasma decomposition using microwaves and electron cyclotron resonance absorption, after the silicon is deposited and formed without heating the substrate, heat treatment is performed at a temperature higher than the formation temperature. Characteristic method for forming semiconductor thin films. (2) Adjust the amount of raw material gas introduced from the outside depending on the pressure of the vacuum device from 5 x 10^-^4 Torr to 2 x 10^-^3
2. The method of forming a semiconductor thin film according to claim 1, wherein the temperature is set to be maintained at Torr.