JPH0445521A - Formation of semiconductor film - Google Patents

Abstract

PURPOSE:To eliminate such a problem as pollution, etc., by forming a semiconductor film while the inside of a vacuum holding container is maintained in a gaseous atmosphere containing at least one or more reactive gases for doping. CONSTITUTION:After a substrate 5 on which a semiconductor film is to be stuck is mounted on a substrate holder 4 in a vacuum holding container 1, the container 1 is evacuated to a vacuum. A mixed gas of Ar and He or H2 gas to be used for thermally spraying a jet-like plasma from a thermal spraying gas leading-in port upon the surface of the substrate 5 is led by l-10 SLM as the thermally spraying gas and, at the same time, a reactive gas for doping is led from a gas leading-in port 10. After confirming that the pressure inside the container 1 is stabilized, the plasma is generated from the thermally spraying gas 2 by means of a plasma generating power source 3 and the raw material for the semiconductor film is led from a raw material leading-in port 7.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for forming a semiconductor film using a low pressure plasma spraying apparatus.

(b) Prior art In recent years, semiconductor thin films have been formed by decomposing or melting metals, metal compounds, and even semiconductor materials using plasma energy, and jetting the decomposed or melted products onto the surface to be processed. A low pressure plasma spray method has been developed.

Conventionally, in thin film formation by low pressure plasma spraying, an inert gas is used as a plasma generating gas, and the various materials mentioned above are decomposed and melted by the energy of the plasma. The inert gas is used to stably generate plasma discharge.

Recently, the low pressure plasma spraying method has been developed to
1id Films, 119 (1984) p, 67-7
3, Applied Physics Letter
s 53 (1988) p, 1011-1013, it is also used for forming semiconductor thin films, superconducting thin films, etc.

Furthermore, decomposition or melting in the plasma spraying apparatus used in the present invention refers to the decomposition or melting of a raw material solid into molecules or atoms or into a liquid phase by the active species of the gas that contributes to plasma generation and the heat of the plasma. means to melt.

(c) Problems to be Solved by the Invention An important technique for forming a semiconductor thin film by such a low pressure plasma spraying method is a method for controlling valence electrons of the semiconductor thin film. The currently practiced method is US Pat.
As disclosed in No. 3770, valence electrons are controlled in the semiconductor thin film by melting or decomposing a solid containing valence electron controlling impurities together with a semiconductor material.

For this reason, boron (B) is generally used as an n-type impurity.
Group 1II elements of the periodic law, represented by: Elements of group V of the periodic law are used as the n-type impurity.

However, there are several ways to use such a solid as an impurity doping source. Firstly, the impurity doping source melts and decomposes together with the semiconductor material, making it difficult to dope uniformly.Secondly, the impurity doping source is purified to prevent contamination from the impurity doping source itself. In addition, the third
Moreover, it is necessary to handle harmful boron and phosphorus as the impurity doping source, and the cost required for safety-related equipment becomes enormous.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a method for forming a semiconductor film in which doping can be easily controlled and uniform doping can be performed over a large area.

(d) Means for Solving the Problems The semiconductor film forming method of the present invention is characterized by a vacuum holding container, a substrate placed in the vacuum holding container, and a surface of the substrate placed in the vacuum holding container. A plasma spraying apparatus comprising a thermal spraying gun disposed at opposing positions and coupled to a plasma generation power source, the thermal spraying gun decomposing or melting a solid raw material by plasma generation and spraying the solid raw material in a jet form. In the semiconductor film forming method of forming a semiconductor film on the substrate, the semiconductor film is formed by forming a gas atmosphere in the vacuum holding container containing at least one doping reaction gas.

(e) Function: In one method of forming a semiconductor film according to the present invention, a semiconductor material is first decomposed and melted by plasma energy in an atmosphere containing at least one desired doping reaction gas. Next, the decomposed and melted semiconductor material is injected toward the surface of the substrate. These decomposed and melted products are
By their own thermal energy, the doping gases are decomposed and reacted before being deposited on the substrate. Due to this reaction in the gas phase, the semiconductor to be formed is uniformly doped.

(f) The embodiment diagram shows a structural diagram of a reduced pressure plasma spraying apparatus for explaining the semiconductor film forming method according to the present invention.

In the figure, (1) is a vacuum holding container, (2) is a thermal spray gun that generates plasma, and is composed of two electrodes (2a) and (2b). (4) is placed in the vacuum holding container (1), a substrate holder is placed opposite the thermal spray gun (2), and (5) is placed on the substrate holder (4). The heated substrate (6) is a thermal spray gun (2) for spraying the material decomposed and melted by plasma toward the substrate (5).
) is a thermal spray gas inlet, and (7) is a thermal spray gun ( ) for introducing raw materials for semiconductors to form a thin film.
2) is the raw material inlet, and (8) is the thermal spray gun (
This is a reservoir of raw materials such as Si, SiC, SiN, Ge, and C powder, which is connected to the raw material inlet provided in 2) by piping. Furthermore, (9) is an exhaust port for evacuating the inside of the vacuum holding container, (10) is a gas inlet port for introducing plasma generation gas and doping reaction gas, and (11) is a gas inlet port for introducing plasma generation gas and doping reaction gas.
) is a plasma jet of decomposed and molten material.

However, piping from the outside to the thermal spray gas inlet (6) is not shown.

These mechanisms are, for example, Applied Physics
Letters 53 (1988) p, 10]1
-1013 is a known method.

The method for forming p-type polycrystalline silicon according to the present invention will be described in detail below using the illustrated diagram of a reduced pressure plasma spraying apparatus.

First, a substrate (5) to be coated with a semiconductor film is placed in a vacuum holding container (1) on a substrate holder (4), and the vacuum holding container is evacuated until the degree of vacuum becomes 10-'' torr or less. During this time, the substrate (5) is evacuated via the substrate holder (4).
is heated and maintained at 500°C.

Next, Ar (
Mixed gas of argon) and He (helium), or H
! 1 to 1105 L of (hydrogen) gas is introduced as a thermal spraying gas, and at the same time, a doping reaction gas, which is a feature of the forming method according to the present invention, is introduced from the gas inlet 00). In this example, in order to form a p-type polycrystalline dinocon, B2H2 (diborane) gas diluted to IOZ with hydrogen gas, or TMA (trimethylaluminum) or TMG ()limethylgallium diluted to 10z with nitrogen gas. ) Furthermore, TMI ()trimethylindium) or the like was used, and a gas flow rate of 0.5 to 5 SLM was introduced. After confirming that the gas pressure in the vacuum holding container (1) has stabilized, plasma is generated in the thermal spray gun (2) using 1-50KW of power from the plasma generation power source (3), and then Insert the raw materials into the raw material inlet (
7) was introduced. In this example, the raw material was 110
Si powder with a particle size distribution of -44p was used. Further, the degree of vacuum during the reaction was 5 torr, and the electric power was 30 KW.

The amount of doping of the formed semiconductor can be controlled by adjusting the flow rate of the doping reaction gas and the degree of vacuum during the reaction.

Such control of the doping amount has extremely poor reproducibility using conventional techniques that use solid doping materials.

Typical physical properties of the p-type polycrystalline silicon obtained in this example are that the carrier mobility is lXl0''-IXIO'ac
m″3 hole mobility was 20 to 30 cm″/Vs, indicating that doping was performed satisfactorily.

Next, the formation of an n-type polycrystalline silicon film by the formation method of the present invention will be described. The formation process is the same as that of p-type polycrystalline silicon film, but the doping reaction gas is PH diluted with hydrogen to 10χ, or 100% of N, NH, etc.
χ gas, and furthermore, AsH gas diluted with nitrogen to 10χ, etc., were used. The gas flow rate is 0.1-0°5 SLM.

Typical physical properties of n-type polycrystalline silicon according to this example are as follows:
The carrier density is lXl0"-IXIO"cm-" and the hole mobility is 30-40 cm"/V-s, which is good.
there were.

Although the embodiments have been described using silicon, according to the formation method of the present invention, p-type, p-type SiC, SiN, Ge,
It is also possible to form a semiconductor film using C, and the inventors have experimentally demonstrated that doping can be easily performed in the formation of microcrystalline semiconductors and amorphous semiconductors using the semiconductor film forming method of the present invention. This has been confirmed by

(G) Effects of the Invention According to the present invention, by including a doping reaction gas in the atmosphere for forming the semiconductor film, it is possible to perform heto-doping in the film at the same time as the formation of the semiconductor film, and because it is a gas phase reaction. Uniform doping is possible. This is effective because the low-pressure plasma spraying method used in the present invention is characterized by forming a large-area semiconductor.

Further, according to the present invention, since gas is used as the impurity doping source, doping can be easily controlled, and there are no problems such as occurrence of contamination when using a solid doping material, making it ideal for manufacturing semiconductor devices.

[Brief explanation of the drawing]

The drawing is a diagram of a reduced pressure plasma spraying apparatus for explaining the forming method according to the present invention. (1) Vacuum holding container (3) Power source for plasma generation (5) Substrate (7) Raw material inlet (9) Exhaust port (2) Thermal spray gun (4) Substrate holder (6) Injection gas inlet (8) Reservoir 00) Gas inlet

Claims (1)

[Claims] (1) Consisting of a vacuum holding container, a substrate placed in the vacuum holding container, and a thermal spray gun placed in the vacuum holding container at a position facing the surface of the substrate and coupled to a plasma generation power source. The plasma spraying apparatus is a semiconductor film forming method in which a solid raw material is decomposed or melted by plasma generation in the thermal spraying gun and sprayed in a jet form to form a semiconductor film on the substrate. A method for forming a semiconductor film, characterized in that the semiconductor film is formed in a gas atmosphere containing at least one reaction gas for doping.