JPS6323826B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plasma chemical vapor deposition apparatus for performing chemical vapor phase growth on the substrate by concentrating plasma between an electrode on which a substrate is placed and an electrode opposite thereto.

In a conventional device of this kind, as shown in FIG. 1, plasma generation electrodes 2 and 3 are arranged vertically facing each other in a reaction chamber 1, and the upper electrode 2 is exposed in the chamber 1. Further, a heater 4 is arranged below the lower electrode.
The lower electrode 3 is grounded together with the reaction chamber 1, and a high frequency power source 5 is connected between the grounded lower electrode 3 and the upper electrode 2. The substrate 6 to be subjected to chemical vapor deposition is placed on the lower electrode 3 and left in a reactive gas introduced into the chamber 1 from the inlet 7 to generate plasma, which removes film forming components in the gas. Chemical vapor phase growth is performed on the substrate 6. Note that 8 is an exhaust port that communicates with an exhaust pump (not shown).

Due to the structure of such a device, the plasma formed between the upper electrode and the lower electrode, which serve as cathodes, has a tendency to spread toward the wall of the chamber 1. For this reason,
The deposition rate of a film grown on a substrate is slow. Additionally, due to the spreading plasma, particles that have once attached to the chamber wall may separate from the chamber wall and fall onto the film that is growing on the substrate, and these particles may cause pinholes in the growing film. As a result, the quality of the grown film deteriorates.

The present invention was devised in view of the above-mentioned drawbacks of the conventional apparatus, and its purpose is to accelerate the film formation rate and improve the film quality by concentrating plasma near the substrate on which the film is grown. An object of the present invention is to provide a plasma chemical vapor deposition apparatus.

Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 2 shows the device of the invention. 10 is a reaction chamber. Inside this reaction chamber 10, first and second plasma generation electrodes 11 and 12 are placed facing each other and separated from each other. These electrodes are, for example, flat plate electrodes, and are provided in the chamber 10 one above the other. The upper electrode 11 is suspended and exposed within the chamber 10 by a shaft 13 which is a suspended body electrically insulated from the chamber 10 and is also a conductor. The lower electrode 12 is supported within the chamber 10 by a support (not shown), and the chambers are both connected to a reference potential, such as ground potential. Between the lower electrode 12 and the shaft 13, both electrodes 1
A high-frequency power source 14 for supplying a high-frequency voltage capable of generating plasma is connected between 1 and 12.

A heater (heating means) 15 is provided below the lower electrode 12, and a third electrode 17 for mounting a substrate is provided above it with an insulator 16 in between. A bias power supply 18 is connected between the third electrode 17 and the reference potential for supplying a voltage that is sequentially or averagely negative with respect to the reference potential. Reference numeral 19 represents a reaction gas inlet port that communicates with a reaction gas supply device (not shown), and 20 represents an exhaust port that communicates with an exhaust pump (not shown).

Next, the operation of the apparatus of the present invention configured as described above will be explained.

After placing the substrate 21 on the third electrode 17 for placing the substrate in the reaction chamber 10, a reaction gas is introduced into the reaction chamber 10 from the reaction gas inlet 19, and the upper electrode 11 and the lower electrode 12 are connected to each other. A reactive gas atmosphere is formed between the two.

A high-frequency voltage capable of generating plasma is applied from a high-frequency power source 14 between the upper electrode 11 and the lower electrode 12, which sandwich this reactive gas atmosphere therebetween, and a bias power source 18 is applied to the third electrode 17 with respect to the reference potential. voltage that is connected or average negative;
That is, a DC voltage or a negatively shifted AC voltage is supplied.

An electric field generated by these voltages causes a discharge between the two electrodes, and plasma is generated in the atmosphere. This plasma is transferred to the third electrode 1
7 is negatively biased with respect to the lower electrode 12, and the third
Since the plasma generated between the electrodes 11 and 12 is concentrated near the substrate 21 placed on the third electrode, the plasma generated in the plasma is concentrated near the substrate 21 placed on the third electrode. A film is formed on the substrate 21 by attracting the film forming components.

The film forming speed is faster than that of the conventional apparatus shown in FIG. 1 because the plasma is concentrated near the substrate by the bias voltage as described above.

In addition, due to the concentration of plasma near the substrate 21, some of the particles grown on the substrate 21, as in the conventional apparatus, once adhere to the chamber wall, and then separate from there and join the crystal growth on the substrate 21. The amount is extremely small, and the occurrence of pinholes is almost eliminated. Therefore, the quality of the grown film is further improved.

In summary, according to the present invention, the following effects can be obtained.

Plasma can be concentrated near the substrate.

Therefore, the growth rate can be improved.

In addition, the film quality is improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional plasma chemical vapor deposition apparatus, and FIG. 2 is a diagram showing a plasma chemical vapor deposition apparatus of the present invention. In the figure, 10 is a reaction chamber, 11 is a first electrode, 12 is a second electrode, 14 is a high frequency power source, and 18
is the bias power supply.

Claims (1)

[Scope of Claims] 1. First and second electrodes are installed facing each other and separated from each other in a reaction chamber, and are connected to a reference potential among these electrodes and are electrically insulated from the electrode heated by the heating means. A third electrode for placing a substrate is provided, and a high frequency voltage that can generate plasma is applied between the first electrode and the second electrode, and the third electrode is set to the reference potential. What is claimed is: 1. A plasma chemical vapor deposition apparatus characterized in that the apparatus is configured to apply a negative voltage to the plasma. 2. The plasma chemical vapor deposition apparatus according to claim 1, wherein the voltage that is negative with respect to the reference potential is a direct current. 3. The plasma chemical vapor deposition apparatus according to claim 1, wherein the voltage that is negative with respect to the reference potential is an alternating current that is shifted negatively.