JPH03150840A - Microwave plasma film deposition equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention utilizes electron cyclotron resonance! Iku μ
The present invention relates to a wave-magnetic film forming apparatus and processing method, and particularly to a semiconductor film forming apparatus and forming method.

[Conventional technology]

A conventional microwave plasma film forming apparatus using electron cyclotron resonance, as disclosed in Japanese Patent Application Laid-open No. 155656/1983, uses microwaves sent through a waveguide to generate plasma in a plasma generation chamber with a cavity resonant structure. The microwaves are introduced into the microwave O to form a standing wave, and the magnetic field that satisfies the electron cyclotron resonance condition is matched to the maximum position of the electric field of the standing wave O, causing the plasma to absorb the microwaves, resulting in high activity. This is to obtain Plas i and use it.

[Problem to be solved by the invention]

The above-mentioned conventional technology has a drawback that a desired semiconductor film cannot be stably obtained if the semiconductor film forming process is repeated. Therefore, the reason why the reproducibility and reliability of the semiconductor film deposition system was low is that when performing the semiconductor film deposition process, the hollow resonant structure made of a metal with good conductivity is grown. A semiconductor film is formed on a part or all of the inner wall of the vacuum chamber, and the electric resistance of the inner wall increases, causing microwave loss.If the above process is repeated, the metal surface of the inner wall of the vacuum chamber may be damaged. , as it is gradually covered with a semiconductor film, the loss of microwaves changes over time, and therefore the properties of the plasma also change over time.

An object of the present invention is to form a thin film, especially a semiconductor film, on a substrate using a microwave plasma film forming apparatus, even if a thin film is formed on the inner wall of a vacuum chamber. The problem is how to obtain a microwave plasma film forming apparatus that does not affect the propagation of microwaves in the process and can form a thin film on the surface of a substrate with high reproducibility.

[Means to solve the problem]

In order to solve the above-mentioned four problems, the microwave plasma film forming apparatus according to the present invention coats the inner wall surface of the vacuum chamber with an electrical insulator film.

The adhesion between the inner wall and the electrical insulator film is not very important;
It is sufficient that the electrical insulating film does not peel off during operation of the device.Although it is not necessary to cover the entire inner wall of the vacuum chamber with the electrically insulating film, there is a possibility that a thin film may adhere to the inner wall. Places where microwaves propagate must be covered.

Furthermore, the thickness of the electrically insulating film may be such that it can prevent the thin film from directly adhering to the metal surface of the inner wall of the vacuum chamber during film formation.The electrically insulating material may include quartz, ceramic, etc. ,
Good insulation in the vacuum chamber.

It must be able to transmit microwaves and shield plasma.The vacuum chamber container may also be made of a composite material of metal and electrical insulator.

In order to prevent damage during the film forming process and to make it easier to clean the walls of the vacuum chamber, there is a method of placing a cylinder inside the vacuum chamber and using it as an inner chamber.

However, making a vacuum chamber container only with electrical insulators
Microwaves leak, which is dangerous, and cannot be used practically. [Function] If an electrical insulating film is coated on the inner wall surface of the vacuum chamber to which the semiconductor film may adhere, the semiconductor film can be directly attached to the metal. It does not adhere to the surface, but adheres to the insulator film.

Therefore, the interface between the good conductor metal on the inner wall and the semiconductor film is not formed, and the two interfaces that are formed are the interface between the good conductor metal and the insulator film, and the interface between the insulator film and the semiconductor film. As shown, when an interface between a good conductor metal and a semiconductor film is not formed, the current when the microwave propagates always flows on the good conductor metal surface of the inner wall, so microwave loss is unlikely to occur. Therefore, the plasma is stable and the reproducibility of the semiconductor thin film formed on the substrate to be processed is good.

On the other hand, when an interface between a good conductor metal and a semiconductor film is formed, a portion of the microwave flows toward the semiconductor and is lost as heat. Therefore, the plasma is unstable and the reproducibility of the semiconductor film formed on the substrate to be processed is poor.

〔Example〕

Next, an embodiment of the present invention will be described.〇 Fig. 1 shows the configuration of an embodiment of a semiconductor film forming apparatus of the present invention.

The semiconductor film deposition apparatus according to this embodiment has a plasma generating section 7.
, a microphone four-wave waveguide 2, a window 3 made of quartz or alumina through which microwaves can pass, a sample chamber 4 having a sample stage 5 therein, and a plasma generation chamber 1 for discharging gas or film-forming gas. an exhaust port 8 for exhausting the exhaust gas after processing, a magnetic field 9 for generating a magnetic field that satisfies the electron cyclotron resonance conditions, and the entire inner wall of the plasma generation chamber 1 and sample chamber. Insulator m10 coated with
It consists of

Note that the insulator film 10 is connected from the plasma generation chamber 1 to the sample chamber 4.
◎This is the magnetic coil 9
This is because if the 9ECR point is moved by the magnetic field control by (not shown) generates microwaves with a frequency of 2.45 GHz and guides them to the plasma generation section through the waveguide 2. The plasma generation section has a cavity resonant structure, and standing microwave waves are formed. The magnetic coil 9 installed around the plasma generation section 7 is
8 75 G (which satisfies the electron cyclotron resonance conditions)
Generates a D@ field - Causes microtron resonance due to the magnetic field No interface is formed between the two, and microwave loss is unlikely to occur. Therefore, a stable and highly active plasma can be obtained, and the reproducibility of the semiconductor film is improved compared to the case where the insulating material is not coated.

An experimental example in which an amorphous silicon film was formed using this apparatus will be described below.

A hydrogenated amorphous silicon film (a-81:H) was formed by flowing 40 seconds of silane gas from the gas supply pipe 7 at a pressure of 0.5 to 2 mTorr. The substrate temperature is 1
80℃~200℃, microwave power 50~500W
And so.

The experimental conditions were all the same except for the walls of the vacuum chamber, and when the film formation process was continued, 9&-8 was formed for each process.
FIG. 2 shows the change in photoconductivity of the i:H film.

In FIG. 2, the vertical axis represents the photoconductivity and the horizontal axis represents the number of times of film formation. Curve (2) shows the change in photoconductivity when the vacuum chamber wall is covered with an electrical insulating film so that the amorphous silicon film is not directly formed on the vacuum chamber wall. Curve ■ shows the change in photoconductivity when an amorphous silicon film is formed directly on the wall of the vacuum chamber without covering m < 1 in the vacuum chamber. This is clear from the curve ■ in Figure 2. As shown, when the inner wall of the vacuum chamber is coated with an electrical insulating film, no decrease in photoconductivity is observed even after 11 consecutive treatments, and the reproducibility is good.

On the other hand, when the vacuum chamber is not plugged with an IIC insulator film, as is clear from the curve ■, when continuous processing is performed,
After 5 times, a decrease in photoconductivity was observed and there was no reproducibility.

〔Effect of the invention〕

According to the present invention, even if a semiconductor film is formed on the inner wall of a vacuum chamber, the loss of microwaves on the inner wall surface can be reduced. Therefore, the semiconductor film can be efficiently formed on the substrate to be processed with good reproducibility. There is.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the basic configuration of a semiconductor film deposition apparatus according to an embodiment of the present invention, and FIG. 2 shows the photoconductivity (curve ■) of the amorphous silicon film formed in Example 1, and the photoconductivity formed for comparison. Photoconductivity of amorphous silicon film (curve ■)
◎ 1... Plasma generation part, 2... Microwave waveguide,
5... window plate, 4... sample chamber, 5... sample stand, 6...
... Board, 7... Gas supply pipe, 8... Exhaust port, 9...
... Magnetic coil, 10... Electrical insulator film.

Claims (1)

[Scope of Claims] 1. In a microwave plasma semiconductor film forming apparatus for forming a semiconductor film on a substrate surface using discharge plasma generated in a vacuum chamber, the inner wall surface of the vacuum chamber is coated with an electrical insulator film. A microwave plasma semiconductor film forming apparatus characterized in that the film is coated with. 2. A method for forming a semiconductor film, comprising generating plasma and forming a semiconductor film on a surface of a substrate using the microwave plasma semiconductor film forming apparatus according to claim 1. 3. A microwave plasma film forming apparatus for forming a thin film on a substrate surface using discharge plasma generated in a vacuum chamber, characterized in that the inner wall surface of the vacuum chamber is coated with an electrical insulator film. Plasma film deposition equipment. 4. In a microwave plasma film forming apparatus that forms a thin film on the surface of a substrate using discharge plasma generated in a vacuum chamber, an insulating cylinder is placed in the vacuum chamber and a thin film is formed directly on the wall of the vacuum chamber. A microwave plasma film forming apparatus characterized by having a structure in which no