JPH0930892A - Plasma cvd device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effect uniform thickness distribution for a thin film developed on a substrate by diffusing a stock gas introduced into a chamber in the vicinity of the inner wall of the chamber and feeding the gas through the circumference of a plasma generating chamber. SOLUTION: This plasma CVD device has a grounded outer vessel 2 and a direct current voltage DC1-applied inner vessel 3, and is equipped with a gas inlet pipe 4 with a shower tip-shaped gas inlet 5 on the tip, which penetrates through the bottom of the inner vessel 3 in a chamber 1. A diffusive plate 11 is located above the gas inlet 5 and supported, via a support member 12, upon the bottom of the inner vessel 3, and a space 13 serving as a flow channel for a stock gas is provided between the edge of the diffusive plate 11 and the inner vessel 3. The upper side of the diffusive plate 11 is mounted with a filament 21 to feed electric power from a high-frequency source AC1 and a counter electrode 22 for discharge biased from a direct current source DC2, and a film formation chamber having a substrate holder 7 with substrates 8 held detachably on the lower surface is located above the upper side lead-through electrode 23 on the upper side of the inner vessel 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma CV for decomposing a raw material gas by plasma discharge under a reduced pressure to form a film.
More particularly, the present invention relates to a plasma CVD apparatus suitable for forming a DLC (Diamond-Like Carbon) thin film.

[0002]

2. Description of the Related Art Conventionally, as a method of forming a thin film such as a DLC film, plasma CVD (Plasma-Chemical Vapo
r Deposition) technology is known. This plasma CV
In the method D, plasma discharge is performed under a reduced pressure to decompose the raw material gas and form a film.

FIG. 5 is a perspective view showing the structure of a conventional plasma CVD apparatus. The chamber 1 is evacuated and decompressed by a vacuum pump. A cylindrical chamber wall 3 is arranged in the chamber 1, and a disc-shaped substrate holder 7 is arranged on the opening side. The substrate holder 7 includes
A plurality of substrates 8 are detachably held. In the center of the bottom surface of the chamber wall 3, a shower-like gas introduction port 5 is provided, through which a source gas such as C _X H _Y (hydrocarbon) is partitioned by the chamber wall 3. Introduced in 6. The raw material gas introduced is
A carbon film is formed on the substrate 8 by the carbon particles obtained by being decomposed by plasma discharge in the plasma generation chamber 6.

[0004]

However, in the above-described conventional plasma CVD apparatus, as shown in FIG. 6 (a), the film forming rate (hereinafter referred to as rate) decreases as the distance from the center position of the substrate holder increases. Therefore, there is a problem that the film thickness distribution within one batch composed of a plurality of substrates varies by about ± 10%.

The present invention has been made in view of the above problems, and an object thereof is to provide a plasma CVD apparatus capable of achieving uniform film thickness distribution among a plurality of substrates.

[0006]

A plasma CVD apparatus according to the present invention comprises a chamber to be decompressed, a raw material gas introduction means having a gas introduction port for introducing a raw material gas into the chamber, and the inside of the chamber. In the plasma CVD apparatus having a plasma generation chamber for decomposing the introduced raw material gas and a substrate holder for detachably holding a plurality of substrates for film formation by the particles decomposed in the plasma generation chamber, It is characterized by comprising a diffusing means for diffusing the source gas near the inner wall of the chamber and supplying it to the plasma generating chamber from the surroundings.

More specifically, the gas inlet is arranged at the center of the bottom of the chamber, and the diffusing means is arranged above the gas inlet and has a gap between the gas inlet and the inner wall of the chamber. It is characterized by comprising a diffusion plate.

Further, more specifically, the diffusion means is
It is characterized in that it is a ring-shaped pipe in which a plurality of gas inlets are dispersed.

[0009]

According to the plasma CVD apparatus of the present invention, the raw material gas introduced into the chamber is diffused in the vicinity of the inner wall of the chamber and supplied to the plasma generation chamber from the periphery thereof, whereby particles decomposed in the plasma generation chamber are generated. The density distribution can be made uniform, and thus the film thickness distribution of thin films formed on a plurality of substrates can be made uniform.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a perspective view showing the configuration of a plasma CVD apparatus according to an embodiment of the present invention, and FIG. 2 is a sectional view.

The chamber 1 is composed of an outer container 2 that is grounded and an inner container (hereinafter referred to as a chamber wall) 2 to which a DC voltage DC1 is applied. The inside of the chamber 1 is evacuated and decompressed by a vacuum pump.

The gas introduction pipe 4 is provided so as to penetrate through the central portion of the bottom of the chamber wall 3, and a shower-like gas introduction port 5 is provided at the tip thereof. A diffusion plate (hereinafter referred to as a baffle plate) 11 is arranged above the gas introduction port 5 and is supported on the bottom surface of the chamber wall 3 via a support member 12. A gap 13 is provided between the edge of the diffusion plate 11 and the chamber wall 3 as a flow path of the raw material gas introduced through the gas introduction port 5.

The upper side of the baffle plate 11 inside the chamber wall 3 constitutes a plasma generating chamber 6. In the plasma generation chamber 6, a filament 21 to which electric power is supplied by the high frequency power supply AC1 and a discharge opposite electrode 22 biased by the direct current power supply DC2 are arranged so that the source gas is turned into plasma by the discharge. There is. Although omitted in FIG. 1, as shown in FIG. 2, a grid-shaped extraction electrode 23 is arranged in the opening of the chamber wall 3 so that the positive ion particles generated in the plasma generation chamber 6 can be extracted. It has become. In addition, the extraction electrode 2
A correction plate 24 that corrects the density distribution of the extracted particles is arranged on the upper part of the unit 3.

Upper extraction electrode 2 of chamber wall 3
An upper part of 3 is a film forming chamber, and a substrate holder 7 which is rotationally driven in the chamber 1 is arranged therein. A plurality of substrates 8 are detachably held on the lower surface of the substrate holder 7.

As a result, the source gas supplied from the gas introduction port 5 is diffused in the vicinity of the chamber wall 3, and the plasma generating chamber 6 is further provided via the space 13 between the chamber wall 3 and the edge of the baffle plate 11. Is supplied from the surroundings.
The raw material gas diffused inside the chamber wall 3 is decomposed by plasma discharge in the plasma generation chamber 6.

As the source gas, for example, when forming a DLC film, C _X H _Y (hydrocarbon) is used. It is also possible to use this to form an amorphous carbon thin film.

According to this embodiment, when the baffle plate 11 is provided, the raw material gas introduced through the gas introduction port 5 is diffused in the vicinity of the inner wall of the chamber wall 3,
As shown in (b), it is possible to improve the variation in the film thickness distribution within the batch. Therefore, for example, the DLC film thickness of the magnetic head or the like can be made uniform, and the product yield can be improved.

Next, the plasma CV thus constructed
The film thickness distribution in the D device will be described. Table 1 shows DLC under various conditions using the plasma CVD apparatus described above.
The results of the film formation test are shown.

In this test, the amount of change Δh [mm] from the current distance between the chamber wall 3 and the substrate holder 7 when the height of the chamber wall 3 is variable, and the distance between the substrate holder 7 and the extraction electrode 23. l [mm], presence / absence of placement of an insulator in the opening of the chamber wall 3, presence / absence of gas correction by the baffle plate 11, placement of a cover above the filament 21 for controlling heat dissipation to the substrate holder 7. The thick film distribution in the batch was examined under the condition items of the presence or absence of the film and the presence or absence of the correction plate 24.

No. 2 shows each test result when the height of the chamber wall 3 was changed, and the plasma became unstable. This shows that the current height is optimized from the viewpoint of plasma stability. Insulation or cover has no effect. No. 1 and N
o. 2 is only the presence or absence of the correction plate 24. If the correction plate 24 is not provided, the variation in the film thickness distribution within one batch is ± 35.1%, but the correction plate 24 is provided. In this case, the variation in the film thickness distribution within one batch is ± 8.
It will be 5%, which will be improved. No. 3 is a test result when the correction plate 24 is provided and the gas is corrected by the baffle plate 11. In this case, the variation in the film thickness distribution within one batch is ± 5.4%, which is further improved.

[0021]

[Table 1]

FIG. 3 is a view showing the film thickness distribution of the DLC film from the center position of the substrate holder in the same test. As shown in FIG. The effect of 3 is clear.

FIG. 4 is a perspective view showing the structure of a plasma CVD apparatus according to another embodiment of the present invention. In this embodiment, the baffle plate 1 of the previous embodiment is used as the gas diffusion means.
Instead of 1, multiple gas inlets 3 for introducing raw material gas
A ring-shaped pipe 32 in which 1s are dispersed is arranged at the bottom of the chamber wall 3 coaxially with the chamber wall 3. Thereby, the source gas introduced through the gas inlet 31 is diffused in the vicinity of the inner wall of the chamber wall 3, and the density distribution of the source gas in the vicinity of the surface of the substrate 8 can be corrected. Therefore, as in the previous embodiment,
It is possible to improve the variation in the film thickness distribution within the batch.

[0024]

As described above, according to the present invention,
The diffusion means supplies the raw material gas introduced by the raw material gas introduction means to the plasma generation chamber from the vicinity of the inner wall of the chamber to make the density distribution of the particles generated in the plasma generation chamber uniform, and The film thickness distribution can be made uniform.

[Brief description of drawings]

FIG. 1 is a perspective view showing the configuration of a plasma CVD apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a detailed structure of a chamber in the example.

FIG. 3 is a diagram showing a film thickness distribution of a DLC film from a central position of a substrate holder in the example.

FIG. 4 is a plasma CV according to another embodiment of the present invention.
It is a perspective view which shows the structure of D apparatus.

FIG. 5 is a perspective view showing a configuration of a conventional plasma CVD apparatus.

FIG. 6 is a diagram showing a film thickness distribution in an example of the present invention and a conventional film thickness distribution.

[Explanation of symbols]

1 ... Chamber, 2 ... Outer container, 3 ... Chamber wall, 4
... gas introduction pipes, 5, 31 ... gas introduction ports, 6 ... plasma generation chamber, 7 ... substrate holder, 8 ... substrate, 11 ... baffle plate, 1
2 ... Support member, 13 ... Void, 21 ... Filament, 22
... counter electrode, 23 ... extraction electrode, 24 ... correction plate, 32
… Ring-shaped pipe.

Claims (3)

[Claims] 1. A decompressed chamber, a raw material gas introduction means having a gas introduction port for introducing a raw material gas into the chamber, and a plasma generation chamber configured in the chamber to decompose the introduced raw material gas. In a plasma CVD apparatus having a substrate holder that detachably holds a plurality of substrates for forming a film with particles decomposed in the plasma generation chamber, the introduced source gas is diffused near the inner wall of the chamber. A plasma CVD apparatus comprising a diffusion means for supplying the plasma generation chamber from the surroundings. 2. The gas introducing port is arranged at the center of the bottom of the chamber, and the diffusing means is a diffusing plate arranged above the gas introducing port and having a space between the gas introducing port and the inner wall of the chamber. The plasma CVD apparatus according to claim 1, wherein: 3. The plasma CVD apparatus according to claim 1, wherein the diffusion means is a ring-shaped pipe in which a plurality of gas inlets are arranged in a dispersed manner.