JP3472224B2 - Method for forming diamond-like carbon film - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a diamond-like carbon thin film forming apparatus. In particular, while maintaining excellent adhesion to the substrate, high wear resistance, high smoothness,
The present invention relates to an apparatus capable of efficiently and rapidly forming a diamond-like carbon thin film having various physical properties such as high insulation and high hardness.

[0002]

2. Description of the Related Art In the PVD field, a sputtering method, an ionization vapor deposition method, etc., and in the CVD field, a plasma CVD method has been studied as a typical forming method using a commercially available apparatus. Particularly in the case of the plasma CVD apparatus, when the capacitively coupled high frequency glow discharge was used, the distance between the electrodes was about 20 to 60 mm, although there was some difference. A schematic of a commercially available high frequency plasma CVD apparatus is shown in FIG.

[0003]

Therefore, in the above-mentioned device, the self-bias required for obtaining the physical properties of the diamond-like carbon thin film required for application is the operating pressure in the low pressure region or the high frequency in the high power region. Due to the limitation of the conditions such as the power supply power, it is difficult to realize the above-mentioned high adhesion to the substrate or high-speed formation.

[0004]

In the physical properties of a diamond-like carbon thin film, the minimum self-bias value that must be imparted during the formation process is the operating pressure, high-frequency power, and electrode of a commercially available device. By investigating from the dependence of the area ratio, etc., we optimized the distance between electrodes with respect to the dimensions of the electrodes that make up the capacitive coupling, and found that there is a universal correlation between the two. The diamond-like carbon thin film forming apparatus of the present invention is a parallel plate type high frequency plasma CVD.
In the device, the inter-electrode distance between the high-frequency power supply electrode on which the substrate is arranged and the ground electrode facing in parallel and in parallel is 9 mm or less, and the working pressure of glow discharge is 10 Pa to 10 Pa.
It is characterized in that the numerical value is limited to an arbitrary value within the range of 0 Pa. In addition, the distance between the high-frequency power supply electrode and the opposing electrode is numerically limited to an inter-electrode distance of 1/30 of a diagonal dimension for a square electrode or 1/20 of a diameter dimension for a circular electrode. It is characterized by having done. In addition, the high frequency power supplied to the film formation is 2 as the power density per unit area.
Characterized in that the W / cm ² was numerically limited to any value within the range of 3W / cm ^2. Further, ethylene gas was used as a carbon source gas for forming the film, and the amount of hydrogen gas added for the purpose of dehydrogenating hydrogen atoms taken into the film was numerically limited to 25 mol% or less based on the carbon source gas. It is characterized by

In the diamond-like carbon thin film forming apparatus of the present invention, the self-bias, which is usually obtained only in the condition range in which a high frequency power is supplied at a low pressure, reduces the operating distance and the high frequency power by reducing the distance between the electrodes. It can be easily and efficiently obtained by control or mutual control of both. Due to this effect, formation in a high pressure region can be realized, and high-speed formation can be performed with the same self-bias. Further, even in the formation in the low power region, the same self-bias can be obtained, so that it has an effect of promoting damage to the underlying substrate and reduction of residual internal stress of the film itself to promote high quality of the film.

[0006]

EXAMPLE An example of the present invention will be described with reference to FIG.
Using a capacitively coupled parallel plate high frequency plasma CVD apparatus, ethylene gas and hydrogen gas were introduced into the vacuum container 1 from the raw material supply system 6 at a predetermined mixing ratio and flow rate, and the high frequency power supply electrodes were arranged in parallel. 2. A high frequency power of 13.56 MHz is applied between the high frequency power supply system 7 and the counter ground electrode 3 to generate a plasma region 10, and the substrate 4 having a thickness of 0.5 mm and a diameter of 6 inches is generated according to the following reaction conditions. Si
A diamond-like carbon thin film was formed on the wafer. The dimensions of the electrodes were square and both sides were 180 × 180 mm.
In this embodiment, the operating pressure of glow discharge is 50 Pa to 1
As an example of an arbitrary value within the range of 00 Pa, the operating pressure
Forming a diamond-like carbon thin film with a force of 75 Pa
It was At this time, although the reaction time was set to 2 minutes, a diamond-like carbon thin film of about 3.4 μm was formed on the Si wafer. In this diamond-like carbon thin film, no peeling was observed and the film was uniformly formed on the entire surface, and when the Vickers hardness was measured, a very clear indentation was generated, and the hardness was 3900 kg / mm ^{2 according to} the formula. It was
Further, FIG. 3 shows the self-bias characteristics when hydrogen gas was introduced at 200 SCCM and high frequency power was applied at a power density of ² W / cm ² .

[Reaction conditions] Reaction gas: Ethylene purity 99.99% 200SCCM Hydrogen purity 99.999% 50SCCM High frequency power: 2.2 W / cm ² Operating pressure: 75 Pa Electrode distance: 8.5 mm Substrate temperature: Unheated reaction Time: 2 min Self-bias: -380 V Formation rate: 1.7 μm / min In this example, ethylene gas was used as the carbon source gas, but it goes without saying that the same effect can be obtained with other hydrocarbon compounds. Yes.

[Comparative Example 1] Under the reaction conditions of Example,
When only the distance between the electrodes was set to 30 mm, the self-bias-
The resulting diamond-like carbon thin film had a thickness of about 0.6 μm, but the Vickers hardness was 2100 kg / mm ² . The formation rate and hardness were not satisfactory values.

[Comparative Example 2] Under the reaction conditions of Example,
Self-bias is -5 when operating pressure is 20Pa.
At 20 V, the electric field strength in the ion sheath becomes high, the etching mode becomes dominant over the deposition mode, damage is further induced, and the peeling of the film is noticeable. Due to the increase of the residual internal stress of the film itself, the film thickness and However, the Vickers hardness could not be evaluated, and it was found that the film forming conditions were out of the allowable range.

[0010]

According to the present invention, the desired self-bias, which is an important factor in the process of forming a diamond-like carbon thin film, can be achieved by setting the distance between the electrodes for realizing capacitive coupling in the high frequency plasma CVD apparatus to 9 mm or less. It has an effect that the operating pressure of the glow discharge can be efficiently and easily obtained even in the high pressure region or the high frequency feeding power in the low power region, and the high speed and high quality diamond-like carbon thin film can be easily obtained. .

[Brief description of drawings]

FIG. 1 Conventionally used high-frequency plasma CVD
Sectional view showing the internal structure of the device

FIG. 2 is a sectional view showing the internal structure of a high-frequency plasma CVD apparatus for forming a diamond-like carbon thin film used in the examples of the present invention.

FIG. 3 is a graph showing the inter-electrode distance and the operating pressure dependency of self-bias.

[Explanation of symbols]

1 vacuum container 2 High frequency power supply electrode 3 Opposite ground electrode 4 substrates 5 Pressure measurement system 6 Raw material supply system 7 High frequency power supply system 8 exhaust system 9 Distance between electrodes 10 plasma region 11 Blocking condenser 12 Self-bias monitor terminal

Claims (3)

(57) [Claims] 1. A high frequency power is supplied from the high frequency supply means to a first electrode connected to the high frequency supply means, and the first electrode and the first electrode are arranged at a constant interval to a ground potential. A method for forming a diamond-like carbon film, wherein plasma is generated between the diamond-like carbon film and a second electrode held at A diamond characterized in that a hydrocarbon gas and a hydrogen gas are used as a forming gas, the gap is set to 9 mm or less, an operating pressure is set to 50 to 100 Pa, and the diamond-like carbon film is formed without heating the substrate. Carbon film forming method. 2. The method for forming a diamond-like carbon film according to claim 1, wherein the hydrocarbon gas is ethylene gas. 3. An apparatus according to claim 1 or 2, wherein the high frequency power is diamond-like carbon film forming method which is a ^{2W / cm 2 ~3W / cm 2} .