JPH06256957A - Diamond-like carbon thin film forming device - Google Patents

Abstract

PURPOSE:To form a diamond-like carbon thin film having high quality on a substrate at a high speed by setting an inter-electrode distance at a specific value at the time of forming the diamond-like carbon thin film on the substrate by a parallel flat plate type high-frequency plasma apparatus. CONSTITUTION:Gaseous carbon source and gaseous H2 of <=25mol% are introduced from an inlet 6 under 50 to 100Pa pressure into a vacuum vessel 1 of the high-frequency plasma CVD apparatus of a capacity coupling type having parallel flat plate constitution. High-frequency electric power is then impressed at 2 to 3W/cm<2> electric power density between a high-frequency electrode 2 mounted to a material 4 arranged in parallel and a counter grounding electrode 3 from a power source 7 to form a plasma region 10 by glow discharge, by which the diamond-like carbon thin film is formed of the C by cracking of the gaseous carbon source. The distance 9 between the high-frequency electrode 2 and the counter grounding electrode 3 is specified to 1/30 the diagonal size in the case of the square type electrodes and to about 1/20 the diameter, more specifically <=9mm in the case of the internal type electrodes. The diamond-like carbon thin film having extra-high hardness and excellent smoothness and insulating characteristic is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diamond-like carbon thin film forming apparatus. Particularly, 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 wear resistance, high smoothness, high insulation, and high hardness while maintaining excellent adhesion to a substrate. It is a thing.

[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.

[0005]

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 operating distance and 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. 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 produced according to the following reaction conditions. A carbon thin film on diamond was formed on a Si wafer. The dimensions of the electrodes were square and both sides were 180 × 180 mm. At this time, although the reaction time was set to 2 min, 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. When the Vickers hardness was measured, a very clear indentation was generated, which was calculated from the formula 390.
It had a hardness of 0 kg / mm ² . 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% 200
SCCM hydrogen purity 99.999% 50 SCCM RF power: 2.2 W / cm ² operating pressure: 75 Pa distance between electrodes: 8.5 mm Substrate temperature: unheated Reaction time: 2min self-bias: -380V formation rate: 1.7 [mu] m / min In the present embodiment, 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.

[0008]

[Comparative Example 1] Under the reaction conditions of Example, when the distance between the electrodes was set to 30 mm, the self-bias decreased to -230 V, and the obtained diamond-like carbon thin film had a thickness of about 0.6 μm.
Had a Vickers hardness of 2100 kg /
It was mm ² . The formation rate and hardness were not satisfactory values.

[0009]

[Comparative Example 2] Under the reaction conditions of Example, when the operating pressure was set to 20 Pa, the self-bias became −520 V, the electric field strength in the ion sheath was increased, the etching mode became dominant over the deposition mode, and further damage was caused. It was found that the film thickness and the Vickers hardness could not be evaluated due to the increase of the residual internal stress of the film itself, and that the film thickness deviated from the allowable range of film forming conditions.

[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 operating pressure dependence of self-bias.

[Explanation of symbols]

 1 Vacuum container 2 High frequency power supply electrode 3 Opposite ground electrode 4 Substrate 5 Pressure measurement system 6 Raw material supply system 7 High frequency power supply system 8 Exhaust system 9 Electrode distance 10 Plasma area 11 Blocking capacitor 12 Self-bias monitor terminal

Claims (4)

[Claims] 1. In a parallel plate type high frequency plasma CVD apparatus, the electrode distance between a high frequency power supply electrode on which a substrate is arranged and a ground electrode facing in parallel and in parallel is set to 9 mm or less, and an operating pressure of glow discharge is 50 Pa. To 100 Pa, the diamond-like carbon thin film forming apparatus is numerically limited to an arbitrary value. 2. The distance between the high-frequency power supply electrode and the facing electrode according to claim 1, wherein the distance between electrodes is 1/30 of a diagonal dimension in a square electrode or 1 / diameter in a circular electrode.
An apparatus for forming a diamond-like carbon thin film, wherein the distance between electrodes is numerically limited. 3. The high-frequency power supplied to the film formation according to claim 1, wherein the power density per unit area is 2
Diamond-like carbon film forming apparatus characterized by numerically limited to any value within the range of W / cm ² of 3W / cm ^2. 4. The method according to claim 1, wherein ethylene gas is used as a carbon source gas for forming a film, and the addition amount of hydrogen gas added for the purpose of dehydrogenating hydrogen atoms taken into the film is relative to the carbon source gas. An apparatus for forming a diamond-like carbon thin film, which is numerically limited to 25 mol% or less.