JPH0234917B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for depositing and forming an artificial diamond film on the surface of a substrate. [Prior Art] Many methods have been proposed to deposit and form an artificial diamond film on the surface of a substrate, and among them, (a) thermionic emissive material as a means of heating and activating the reaction mixture gas; , (b) Plasma discharge by high frequency, (c) Plasma discharge by microwave, methods that employ any of the above (a) to (c) are attracting attention as representative methods. In the conventional method (a), as shown in a schematic cross-sectional view in FIG. A reactive mixed gas composed of hydrogen and hydrogen is flowed toward a filament 3 made of, for example, metal tungsten as a thermionic emitting material and a base 5 supported on a base plate 4, which is disposed below the base body 5, and during this time, Atmospheric pressure inside reaction vessel 1
While holding at 0.1 to 300 torr, filament 3
is heated to 1,500 to 2,500°C to activate the reaction mixture gas and heat the surface of the substrate placed below at a predetermined interval to a temperature within the range of 300 to 1,300°C. This is a method of precipitating and forming a diamond film on the surface of the substrate 5 by performing a reaction over time.
- The method described in Publication No. 91100 is a method equivalent to this method. Further, in the conventional method (b), as shown in a schematic cross-sectional view in FIG.
A base body 5 is placed in the center of the reaction vessel 1, and a reaction mixture gas consisting mainly of hydrocarbons and hydrogen is introduced from a reaction mixture gas inlet pipe 2 provided on one side of the reaction vessel 1, while a reaction mixture gas mainly composed of hydrocarbons and hydrogen is introduced into the reaction mixture gas on the other side of the reaction vessel 1. During this time, the atmospheric pressure in the reaction vessel 1 is reduced to several torr to several torr.
10 torr, and a high frequency coil 6 provided on the outer periphery of the central part of the reaction vessel 1, for example, at a frequency of:
Adding the conditions of 13.56 MHz and output: 500 W to induce a plasma discharge around the substrate 5 in the reaction vessel 1, and use this plasma discharge to heat and activate the reaction mixture gas and increase the substrate surface temperature. This is a method in which a diamond film is precipitated and formed on the surface of a substrate by carrying out a reaction for a predetermined period of time in this state, and for example, the method described in Japanese Patent Application Laid-Open No. 135117/1983 corresponds to this method. Furthermore, in the conventional method (c), as similarly shown in the schematic cross-sectional view in FIG.
A reaction mixture gas mainly composed of hydrocarbons and hydrogen is introduced from the reaction mixture gas inlet pipe 2 provided at the upper part of the reaction vessel 1, while being exhausted from the lower part of the reaction vessel 1. During this time, the atmospheric pressure inside the reaction vessel is kept at 0.1~ While maintaining the pressure at 300 torr, a microwave of, for example, 2450 MHz, which is supplied through a waveguide 7 provided on the outer periphery of the center of the reaction vessel 1, is adjusted by a plasma adjustment plunger 8, and the substrate 5 in the reaction vessel 1 is heated. A plasma discharge is generated around the substrate, and this plasma discharge heats and activates the reaction mixture gas and raises the substrate surface temperature. By allowing the reaction to occur in this state for a predetermined period of time, a diamond film is deposited on the substrate surface. This is a method of forming
The method described in Publication No. 110494 is a method corresponding to this. [Problems to be solved by the invention] However, in all of these conventional methods, the number of diamond crystal nuclei that precipitate on the substrate surface at the initial stage of the reaction is small, and on the other hand, diamond grows around these crystal nuclei. However, since it takes on the form of a film, a considerable amount of reaction time is required to deposit and form an artificial diamond film having a predetermined thickness. [Means for Solving the Problems] Therefore, from the above-mentioned viewpoint, the present inventors decided to increase the precipitation of diamond crystal nuclei on the surface of the substrate at the initial stage of the reaction when depositing and forming an artificial diamond film on the surface of the substrate. As a result of our research, we found that when the surface of a substrate is subjected to oxygen diffusion treatment as a pretreatment and then subjected to the precipitation formation of an artificial diamond film, the oxygen diffused onto the surface of the substrate by the oxygen diffusion treatment is At least a portion of the diamond is removed by reacting with the heated reaction mixture gas, and as a result, the substrate surface becomes significantly activated, which further promotes the precipitation of diamond crystal nuclei in the early stage of the reaction, resulting in a rapid reaction rate. We obtained the knowledge that it is possible to form an artificial diamond film at the same rate of precipitation formation. Therefore, the present invention has been made based on the above knowledge, and consists of hydrocarbons and hydrogen as main components, and is activated by a thermionic emitting material, plasma discharge by high frequency, plasma discharge by microwave, etc. When depositing and forming an artificial diamond film on the surface of the substrate by placing the heated substrate in a flow of heated reaction mixture gas, the surface of the substrate is subjected to oxygen diffusion treatment as a pretreatment, and this The method is characterized in that it increases the precipitation of diamond crystal nuclei at the initial stage of the reaction by subjecting it to the precipitation formation of an artificial diamond film in a state where the artificial diamond film is precipitated and formed at a high speed. It is. [Example] Next, the method of the present invention will be specifically explained with reference to Examples. Example 1 A metal tungsten chip with dimensions of 10 mm (flat surface) x 1 mm (thickness) was prepared as a substrate, and this substrate was subjected to pretreatment at a temperature of 400°C for 1 hour in an air atmosphere. Oxygen diffusion treatment is performed under the following conditions, and then a first
Using the apparatus shown in the figure, reaction vessel 1: made of quartz with an outer diameter of 50 mmφ, reaction mixture gas composition: volume ratio, H ₂ /CH ₄ =
100/1.5, Distance between the surface of the metal tungsten filament 3 and the substrate 5: 20 mm, Heating temperature of the filament 3: 2000℃, Surface heating temperature of the substrate 5 by the filament 3:
An artificial diamond film was formed under the following conditions: 900°C, atmospheric pressure in reaction vessel 1: 15 torr, reaction time: 1 hour and 6 hours. Example 2 A chip made of tungsten carbide-based cemented carbide (Co: 6% by weight, WC: remainder) having dimensions of 12.7 mm (flat surface) x 4.8 mm (thickness) was prepared as a base,
The surface of this substrate was subjected to oxygen diffusion treatment under the same conditions as in Example 1, and then the apparatus shown in FIG. , Reaction container 1: Made of quartz with an outer diameter of 50 mmφ, Reaction mixture gas composition: Volume ratio, H ₂ /CH ₄ =
100/1, application conditions to high frequency coil 6 (frequency:
13.56 MHz, output: 500 W), atmospheric pressure in reaction vessel 1: 20 torr, reaction time: 1 hour and 6 hours. Example 3 As a base, both flat surfaces: 15 mm opening x thickness: 3
A pure Ni plate material and a Ni alloy (Cu: 20% by weight content) plate material with dimensions of Then, using the apparatus shown in Fig. 3, the surfaces of the substrate subjected to the oxygen diffusion treatment and the surface of the substrate not subjected to the oxygen diffusion treatment were subjected to reaction mixing. Gas composition: H ₂ /CH ₄ = volumetric ratio
An artificial diamond film was formed under the following conditions: 100/3 microwave: 2450 MHz (output: 500 W), atmospheric pressure in reaction vessel 1: 30 torr, reaction time: 1 hour and 6 hours. Example 4 A pure copper chip with dimensions of 15 mm (flat surface) x 3 mm (thickness) was used as the substrate. Oxygen was applied to the surface of this pure copper chip at a temperature of 200°C for 1 hour in an air atmosphere. A diffusion treatment was performed, and then an artificial diamond film was formed under the same conditions as in Example 1 on the surfaces of the resulting substrate subjected to the oxygen diffusion treatment and the substrate not subjected to the oxygen diffusion treatment. Example 5 As a base, both flat surfaces: 15 mm opening x thickness: 3
A pure Ti plate and a Ti alloy (containing Al: 6% by weight, V: 4% by weight) plate with dimensions of Medium temperature: 20 to 400℃
An artificial diamond film was formed on the surface of the substrate under the same conditions as in Example 2 except that the test was held for a minute. In Examples 1 to 5 above, for the substrates for which the reaction time was 1 hour, the surface was observed with a scanning electron microscope at 1700x magnification, photographed, and the number of crystal nuclei per unit area was measured. The precipitation and formation of diamond crystal nuclei at the initial stage of the reaction was evaluated, and for the substrate with a reaction time of 6 hours,
The precipitation formation rate of the artificial diamond film was evaluated by measuring the average thickness of the artificial diamond film deposited on the surface. these

【table】

〔Effect of the invention〕

From the results shown in the attached table, when oxygen diffusion treatment is applied to the substrate surface as a pretreatment, the number of diamond crystal nuclei generated at the initial stage of the reaction increases significantly compared to when no oxygen diffusion treatment is applied to the substrate surface, and this causes artificial It is clear that the formation of diamond film precipitates becomes significantly accelerated. As described above, according to the method of the present invention, by subjecting the substrate surface to oxygen diffusion treatment as a pretreatment, a dense artificial diamond film can be formed at a significantly high deposition rate.

[Brief explanation of drawings]

FIG. 1, FIG. 2, and FIG. 3 are all schematic cross-sectional views showing an apparatus for depositing an artificial diamond film. 1... Reaction container, 2... Reaction mixed gas introduction pipe, 3...
Filament as thermionic emitting material, 4...base plate,
5...Base body, 6...High frequency coil, 7... Waveguide.

Claims (1)

[Claims] 1 By placing a heated substrate in the flow of a heated reaction mixture whose main components are hydrocarbon and hydrogen and which have been activated by a thermionic radiation material, plasma discharge by high frequency, plasma discharge by microwave, etc. The method for depositing and forming an artificial diamond film on the surface of the substrate is characterized in that, as a pretreatment, the surface of the substrate is subjected to oxygen diffusion treatment to increase the number of diamond crystal nuclei that are precipitated at the initial stage of the reaction. A method for depositing and forming an artificial diamond film.