JPS6197194A - Process for forming deposited artificial diamond film - Google Patents

Abstract

PURPOSE:To increase the number of generated crystal nuclei and to form the titled film with high deposition velocity by placing a heated substrate which has been subjected to oxygen diffusion treatment previously in a hot gaseous reaction mixture comprising hydrocarbon and H2 and being activated by a specified means. CONSTITUTION:A gaseous reaction mixture consisting mainly of hydrocarbon and H2 is introduced through an inlet pipe 2 for the gaseous mixture opening at an upper section in a vertical quartz reaction vessel 1. On one hand, the pressure of the atmosphere in the vessel 1 is held at 0.1-300Torr, and the gaseous reaction mixture is activated by heating with a filament 3 comprising W, etc. as thermionic radiator being heated at 1,500-2,500 deg.C, and the reaction is proceeded for a specified time on the surface of a substrate 5 which has been previously subjected to oxygen diffusion treatment to activate the surface remarkably, placed on a base plate 4 provided below the filament with a specified distance. Thus, the velocity for deposition and formation of the titled film is remarkably prompted because of generation of remarkably large number of diamond crystal nuclei.

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.

[Conventional technology]

Conventionally, many methods have been proposed for forming an artificial diamond film on the surface of a substrate by heating and activating the reaction mixture gas. Plasma discharge, (cl) Plasma discharge by microwaves, methods employing any of the above (al to (cl) are attracting attention as representative methods.

As shown in the schematic cross-sectional view in FIG. The reaction mixture gas composed of The filament 3 is heated to 1,500 to 2,500° C. while maintaining the atmospheric pressure within the chamber at 0.1 to 300 torr to activate the reaction mixture gas and to release 300 torr of the substrate surface arranged below at a predetermined interval. This is a method in which a diamond film is precipitated and formed on the surface of the substrate 50 by heating to a temperature in the range of ~1300°C and carrying out a reaction in this state for a predetermined time.
The method described in Publication No. 0 is a method corresponding to this method.

Further, in the conventional method (b), as 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 introduction pipe 2, and is exhausted from the other side of the reaction vessel 1. During this time, the atmospheric pressure inside the reaction vessel 1 is kept at several tons.
The substrate 5 in the reaction container 1 is maintained at a pressure of several tens of torr and the high frequency coil 6 provided at the outer periphery of the center of the reaction container 1 is subjected to, for example, a frequency of 13.56 MHz and an output of 500 W (7). A plasma discharge is induced around the substrate, and this plasma discharge heats and activates the reaction mixture gas and increases the substrate surface temperature. By allowing the reaction to occur in this state for a predetermined period of time, a diamond film is deposited and formed on the substrate surface. For example, the method described in Japanese Unexamined Patent Publication No. 58-135117 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 consisting mainly of hydrocarbons and hydrogen is introduced from the reaction mixture gas inlet pipe 2, while being exhausted from the lower part of the reaction vessel 1, during which time the atmospheric pressure inside the reaction vessel is maintained at 0.
While maintaining the temperature at 1 to 300 torr, a microwave of, for example, 2450 MHz, which is supplied through a waveguide 7 provided at the outer periphery of the center of the reaction vessel 1, is adjusted by a plasma adjustment plunger 8, and the substrate inside the reaction vessel 1 is heated. Plasma discharge is generated around 5, and this plasma discharge heats and activates the reaction mixture gas and increases the substrate surface temperature. By allowing the reaction to occur in this state for a predetermined period of time, a diamond film is deposited and formed on the substrate surface. For example, the method described in JP-A-58-110494 is an equivalent method.

[Problem that the invention seeks to solve]

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 and takes on a film-like appearance. Therefore, a considerable reaction time is required to deposit and form an artificial diamond film having a predetermined thickness.

[Means for solving problems]

Therefore, from the above-mentioned viewpoint, the present inventors have determined that when depositing and forming an artificial diamond film on the surface of a substrate, it is necessary to increase the precipitation of diamond crystal nuclei on the surface of the substrate in the early stage of the reaction (as a result of research, When the substrate surface is subjected to oxygen diffusion treatment as a pretreatment and subjected to the precipitation formation of an artificial diamond film, a small amount of the oxygen diffused to the substrate surface by the oxygen diffusion treatment (and some of it is mixed with the heated reaction mixture gas). As a result, the surface of the substrate becomes significantly activated, which further promotes the precipitation of diamond crystal nuclei in the early stage of the reaction, resulting in the formation of an artificial diamond film at a high precipitation rate. We obtained the knowledge that this is possible.

Therefore, this invention was made based on the above knowledge, and the main components are hydrocarbons and hydrogen and 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 in this state, the artificial diamond is deposited on the surface of the substrate. By providing the film for precipitation, it is possible to increase the precipitation of diamond crystal nuclei in the early stage of the reaction, thereby making it possible to deposit and form an artificial diamond film at a high rate.

〔Example〕

Next, the method of the present invention will be specifically explained using a practical example.

Example 1 A metal tungsten chip with dimensions of 10 m (flat surface) x 1 mm (thickness) was prepared as a substrate, and this substrate was pretreated at a temperature of 400° C. for 1 hour in an air atmosphere. Oxygen diffusion treatment was performed under holding conditions, and then the surface of the resulting substrate subjected to the oxygen diffusion treatment and the surface of the substrate not subjected to the oxygen diffusion treatment was treated using the apparatus shown in FIG. 1. Reaction vessel (1): Made of quartz with outer diameter 5C) + mφ, reaction mixture gas composition: volume ratio, H2/CH4 = 100/
1.5.

Distance between the surface of the metallic tungsten filament (3) and the substrate (5): 20 mm.

Heating temperature of filament (3): 2000°C, surface heating temperature of substrate (5) by filament (3) = 900°C
An artificial diamond film was formed under the following conditions: the atmospheric pressure in the reaction vessel (1) was 15 torr, and the reaction time was 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 plane: 12.7 x thickness = 4.8 mm was prepared as a base, and this base was The surface was subjected to oxygen diffusion treatment under the same conditions as in Example 1,
Next, the surface of the substrate subjected to this oxygen diffusion treatment and the surface of the substrate not subjected to this treatment were treated using the apparatus shown in FIG. : Capacity ratio, H2/CI (4 = 100/1°) Application conditions to the high frequency coil (6) (frequency: 13.56
An artificial diamond film was formed under the following conditions.

Example 3 Pure N1 plate material and Ni alloy (Cu: 2
Prepare plate materials (containing 0% by weight) and apply them to the surface of these substrates.

Oxygen diffusion treatment was carried out under conditions of holding the temperature at 2,500°C for 3 hours in an air atmosphere, and then the resulting substrates subjected to the phosphorus diffusion treatment and the surfaces of the substrates that were not subjected to this treatment were coated with the oxides shown in Fig. 3. Reaction vessel (1): outer diameter 30 mr
Made of quartz with nφ, reaction mixture gas composition: in volume proportion,
H2/CH4=Microwave: 2450MHz
500W), atmospheric pressure in the reaction vessel (1) 30
torr, reaction time: 1 hour and 6 hours.

An artificial diamond film was formed under these conditions.

Example 4 A pure copper chip with dimensions of 15 nl + ID x 3 mm in plane size was used as the substrate, and oxygen was diffused onto the surface of the pure copper chip under conditions of holding the temperature at 200°C for 1 hour in an air atmosphere. Then, an artificial diamond film was formed under the same conditions as in Example 1 on the surface 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 planes: 15+utoX thickness: 3
Pure Ti plate material and T1 alloy (A6
: 6% by weight, ■ = 4% by weight) plate materials were prepared, and the conditions for the oxygen diffusion treatment applied to the surface of these substrates were maintained at a temperature of 400°C for 20 minutes in an air atmosphere. Same as Gero in Example 2.

An artificial diamond film was formed on the surface of the substrate under these conditions.

In Examples 1 to 5 above, for the substrates for which the reaction time was 1 hour, the surface of the substrate was observed with a scanning electron microscope at 1700 times magnification, photographed, and the number of crystal nuclei per unit area was measured. The precipitation formation rate of the artificial diamond film was evaluated by evaluating the precipitation formation of diamond crystal nuclei in the initial stage, and by measuring the average thickness of the artificial diamond film deposited on the surface of the substrate for which one reaction time was 6 hours. was evaluated. These results are shown in the attached table.

〔Effect of the invention〕

From the results shown in the attached table, when the substrate surface is subjected to oxygen diffusion treatment 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 results in an artificial diamond coating. It is clear that the formation of precipitates is significantly promoted.

As described above, according to the method of the present invention, on the substrate surface,
By performing 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 a thermionic emitting material. 4... Base plate, 5... Base. 6...High frequency coil, 7... Waveguide.

Claims (1)

[Claims] The main components are hydrocarbons and hydrogen, and thermionic emitting material,
In the method of depositing and forming an artificial diamond film on the surface of a heated substrate by placing the heated substrate in a flow of heated reaction mixture gas activated by plasma discharge by high frequency or plasma discharge by microwave, etc. A method for depositing and forming an artificial diamond film, characterized in that, as a treatment, an oxygen diffusion treatment is applied to the surface of the substrate in order to increase the number of diamond crystal nuclei that are deposited at the initial stage of the reaction.