JPH0214897A - Production of filmy diamond - Google Patents

Abstract

PURPOSE:To obtain a high-quality, uniform diamond thin film at high growth rate by providing, in advance, the surface of a substrate with a layer of fine diamond granules of specified size followed by vapor growth of the diamond. CONSTITUTION:The surface of a substrate is provided, in advance, with a layer of fine diamond granules <=10mum in mean size to increase the nucleation energy for diamond and the degree of supersaturation. Thence, a filmy diamond is formed on the above surface through vapor synthesis, thereby obtaining the objective uniform, high-quality diamond thin film at high growth rate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an improvement in a method for producing film-like diamond. More specifically, the present invention relates to a method for producing diamond film, in which a uniform diamond film of good quality is formed on the surface of a substrate at a high growth rate using a vapor phase synthesis method.

[Conventional technology] In recent years, diamond synthesis technology has made remarkable progress. For example, diamond synthesis technology has been used for cutting tools, wear-resistant tools, various protective films, optical materials, electronic materials, chemical industrial materials, etc. Diamonds are widely used.

As a method for forming such a diamond film on the surface of a substrate, there are various gas phase synthesis methods, for example, using a raw material gas containing a carbon source and subjecting it to plasma decomposition, or using a non-equilibrium reaction. Known methods include the chemical vapor deposition method (CVD method) in which diamond film is deposited on the surface of a substrate, and the ionization vapor deposition method in which diamond film is formed on the surface of the substrate using a hot cathode PIG gun, cold cathode PIG gun, sputter gun, etc. ing. In particular, the method of depositing diamond film on the surface of a substrate by the CVD method has recently attracted attention because it is easy to operate continuously and is industrially advantageous.

In the method of forming a diamond film on the surface of a substrate by such a vapor phase synthesis method, the diamond is synthesized in a thermodynamically metastable region. is extremely narrow, and its precipitation is limited by synthesis conditions such as substrate temperature, gas flow rate, total pressure in the reaction tube, and type of carbon source, and therefore the degree of supersaturation that is the driving force for diamond nucleation can be freely controlled. Therefore, it is easy to precipitate granular diamond crystals, but it is difficult to precipitate film-like diamonds.

Therefore, in order to solve such problems, conventionally when using materials other than diamond as a substrate, such as silicon, molybdenum, tantalum, tungsten, or carbides such as tungsten carbide, silicon carbide, and tantalum carbide, Attempts have been made to form sharp scratches on the surface of the diamond by applying abrasion treatment using high-hardness powder or impact treatment in advance, thereby increasing the diamond nucleation energy and increasing the degree of saturation.

However, in such a method, it is difficult to form uniform scratches on the surface of the substrate, and it is difficult to obtain a uniform and high-quality film of diamond. There is a problem.

[Problems to be Solved by the Invention] The present invention overcomes the drawbacks of the conventional diamond manufacturing method using a film-like diamond, and uses a vapor phase synthesis method to produce a uniform and high-quality film-like diamond on the surface of a substrate. This was developed for the purpose of providing a method for forming the film at a high growth rate.

[Means for Solving the Problems] As a result of extensive research into a method for forming a diamond film on the surface of a substrate using a vapor phase synthesis method, the present inventors found that the nucleation energy of diamond on the diamond surface is normally Focusing on the fact that it is lower than that on the surface of a substrate (other than diamond) used for diamond formation, by providing a layer of diamond fine particles with a predetermined particle size on the surface of the substrate in advance, diamond nucleation is possible. The inventors have discovered that the above objects can be achieved by increasing the energy and increasing the degree of supersaturation, and have completed the present invention based on this knowledge.

That is, the present invention provides a method for producing a diamond film, which is characterized in that, before forming a diamond film on the surface of a substrate by a vapor phase synthesis method, a layer of fine diamond particles having an average particle size of 10 μm or less is provided on the surface of the substrate in advance. The present invention provides a method.

The present invention will be explained in detail below.

There are no particular restrictions on the material of the substrate used in the method of the present invention, and materials conventionally used for forming diamond films, such as silicon, molybdenum, tantalum, gesten, titanium, cobalt, chromium, nickel,
Metals such as copper, iron, aluminum, alloys of these metals, carbides, nitrides, oxides of various metals, or Ti
Any material can be selected from among cermets such as C--Ni, TiC--Co, AQ, and 03-Fe, various glasses, and ceramics. There is also no particular restriction on the shape of the base, and any shape can be used depending on the purpose of use, such as a plate, a line, or a pipe.

In the method of the present invention, it is necessary to previously provide a layer of fine diamond particles on the surface of the substrate before forming a diamond film.

By providing this diamond fine particle layer, the diamond nucleation energy is increased and the supersaturation degree is increased, and a uniform and high quality diamond film can be formed at a high growth rate.

At this time, the average particle size of the diamond fine particles used was 10 μm.
m or less, preferably in the range of 0.1 to 10 μm, and more preferably in the range of 1 to 6 μm. If the average particle diameter exceeds 10 μm, diamond will precipitate only on the diamond fine particles, making it difficult to obtain a diamond film.

As a method for providing the diamond fine particle layer on the surface of the substrate, for example, a method of spreading synthetic diamond powder on the surface of the substrate by a sedimentation method, a method of forming a layer of synthetic diamond powder on the surface of the substrate by a pressurization method, etc. can be used. . At this time, the thickness of the diamond fine particle layer to be formed is usually selected within the range of 5 to 100 μm.

FIG. 1 shows a state in which a diamond fine particle layer 1 is provided on the surface of a substrate 2 by the sedimentation method, and FIG. 2 shows a state in which a diamond fine particle layer 3 is provided on the surface of the substrate 2 by a pressure method.

Furthermore, as a method other than the above, for example, a method can be used in which diamond fine particles are contained in the base material and the base body is prepared so that the fine particles are uniformly dispersed on the surface of the base body.

In the method of the present invention, a substrate whose surface has been provided with a layer of diamond fine particles in advance is used, and a diamond film is formed on the surface of the substrate by vapor phase synthesis.

There are no particular restrictions on the vapor phase synthesis method, and any method may be used from among the methods conventionally used for forming diamond film, for example, physical vapor deposition methods such as various chemical vapor deposition methods (CVD methods) and ionization vapor deposition methods. can be used in selection A7, but the CVD method is preferred.

This CVD method includes means for bringing the raw material gas into an activated state, such as (1) a pyrolysis CVD method in which the raw material gas is brought into an activated state by passing near a red-hot filament, (2) a raw material gas High-frequency plasma CVD that applies high-frequency waves to the gas introduction section and forms plasma using the high-frequency waves, thereby leading the raw material gas to an activated state.
(3) a microwave plasma CVD method that uses microwaves instead of the high frequency, and (4) an ion beam CVD method that brings the raw material gas into an activated state with an ion beam. Can be used.

As the raw material gas used in the CVD method, a mixed gas of carbon source gas and hydrogen is used. There are no particular restrictions on the carbon source gas, and gases that are not normally used to form diamonds by the CVD method, such as carbon oxide, carbon dioxide, alkanes, alkenes, etc.
Alkynes, aromatic hydrocarbons, cycloparaffins,
One type or a mixture of two or more types selected from cycloolefins, oxygen-containing carbon compounds, nitrogen-containing carbon compounds, etc. is used. Further, these raw material gases may contain an inert gas such as nitrogen, argon, neon, or xenon, if desired.

In this way, a diamond film is formed on the diamond fine particle layer provided on the surface of the substrate.

The thickness of this diamond film varies depending on the purpose of use, but is usually selected in the range of 10 to 1000 μm.

Next, an example of the growth process of film-like diamond according to the method of the present invention is shown using electron micrographs. (B), (C) and (D) are CV
The state of the substrate surface 15 minutes, 30 minutes and 60 minutes after the start of the reaction by method D is shown.

The film-like diamond thus formed is suitably used for various diamond tools, optical materials, electrical materials, chemical industrial materials, and the like.

To give an example of making a tool using the diamond film, the diamond film is brazed onto the tool base with the base attached, and then the base is removed by appropriate means to create the desired diamond tool. Alternatively, by using a suitable wire material as a base and forming a coating layer of diamond film, this material can be used directly as a wire for a wire cutting machine or the like.

Roughly, a layer of diamond fine particles of several tens of microns is placed on the surface of the substrate.
When diamond is precipitated by vapor phase synthesis after being deposited thickly to a thickness of more than m, the diamond precipitated by vapor phase synthesis acts as if it were a binder for each of the diamond particles that were initially laid out. It is also possible to create a polycrystalline diamond in which these diamond particles are aggregated together.

[Examples] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1 As shown in FIG.
Synthetic diamond powder of 4 μm was spread by a sedimentation method. Using this substrate, electron beam irradiation CVD was performed at an ambient temperature of 800°C, a filament temperature of 1800°C, and a pressure of 40 Torr.

CH, / H2 volume ratio 1g1oo, acceleration voltage], 50V
.

Film-like diamond was deposited under conditions of a current density of 10 mA/cm2 and a reaction time of 1 hr. FIG. 3 is an electron-electron mirror photograph showing the growth process of diamond film, and (A), (B), (C), and (D) are before the reaction, 15 minutes after the start of the reaction, and After 30 minutes and 60 minutes
Shows the status after minutes have elapsed.

The film formation rate by this method was 10 μm/hr,
Under similar experimental conditions, film-like diamond was deposited on the surface of a NRICON substrate with surface scratches formed using Tiremond powder with an average particle size of 2 to 4 μm, and the film formation rate was 2.5 μm/min. It was hr. This proves that the method according to the present invention has an extremely fast film formation rate.

Example 2 As shown in FIG.
A layer of 2 μnl of synthetic diamond powder was deposited at 500 IHt/
After setting it at a pressure of cm2, DC plasma? By CVD method, pressure 200 Torr, substrate temperature 750°C, CH
7/H2 capacity ratio 1:100. When diamond was precipitated under conditions of a reaction time of 4 hours, a diamond film with a thickness of 100 μm could be obtained.

After this film-like diamond is brazed onto a cemented carbide indexable tip base, the molybdenum precipitated base is easily removed by mechanical impact, and the blade is polished to create a vapor-phase synthetic polycrystalline diamond tool. did.

[Effects of the Invention] According to the method of the present invention, uniform and high-quality film-like diamond can be formed at a faster rate without the need for pretreatment of a substrate with a high-hardness powder, which is conventionally performed.

[Brief explanation of the drawing]

Figures 1 and 2 are schematic diagrams showing the state in which a diamond fine particle layer is provided on the substrate surface by the sedimentation method and the pressure method, respectively, and Figures 3 (A) to (D) are the growth of film-like diamond by the CVD method. It is an electron micrograph diagram of the grain structure of the growth surface showing one example of the process. Figures (A) (B)

Claims (1)

[Claims] 1. When forming a diamond film on the surface of a substrate by vapor phase synthesis, an average particle size of 1.
A method for producing a film-like diamond, characterized in that a layer of diamond fine particles of 0 μm or less is provided.