JP2649430B2 - Method for producing diamond single crystal film and diamond single crystal film obtained thereby - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a novel method for producing a diamond single crystal film and a diamond single crystal film obtained by the method. More specifically, the present invention provides a method of forming a diamond single crystal film suitable as an electronic material, a wear-resistant material, a jewelry material, and the like on a c-BN substrate by a vapor phase synthesis method, and a method obtained by the method. It relates to a diamond single crystal film.

[Prior art] In recent years, diamond synthesis technology has made remarkable progress,
For example, for industrial use, cutting tools made of non-ferrous and non-metallic materials, wear-resistant tools and wear-resistant members that require high wear resistance, or various protective films, optical materials, electronic materials, chemical industrial materials For example, synthetic diamond thin films are widely used.

As a method for producing a diamond thin film used in such an application, a physical vapor deposition method or a chemical vapor deposition method is usually used on a substrate surface such as silicon, molybdenum, tantalum, tungsten, tungsten carbide, silicon tantalum, tantalum carbide, or c-BN. A method of forming a diamond thin film by a vapor phase synthesis method such as a vapor deposition method has been used.

However, the diamond thin film obtained by such a vapor phase synthesis method is a polycrystalline film, and when it is doped with boron or phosphorus to form a semiconductor, sufficient semiconductor characteristics cannot be obtained, and When used as a cutting tool or wear-resistant tool due to insufficient smoothness of
There are few fields that can be used as they are, and it is necessary to polish the surface of the film as a post-process. For this purpose, a thick diamond thin film is required. It is difficult to form with high adhesive strength.

By the way, since the diamond single crystal film has an extremely smooth film surface, the above-mentioned problem is solved. However, this diamond single crystal film can be produced by epitaxial growth on a substrate by a vapor phase synthesis method, but it has been successful only when the substrate is diamond, and when it is a non-diamond substrate, The fact is that they have not been successful.

Therefore, especially when a diamond thin film is to be applied to an electronic device or the like, it has been a problem to establish a heteroepitaxial growth technique for forming a diamond single crystal film on a non-diamond substrate.

[Problems to be Solved by the Invention] Under such circumstances, the present invention is suitable for an electronic device, a cutting tool, a wear-resistant tool, a wear-resistant member, and the like that do not require post-processing such as polishing. The purpose of the present invention is to form a diamond single crystal film to be used on a non-diamond substrate.

[Means for Solving the Problems] The present inventors have conducted intensive studies to achieve the above object, and as a result, the object can be achieved by using c-BN having a single crystal plane as a substrate. The inventors have found that the present invention has been completed based on this finding.

That is, the present invention provides a method for producing a diamond single crystal film, characterized in that a diamond thin film is epitaxially grown on a c-BN single crystal surface to a thickness of 10 to 1,000 μm by a vapor phase synthesis method, and An object of the present invention is to provide a manufactured diamond single crystal film.

 Hereinafter, the present invention will be described in detail.

In the present invention, c- having a single crystal plane as a substrate
It is necessary to use BN. C- having no single crystal plane
With BN, a diamond thin film cannot be epitaxially grown, and a single crystal plane cannot be obtained. In addition, other than c-BN, for example, silicon, boron, molybdenum, tungsten, tungsten carbide, titanium, tantalum, and the like, even if they have a single crystal plane, cannot grow a diamond thin film epitaxially. Crystal film cannot be obtained. Note that the single crystal plane in the present invention is a single crystal plane confirmed as a single crystal by electron beam diffraction. The c-BN having such a single crystal plane may be a c-BN single crystal particle or a c-BN single crystal thin film.

In the present invention, a diamond thin film is epitaxially grown on the c-BN single crystal surface by a vapor phase synthesis method. However, the vapor phase synthesis method is not particularly limited, and conventionally, a diamond thin film is produced by vapor phase synthesis. Any method can be selected and used from commonly used methods such as physical vapor deposition and chemical vapor deposition, but chemical vapor deposition (CVD) does not require much high temperature,
In addition, continuous operation is easy, which is industrially advantageous.

This CVD method includes, for example, (1) a pyrolysis CVD method in which a raw material gas is brought into an activated state by passing the raw gas through an area near a glowing filament; Apply high frequency to the introduction section,
A high-frequency plasma CVD method for introducing the source gas into an activated state by forming plasma with high frequency,
(3) A microwave plasma CVD method using microwaves instead of the high frequency, (4) a DC plasma CVD method in which a DC current is applied to form plasma, and (5) a source gas is activated by an ion beam. Guiding ion beam
There are a CVD method and the like, and any of these methods can be used in the present invention.

As a raw material gas used in the CVD method, a mixed gas of a carbon source gas, hydrogen, and oxygen optionally used is used. The carbon source gas is not particularly limited, and is usually used for forming diamond by CVD, for example, carbon monoxide or carbon dioxide, or alkanes, alkenes, alkynes, aromatic hydrocarbons, One or a mixture of two or more selected from cycloparaffins, silcoolefins, oxygen-containing carbon compounds, nitrogen-containing carbon compounds, and the like is used. In addition, these source gases may contain an inert gas such as nitrogen gas, argon, neon, or xenon, if desired.

Thus, the thickness of the diamond thin film epitaxially grown on the c-BN single crystal plane is 10 mm to 1,000 mm.
It needs to be in the range of μm. If the thickness is less than 10 mm, it is too thin to be practical, and if it exceeds 1,000 μm, the performance as a diamond thin film is not so much improved for the thickness, and the film formation by vapor phase synthesis takes time and is efficient. Not.

In addition, the diamond single crystal film in the present invention is a film in a range from a network to a continuous film confirmed as a single crystal by electron beam diffraction.

Since the diamond thin film thus formed is a single crystal film, not only electronic materials such as electronic devices, but also the film surface is extremely smooth, so that the film can be formed without post-processing such as polishing. It is suitably used for optical materials, jewelry materials, cutting tools, wear-resistant tools, wear-resistant members, etc., utilizing surface smoothness.

In the present invention, the single crystal diamond film is formed of c-
The composite with BN may be used as it is for the above-mentioned use, or c-BN of the substrate may be removed by mechanical polishing or the like, and only the diamond single crystal film itself may be used for the above-mentioned use.

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

Example 1 As a substrate, a particle diameter of 300 μm obtained by a high-pressure synthesis method
Using the c-BN single crystal particles of
1) A diamond thin film was epitaxially grown on the surface by DC plasma CVD.

In the gas phase synthesis, H ₂ and CH ₄ having a CH ₄ concentration of 1% by volume are used as raw materials.
850 ° C, discharge current density 1.8
The reaction was performed for 30 minutes under the condition of A / cm ² to obtain a diamond single crystal film having a thickness of 2 μm. FIG. 1 shows an SEM image of a diamond single crystal film grown in parallel epitaxially on the c-BN (111) surface.

Example 2 As in Example 1, the (100) surface of c-BN single crystal particles having a particle size of 300 μm was provided with a CH ₄ / H ₂ capacity ratio of 2/98 and a discharge current density of 2 A /
Under a condition of cm ² , a base temperature of 900 ° C. and a reaction time of 2 hours, a diamond thin film having a thickness of 10 μm was epitaxially grown by a DC plasma CVD method.

FIG. 2 shows an SEM image of the (100) plane of the diamond thin film epitaxially grown on the c-BN (100) surface. From FIG. 2, it is confirmed that non-oriented particles are not present and a smooth single crystal plane is formed.

Example 3 As in Example 1, a diamond thin film was epitaxially grown on the (221) surface of c-BN single crystal particles having a particle size of 150 μm by DC plasma CVD.

In the gas phase synthesis, a reaction gas was reacted for 1 hour under the conditions of a discharge current density of 2 A / cm ² and a base temperature of 950 ° C. using a mixed gas of H ₂ / CH ₄ / O _{2 in a} volume ratio of 92/5/3 as a raw material. . As a result, via the parallel epitaxy of diamond, the 5μ
Thus, a diamond single crystal film having a thickness of m was obtained.

Example 4 In the same manner as in Example 1, a (100) surface of c-BN single crystal particles having a particle size of 200 μm was provided with a CH ₄ / H ₂ capacity ratio of 2/98 and a discharge current density of 2
Under the conditions of A / cm ² , a base temperature of 900 ° C., and a reaction time of 4 hours, diamond was epitaxially grown by a DC plasma CVD method to produce a parallel epitaxially grown diamond single crystal film having a thickness of about 5 μm.

The c-BN particle substrate in the composite of the formed c-BN particle substrate and the formed diamond single crystal film was brazed to a bite shank, bladed, and then used.
Cutting test of Al-12% Si alloy, cutting speed 500m / min, feed
Continuously performed for 60 minutes in a dry condition under the conditions of 0.05 mm / rev and 0.3 mm notch, the flank wear width is about 10 μm, and the surface roughness of the work material is less than Rmax 5 μm. It showed comparable performance.

[Effect of the Invention] Epitaxial growth of a diamond thin film by vapor phase synthesis has conventionally been limited only on the surface of a diamond substrate. A diamond thin film can be epitaxially grown on a crystal plane, and heteroepitaxial growth is possible, and its industrial value is extremely large.

The diamond single crystal thin film thus obtained is
The film surface is extremely smooth, and is suitably used for cutting materials, wear-resistant tools, wear-resistant members, and even jewelry materials without performing post-processing such as polishing, including electronic materials such as electronic devices. .

[Brief description of the drawings]

1 and 2 show (11) of c-BN single crystal particles, respectively.
1) The diamond single crystal film on the surface and (100) surface
It is a SEM image.

Continuation of the front page (72) Inventor Inu ▲ tsuka ▼ Nao Aoyama Gakuin University 6-16-1 Chitosedai, Setagaya-ku, Tokyo (56) References JP-A-4-333291 (JP, A)

Claims (2)

(57) [Claims] 1. A method for producing a diamond single crystal film, comprising: epitaxially growing a diamond thin film to a thickness of 10 to 1,000 μm on a c-BN single crystal surface by a vapor phase synthesis method. 2. A diamond single crystal film produced by the method according to claim 1.