JPH01261298A - Synthesis of diamond - Google Patents

Abstract

PURPOSE:To synthesize diamond constituted of fine polycrystal of high crystal nucleus density, outstanding in adherability, by low-pressure vapor synthesis through the CVD process while vibrating a base substance. CONSTITUTION:The interior of a reaction chamber 1 consisting of e.g., quartz tube is kept under a pressure of 10<-5>-10<3>, and a microwave generated by a magnetron 2 is irradiated on a raw material gas such as CO+H2 introduced into said chamber 1 through a waveguide 3 to excite and decompose the raw material gas. A base substance 4 is held on its holder 5 in the reaction chamber 1 and heated by a heating means along with application a supersonic vibration from a supersonic vibration generator 10. Thence, plasma particles produced by excitation and decomposition of the raw material gas are emitted on the base substance 4 under vibration heated at 400-1200 deg.C, thus forming the objective diamond on the base substance 4 in high adhesiveness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for synthesizing diamond using a CVD method, and particularly to a method for synthesizing diamond while vibrating a substrate.

[Conventional technology] In recent years, diamond in the form of a thin film has been synthesized from the gas phase in the low-pressure range, and the various properties of diamond have been utilized to produce cutting tools, wear-resistant coatings, speaker materials, and optical components. Furthermore, it is expected to be applied in various fields such as as an electronics material.

The low-pressure vapor phase synthesis method for diamond thin films can be broadly classified into P.
There are VD method and CVD method. Among these, CVD methods that deposit diamonds stably over a long period of time are being actively researched.

[Problems to be solved] In diamond synthesis, in order to obtain diamond of excellent quality, it is necessary to improve the nucleation density of the crystals, to make the film thickness 9, structure 1, and composition uniform, and to ensure close contact between the diamond and the base material. We need to improve our sexuality.

For this reason, in the CVD method, various improvements have been made to improve the quality of diamond, such as scratching the surface of the substrate (Japanese Patent Laid-Open No. 50-200897,
No. 61-155295, No. 61-201698, etc.), or a method of applying some kind of energy to increase the precipitation rate (Jiko No. 60-185499).

In addition to the above, in addition to increasing the nucleus density of the crystal,
A new CVD method aimed at improving film adhesion
Methods include pulse CVD method, ultrasonic CVD method, CNTD method.
method (nucleation controlled thermochemical precipitation method) or fluidized bed CVD
([Functional Materials J 19B6 year 3
Monthly issue, pages 33-3-'5).
'The present invention has been made from the same viewpoint as the above-mentioned situation, and by carrying out synthesis while applying vibration to the base material, it aims to improve the nucleation density and the preparation properties of the base material and diamond, thereby improving the quality. The purpose of the present invention is to provide a diamond synthesis method that makes it possible to obtain excellent diamonds.

In addition, the above-mentioned literature ("Functional Materials J March 1986 issue
(pp. 33-34) also discloses a technique for irradiating a substrate with ultrasonic waves. However, the above-mentioned literature does not describe any specific synthesis conditions, and it is unclear which types of raw material gases the method can be applied to.

[Means for Solving Problems] In order to achieve the above object, the tire cent synthesis method of the present invention supplies a predetermined raw material gas to a reaction chamber and a substrate when synthesizing diamond in a low-pressure gas phase by a CVD method. There is a method of synthesizing diamond while vibrating, and in particular, a method of synthesizing diamond by applying vibration to a substrate while supplying carbon gas or carbon gas and hydrogen gas as raw material gases.

[Example] An example method of the present invention will be described below.

First, an example of an apparatus for carrying out the present diamond synthesis method will be described based on FIG.

Figure 1 shows an example of a microwave plasma device.
is a reaction chamber made of a quartz tube or the like, into which a raw material gas such as carbon-based or hydrocarbon-based gas is supplied. Also 1
The interior of the reaction chamber 1 is maintained at a reaction pressure of 10-5 to 10' torr, preferably 10-' to 800 torr. 2 is a magnetron which generates microwaves of 2.45 Glh. Then, the source gas in the reaction chamber 1 is irradiated through the waveguide 3 to excite and decompose the source gas.

Further, 4 is a substrate, and 5 is a substrate holder for holding the substrate 4, which are located inside the reaction chamber l. The base body 4 is heated by heating means (not shown). Reference numeral 10 denotes an ultrasonic vibration generator, which consists of a vibrator 11 and a horn 12, and is attached to a base holder 5 at a temperature of 10 to 80K)1. gives a vibration.

　　　　.

Next, a diamond synthesis method performed using the above apparatus will be explained.

For example, 0.1 to 1.00 mol of -carbon oxide gas and hydrogen gas (Co/
Hz mol ratio) and (0,1
If the wolX ratio is less than that, diamondent may not be precipitated in some cases. ), 2.45G) 12 microwaves are irradiated from magnetron 2. As a result, the raw material gas is excited and decomposed inside the reaction chamber 1, and becomes plasma particles.
It flies towards base 4.

On the other hand, the substrate 4 is placed in the reaction chamber 1 at 1. ．． 400-1
While being heated to 200°C, via the substrate holder 5,
Ultrasonic vibrations are applied from an ultrasonic vibration generator IO.

Therefore, the substrate 4 and the
As a result, the chemical species located near the surface of the substrate 4 are activated. Therefore, the amount of crystal nuclei generated on the substrate 4 increases, a fine-grained polycrystalline film is less likely to precipitate, and the adhesion of the diamond film to the substrate 4 is improved.

Note that the diamond synthesis method of the present invention is not limited to the above-mentioned embodiments, but includes the following modifications, for example.

(2) The CVD method includes not only the microwave plasma method but also the thermal filament method, the high frequency plasma method, the electron cyclotron resonance plasma method, and the like. .

(2) The vibration of the base body may be a vibration applied by a source other than ultrasonic waves, as long as the vibration is similar (frequency, etc.) to the vibration applied by ultrasonic waves.

■ Also, the vibration of the base body is not only unidirectional vibration.
The vibration may be multidirectional.

(2) The raw material gas also includes carbon dioxide gas other than -carbon oxide gas, and gases other than carbon-based gases, such as carbide-based, oxygen-containing compounds, or nitrogen-containing compounds.

■ Diamond contains diamond-like carbon.

Next, we will look at specific examples of tests carried out using the method of the present invention and tests carried out using conventional methods. A comparative example is shown below.

Specific Example 1 Diamond synthesis was performed using a silicon wafer as a substrate.

Synthesis conditions 0 Equipment used Microwave reactor, (Frequency 2, 45., GH2) 0 Vibration of substrate 40 KH2 O Substrate temperature 900°C 0 Reaction pressure 50 torr O raw material gas - Carbon oxide (flow rate: 10 sec) Hydrogen (flow rate: 90 sec+m) O time 1 hour As a result, a deposit of 15 p-* was obtained on the substrate.

When the obtained deposit was subjected to Raman spectroscopic analysis, it was confirmed that it was diamond without any impurities. Also, diamond SEM lll! 1.0μ
It was confirmed that it was an aggregate of microscopic particles. Furthermore, it was confirmed that the film thickness 2 structure and composition were also uniform.

Specific Example 2 Synthesis was performed under the same conditions as in Specific Example 1, except that instead of carbon monoxide, methane gas was supplied at a flow rate of 0.5 sec, and hydrogen gas was supplied at a flow rate of 1 OOsccm, and synthesis was performed for 4 hours. This resulted in a 2.5 gm deposit on the substrate. Also, the SEM observation of diamond was 1.0. It was confirmed that it was an aggregate of fine particles smaller than a layer. Furthermore, it was confirmed that the film thickness 9 structure and composition were also uniform.

Synthesis was carried out under the same conditions as in Example 1, except that no vibration was applied to the main L support.

As a result, eight river layers of deposits were obtained on the substrate.

In addition, an average of 1107
It was confirmed that it was an aggregate of particles of about z size.

As a result, according to the diamond synthesis method of the present invention,
It has been found that it is possible to synthesize a thin film of diamond that is composed of fine polycrystalline materials and is difficult to separate from the substrate.

[Effects of the Invention] As described above, according to the diamond synthesis method of the present invention,
It is possible to synthesize diamond that has a fine multicrystalline quality with high crystal nucleation density and excellent adhesion. In particular, when a carbon-based gas is used as the raw material gas, it is effective to obtain better polycrystalline fineness and adhesion.

[Brief explanation of the drawing]

FIG. 1 shows an example of the configuration of an apparatus for carrying out an embodiment of the diamond synthesis method of the present invention. l: Reaction chamber 2: Magnetron 4/Substrate
5: Substrate holder lO: Ultrasonic vibration generator.

Claims (2)

[Claims] (1) A method for synthesizing diamond in a low-pressure vapor phase synthesis method using the CVD method, which is characterized in that diamond is synthesized while vibrating a substrate. (2) In the low-pressure vapor phase synthesis of diamond using the CVD method, carbon-based gas or carbon-based gas and hydrogen gas are supplied as raw material gases to the reaction chamber, and diamond is synthesized while vibrating the substrate. Characteristic diamond synthesis method.