JPH06279186A - Method for synthesizing diamond thin film - Google Patents

Abstract

PURPOSE:To provide a method for synthesizing a diamond thin film by which a diamond thin film can be grown on the clean surface of a substrate free from physical damage. CONSTITUTION:A thin film 4 contg. an iron family element is formed on a substrate 1 and a diamond thin film 5 is formed on the metallic thin film 4 by chemical vapor deposition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for synthesizing a diamond thin film by a thermochemical reaction of a reaction gas.

[0002]

2. Description of the Related Art In recent years, diamond has excellent thermal conductivity,
Due to the characteristic of being the hardest, the demand for diamond thin films applied to electronic materials, optical materials, cemented carbide tools and the like is increasing. And as a manufacturing technology of diamond thin film, a chemical vapor deposition method (Chemical Vapor Depositoin
A method called a CVD method) has been attracting attention. In this method, a hydrocarbon compound such as methane gas is heated and decomposed using a filament or plasma to grow a carbon film having a diamond structure on a metal, semiconductor or ceramic substrate. With this CVD method, except for the diamond substrate, the frequency of diamond crystal nuclei generation on the substrate is extremely low, so that a film-like structure cannot be obtained. Therefore, the surface of the substrate is scratched with a hard material such as diamond powder to increase the generation density of crystal nuclei and deposit a dense diamond thin film.

[0003]

However, the treatment of damaging the surface of the substrate in the above-mentioned CVD method causes physical damage to the surface of the substrate and avoids chemical contamination of the surface of the substrate. However, the quality of the obtained diamond thin film itself may be adversely affected. In addition, in the diamond thin film growth method by the scratch treatment, it is difficult to perform so-called selective growth in which the diamond thin film is synthesized only on a part of the substrate surface because of the accuracy and precision of the scratch treatment. Therefore, it has not been realized to deposit a diamond thin film in an arbitrary fine shape. Therefore, an object of the present invention is to provide a method for synthesizing a diamond thin film, which allows a diamond thin film to grow on a clean substrate surface without physical damage.
Another object of the present invention is to provide a method for synthesizing a diamond thin film, which allows a diamond thin film to be easily selectively grown in a fine region on the surface of a substrate.

[0004]

In order to solve the above technical problems, the inventors of the present invention have made extensive studies by paying attention to the action of the iron group element in the growth of the diamond thin film, and have completed the following inventions. That is, as one means, it comprises a step of forming a metal thin film containing an iron group element on the substrate, and a step of forming a diamond thin film on the metal thin film of the substrate formed in the above step by a chemical vapor deposition method. A method for synthesizing the characteristic diamond thin film was created. Furthermore, as another means, a step of forming a metal thin film containing an iron group element in a region where a diamond thin film is to be formed on a substrate,
And a step of forming a diamond thin film on the metal thin film of the substrate formed in the above-mentioned step by a chemical vapor deposition method.

Here, the substrate means a plate material made of metal, semiconductor, or ceramics on which a thin film can be formed. Further, a material having a surface that can serve as a substrate can also be used. In addition, the iron group element means Fe, Ni, and Co among the group VIII elements. The iron group element has a catalytic action for decomposing a carbon compound and a catalytic action for promoting the decomposition of a carbon compound in the CVD method. Therefore, the hydrocarbon compound that is a raw material of the diamond thin film is easily decomposed near the surface of the iron group element metal thin film, and a large amount of carbon, which is a decomposition reaction product, is generated. Furthermore, the iron group elements and alloys containing these elements as the main components are used as a metal solvent for diamond synthesis under high temperature and high pressure, and are considered to have a catalytic action for transforming graphite-like carbon into diamond structure carbon. Has been. In addition to the iron group element, Ru, Rh, Pd, and O which are group VIII elements
s, Ir, and Pt also have the same catalytic action as the iron group element, and can be used similarly to the iron group element.

The metal thin film containing an iron group element is a metal of the above iron group element, an alloy of two or more elements of these elements, or an alloy of one or more iron group elements and another metal. A thin film. In the case of an alloy of an iron group element and another metal element, the proportion of the iron group element is preferably 50% or more. This is because the catalytic action of the iron group element on hydrocarbon decomposition and the catalytic action on the diamond structure are weakened.
Especially for low temperature production of diamond, pure Fe, N
It is known that alloys containing i, Co, and the like as the main components have larger effects than those of metals, and the Inconel alloy is preferable.

The thickness of the metal thin film is preferably 1 atomic layer or more and 5000 angstroms or less. If it is not more than 1 atom, the surface of the substrate cannot be covered, and 500
This is because if it exceeds 0 angstrom, there is a risk of quality problems such as separation of the metal thin film from the substrate.

As a means for forming a metal thin film, a means for forming a thin film can be usually used, and a vacuum deposition method, a sputtering method, an ion plating method, a CVD method, a liquid phase epitaxy method, a vapor phase growth method, an organic metal. A vapor phase growth method, a molecular beam epitaxy method, a gas source molecular beam epitaxy method, etc. can be used.

In the chemical vapor deposition method (CVD method), a gas of a compound consisting of elements constituting a thin film material to be formed is supplied onto a substrate and a desired thin film is formed by a thermochemical reaction in a vapor phase or on the surface of the substrate. It is a method of forming. As the CVD method, thermal CVD is performed depending on the gas decomposition method of the compound used.
Method, plasma CVD method, optical CVD method, microwave CVD
There is a law.

[0010]

With the above structure, the frequency of crystal nucleus generation of diamond on the surface of the iron group metal thin film on the substrate in the CVD method is compared with the frequency of crystal nucleus generation on the substrate surface not covered with the metal thin film. And it is extremely expensive.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIG. This example is an example of the present invention, and the present invention is not limited to this. In FIG. 1, the substrate 1
An outline of the process for selectively growing a diamond thin film is shown above. Si (100) is used as the substrate 1. Substrate 1 is washed with an organic solvent in advance and then 1%
It is soaked in hydrofluoric acid for 30 minutes, washed with pure water, dried, and washed. The surface of this cleaned substrate 1 was covered with a metal foil mask 3 in which 10 mm square holes 3a and 5 mm square holes 3b were opened, and the substrate 1 was installed in a sputtering device (not shown). Inconel 600 (containing 76% of Ni and 7.2% of Fe) was used as a sputtering target material, and an Inconel 600 alloy film 4 was deposited on the surface of the substrate 1 through the mask 3 to a thickness of about 100 angstroms ( See FIG. 1 (a). As a result, the alloy films 4a and 4b are formed on the substrate 1 following the pattern of the mask 3.

Next, the substrate 1 was placed in a reaction chamber (not shown) of a microwave CVD apparatus for synthesizing a diamond thin film, the substrate temperature was heated to 650 ° C., and 0.5% concentration of hydrogen was used as a source gas. The methane gas diluted to was supplied to the reactor, and the reaction pressure was kept at 35 Torr for 4 hours.

When the substrate 1 was taken out of the CVD apparatus and the formation of deposits was observed, the Inconel alloy films 4a, 4
Films 5a and 5b having a thickness of 0.5 μm were deposited on the region above b, and the films 5a and 5b completely covered the Inconel alloy films 4a and 4b with dense crystals. Also,
It was confirmed by laser Raman spectroscopy that the films 5a and 5b were composed of diamond fine particles. On the other hand, no deposit was found in the surface region of the substrate 1 where the alloy films 4a and 4b were not formed. From this result, it was confirmed that the diamond thin films 5a and 5b can be selectively grown on the substrate 1 by forming the alloy films 4a and 4b on the substrate 1.

The substrate 1 is of high quality having the diamond thin film 5 on a clean surface without physical damage, and the diamond film 5 is integrated with the substrate 1 through the alloy film 4. It was recognized that

In this example, after the alloy films 4a and 4b are formed in a pattern on the surface of the substrate 1, the diamond thin film 5 is formed.
Although a and 5b are selectively formed on the alloy films 4a and 4b, the selective growth method of the diamond thin film is not limited to this. For example, after forming the alloy film 4 on the entire surface of the substrate 1, the diamond thin film 5 can be formed in a pattern using a lithography technique.

In this example, the case where the diamond thin film 5 is formed on the substrate 1 and applied to an electronic device material has been described. However, the present invention is not limited to this. It can also be used for forming a protective film using the above-mentioned coating and corrosion resistance.

[0017]

As described in detail above, according to the present invention,
The diamond thin film can be formed on a clean surface without physically damaging the substrate surface, and the diamond thin film can be selectively deposited on any area of the substrate surface. Can be easily provided.

[Brief description of drawings]

FIG. 1 is a process drawing showing the outline of formation of a diamond thin film according to the present invention.

[Explanation of symbols]

 1 ... Substrate 4 ... Metal thin film containing iron group element 5 ... Diamond thin film

Claims (2)

[Claims] 1. A step of forming a metal thin film containing an iron group element on a substrate, and a step of forming a diamond thin film on the metal thin film of the substrate formed in the step by a chemical vapor deposition method. Method for synthesizing diamond thin film. 2. A step of forming a metal thin film containing an iron group element in a region where a diamond thin film is to be formed on a substrate, and a diamond thin film is formed on the metal thin film of the substrate formed in the above step by a chemical vapor deposition method. A method for synthesizing a diamond thin film, which comprises the steps of: