JPH05330987A - Production of thin film of diamond - Google Patents

Abstract

PURPOSE:To form a thin film of diamond having excellent controllability, given thickness and area and improved crystallinity on a substrate by feeding a carbon atom and a hydrogen atom from different supply sources, respectively to a vacuum container in which the substrate is arranged. CONSTITUTION:In a vacuum container l, H2 is decomposed by an ionic gun 2 and H<+> is removed by an ionic filter 5 to give an excited H atom, which is fed to the surface of a substrate 4. On the other hand, a carbon atom supply source 3 such as methanol is heated, evaporated and decomposed by a high-frequency coil 7 to give a C atom, which is supplied to the substrate 4. The C atom is deposited on the substrate 4 to pile the thin film of diamond. In the operation, graphite, etc., piled together with the diamond are bonded to the H atom and discharged to improve crystallinity of diamond. The supply source of hydrogen atom such as the ionic gun 2 and the feed source 3 of carbon atom are readily controlled respectively and separately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a diamond thin film.

[0002]

2. Description of the Related Art Conventionally, as a method for manufacturing a diamond thin film, a hot filament 9 is arranged near a substrate 4 in a vacuum container 8 as shown in FIG. 2, and the hot filament 9 is evacuated to about 2000 ° C. and vacuumed. A hot filament for depositing diamond on the surface of the substrate 4 by supplying a raw material gas in which hydrogen gas is mixed with methane, alcohol or the like into the container 8 and thermally decomposing the raw material gas into carbon atoms C and hydrogen atoms H. Method, by attaching a microwave generator 11 to the vacuum container 10 as shown in FIG. 3 and decomposing a raw material gas similar to the above supplied into the container 10 into carbon atoms C and hydrogen atoms H by microwaves. A microwave plasma CVD method for depositing diamond on the surface of the substrate 4 is known.

The method for producing a diamond thin film by this type of deposition is to obtain a diamond thin film by decomposing methane or alcohol into carbon atoms C and hydrogen atoms H and depositing diamond crystals on the substrate 4. However, when the diamond thin film is formed, graphite and amorphous carbon are also deposited on the substrate 4 at the same time. The reason for introducing hydrogen gas is to discharge graphite and amorphous carbon. That is, the hydrogen atom H has the action of extracting hydrogen of hydrocarbons and the action of etching carbon, but diamond is said to have a significantly lower etching rate than other carbons, and in the process of forming a diamond thin film, Carbon other than diamond is discharged by being combined with hydrogen atoms H, and only diamond is deposited on the surface of the substrate 4 to form a thin film. Therefore, in order to obtain a diamond thin film having good crystallinity, it is necessary to deposit diamond in an atmosphere having an appropriate composition ratio of hydrogen atoms H excess.

[0004]

However, in the conventional method for producing a diamond thin film, since a mixed gas of methane, alcohol or the like and hydrogen is used as a raw material gas, carbon atoms generated by decomposition of the carbon atom are generated. It is difficult to independently control the amounts of C and hydrogen atoms H. Therefore, it is desirable to control the filament 9 of FIG. 2 and the microwave power source (discharge) of FIG. 3 so that the optimum conditions for the decomposition of methane and alcohol are obtained. When hydrogen is present, energy is also given to hydrogen, and it is impossible to judge whether or not methane or alcohol (carbon raw material) is given the optimum energy for its decomposition. Therefore, there is a problem that the controllability of the reaction is poor and the diamond thin film cannot be formed in a desired thickness and area with good crystallinity.

The present invention was devised to solve the above problems, and provides a method for producing a diamond thin film having good reaction controllability, in which the amounts of carbon atoms C and hydrogen atoms H can be independently controlled. The purpose is to do.

[0006]

In order to achieve the above object, in the method for producing a diamond thin film of the present invention,
A raw material mainly composed of carbon and hydrogen atoms are supplied from different sources into the vacuum container to deposit diamond on the surface of the substrate in the container.

[0007]

By supplying the raw materials mainly composed of carbon and the hydrogen atoms H into the vacuum vessel from different sources, the amounts of the carbon atoms C and the hydrogen atoms H to be fed into the vacuum vessel can be adjusted in the respective sources. Since it can be controlled independently, the atmosphere used for diamond deposition can be controlled by hydrogen atoms H.
A diamond thin film having good crystallinity can be obtained by adjusting the component ratio to be excessive.

[0008]

Next, an embodiment of the present invention will be described.

FIG. 1 shows a structural example of a manufacturing apparatus for manufacturing a diamond thin film by the method of the present invention. An ion gun 2 as a supply source of hydrogen atoms H is attached to the upper part of the side wall of the vacuum container 1 with its ion emission port 2a facing the inside of the vacuum container 1, and a carbon atom C supply source is provided in the center of the bottom of the vacuum container 1. Raw material cup 3 containing methane, alcohol, etc.
Is provided. A high frequency coil 7 is provided near the upper portion of the raw material cup 3. The substrate 4 for depositing diamond is horizontally installed right above the raw material cup 3 in the vacuum container 1 and at a position slightly higher than the ion emission port 2a. An ion filter (mesh-shaped electrode) 5 is provided between the ion emission port 2 a and the substrate 4. The ion filter 5 is negatively biased and the substrate 4 is positively biased. In addition, 6 is a vacuum container 1
This is an exhaust port formed at the bottom of the container 1, and the inside of the container 1 is exhausted from the exhaust port 6 to maintain a constant degree of vacuum.

The ion gun 2 is originally constructed so as to generate hydrogen ions H ⁺ by decomposing hydrogen molecules H ₂ and the like, but excitation that is not ionized when the hydrogen ions H ⁺ are generated The generated hydrogen atoms H are also generated at a predetermined rate. Therefore, hydrogen ions H ⁺ and excited hydrogen atoms H are supplied into the vacuum chamber 1 in a mixed state. Then, the hydrogen ions H ⁺ which inhibit the growth of the diamond crystal are trapped by the ion filter 5, and only the excited hydrogen atoms H pass through the electrode 5 and are supplied to the periphery of the substrate 4.

On the other hand, the methane, alcohol, etc. that evaporate and rise from the raw material cup 3 are decomposed when passing through the high frequency coil 7 and by the action of extracting hydrogen by the excited hydrogen atoms H, and the surroundings of the substrate 4. Is supplied to.

Thus, the substrate 4 is exposed to an atmosphere in which hydrogen atoms H excited by the ion gun 2 and carbon atoms C and hydrogen atoms H from the raw material cup 3 are in excess of the hydrogen atoms H, and the surface thereof (here Then, diamond and graphite are deposited on the bottom surface. Then, carbon other than diamond combines with the excited hydrogen atom H and is discharged. The state and supply amount of the excited hydrogen atom H are
It can be controlled by the ion gun 2. Positive ions such as hydrogen ions H ⁺ mixed in the atmosphere are rejected by the positively biased substrate 1 itself, so that a diamond thin film with good crystallinity can be obtained. By adjusting the supply amount of hydrogen atom H from the ion gun 2 and the vaporization amount of methane, alcohol, etc. from the raw material cup 3, the amounts of carbon atom C and hydrogen atom H in the atmosphere can be independently adjusted. Since it can be controlled, the reaction controllability during crystal growth is good. Therefore, according to this apparatus, a diamond thin film having a desired thickness and area can be obtained.

A plasma gun may be used instead of the ion gun 2 to supply the excited hydrogen atoms H into the vacuum chamber 1 in a mixed state with the electrons e ⁻ and hydrogen ions H ^+. .. Even in that case, the hydrogen ion H ⁺ is trapped by the ion filter 5. Electronic e
^{The −} passes through the ion filter 5, but it is said that the existence of the electron e ⁻ is rather advantageous in forming the diamond thin film.

The diamond thin film produced as described above has various applications. The following are examples of main applications that utilize the characteristic properties of diamond thin films.

(1) Utilizing the property of being extremely hard, the tool edge is extended by coating the cutting edge of a cutting tool or the like.

(2) Utilizing the property of high thermal conductivity,
Heat sink (heat sink) for cooling semiconductor laser devices, etc.
Used for.

(3) Utilizing the property of having a high refractive index, it is used as an optical window material.

(4) It is applied to a blue light emitting device by utilizing the property that the band gap is large.

(5) Utilizing the acoustic characteristic, the speaker characteristic is improved by coating the speaker cone with the speaker characteristic.

[0020]

In summary, according to the method for producing a diamond thin film of the present invention, carbon atoms C and hydrogen atoms H are supplied from different sources into the vacuum container, respectively.
Since the amounts of carbon atoms C and hydrogen atoms H supplied into the vacuum chamber can be controlled independently in each supply source, the atmosphere used for diamond deposition is adjusted to a proper component ratio of hydrogen atom H excess. Thus, a diamond thin film having a desired crystallinity and a desired thickness and area can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a manufacturing apparatus for manufacturing a diamond thin film by the method of the present invention.

FIG. 2 is a schematic configuration diagram showing a conventional example.

FIG. 3 is a schematic configuration diagram showing a conventional example.

[Explanation of symbols]

 1 Vacuum container 2 Hydrogen atom supply source 3 Carbon atom supply source 4 Substrate 5 Ion filter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Joji Shinohara 3-15-1 Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries Ltd. Technical Research Institute

Claims (1)

[Claims] 1. A method for producing a diamond thin film, wherein carbon atoms and hydrogen atoms are supplied from different sources into a vacuum container to deposit diamond on the surface of a substrate in the container.