JPS6296397A - Production of diamond - Google Patents

Abstract

PURPOSE:The vapor-phase reaction of an oxygen-containing compound is carried out with electron cyclotron resonance plasma to produce crystalline diamond of very little content of black carbon and amorphous carbon. CONSTITUTION:An oxygen-containing compound is subjected to vapor-phase reaction using electron cyclotron resonance plasma to effect vapor-phase deposition of diamond. The oxygen-containing compound is, e.g., saturated monohydric alcohols, ketones, aldehydes, ethers, carboxylic acids, esters and polyhydric alcohols. The compounds of 30 or less carbon atoms, especially 15 or less carbon atoms, are preferred, because they are easy to handle.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing diamond, which has excellent properties as an insulating material and a material for electronic devices such as heat sinks.

(Prior Art) Recently, various methods of producing diamond from a gas phase have been attempted. However, the conventional method has many problems in terms of manufacturing technology, and as a result, the diamond production rate is low and the technology has not been developed for practical use.

For example, the ion beam method using hydrocarbons such as methane as a raw material (Japanese Patent Application Laid-Open No. 60-103099), chemical vapor deposition method, and plasma vapor phase method are being studied, but black carbon is likely to be produced as a by-product. It is necessary to make the raw material extremely thin with a diluent gas such as hydrogen gas, and as a result, the growth rate is 1 μm /
In addition, the ion beam method had the problem of being extremely slow at less than hr, and the ion beam method had problems such as the tendency to generate amorphous carbon.

(Problems to be Solved by the Present Invention) The present inventor has tried various methods for suppressing the by-production of black carbon and increasing the growth rate of diamond when diamond is precipitated from the gas phase. As part of this research, we investigated using carbon sources other than hydrocarbons as raw materials, and discovered that compounds containing oxygen exhibit a surprisingly unique phenomenon.As a result of further intensive research, we have arrived at the present invention.

(Means for Solving the Problems) That is, the present invention relates to a diamond manufacturing method characterized by causing an oxygen-containing compound to undergo a gas phase reaction using electron cyclotron resonance plasma and precipitating diamond from the gas phase.

The oxygen-containing compound containing oxygen, carbon, and hydrogen used in the present invention may be entrained in a gaseous, solid, or liquid state by a carrier gas or under reduced pressure and supplied to the reaction system. Preferably, it is supplied in the form. In particular, it is a compound with a carbon number of 30 or less, and a compound with a carbon number of 15 or less is preferred for ease of handling.

These oxygen-containing compounds are compounds containing oxygen, carbon, and hydrogen, but may also contain sulfur, nitrogen, and/or rogens.

Examples of the oxygen-containing compounds of the present invention include ethanol,
Methanol, propatool, butanol, 8ec-butyl alcohol, tert-7'yl alcohol, pentanol, hexanol, octatool, 4-methyl-2
- Saturated alcohols such as pentanol, adamantanol, 2,3-dimethyl-2-butanol, furfuryl alcohol, cyclohexanol, acetone, acetylacetone, methylpropyl ketone, acetonyl acetone, ethyl methyl ketone, diethyl ketone, Diisobutyl ketone, dibutyl ketone, diethyl ketone, 3゜3-
Dimethyl-2-butanone, butyl methyl ketone, methyl isopropyl ketone, isobutyl methyl ketone, ketones such as cyclohexanone, acetaldehyde, propionaldehyde, butyraldehyde, formaldehyde,
Aldehydes such as propionaldehyde, 2-ethylhexylaldehyde, propylaldehyde, methyl vinyl ether, ethyl ether, methyl ethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, cyclobyl ether, diisopropyl ether, trimethoxydimethane, ethyl vinyl ether , butyl ether, methylene glycol dimethyl ether, ethers such as furan, phenic acid, succinic acid, acetic acid, 3.3-dimethylglutaric acid% 2-ketopropionic acid, 7-maric acid, phlopionic acid, maleic acid, caproic acid, glutaric acid Carboxylic acids such as methyl acetate,
Ethyl acetate, trimethylacetic acid, methyl formate, ethyl formate, propyl formate, isopropyl formate, trimethyl citrate, triethyl citrate, dimethyl succinate, diethyl succinate, dimethyl oxalate.

Diethyl oxalate, methyl methacrylate, ethyl methacrylate, trimethyl acetate, methyl 2-ketopropionate, dimethyl fumarate, diethyl fumarate, ethyl propionate, methyl propionate, butyl propionate, propyl acetate, isopropyl acetate, maleic acid Ethyl, methyl maleate.

esters such as dimethyl malonate, ethyl malonate, and methyl malonate; polyhydric alcohols such as 17-ethylene glycol, 2-tetramethylethylene glycol, butanediol, butylene glycol, and cyclohexane dimetatool;

It also includes ether alcohols, ester ethers, ester alcohols, ester ketones, ketone alcohols, and further includes aromatic compounds such as phenol and unsaturated compounds.

Among these oxygen-containing compounds, preferred compounds are alcohols represented by the structural formula of HO-CH, -R, -CH, -OH.

R, -C-R.

Yam A ketone represented by the structural formula.

几, -CH An aldehyde represented by the structural formula of
Also included are ether carboxylic acids, ether esters, ketone esters, ether alcohols, ketone alcohols, etc. represented by the structural formulas -R2-COOH, R,-0-2-CO0-R,1O.

However, in the above structural formula, R,, R2 and 几 have 3 carbon atoms.
It is an aliphatic or alicyclic hydrocarbon of 0 or less, and some hydrogen atoms may be substituted with halogen atoms, and carbon atoms may be substituted with sulfur or nitrogen atoms.

Further, these oxygen-containing compounds are compounds in which the ratio (0/C) of the number of oxygen atoms to the number of carbon atoms is 1/1-Zoo, and preferably 1/1 to 1/30.

Further, these oxygen-containing compounds and hydrocarbons basically consisting of carbon and hydrogen may be used in combination. In this case, the hydrocarbons used may be entrained in a gaseous, liquid, or solid state by a diluent gas or under reduced pressure and supplied to one reaction system, but they are supplied in an extremely minute state, preferably in a sublimated or gaseous state. Preferably. In particular, it is a hydrocarbon with a carbon number of 30 or less, and a hydrocarbon with a carbon number of 15 or less is preferred from the viewpoint of ease of handling.

In the present invention, the amount of oxygen-containing compound supplied varies depending on the type of oxygen-containing compound, the gas phase reaction method and apparatus, the use of carrier gas, etc., but generally increases with the size of the reaction chamber. In the case of a reaction tube with a diameter of 205 m, 0.001 f/hr - 100 r/hr is preferable. If it is less than 0.001 f/hr, the growth rate will be low, and if it is more than 100 t/hr, black carbon will be produced, which is not preferable.

Although these oxygen-containing compounds may be supplied alone to the reaction system, it is preferable to supply them together with an inert gas such as argon or a carrier gas such as hydrogen gas. At this time, the flow rate of the carrier gas is within a range where the gas pressure can be controlled. Also, the gas pressure is generally 10-'
~10-” Torr.

In the present invention, electron cyclotron resonance plasma refers to
2.45 G while applying a magnetic field of 875 Gauss under reduced pressure
This is plasma generated by cyclotron resonance of the electrons generated by irradiating Hz microwaves.

In the present invention, it is preferable to use an ion accelerating voltage to accelerate the ions generated in the plasma when depositing diamonds from the gas phase so as to cause them to collide with the substrate, and the ion accelerating voltage is preferably 100 V to 2000 V.

In the present invention, it is preferably used to provide a base material as a place for depositing diamond.

Such substrates include 1, for example, single crystal silicon wafers, quartz, silicon compounds such as silicon carbide, silicon nitride, etc.
Carbonaceous materials such as graphite, glassy carbon, and diamonds,
Metals such as stainless steel, molybdenum, iron, nickel, copper, tungsten, niobium, tantalum, vanadium, chromium, hafnium, and alloys containing these components as main components, oxides such as '9-fire, alumina, and zirconia are used. These base materials are used in various shapes such as plate, flake, granule, powder, and filament.

The substrate may be heated by gas or by an external or internal heater. Generally, the temperature of the substrate is Zoo
℃ to 1200°C, for example, in the case of plasma gas phase reaction, 20o'C to 1000°C is preferable, and below 100°C, carbon tends to become amorphous.

At 1200° C. or higher, black carbon is also produced as a by-product, which is not preferable.

The present invention will be explained below with reference to the drawings.

FIG. 1 is an example of the apparatus used in the present invention. Inside the reaction chamber (4) and (Tor)
r) After reducing the pressure by K, open the valve (2) and supply the oxygen-containing compound at a predetermined amount from the raw material gas supply device (1).

While maintaining the gas pressure at a predetermined gas pressure, a magnetic field is applied in the reaction chamber by the electromagnetic coil (7) K, and microwaves are radiated from the microwave oscillator (3) to react with the cyclotron resonance plasma. It is generated in the chamber (4). A ground electrode (5) provided on the inner wall of the reaction chamber (4)
) and the porous bias electrode (6).
The ion beam is applied in the ovo range to accelerate the ions in the plasma to form an ion beam that collides with the substrate (8) to deposit a carbon film on the surface of the substrate. X of the carbon film obtained in this way
As a result of measuring the line diffraction pattern (shown in Figure 3, where the vertical axis shows the X-ray diffraction intensity and the horizontal axis shows the diffraction angle (2θ)) and laser Raman scattering spectrum, it was found to be diamond.

(Effects of the Present Invention) According to the present invention, by using an oxygen-containing compound as a raw material, it is possible to obtain a crystalline diamond containing little black carbon or amorphous carbon, which is extremely useful industrially.

(Example) The present invention will be explained below using examples.

Example 1 Reaction chambers (4) and (g) were prepared using the equipment shown in Figure 1.
After reducing the pressure inside the reactor to 10-' Torr, ethanol was supplied at a rate of 2 f/hr) while flowing hydrogen gas at t-26 cc/m from the raw material supply device (1). At this time, the gas pressure in the reaction chamber was 10-' Tor
r while applying a magnetic field of 875 Gauss and 2.45 GH! irradiated with microwaves to generate electron cyclotron resonance plasma. Furthermore, the earth electrode (5
) and bias electrode (6), 800 V'jr is applied,
The St wafer used as the base material (8) was heated to 400°C. One hour later, it was found by electron microscope observation and X-ray diffraction pattern measurement that a 3 μm diamond film had been formed on the SN wafer. The XS diffraction pattern obtained in this example is shown in FIG.

Example 2 Using the apparatus shown in Fig. 2, the inside of the reaction chamber (4) was
After reducing the pressure to Torr, hydrogen gas was supplied from the raw material supply device (1) at a rate of C2.51/hr while flowing hydrogen gas at 26 cc/ma along with acetic acid. At this time, the gas pressure in the reaction chamber is 10 Torr.
While maintaining the temperature, a magnetic field of 875 Gauss was applied and microwaves of 2.45 GH2 were irradiated to generate electron cyclotron resonance plasma. Si used as base material
Ueno was heated to 300°C. 1 hour later Si sea urchin/
- It was confirmed by electron microscope observation and X-ray diffraction pattern measurement that a diamond thin film with a thickness of 2.5 μm was formed on the surface.

[Brief explanation of drawings]

1 and 2 are schematic diagrams of the apparatus used in the present invention, and FIG. 3 is an X-ray diffraction pattern obtained in the present invention. In FIGS. 1 and 2, l: raw material supply device; 2°/° valve, 3/°° microwave oscillator, 4.
10 - Reaction chamber, 5°゛° earth electrode, 6-°° bias electrode, 7°°゛ electromagnet coil, 8°゛・substrate, 9
°・°Heater, 11°°. It is a vacuum exhaust device. In Figure 3, the vertical axis is the X-ray diffraction intensity, and the horizontal axis is the diffraction angle (
2θ). Patent applicant: Asahi Kasei Industries, Ltd. Figure 1 Figure 2 Figure 3 26 2e

Claims (1)

[Claims] A diamond manufacturing method characterized by causing an oxygen-containing compound to undergo a gas phase reaction using electron cyclotron resonance plasma and precipitating diamond from the gas phase.