JPS63265890A - Production of thin diamond film or thin diamond-like film - Google Patents

Abstract

PURPOSE:To enhance formation velocity of the titled thin film by impressing positive electric charge on a base body utilizing microwave plasma and forming the thin film on the base body. CONSTITUTION:In the case of exerting a magnetic field to the inside of a vacuum tank 11 and introducing microwave thereinto through a waveguide 12, resonance of an electron cyclotron is caused in the vacuum tank 11. When introducing H2 as reactive gas g0 and methane as a raw material g1 contg. carbon thereinto, high-energy radicals CH3*, CH2* or the like, electron and ions such as C<+> and CH3<+> are formed as reaction formation gas and these are reached on a base body 15 to form a thin film thereon. At this time, when the temp. of the base body 15 is controlled by a base body holder 16 capable of heating or cooling, a thin diamond-like film and a thin diamond film are grown respectively at low and high temp. In this case, when impressing positive electric charge on the base body 15, electrons are reached on the surface of the base body and these contribute to decomposition and excitation of methane and H2 on the surface of the base body. Further in case the base body is etched and it consists of Si, the film can be formed at high velocity because cations forming SiC are prevented from being reached on the surface of the base body.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing diamond thin films or diamond-like thin films using microwave plasma.

Conventional technology Diamond is a material with excellent electrical insulation, thermal conductivity, hardness, and wear resistance.In addition to its traditional uses as cutting parts and wear-resistant parts, in recent years diamond has been used to take advantage of its properties. With the increasing integration of semiconductors, it is attracting attention as an electronic material such as an insulating film with good thermal conductivity, a surface protective film, and a semiconductor with a large band gap. Attempts have been made to synthesize

Although a diamond-like thin film cannot be identified as a diamond crystal structure, it has an amorphous structure and has properties similar to diamond, such as a Vickers hardness of 3oOoKg/
++112 or more, refers to those having properties such as high infrared light transmittance.

Conventionally, many methods have been proposed for producing diamond thin films. Representative examples of conventional devices are shown in FIGS. 2a and 2b. Figure 2a shows that when using thermionic number pair, the second
The figure is a diagram of an apparatus in which microwave plasma discharge is used. 1 is a vacuum chamber, 2 is a waveguide, 3 is a gas introduction section, 6 is a substrate, 6 is a substrate holder, and 8 is a thermionic emitting material. A mixed gas of hydrocarbon and hydrogen is introduced into the vacuum chamber 1 from the gas introduction part 3, and the interior of the vacuum chamber 1 is maintained at a required pressure (1 to several hundred Torrτ) by performing exhaust. The introduced mixed gas is activated by thermal decomposition by the thermionic radiation material 48 in case a, or by plasma discharge using microwaves introduced from the waveguide 42 in case b, to generate excited carbon such as ions and radicals. A diamond thin film or a diamond-like thin film is formed on the substrate 46. At this time, if the temperature of the substrate is adjusted using a substrate holder 〇 that can be heated or cooled, a diamond-like thin film can be obtained at low temperatures, and a diamond-like thin film can be obtained at high temperatures. (Japanese Patent Publication No. Sho EO-54995, etc.) However, a thin film of good quality suitable for practical use has not been obtained by any of these methods.

Problems to be Solved by the Invention These conventional techniques have the disadvantage that the film formation rate is extremely slow. In order to solve this problem, the present invention provides a diamond thin film that can be formed at a high rate and a method for manufacturing the same.

Means for Solving the Problems In order to solve the above problems, the present invention introduces at least one type of carbon-free reaction gas and at least a carbon-containing raw material into a vacuum chamber, and generates plasma by high-frequency discharge. A diamond thin film or a diamond-like thin film is deposited on the substrate surface to which a positive voltage is applied.

Effects The present invention has found that with the above-described configuration, by applying a positive voltage to the substrate, the film formation rate can be greatly increased. By using an inert gas as a reactive gas, plasma can be easily created and activation can be promoted. In addition, at least one of hydrogen, oxygen, and nitrogen is used as a reaction gas.
It was found that parts different from the diamond structure can be removed at high speed by using one. It also contributes to the activation of carbon-containing raw materials, making it possible to achieve higher speeds. Furthermore, if a material containing at least one of saturated or unsaturated hydrocarbons, aromatic hydrocarbons, alicyclic hydrocarbons, and polynuclear hydrocarbons is used as the carbon-containing raw material, a thin film with a lower impurity concentration can be obtained. .

In addition, alcohol, ether,
Those containing at least oxygen, such as aldehydes, ketones, and carboxylic acids, or aromatic amines.

If an aliphatic amine containing at least nitrogen is used, the speed can be further increased. Furthermore, when a magnetic field is applied and the intensity of the magnetic field is created above the electron cycloton resonance condition, it becomes possible to highly excite the reactive gas, and the effect of reacting and removing parts different from diamond becomes greater.

Embodiment FIG. 1 shows an embodiment of a plasma apparatus for forming a diamond thin film or a diamond-like thin film according to the present invention.

11 is a vacuum chamber, 12 is a waveguide, 13 is a reaction gas introduction part,
14 is a raw material introduction part, 15 is a substrate, 16 is a substrate holder,
17 is an electromagnet.

A magnetic field is applied inside the vacuum chamber 11 to make it 876 Gauss, and the waveguide 1
When microwaves (2.45 GHz) are introduced from 2, electron cycloton resonance occurs within the vacuum chamber 11. This is followed by a reaction gas q. and raw material q1 containing carbon are introduced to generate plasma discharge. At this time, for example, the reaction gas q.

When methane is introduced as a raw material q1 containing hydrogen and carbon, high-energy radicals are produced as a reaction product gas, as shown in the figure.

For example, CH3, CH2 rice, CH rice, C coming, H2 rice, H*
etc., generate electrons and ions such as C", CH3", H2+, etc., which reach the substrate 16 and form a thin film.

At this time, when the temperature of the substrate is adjusted using a substrate holder 16 capable of heating or cooling, a diamond-like thin film grows at low temperatures and a diamond-like thin film grows at high temperatures.

When a positive voltage is applied to the substrate, electrons reach the surface of the substrate. These electrons decompose carbon-containing raw materials and reactant gases on the substrate surface.

Contributes to excitation. By etching the substrate, if the substrate is silicon, it is possible to prevent the cations that form SiC from reaching the surface of the substrate.

Therefore, it becomes possible to perform film formation at high speed.

Actually, the diamond thin film was obtained by maintaining the microwave output at 300 to 50 oW, the pressure in the vacuum chamber 11 at about 10 -5 to several Torr, and setting the temperature of the silicon substrate at 300 to 1000°C. Reactant gas q. and raw material q1 were introduced at a volume ratio of (1:1oo to 1:1). A positive voltage (~1 Kv) was applied to the substrate through the substrate holder.

The thus obtained diamond thin film was subjected to X-ray diffraction and Raman spectroscopy, and a peak identified as diamond was confirmed. In addition, Vickers hardness and electrical properties were measured: 1 ooooicg/lram2 and resistance 109Qcn
In summary, a film quality closer to that of natural diamond was obtained compared to conventional thin films. The growth rate was 571 m/hr or more. In addition, when the substrate temperature was room temperature 2, no diamond structure peak was observed in X-rays, etc., but a Vickers hardness of 4000 Kf/B2 was confirmed, and a resistance of 108
A high-quality film with a thickness of 0 m or more was formed. Furthermore, in observation of the SEM image, a smooth film was formed on the surface.

Note that the reaction gas 9o is a raw material q1 containing hydrogen and carbon.
Although methane was used as the reaction gas, the reaction gas is not limited to these, and instead of hydrogen, an inert gas, oxygen, or nitrogen may be used. Further, the reactive gas may be used alone, and Ar
Two or more types, such as and H2, may be mixed. Alternatively, an inert gas or the like that does not chemically react with the carbon-containing raw material may be used. Mixing an inert gas increases the speed, and hydrogen and the like have a great effect on creating a film closer to a diamond structure.

In addition, raw materials containing carbon include saturated or unsaturated hydrocarbons, aromatic hydrocarbons, and alicyclic hydrocarbons.

Polynuclear hydrocarbons, or those containing at least oxygen or nitrogen, are preferred; using hydrocarbons will result in films with fewer impurities,
Or when using raw materials containing at least oxygen or nitrogen, such as alcohols, ethers, aldehydes, ketones, carboxylic acids, aliphatic amines, aromatic amines, etc.
Oxygen and nitrogen are thought to play a catalytic role, speeding up oil production.

It is believed that it will be possible to use city gas, etc., resulting in lower costs. Energy can be given even if the intensity of the magnetic field is below the electron cycloton resonance condition, but when it is above the resonance condition, both the reactant gas and the raw material are highly excited, making it possible to increase the speed and improve the film quality.

Effects of the Invention The present invention can form a diamond thin film or a diamond-like thin film at high speed by applying a positive voltage to a substrate, and has a great effect on these industrial fields of application.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the plasma device used in the present invention, and Fig. 2 is a diagram of a plasma device commonly used in the past. It is a schematic diagram. 11... Vacuum chamber, 12... Waveguide, 13
・Old gas introduction section, 14... Raw material introduction section, 15
・・Group・Substrate, 16・・・・Substrate holder, 17・
····electromagnet. 1f-Soukou IC--Guno Ni Ruder (-11 Broan 1.5-44 Non

Claims (8)

[Claims] (1) Introducing at least one type of carbon-free reactive gas and a raw material containing at least carbon into a vacuum chamber, generating plasma by high-frequency discharge, and applying a positive voltage to a diamond thin film or diamond-like thin film on the substrate surface. A method for producing a diamond thin film or a diamond-like thin film, which comprises depositing. (2) The method for producing a diamond thin film or a diamond-like thin film according to claim 1, wherein the reaction gas contains an inert gas. (3) The method for producing a diamond thin film or a diamond-like thin film according to claim 1, wherein the reactive gas is hydrogen, oxygen, or nitrogen. (4) Claim 1, characterized in that the raw material containing carbon contains at least one of saturated or unsaturated hydrocarbons, aromatic hydrocarbons, alicyclic hydrocarbons, and polynuclear hydrocarbons. A method for producing the diamond thin film or diamond-like thin film described above. (5) The method for producing a diamond thin film or a diamond-like thin film according to claim 1, wherein the carbon-containing raw material contains at least oxygen such as alcohol, ether, aldehyde, ketone, carboxylic acid, etc. (6) The method for producing a diamond thin film or a diamond-like thin film according to claim 1, wherein the raw material containing carbon contains nitrogen such as an aromatic amine or an aliphatic amine. (7) A method for producing a diamond thin film or a diamond-like thin film according to claim 1, characterized in that a magnetic field is applied within a vacuum chamber. (8) The method for producing a diamond thin film or a diamond-like thin film according to claim 7, wherein the strength of the magnetic field is at least equal to or higher than an electron cycloton resonance condition.