JPS6385092A - Production of diamond film - Google Patents

Abstract

PURPOSE:To economically produce a diamond film having high diamond properties at a high film-forming rate, by introducing a gas of a carbon compound into electron cyclotron resonance plasma of hydrogen gas and leading the gas onto a substrate. CONSTITUTION:A plasma formation chamber 1 divided with a partition wall 6 having an opening 7 and a reaction chamber 2 having a substrate 9 placed at a distance of 10-30cm from the partition wall 6 are previously evacuated and the opening 7 of the partition wall 6 is then closed with a shutter. Hydrogen gas is introduced from an inlet 3 into the formation chamber 1 and microwave electromagnetic energy is applied from a microwave generator through a waveguide 4. A magnetic field is simultaneously applied to a coil 5 to form an electron cyclotron resonance plasma of the hydrogen gas. A bias voltage is then applied from a high-frequency electric power source 11 for bias to an electrode supporting the substrate 9 and a gas of a carbon compound, e.g. CH4, etc., is simultaneously introduced into the reaction chamber 2. The shutter is then opened to flow the resonance plasma into the reaction chamber 2 and the flows of both are led onto the substrate 9 to form a diamond film.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method corresponding to the improvement of the ion beam method described above, in which a hydrogen gas plasma is formed in advance by electron cyclotron resonance (ECR) and then a carbon compound raw material gas is used. Its main feature is to bring it into contact. Hydrogen gas ECR plasma is thus formed in a plasma formation chamber separate from the reaction chamber in which the raw material gas is decomposed and the film forming reaction takes place, and this hydrogen plasma decomposes hydrocarbons in the reaction chamber and at the same time decomposes the substrate. Since it is irradiated upward as well, it is possible to form a high-quality diamond thin film. EC
Since the R plasma can have a uniform plasma density and the plasma energy is sufficiently high, when the plasma stream enters the reaction chamber, it can achieve highly efficient decomposition of the raw material hydrocarbons and highly efficient deposition of diamond onto the substrate. This means that the film can be formed. Moreover, according to the present invention, there is no need to heat the substrate to a high temperature such as 1000° C., so that maintenance of the substrate and thermal economy are also excellent.

Furthermore, by applying an appropriate high-frequency bias voltage to the substrate, carbon ions generated by decomposition of the source gas can be accelerated toward the substrate surface, thereby increasing the film formation rate and further improving the quality of the diamond film.

FIG. 1 shows an example of a diamond film forming apparatus constructed according to the principles of the present invention. The principle of the present invention can be applied to other configurations [
It is clear that this can also be achieved. Now, as shown in the diagram, the diamond film forming apparatus has a plasma forming chamber 1 and a reaction chamber 2.
The two chambers are separated by a partition wall 6 having an opening lower part, and this opening can be opened and closed by a shutter (not shown). Hydrogen gas is introduced into the plasma forming chamber 1 from an inlet 3. The plasma formation chamber 1 is connected to a microwave oscillator (not shown) through a waveguide 4.
The plasma forming chamber 1 is connected to the plasma forming chamber 1 so that microwave electromagnetic energy of, for example, 2.45 GHz is applied to the plasma forming chamber 1. As a result, the hydrogen gas introduced into the chamber 1 is turned into plasma. Around plasma formation chamber 1
A coil 5 is disposed, and an ECR resonance plasma is generated by a magnetic field formed by a current applied thereto. For example, when a microwave of 2.45 GH is applied, the electron cyclotron frequency f is given by the following equation.

However, m is the mass of the electron, e is the electric charge, and B is the magnetic field applied by the coil 5. Substituting f = 2.45 GHz, when B = 875 (Gauss), electrons absorb the energy of the magnetic field, a resonance phenomenon occurs, and ECR resonance plasma is formed. The energy of plasma is 15
~20 eV is possible.

The plasma formation chamber 1 communicates with the reaction chamber 2 through the open lower portion of the partition wall 6 . An annular pipe 8 having a number of nozzle ports for introducing a carbon compound (for example, CH4) gas is arranged immediately downstream of the opening lower, so that the gas flows in when the shutter of the opening lower is opened. A carbon compound as a raw material gas is introduced into the ECR resonance plasma. This raw material gas is C
Hydrocarbons such as H4, C2H4, C2H2, C2H6, C
Alcohols such as H, OH, C2H50H, (CH3)
Any carbon compound such as ketones such as CO may be used.

Further downstream, an electrode 10 supporting a film-forming substrate 9 is arranged. Preferably, a bias voltage is applied to the electrode 10 from a high frequency power source 11.

As a result, the hydrogen plasma formed in the plasma formation chamber is extracted as an ion beam into the reaction chamber, and the carbon compound gas introduced into the reaction chamber is decomposed by the hydrogen plasma and becomes carbon ions, which are deposited on the substrate together with atomic hydrogen. A diamond film is formed.

Hydrogen gas and carbon compounds (CH4, C2H4, C6H6,
CH, OH, etc.) flow rate ratio is 1 to 0.001, preferably 1 to 0.01.

The distance between the reaction chamber partition wall and the substrate is 10 to 50 C11s, preferably 15 to 20 C1L.

As bias voltage, frequency vf = 1156 M
High frequency such as Hz, 0~100W, preferably 30~
It is aOW. Although it is possible to form a film at 3 OW or less, a high quality diamond film is formed at 50 W or more. When the temperature exceeds SOW, the film formation rate decreases. The bias voltage was a negative bias, and it was found that the optimum distance between the partition wall and the substrate was 15 to 20 cIrL.

The essential feature of the present invention is that ECR hydrogen plasma is used. ECR plasma is formed in a high vacuum, such as 10-' Torr. Therefore, there is no contamination of impurity gas or reaction gas. Furthermore, since the activity of the plasma is extremely high, no means for heating the substrate is required, or heating to about 400'C is sufficient. For this reason, it is possible to remove the necessary protective film without damaging the substrate of semiconductor functional elements such as Si.
A heat sink, an interlayer insulating film, etc. can be formed. Here, forming plasma using hydrogen gas plays an important role in forming a diamond thin film. In other words, atomic hydrogen decomposed and produced by plasma is irradiated onto the substrate as an ion beam, which serves to selectively remove the graphite bonds of carbon present on the substrate (which deteriorates the film quality). . As a result, only diamond bonds remain on the substrate, resulting in a high-quality diamond film.

The substrate may be Si, Mo, W, or SiC depending on the application.
, AIN, AI, Al2O3, etc. can be used.

EXAMPLE A diamond film was formed using the apparatus shown in FIG. First, the plasma formation chamber 1 and reaction chamber 2 are heated to 10” Torr.
Pre-exhaust until. The lower opening of the partition wall 6 was shut off by a shutter, and hydrogen gas was introduced into the plasma formation chamber at a flow rate of 50 d/min, and the pressure was adjusted to 10-' Torr. 2
．． ECR resonance plasma was formed by introducing microwaves of 45 GHz into the plasma formation chamber and applying a magnetic field of 875 Gauss to the coil 5.

On the other hand, in the reaction chamber 2, there is an S
i A single crystal substrate 9 was placed at room temperature, and 0 (4 gas) was introduced from the nozzle 8 at a flow rate of 5 d/min.
156MH 250W applied and no applied 2'
I used s.

Hydrogen plasma was allowed to flow into the reaction chamber using a shutter.

A film of about 10 μm was formed in a reaction time of about 2 hours.

When this film was examined by X-ray diffraction, peaks were found at the same (111) and (220) positions as in bulk diamond. The resistivity was 1013Ωα.

This value is close to that of bulk diamond. Further, the Vickers hardness was approximately 8,000. Note that, although the X-ray peak of the film without applying a bias voltage was slightly lower than the above, the crystallinity deteriorated and the characteristics deteriorated accordingly, but other advantages such as film formation speed were the same as those with the application of a bias voltage.

(Operation and Effect) As described above, it can be seen that according to the method of the present invention, a film with high diamond properties can be obtained at a high film formation rate.

Since the reactant gas pressure is in a high vacuum state of about 10-' Torr, high-purity ECR plasma can be used and a high-quality film can be produced. In addition, since the activity of the plasma is extremely high, the temperature of the substrate can be lowered, and the characteristics of the semiconductor element and the like that serve as the substrate can be maintained. In addition, because the plasma has high activity, it is possible to form a high-quality thin film that is close to that of bulk diamond. Furthermore, in the present invention, since hydrogen atoms are turned into plasma and directly irradiated onto the substrate, a high quality diamond film is formed.

Further, in a preferable case, by applying a bias from a high frequency power source, the generated carbon ions can be accelerated with high energy, and a film of even better quality can be generated.

[Brief explanation of the drawing]

FIG. 1 shows an apparatus for carrying out the manufacturing method of the present invention.

Claims (1)

[Claims] 1. Forming an electron cyclotron resonance plasma of hydrogen gas, introducing a carbon compound gas into this resonance plasma, and then guiding the flow of both onto a substrate to form a film. Method for manufacturing diamond film. 2. The manufacturing method according to item 1, wherein the electron cyclotron resonance plasma is formed in a plasma chamber, the substrate is placed in the reaction chamber, and the carbon compound gas is introduced into the resonance plasma led to the reaction chamber. 3. The first substrate has a high frequency bias applied to the substrate.
The manufacturing method according to item 1 or 2.