JPS63206389A - Production of diamond thin film - Google Patents

Abstract

PURPOSE:To form the titled thin film having excellent adhesivity and high quality, on a substrate in high efficiency, suppressing deposition of graphite, by carrying out carbon deposition in combination with carbon ion irradiation in vacuum. CONSTITUTION:A substrate 4 is attached to a holder 2 placed in a vacuum chamber evacuated to a vacuum of about 10<-5>-10<-7>Torr. Carbon 12 is heated and evaporated from an evaporation source 8 such as electron beam having an evaporation material 10 such as carbon pellet and is deposited on the substrate 4. Simultaneous or alternate to the carbon deposition process, ion beam 22 containing carbon ion and extracted from an ion source 20 is subjected to mass spectrum analysis with a mass analyzer 24. A low energy carbon ion beam 26 having an energy of <=10keV is optionally scanned along XY direction with a scanning electrode 28, etc., to expand the beam area and irradiated to the substrate 4 at an ion/carbon ratio of 0.1-100% in terms of particle ratio (compositional ratio) based on the deposited carbon 12. The titled thin film 6 can be formed on the substrate 4 by this process while monitoring the film thickness with a thickness monitor 14. The adhesivity of the thin film is improved by the presence of a mixed layer 5 composed of the constituent substances of the substrate 4 and of the thin film 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] This invention relates to a method for producing a diamond thin film on a substrate by a combination of vacuum evaporation and ion beam irradiation.

[Conventional technology]

Conventionally, as means for producing (synthesizing) a diamond thin film on a substrate, a chemical vapor deposition method such as a plasma CVD method using a hydrocarbon or organic compound gas or a photoCVD method has been adopted.

[Problem that the invention seeks to solve]

However, in the conventional methods described above, (1) graphite precipitation occurs at the same time as diamond crystal growth occurs in hydrocarbon or organic compound gases, and (2) the substrate and gas atmosphere are heated to high temperatures (e.g., about 800°C to 1000°C). Since it is necessary to heat and process, there are problems such as the materials that can be used as the substrate are greatly limited.

Therefore, the main object of the present invention is to provide a method for manufacturing a diamond thin film that solves these problems.

[Means for solving problems]

The method for producing a diamond thin film of the present invention is characterized in that a diamond thin film is produced on a substrate by vapor depositing carbon and irradiating the substrate with a carbon ion beam in a vacuum.

[Effect]

When the substrate is evaporated with carbon and irradiated with a carbon ion beam, the irradiated carbon ions act as a nucleation energy source to cause the graphite-structured carbon deposited on the substrate to grow into diamond crystals. A diamond thin film is fabricated on top.

〔Example〕

FIG. 1 is a schematic diagram showing an example of an apparatus for carrying out the method according to the invention. A substrate (for example, a substrate) 4 is housed in a vacuum container (not shown) attached to, for example, a holder 2, and an evaporation source 8, an ion source 20, a mass spectrometer 24, and a scanning electrode 28 are directed toward the substrate 4. A beamline with a

The evaporation source 8 in the illustrated example is an electron beam kiln source,
A carbon pellet is used as the evaporation material 10, and carbon 12 obtained by heating and vaporizing it with an electron beam can be deposited on the surface of the base 4. However, since carbon is sublimable, the film formation rate may be slow when using an electron beam evaporation source. It may be an evaporation source, or an evaporation source of a type in which carbon is evaporated by vacuum arc discharge at a cathode made of carbon, or the above may be used in combination.

The ion source 20 is also not limited to a specific type, and an ion beam 22 containing carbon ions is extracted from it at a predetermined energy, and then sent to a mass spectrometer 24.
The carbon ion beam 26 is extracted by mass spectrometry using a scanning electrode 28 or the like, and is scanned in the X and Y directions using a scanning electrode 28 or the like to enlarge the area and irradiate it toward the surface of the base 4. . Note that 14 is a film thickness monitor for a thin film produced on the substrate 4.

When preparing the film, the inside of the vacuum container should be heated at a temperature of, for example, 10-' to 10-10
After evacuation to about -' Tor r, the carbon ion beam 26 subjected to mass spectrometry as described above is applied to the substrate 4 at the same time as or alternately with the carbon 12 from the evaporation source 8 being evaporated onto the substrate 4. irradiate towards. At that time, the particle ratio (composition ratio) ions/carbon of the irradiated carbon ions to the deposited carbon 12 is preferably within the range of about 0.1% to 100%, and specifically within this range, the carbon ion beam Appropriate values are selected depending on the energy of 26 and the deposition rate of carbon 12.

As a result of the above treatment, the irradiated carbon ions act as a nucleation energy source for crystallizing the graphite-structured carbon 12 deposited on the substrate 4 into diamond, thereby e.g. A diamond thin film 6 is produced on the surface of the base 4.

In that case, the energy of the carbon ion beam 26 is set to 10K from the viewpoint of minimizing damage (defects) caused inside the diamond thin film 6 by the irradiation.
Low energy of about eV or less, more preferably several hundred eV
Although there is no particular lower limit, it is realistically about 10 eV or more, as it is the limit at which the ion beam 22 can be extracted from the ion source 20.

Further, the irradiation angle of the carbon ion beam 26 to the substrate 4 (the angle between the perpendicular to the surface of the substrate 4 and the carbon ion beam 26) is preferably within the range of about 0° to 60'; In this way, sputtering of the deposited carbon 12 due to irradiation with the carbon ion beam 26 can be suppressed.

In addition, during film production, the substrate 4 may be heated by heating means (
It may be heated to about several hundred degrees Celsius by heating (not shown) or cooled by a cooling means (not shown).Heating can promote the diamond formation reaction by thermal excitation, and the diamond formation reaction can be generated in the diamond thin film 6. Defects can be removed during film formation, and cooling can protect the base 4 if it is sensitive to heat.

The characteristics of the film forming method as described above are listed below.

(2) Precipitation of graphite can be suppressed by the energy of the irradiated carbon ions, and a homogeneous diamond thin film 6 can be obtained. In particular, in this method, the vapor deposited carbon 12 is irradiated with a carbon ion beam 26 of the same quality as the carbon ion beam 26, so that the vapor deposited carbon 12 can be excited easily, diamond formation is efficient, and a high quality diamond thin film 6 without contamination with impurities can be obtained. .

(2) Low-temperature processing is possible because thermal excitation is not the main component, and as a result, the range of materials that can be used as the substrate 4 is greatly expanded.

■ In the conventional method, the kinetic energy of the ions generated in the gas phase is small, so there was a problem that the adhesion of the diamond thin film to the substrate was poor and it was easy to peel off.
In the method of this example, if the energy of the carbon ion beam 26 is increased to a certain extent within the above-mentioned range, the knock-on effect of the carbon ions will cause the area near the interface between the substrate 4 and the diamond thin film 6 to appear, for example, as shown in FIG. A mixed layer 5 consisting of the constituent substances of the two is formed on the substrate 4, which acts like a model.
The adhesion of the diamond thin film 6 to the diamond film is good and it becomes difficult to peel off.

■ Since thin deposition of carbon-12 and irradiation with carbon ion beam 26 are used together, and both contribute to film formation, a larger film thickness can be obtained in a shorter time than with conventional methods, increasing the production efficiency of diamond thin film 6. is good.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to efficiently produce a high quality diamond thin film that suppresses the precipitation of graphite and is free of impurities. Moreover, since low-temperature treatment is possible, the range of materials that can be used as a substrate is greatly expanded. It is also possible to improve the adhesion of the diamond thin film to the substrate.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of an apparatus for carrying out the method according to the invention. FIG. 2 is a schematic cross-sectional view partially showing an enlarged example of a substrate on which a diamond thin film is formed by the method according to the present invention. 4... Substrate, 6... Diamond thin film, 88. . Evaporation source, 12... Carbon, 20... Ion source, 24.
...Mass spectrometer, 26...Carbon ion beam.

Claims (1)

[Claims] (1) A method for producing a diamond thin film, which comprises producing a diamond thin film on a substrate by vapor depositing carbon and irradiating the substrate with a carbon ion beam in a vacuum.