JPH01172203A - Carbon film - Google Patents

Abstract

PURPOSE:To provide a novel carbon film different from conventional carbon films by specifying Raman spectrum of the carbon film. CONSTITUTION:A novel carbon film exhibiting Raman spectrum having principal peaks at 1,410cm<-1> and 1,450cm<-1> is provided. Said carbon film exhibits quite different Raman spectrum from that exhibited by carbon films known in the prior part, such as thin diamond film synthesized by several method, i-carbon film or carbon film contg. scattered crystallite of diamond in i-carbon, etc. The carbon film of the present invention has an amorphous structure consisting primarily of a same structure as turbulent diamond, containing scarcely graphitic structure, and having high hardness and high insulating property, etc. The carbon film can be synthesized by arc discharge, or arc discharge plus glow discharge.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a new carbon film different from conventional carbon films synthesized by PVD methods such as vapor deposition method, sputtering method, ion blating method, etc., and various CVD methods. It is related to.

Conventional technology Recently, many studies have been reported on diamond films and diamond-like carbon films that have hardness, thermal conductivity, resistivity, and other properties similar to those of diamond (Suzuki et al.; 1982).
Proceedings of the Japan Society of Applied Physics Autumn 2016, p. 18, p-T-6, etc.).

Regarding the synthesis method of diamond film, relatively high temperature,
CVD methods (thermal decomposition method, thermal filament method, plasma method, etc.) in which carbon is deposited using sufficient chemical reaction between the gas phase containing carbon or carbon compounds and the growth surface under gas pressure conditions; A PVD method (ion beam method, ionization vapor deposition method, etc.) has been proposed in which high-speed carbon atoms, ions, hydrocarbon ions, etc. are bombarded onto a relatively low-temperature substrate in a higher vacuum.

A number of carbon films ranging from crystalline to amorphous have been reported using these synthesis methods. Carbon films are evaluated using energy loss spectroscopy, electron beam diffraction, etc., but Raman spectroscopy is considered particularly effective because it can clearly separate carbon allotropes. The Raman spectrum of diamond shows a sharp peak near 1330c+w-', and for graphite it shows a sharp peak near 1580c+a-' and 13
A peak is shown near 60 cm-' (see Figure 2).

Examining the Raman spectrum of the carbon film synthesized by the above synthesis method, a crystalline film with almost the same properties as diamond has a sharp peak at 1330 cm-' among the broad peaks as shown in Figure 3. is observed, and it is considered to be a polycrystalline film of diamond. A collection of microcrystals is observed on the surface of the film, which is called a diamond thin film.

Furthermore, in a relatively hard amorphous film called i-carbon, a broad Raman spectrum with a main peak at 1520 to 1580 cm-' is observed (see FIG. 4).

The i-carbon film is an amorphous hard carbon film.

Alternatively, it is sometimes called a diamond-like carbon film.

If diamond microcrystal grains are scattered in the i-carbon film, the Raman spectrum will have a sharp diamond peak among the broad peaks.

Problems to be Solved by the Invention The present invention provides diamond thin films made by various synthetic methods, i.
The present invention provides a new carbon film that exhibits a Raman spectrum completely different from conventionally reported films, such as carbon films or i-carbon films in which diamond microcrystals are interspersed.

Means for Solving the Problems The new carbon film described in the present invention is realized by adding arc discharge to arc discharge or glow discharge.

The mechanism by which a carbon film that exhibits a Raman spectrum that is completely different from that of previously reported films is synthesized by using working arc discharge is not yet known. We believe that the cause is that, compared to electric discharges, it becomes a high-temperature plasma state, albeit locally, and the density of ions, electrons, and neutral particles such as radicals increases.Therefore, other than arc discharges, for example, atmospheric pressure We believe that it is possible to synthesize similar films by creating thermal plasma nearby using microwaves or the like.

EXAMPLE FIG. 1 shows an outline of the apparatus used to synthesize the carbon film of the present application. This is a plasma injection CVD apparatus that the present inventors have already proposed (Japanese Patent Laid-Open No. 6
No. 1-130487: Plasma Injection CVD Apparatus) is composed of a plasma tube 1 and a vacuum chamber 2 in which a substrate 11 is installed. An excitation coil 3 is installed around the outer periphery of the plasma tube 1 to generate a glow discharge inside the tube.

Further, an electrode 9 is installed inside the plasma tube 1, and a potential is set between it and the substrate 11 or the substrate installation table 12. 10
Ar gas and CI4 gas are introduced into a plasma tube 1 evacuated to a high vacuum of Torr or higher.

The introduced gas is turned into plasma by high frequency power applied to the excitation coil 3. Thereafter, a potential difference is set between the electrode 9 and the substrate 11 or the substrate installation stand 12 using the DC power supply 10. Usually, this potential difference accelerates ions in the plasma or causes glow discharge between the electrode 9 and the base 11. If the pressure inside the plasma tube, the potential difference between the electrode 9 and the base 11, the distance 2 between the electrode 9 and the base 11, etc. are appropriately set, arc discharge will occur between the electrode 9 and the base 11. For example, the distance between the electrode 9 and the base 11 is 15 cm.

The gas pressure in the plasma tube 1 is 0.3 Torr (the introduced gases are Ar gas and CH4 gas), and the specific resistance of the substrate is approximately 0.1.
In the case of ΩCS, the potential difference between the electrode 9 and the substrate 11 is 0.8
Arc discharge occurs near kV. A film is synthesized on the surface of the substrate 11 using this arc discharge. The raw material gas used is not limited to CHa gas (any hydrocarbon gas may be used. Also, the equipment used is PI gas).
- It is not limited to a CVD apparatus (for example, it may be of any configuration as long as it generates arc discharge, such as a parallel plate type sputtering apparatus).

Film synthesized using this method (hereinafter abbreviated as arc discharge film)
The Raman spectrum of is shown in FIG. As can be seen from Fig. 5, the Raman spectrum of the film synthesized using arc discharge shows broad main peaks at 1410 and 145 Qcm-', and it is found that -It is completely different from the Raman spectrum of carbon or amorphous carbon.High-energy Ar ions (100Kev) on the surface of natural diamond
(above)) and then measure the Raman spectrum, it is found that the diamond crystal is not at 1330 cm-' but at 1
370.1410, 1450c "1 Nigo (weak peak was observed. This is thought to be due to the disturbance of the crystallinity of the diamond on the surface by high-energy Ar ions.
It is presumed that the arc discharge film that mainly has the same peak is a film with the same structure as disordered diamond. When the arc discharge film was analyzed by electron diffraction and transmission electron microscopy, no crystallinity was observed and it was found to be amorphous. Also, according to energy loss spectroscopy (ELLS) (see Figure 7)5
A plasmon peak due to π electrons of ~8 ev was not observed, and it is thought that a graphite-like structure is not included much.

From the above, the arc discharge film is an amorphous film that does not contain much graphite-like structure and has the same structure as disordered diamond, and it shows a Raman spectrum with a broad peak at 1410.14500 "1". This can be said to be a new carbon film, different from the film reported by.

The characteristic of the arc discharge film is that it is extremely hard (it could only be scratched with a glass cutter equipped with a diamond tip.The arc discharge film also exhibits insulating properties and has a specific resistance of IQIOΩC1 or higher.Adhesion of the film is good, especially Si,
It exhibits extremely strong adhesion to Ge and Sn substrates. A
Although adhesion is insufficient for some substrates such as U, Ag, and Cu, this can be overcome by providing an intermediate layer such as Si that exhibits good adhesion.

Taking advantage of the above characteristics, we can improve the durability of tools such as wear-resistant coatings,
It can be expected to be applied to applications that require wear resistance.

Effects of the Invention The present invention provides a carbon film that is different from those previously reported, with an amorphous structure that does not contain much graphite-like structure and is mainly the same structure as disordered diamond. It has become possible to develop a wide range of applications by taking advantage of its excellent properties such as hardness and insulation, and its effects are significant.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of the apparatus used in carrying out the present invention;
Figure 2 is a Raman spectrum diagram of diamond and graphite, Figures 3 and 4 are Raman spectrum diagrams of a diamond film and an i-carbon film, respectively, and Figure 5 is a Raman spectrum diagram of a carbon film described in the present invention. FIG. 6 is a Raman spectrum diagram of diamond before and after the surface is bombarded with Ar ions, and FIG. 7 is a Raman spectrum diagram of diamond, graphite, and the carbon film described in the present invention. Name of agent: Patent attorney Toshio Nakao and 1 other person
J Diagram 2;・Friend Salvation (Nosei Diagram 3 2 no Danta) (C□-ri 4th Mathematics (1 for C)) Diagram 5! 2・°°・1: 11.-°. 016. ,,,:,,:2:;;,':E・,-゛. /π0 /,!;l)0 /,3% thread (cm”) Fig. 6↓ノ340 /,fl)0 147) 0 /, 300
Blade pattern a (cm-ri)

Claims (5)

[Claims] (1) 1410cm^-^1 and 1450cm^-
A carbon film showing a Raman spectrum with ^1 as the main peak. (2) The carbon film according to claim 1, wherein the carbon film is synthesized using arc discharge. (3) The carbon film according to claim 1, wherein the carbon film is synthesized using a combination of arc discharge and glow discharge. (4) The carbon film according to claim 1, wherein the carbon film is synthesized using thermal plasma. (5) The carbon film according to claim 1, wherein the carbon film is amorphous.