JPH1087396A - Hard carbon film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hard amorphous carbon film having an improved sliding characteristics and releasability. SOLUTION: This hard carbon film consists essentially of carbon and hydrogen, has <=0.5μm surface roughness Rmax without polishing and is very smooth. It is preferable that this hard carbon film has an amorphous structure from the standpoint of X-ray diffraction crystallography and is made of a cluster mixture having diamond and graphite structures. The number of the constituent carbon atoms of each cluster having a diamond structure is preferably 100-2,000 on average and that of each cluster having a graphite structure is preferably 100-2,000 on average.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amorphous thin film made of carbon and hydrogen. In particular, the present invention relates to an amorphous thin film having high hardness, low friction coefficient, and excellent sliding characteristics. INDUSTRIAL APPLICABILITY The present invention can be applied to hard carbon coatings used for wear-resistant parts such as tools and dies, industrial and general mechanical parts, sliding parts, electronic / electric parts, infrared optical parts, and the like. Above all, it is extremely effective for use in sliding members and releasable members where the smoothness of the surface greatly affects.

[0002]

2. Description of the Related Art A hard carbon film is an amorphous carbon film or a hydrogenated carbon film. aC: H, iC, DL
It may be written as C (diamond-like carbon) or the like. An amorphous hard carbon film has a Knoop hardness of 10
It is a material having a hardness of 00 to 3000 and a high hardness. The coefficient of friction with many mating materials without lubrication is extremely low at 0.1 to 0.2. Good releasability from soft metals.

The electric resistance is 10 ⁶ to 10 ¹⁴ Ωcm,
Has high insulation properties. It has many excellent properties similar to diamond, such as high transmittance to infrared rays. Since the amorphous carbon film has these excellent properties, application to various fields is expected. For example, the development and application of coating of a hard carbon film on wear-resistant parts, sliding parts, electric / electronic parts, infrared optical parts, molded / molded parts, and the like are progressing.

In particular, it is used for protective coating for improving the lubricity and scratch resistance of video components and video tapes. It is also used for lubricity coating for reducing the friction coefficient of various rotating shafts and valves. Further, it has been put to practical use in releasable coating for preventing welding of soft metals such as solder and aluminum.

[0005] As described above, the amorphous carbon film is applied to a wide range of fields by skillfully utilizing such characteristics as a low coefficient of friction, high hardness, and releasability. Hard carbon films (amorphous carbon films) are made by several methods. Plasma CVD for decomposing hydrocarbon gas by plasma to form a film
A gas phase synthesis method such as an ion beam evaporation method using carbon or hydrocarbon ions, a method of vaporizing carbon from a solid carbon source by sputtering or arc discharge, and forming a film on a substrate is used. These methods are properly used depending on the target substrate, application, number of treatments, and the like.

[0006] An amorphous film containing carbon as a main component may have various structures. Since it is amorphous, it does not have a crystal structure even in a wide range. However, in a narrow range, it should have a structure similar to a crystal. A fine structure is called a cluster. Diamond and graphite are typical examples of a crystal composed of only carbon. In the case of amorphous, it is composed of clusters composed of this structure.

[0007] Diamond has a SP ³ hybrid orbital. S
P ³ that hybridization. This is a combination of four orbitals created by 2s orbitals and three 2p orbitals.
These are orbits giving four covalent hands of diamond whose included angles are 109 °. Diamond has a three-dimensional spread. Diamond clusters also have a three-dimensional spread.

[0008] Graphite has a 2s orbit and two 2p orbits.
It is a trajectory consisting of orbits, and the angle made by the joints is 120
゜. It has a planar spread. It is not three-dimensional. There are many possibilities for the composition structure of the amorphous film. It may consist of only graphite-structured clusters. Even then, the size of the cluster must be specified as a parameter. It is possible that it may consist only of diamond-structured clusters. In this case, the size of the cluster must be specified as a parameter.

Further, a cluster having a diamond structure,
Clusters of graphite structure may be mixed. In that case, the size of the cluster of the diamond structure, the size of the graphite structure, and the ratio of the number of the diamond structure to the number of the graphite structure are parameters.

FIG. 4 schematically shows such an amorphous structure. Graphite clusters are described as SP ² structures in the elliptical frame. Of there and SP ³ in the elliptical frame is a cluster of diamond structure.

[0011]

The surface roughness of a hard carbon film is generally small. Therefore, the friction is small, the releasability is good, and the welding can be prevented. Taking advantage of the small surface roughness, coatings have been applied as sliding materials and welding prevention materials.

However, in recent years, the required level of a lubricating film and a releasable film has become more severe. Further, a film having good lubricity and excellent releasability has been required. Certainly, the hard carbon film is characterized by a low coefficient of friction, a high hardness, and a high releasability.

The lubricity and releasability are strongly related to the surface roughness of the coating. Even if it is excellent in lubricity, releasability and low friction, it cannot be evaluated unless it can be expressed by specific constants. Here, the surface roughness Rmax is used to evaluate the amorphous carbon film. Rmax of the conventional amorphous carbon film was larger than 0.5 μm.

The larger the Rmax, the larger the coefficient of friction, the poorer the lubricity and the lower the releasability. Although not all surface roughness of many conventional films have been measured, all of them have a surface roughness of 0.1.
The roughness was 5 μm or more. When the surface roughness is large as described above, it is not possible to satisfy new requirements that are more severe in terms of lubricity, releasability, friction coefficient, and the like.

In order to further improve the sliding characteristics and releasability, the surface roughness must be Rmax 0.5 μm or less. Here, the properties of the thin film are specified by the surface roughness,
This is one of the parameters for expressing the coefficient of friction, lubricity, releasability, sliding characteristics, and the like in a uniform and quantitative manner.

It has not been sufficiently improved to improve the surface roughness of an amorphous carbon film (DLC film). One of the reasons is that it is not known that the surface roughness strongly affects the properties of the amorphous carbon film. And how can you reduce surface roughness?
Sometimes it is not clear. It is an object of the present invention to provide an amorphous carbon film having improved sliding characteristics and releasability. It is a second object of the present invention to provide a method for producing an amorphous carbon film having a small surface roughness. It is a third object of the present invention to clarify the structure of a carbon film having a small surface roughness and to clarify a method for realizing such a structure.

[0017]

Means for Solving the Problems The present inventor has conducted intensive studies in search of a carbon film having excellent slidability and releasability. As a result, it was found that the following were particularly excellent in slidability and provided excellent releasability in which welding was less likely to occur.

The hard carbon film of the present invention can be defined as follows. First, it is mainly composed of carbon and hydrogen and has a surface roughness of Rmax 0.5 μm or less without polishing. Second, the hard carbon film of the present invention has an amorphous structure by X-ray diffraction crystallography, and is a mixture of a cluster having a diamond structure and a cluster having a graphite structure at an atomic level. Third, the average number of carbon atoms nd of the diamond-structure cluster is in the range of 100 to 2000. 4th
The average number of carbon atoms in the graphite cluster is ng
Is in the range of 100 to 2000. Fifth, assuming that the number of clusters having a graphite structure in a given volume is Mg, and the number of clusters having a diamond structure in a given volume is Md, the graphite / diamond ratio α is α = Mngng /
When defined by Mdnd, 0.3 <α <3.0.

The film itself grown by vapor phase has an Rmax 50
It has a surface roughness of 0 nm or less. If it is polished, it may have such roughness. However, the present invention refers to a material having a roughness of Rmax 500 nm or less even if it is not polished. Polishing reduces roughness even more. That is, of course. Here, roughness is used to define the material.

FIG. 5 explains parameters defining the structure of the amorphous film of the present invention. Made from carbon bond (diamond structure) in the SP ³ orbit consists of carbon and hydrogen and SP
^It indicates that it is a mixture of ^two orbital carbon bonds (graphite structure).

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The surface roughness of a material strongly depends on the friction coefficient, the amount of abrasion, the amount of dust generated due to abrasion, and the like when sliding a mechanical part or a flank of a tool. If the surface roughness is large, abrasion is severe and the amount of dust increases. The smoother the surface, the better the sliding material. If it is smooth, friction is small and wear is small. In addition, the surface roughness affects the releasability of a mold whose releasability is most important. If the surface roughness is large, welding occurs in a portion having irregularities, and thereafter, the welding spreads from here. It is important that the surface roughness is small to enhance the releasability. Thus, it is desired that the surface roughness of the material is small and smooth in the machine parts, tools and dies.

Even with general wear-resistant parts, if there are irregularities, the convex parts fall off and wear proceeds. Also in other electric and electronic parts, if the unevenness is remarkable, it causes operation failure such as insulation failure. In optical parts and optical products, if the surface is extremely uneven, light scattering may occur. Machine parts, tools, molds,
If the surface roughness is large in abrasion-resistant parts, electric parts, optical parts, etc., various difficulties are caused.

The hard carbon film proposed by the present invention has a surface roughness of Rmax 0.5 μm or less and is extremely smooth. Since the surface roughness is small, the original characteristics of the amorphous carbon film, such as high hardness, wear resistance, low sliding resistance, and low friction, can be sufficiently exhibited.

The advantage of the amorphous carbon film of the present invention due to the low surface roughness is easier to understand as compared with a crystalline material such as diamond. Diamond can be made by gas phase synthesis. However, since this is polycrystalline, it also appears on the crystal's self-shaped (original shape of each crystal) surface. Therefore, many irregularities and wave shapes appear on the surface. Diamond films have very high surface roughness. It cannot be used as it is. It must be polished. Polishing is not easy because diamond has the strongest hardness. You must "co-cut" with a diamond whetstone over time.

However, the hard carbon film of the present invention is amorphous by X-ray diffraction crystallography and does not have a "crystal self-form". Therefore there are few irregularities. It becomes flat naturally. No polishing but low surface roughness. That is not all.

The hard carbon film of the present invention contains a diamond-structured cluster. For that reason, it also has the characteristics of diamond. The average cluster size is 1
It is as small as 00 to 2000 atoms. In addition, it includes clusters of graphite structure. The hard carbon film of the present invention is an aggregate of diamond clusters and graphite clusters. Graphite clusters are also small clusters of 100 to 2000 atoms in size. It is a composite composed of these same small diamond clusters and graphite clusters.
Since the size is small, no large irregularities appear on the surface.

Furthermore, since the number of carbon atoms constituting the cluster is similar and the number of clusters themselves is also close, mutual abnormal growth can be prevented. No irregularities can be formed on the surface because abnormal growth does not occur. The flatness of the surface is such that the diamond cluster and the graphite cluster are relatively small, and the ratio is (0.3 to 3).
Derived from antagonism. Since the conventional carbon film is mainly composed of diamond and has a large cluster (the number of carbon atoms constituting the cluster is large), the Rmax cannot be reduced to 500 nm or less.

[0028]

EXAMPLE A cemented carbide having a composition of JIS K10 was prepared as a substrate. It is a flat plate of 20 mm × 20 mm × 2 mm. The base material surface is mirror-polished and Rmax 0.1 μm,
The surface was made flat with Ra of 0.03 μm. A hard carbon film was grown on the cemented carbide substrate by a high-frequency plasma CVD method using a capacitively coupled parallel plate electrode. The high-frequency plasma CVD method is a method in which a raw material gas is excited by applying high-frequency power between two upper and lower plate electrodes in parallel to a chamber capable of being evacuated, and a gas-phase reaction occurs. It is to let.

Here, the upper electrode is grounded, and the substrate is placed on the lower electrode. A high frequency of 13.5 MHz is applied between the electrodes. A mixed gas of hydrocarbon gas and hydrogen gas or only hydrocarbon gas is introduced into the chamber. In a high-frequency plasma CVD apparatus, several hard carbon films having different surface roughness were synthesized under different conditions. Conditions are hydrocarbon flow rate, hydrogen gas flow rate, pressure, substrate temperature,
RF power.

The method was further changed, and a hard carbon film was synthesized on a base material having the same material dimensions by an ion beam evaporation method. A substrate is placed on a grounded electrode and irradiated with hydrocarbon ion beams to grow a carbon film on the substrate. Ion beam current, acceleration voltage, degree of vacuum, substrate temperature, etc. are parameters that determine conditions. For these hard carbon films, the surface roughness, the friction coefficient by the pin-on-disk method using the SUJ2 pin as the mating material, the mating material wear amount,
The amount of solder welded by the pin-on-disk method using the counterpart material as a solder pin was compared.

[0031]

[Table 1]

First, the thermal stability of Examples and Comparative Examples of the present invention was examined by thermal analysis. As a result, the films of the present invention and the comparative examples were thermally stable up to 540 ° C. or 610 ° C. with almost no generated gas detected. This indicates that the amorphous thin films in the examples and comparative examples of the present invention have no thermally unstable long-chain hydrocarbon bonds. Also, it can be seen that the hydrogen molecules adsorbed in the film do not exist at all or exist only to a negligible extent.

Further, it was confirmed that these films were stable in the atmosphere. Since it is stable in the atmosphere, it is presumed that there is almost no active terminal such as a radical.

Since there are no long-chain hydrocarbons, hydrogen molecules and radicals, the amorphous films of the present invention and the comparative example may be a mixture of a graphite structure composed of carbon and hydrogen and a diamond structure cluster. I understand. Therefore, to determine the structure at the atomic level: 1. ng average cluster size of graphite structure 2. Average cluster size nd of diamond structure It is necessary to determine the cluster abundance Mg / Md.

How should the size of a diamond-structured cluster be determined? This is one problem. Carbon atoms are diamond-bonded inside one cluster. What are at the boundaries of the cluster? Assuming that there is no chemical bond with the adjacent cluster, something other than a carbon atom that terminates a carbon bond is needed here. This cannot be considered other than a hydrogen atom. Actually, it is considered that there is also a bond between carbon atoms at the interface of the cluster, but the ratio is small. Most of the outermost carbon in the cluster is thought to be terminated by hydrogen.

However, even if this is known, it is not easy to determine the size of the cluster. This is because it is difficult to directly count the number of carbon atoms in one cluster surrounded by hydrogen atoms. Therefore, we consider whether the size of the cluster can be estimated based on the ratio of hydrogen to carbon. Assuming that the outermost part of the cluster is surrounded by one layer of hydrogen, the proportion of hydrogen in one cluster should decrease if the size is large, and the proportion of hydrogen should increase if the size is small.

The smallest cluster having a diamond-structured electron configuration is methane, which is H = 4, C
= 1 and H / C = 4. On the other hand, for an infinitely large cluster, H / C = 0. Therefore, for a diamond cluster of finite size, H / C is 0 <H / C
It should take a value of <4. Even if it is assumed that the outermost part is covered with hydrogen, the relationship between the cluster size nd and H / C is not uniform. The diamond structure has a three-dimensional structure, and the carbon number and the hydrogen number do not have a simple ratio.

A more straightforward relationship for the numbers of carbon and hydrogen also holds for graphite clusters.
That is, ng is estimated by the value of H / C. Further C
And the relationship between H / C is unique. Here, the ratio of hydrogen and carbon belonging to the graphite structure cluster to DLC is Hg and Cg, and the ratio of hydrogen and carbon belonging to the diamond structure cluster to DLC is Hd and Cd. Ng is determined from Hg / Cg for the reason described above.

FIG. 2 shows carbon having a graphite structure. Structure C24 in which 24 small cluster carbon atoms are arranged
Has 12 hydrogen atoms. C42, C54,
The C72 and C84 clusters are shown. In each case, a carbon atom having three bonds, a double bond and a single bond, is inside, and the outermost carbon terminates one extra bond by hydrogen. In the case of C84, the number of hydrogen is 24. As described above, the graphite cluster has a two-dimensional structure, and the number of hydrogen atoms is determined when the number of carbon atoms is determined.

Nevertheless, the number of carbon atoms does not always take any whole number. The possible carbon numbers are fixed. Good symmetry is a cluster of a multiple of 6 as shown here. However, clusters that are not necessarily a multiple of 6 are possible. In the case of C54, the next largest cluster is C57. In the case of C42, the next largest is C44
It is. However, two or more clusters having different symmetry are possible even with the same carbon number. But in that case the hydrogen numbers are different. Different, but the difference is one.

Thus, in the case of graphite,
The hydrogen number H is determined with respect to the appropriate carbon number C, and the hydrogen / carbon ratio (H / C) is found for them. As will be described later, the carbon number of the graphite cluster can be determined from the spectrum of Raman scattering. Diamond clusters are not that simple. 3D size, C and H
The relationship of / C is complicated. Furthermore, since there is only one Raman scattering peak, C is not determined from the Raman scattering peak intensity. So we don't do that for diamond clusters.

In the amorphous film of the present invention, diamond clusters and graphite clusters are mixed. Such a carbon film must be defined and limited. Cluster abundance Mg / Md

Mg / Md = (Hg + Cg) / (Hd + Cd)

In order to analyze the structures of the films of the present invention and the comparative example at the atomic level, it is necessary to determine the ratio of these four variables. The following four relational expressions were established to determine the ratio of these four variables, and were derived by computer simulation and analytical experiments.

Hg / Cg = a (1) Determined by Raman scattering spectrum and computer simulation Hg / Hd = b (2) Determined by measurement of infrared spectrum (Hg + Hd) / (Cg + Cd) = c (3) Determined by gas analysis Hg + Cg + Hd + Cd = 1 (4) The composition ratio of each component is expressed assuming that the entire film is 1.

First, in order to know the value of a, a Raman scattering spectrum and computer simulation were performed. FIG. 1 shows the results of Raman scattering spectrum analysis of the amorphous thin film of the present invention. Peak in 1500cm ^-1 and 1300cm ^-1 appear. The peak appearing at 1500 cm ^-1 is called the G band. The peak appearing at 1300 cm ^-1 is called the D band. The G band is attributed to vibrations at the edges of the graphite, called edge modes. The D band is assigned to the skeletal vibration of graphite having a vibration mode of E _2g .

The peak intensity ratio between the two peaks (G band and D band) is related to the size of the graphite cluster. Therefore, by simulating the Raman spectrum by the molecular orbital method, the average size of graphite should be known.

First, graphite cluster models (C24, C42, C54, C54) of different sizes shown in FIG.
72, C84), the vibration calculation is performed by the molecular orbital method. Using the molecular orbital method calculation program MOPAC93,
PM3 parameters were used.

As a calculation procedure, first, a rough structure of a graphite structure was input, the structure was optimized by a keyword EF, and a vibration analysis calculation was performed by a FORCE keyword. Select the mode of E _{2g from} the obtained vibration modes,
Each peak was integrated by approximating a Gaussian function with a full width at half maximum (FWHM) of 150 cm ^-1 . Thereby, the intensity of Raman spectroscopy of the model of the graphite structure is obtained.

The 1500 cm ^-1 and two which obtained 1300 cm ^-1 of the intensity ratio and the model of the peaks a plot of the number of carbon atoms is shown in FIG. The horizontal axis is carbon number. The vertical axis is the peak intensity ratio. Although there are only five points, these points are connected to linearly approximate the carbon number / peak intensity ratio. When the amorphous film of the present invention was actually measured, it was found that the Raman scattering was 1500 cm ^-1.
And the peak intensity ratio between the two peak intensities at 1300 cm ^-1 was about 1.7. From FIG. 3, the carbon number which gives this is 150.
That is, the average carbon number of the graphite structure of the amorphous film of the embodiment of the present invention is 150. The number of hydrogen atoms in the graphite cluster corresponding to 150 carbon atoms is 30. Therefore, a = 0.2 in equation (1).

The ratio Hg / Hd of hydrogen Hg bonded to graphite type carbon and hydrogen Hd bonded to diamond type carbon is obtained from the integrated intensity ratio of the infrared absorption spectrum. When a sample is irradiated with infrared light, infrared light is absorbed at various wavelengths, but the wavelength of the absorption line due to hydrogen differs depending on hydrogen attached to graphite carbon and hydrogen attached to diamond carbon. It is assumed that the integral value of each absorption line is the intensity of absorption, and that the ratio between these and the hydrogen ratio Hg / Hd is the same. The ratio of the absorption intensities was 0.25. Close, H
g / Hd = b = 0.25.

Further, the amount of carbon and the amount of hydrogen in the amorphous thin film were determined by gas analysis, and c = 0.45 in the equation (3) was obtained. By solving the simultaneous equations (1) to (4), the ratio Hg = 0.0621 Cg = 0.3103 Hd = 0.2483 Cd = 0.793 of each atom constituting the DLC was obtained.

Hd / Cd of diamond cluster =
From the value of 0.6546, the average carbon number of the diamond cluster is about 180. The average number of hydrogen is 118
(Nd = 298). The graphite cluster has an average carbon number of 150 and an average of 30 hydrogen atoms (ng = 180). From the above results, this amorphous thin film is composed of a cluster having a diamond structure having about 180 carbon atoms and a cluster having a graphite structure having about 150 carbon atoms in a particle number ratio of about 1: 1. It is estimated that there is.

As a comparative example, the structure of an amorphous thin film formed by an ion beam evaporation method is shown. The amorphous thin film of the present invention has a smaller cluster size than the comparative example, and the number ratio between the diamond type cluster and the graphite type cluster is 1: 1 and the graphite structure is larger than that of the comparative example.

In this embodiment, the carbon number of the graphite cluster is 150. In general, in the amorphous film of the present invention, the carbon number of the graphite structure cluster is about 100 to 2,000. The diamond structure has 100 to 2,000 carbon atoms. This is a small number of carbon atoms in the cluster.

The number of carbon atoms inside the cluster is adjusted by changing the value of the self-bias when forming an amorphous film by a high-frequency plasma CVD method. FIG. 6 is a graph for explaining this. The horizontal axis is the self-bias (V). The vertical axis indicates the SP ³ peak (G band) and the SP ² peak (D
Band) SP ³ / SP ² . Since the electrode on which the sample is placed receives high frequency and the counter electrode is grounded, the sample electrode is negatively self-biased. -160V self bias
Then, SP ³ / SP ² becomes about 1.7. This corresponds to the example of FIG. 3 and gave 150 carbon atoms. However, increasing the self-bias increases the ratio value beyond 1.7,
The ratio exceeds 2 at -300V. Ratio at -380V SP ³ /
SP ² becomes 2.2 or more. With this, the number of cluster carbons becomes 200 or more.

[0057]

The amorphous thin film of the present invention has a graphite structure cluster and a diamond structure cluster.
Approximately the same level, and the number of carbon
It is on the order of 0 to 2000 pieces. Graphite clusters and diamond clusters are mixed. Since it is an amorphous thin film, it can be formed on any uneven substrate. Since it is a mixture of diamond and graphite, it has both advantages. Since the cluster is relatively small, the unevenness of the surface is small and it is not polished.
Smoothness of 500 nm or less can be realized. Since the quantitative ratio of the clusters is close to 1 (0.3 to 3), abnormal growth does not occur, the surface is smooth, the adhesion to the substrate is excellent, and the cluster does not peel.

The amorphous thin film of the present invention has high hardness, particularly excellent sliding properties, and good wear resistance. Diamond has high hardness and good wear resistance. Since the amorphous thin film of the present invention contains a considerable amount of diamond, it has excellent properties of high hardness and high wear resistance. The sliding characteristics and the adhesion to the substrate are improved by the mixture of graphite.

It is most suitable for a valve rod, a valve seat, a sealing material of a hot water valve, and a material covering the surface of a material requiring abrasion resistance. By imparting wear resistance to these members, excellent sliding characteristics can be imparted. Also, since the hardness is high, it is hard to be damaged, so that the life is long.

[Brief description of the drawings]

[1] and G band with a peak at 1500 cm ^-1 which appears when the carbon of the graphite cluster was Raman scattering measurement, Raman scattering distribution diagram showing that D band appears having a peak at 1300 cm ^-1.

FIG. 2 is a structural diagram of graphite clusters C24, C42, C54, C72, and C84. The intensity ratio of D band and G band of Raman scattering and carbon number have a unique relationship,
The figure for demonstrating that the carbon number, ie, the magnitude | size of a graphite cluster, can be known by D band and G band intensity ratio.

In Figure 3 graphite cluster, when performing Raman scattering measurement, the G band appearing in the vicinity of 1500 cm ^-1, the graphite cluster with the number of carbon definite intensity ratio of D band appearing in the vicinity of 1300 cm ^-1 calculation Then, the number of carbon atoms and the intensity ratio have a linear relationship, and the graph of the number of carbon atoms and the intensity ratio to show that the intensity ratio can be determined from the Raman scattering spectrum of the actually manufactured amorphous film and the number of carbon atoms can be determined. .

FIG. 4 is an explanatory diagram showing that the amorphous film of the present invention contains a mixture of graphite clusters and diamond clusters.

FIG. 5 is a view for explaining a measurement method of the present invention in which a carbon number is determined from a peak intensity of Raman scattering for a graphite cluster in order to identify an amorphous film of the present invention.

FIG. 6 shows the self-bias and SP ³ / SP ² when forming the amorphous film of the present invention by the high frequency plasma CVD method.
7 is a graph showing the measured relationship of the ratios of FIG.

Continued on the front page (72) Inventor Kazuhiko Oda 1-1-1, Koyokita, Itami-shi, Hyogo Sumitomo Electric Industries, Ltd. Itami Works (72) Inventor Haruyo Fukui 1-1-1, Koyo-Kita, Itami-shi, Hyogo No. Sumitomo Electric Industries, Ltd. Itami Works

Claims (5)

[Claims] 1. A method comprising carbon and hydrogen as main components and having a surface roughness of R
A hard carbon film having a maximum of 0.5 μm or less. 2. The hard carbon film according to claim 1, wherein the hard carbon film has an amorphous structure in X-ray diffraction crystallography, and its constituent element is a mixture of clusters having a diamond structure and a graphite structure. . 3. The hard carbon film according to claim 1, wherein the number of carbon atoms of the diamond structure cluster is 100 to 2,000 on average. 4. The hard carbon film according to claim 1, wherein the number of carbon atoms of the graphite structure cluster is 100 to 2,000 on average. 5. The diamond structure cluster has an average of 100 to 2,000 carbon atoms and the graphite structure cluster has an average of 100 to 2,000 carbon atoms. Mg, the number of diamond clusters in a given volume is Md, the average carbon number of the graphite structure clusters is ng, and the average number of carbon atoms of the diamond structure clusters is nd. 3. The hard carbon film according to claim 1, wherein α satisfies 0.3 <α <3 when defined.