JP3245320B2 - Hard carbon film and hard carbon film coated member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is applicable to, for example, cutting tools, wear-resistant sliding parts, wire-drawing dies, molding dies, can-making punches, dies, and seaming rolls.
Utilizing high thermal conductivity, it is used for MCM substrates and semiconductor heat sinks, and also for optical windows, microwave introduction windows, X-ray transmission windows, etc., utilizing high transmission characteristics of light, microwaves, X-rays, etc. The present invention relates to a hard carbon film having high abrasion resistance, high thermal conductivity, and high light transmission properties, and a hard carbon film-coated member.

[0002]

2. Description of the Related Art In recent years, diamond has been applied in various fields because of its excellent properties such as high hardness, high thermal conductivity and chemical resistance. Conventionally, industrial diamond was mainly synthesized under ultra-high pressure and high temperature, but in recent years, it has been easily synthesized at relatively low cost in consideration of its application to a wide range of applications such as cutting tools and wear-resistant members. Possible vapor deposition methods are being actively studied. In particular, since the vapor phase growth method can obtain diamonds over a wide area, it is expected to be applied to window materials for light transmission and the like, which were not possible with natural and high-pressure synthetic diamonds in terms of cost.

[0003] These diamonds obtained by the gas phase method are generally disclosed in Japanese Patent Application Laid-Open Nos. 58-91100 and 58-1.
As disclosed in Japanese Patent Publication No. 10494, a synthesis is performed by introducing a raw material gas containing carbon such as hydrocarbon into a reaction chamber, thermally decomposing the raw material gas with a microwave plasma or a filament, and then depositing it on the substrate surface.

[0004] The diamond thus obtained is:
Usually, the film contains amorphous carbon, graphite, hydrogen, nitrogen, or the like as impurities, and it is generally appropriate to call it a hard carbon film. By reducing the amount of impurities in the hard carbon film, a film made of high-purity diamond having excellent characteristics can be generated, and various high-purity techniques have been developed. JP-A-2-232106, JP-A-2-248396 or JP-A-4
Japanese Unexamined Patent Publication No. 92894/92 and Japanese Unexamined Patent Publication No. Hei 4-1044992 disclose such techniques.

[0005] A hard carbon film made of high-purity diamond obtained by such a method generally has a large diamond crystal grain size, has a self-shaped surface exposed on the film surface, and has severe irregularities. Therefore, in actual use,
JP-A-61-252004 and JP-A-62-418
The surface of the film is smoothed using physical or chemical polishing as described in JP-A-00-00, or disclosed in JP-A-61-151097 or JP-A-1-15-15.
As disclosed in Japanese Unexamined Patent Publication No. 3228 and Japanese Unexamined Patent Publication No. Hei 4-101702, a method of growing a film on a smooth substrate and using the back surface of the film is generally employed.

On the other hand, JP-A-60-71597, JP-A-1-152621, and JP-A-1-20
As disclosed in Japanese Patent Application Laid-Open No. 8309 and Japanese Patent Application Laid-Open No. 1-230496, the presence of amorphous carbon, graphite, or hydrogen in a hard carbon film in addition to diamond allows the particle size to have no self-form. There is also an attempt to obtain a smooth film having a small size.

[0007]

However, the conventional method has the following problems.

First, a hard carbon film containing high-purity diamond usually has a rough surface with large irregularities, and is therefore used in applications such as sliding and cutting, or as a light transmitting member for transmitting light uniformly. As described in the previous section, it is necessary to grind the surface when polishing, but diamond is a very abrasion-resistant substance, so polishing is difficult. There are
There was a problem of lack of industrial productivity.

[0009] As a method of polishing diamond, a method such as SKYF polishing, in which a workpiece is pressed and polished while a fluid containing diamond abrasive grains is passed through an iron plate rotating at a high speed, is generally used. The method is a polishing method for a flat surface, and has a problem that it is not suitable for a work having a complicated curved surface shape manufactured by a gas phase method.

The chemical polishing method disclosed in Japanese Patent Application Laid-Open No. Sho 62-41800 is also a polishing technique for a flat work, and therefore it is difficult to polish a work having a complicated curved surface. Further, since polishing must be performed in a high-temperature hydrogen atmosphere, not only is it time-consuming, but also there is a problem in safety.

Further, JP-A-61-151097, JP-A-1-153228, and JP-A-4-10170.
The method of using the back surface of a film grown on a smooth substrate, which is disclosed in Japanese Patent Application Publication No. 2 (1995) -207, is difficult to apply when the target product is not flat. For example, Japanese Patent Application Laid-Open No. 4-2652
As shown in Japanese Patent Publication No. 98, when an object has a complicated shape, it is necessary to produce a mold having the same shape as the surface shape of the object, which requires extremely labor and cost. . Furthermore, these methods require a step of attaching a film to an object by brazing or the like, and thus have a problem that they are not suitable for manufacturing a product having strict dimensional accuracy.

On the other hand, JP-A-60-71597, JP-A-1-152621, and JP-A-1-20
In the hard carbon film containing impurities as disclosed in JP-A-8309 and JP-A-1-230496, a film having a small particle size having no self-form can be obtained. It seems to be suitable for application in the field. However, in these films, diamond exists not in a crystalline state but in an amorphous state, or contains a large amount of impurities in the film. As shown, the wear resistance is insufficient, and the film is worn away quickly, so that at present, the original characteristics of diamond cannot be sufficiently exhibited. Further, such a film has a problem in that phonons contributing to heat conduction are scattered by impurities present at the grain boundaries, so that the high thermal conductivity of diamond cannot be sufficiently exhibited.

Japanese Patent Application Laid-Open Nos. 62-107068 and 63-307196 disclose attempts to grow the (110) plane by orientation, and use the (100) plane. ) And (110) planes are present in a mixture, making it difficult to obtain a completely smooth surface.
Furthermore, the conditions under which only the (100) plane and the (110) plane are simultaneously precipitated are very narrow, and there is a problem that versatility is lacking. In the latter, the (110) plane is grown on a microcrystalline film synthesized at a high concentration and having poor crystallinity. However, the diamond is very easily affected by the underlayer, and is grown later. The crystallinity of the (110) orientation film is deteriorated, and another surface (for example, the (311) plane or the (400)
Plane, (331) plane and the like, but there is a problem that these grow secondarily and cause disturbance of the smoothness of the film.

An object of the present invention is to solve the above problems and provide a hard carbon film and a hard carbon film-coated member which are excellent in surface smoothness and have high wear resistance, high thermal conductivity and high light transmission characteristics. Is to do.

[0015]

Means for Solving the Problems The present inventors have studied the above problems and have studied various film forming methods, film forming conditions, and formed hard carbon films when forming a hard carbon film. The characteristics of the hard carbon film were examined in detail.
The inventors have found that a film that achieves the above object can be obtained when the intensity between diamond peaks and the average particle diameter in line diffraction satisfy a certain relationship.

That is, in the hard carbon film of the present invention, in the hard carbon film containing diamond, the intensity of the diamond peak in X-ray diffraction is represented by f = (p-p ₀ ).
/ (1−p ₀ ) (where p is (attention peak intensity) in the oriented sample / (sum of all peak intensities), and p ₀ is (attention peak intensity) / (total peak intensity) at the unoriented sample (powder diamond). F (hkl) where f (hkl) represents f at each peak when
1) ≦ −0.1, 0.2 ≦ f (220) ≦ 0.9, | f
(311) + f (400) + f (331) | ≦ 0.1, and the average size of crystal grains in the major axis direction on the surface of the film is 2 μm or more. Also, f at each peak is f (hkl)
F (111) ≦ −0.5, 0.4 ≦ f
(220) ≦ 0.75, | f (311) + f (400)
+ F (331) | ≦ 0.05 is preferably satisfied.

Further, when the Raman spectrum of the surface of the hard carbon film was measured by micro Raman spectroscopy, 133
The half-width of the peak of the diamond present at 3 ± 5 cm ⁻¹ is desirably 10 cm ⁻¹ or less, and 1333 ± 5 cm
The peak half width of the diamond peak at cm ^-1 is 8c
It is more desirable that the value be not more than m ⁻¹ . The thermal conductivity of the film is desirably 800 W / mk or more. And it is a hard carbon film covering member obtained by forming the above-mentioned hard carbon film on the surface of the base.

The hard carbon film is formed, for example, by decomposing a raw material gas containing carbon into plasma and forming a hard carbon film on the surface of the substrate, wherein the electron temperature of the plasma on the surface of the substrate is 8 eV or less and the electron density is 1 ×. It is formed under the conditions of 10 ¹¹ cm ^-3 or more and the substrate temperature of 800 ° C. or more.

Hereinafter, the present invention will be described in detail.

The hard carbon film of the present invention contains diamond in the film. First, regarding the intensity of the diamond peak in X-ray diffraction, f = (pp)
₀ ) / (1−p ₀ ) (where p is (target peak intensity) / (sum of all peak intensities) in the oriented sample, and p
₀ is f in each peak when (indicated peak intensity) / (sum of all peak intensities) in the unoriented sample is defined as f
When expressed as (hkl), f (111) ≦ −0.1,
0.2 ≦ f (220) ≦ 0.9, | f (311) + f
(400) + f (331) | ≦ 0.1,
f (111) ≦ −0.5 and 0.4 ≦ f (220)
≦ 0.75, | f (311) + f (400) + f (33
1) It is desirable to satisfy | ≦ 0.05.

The meaning of the above equation is as follows. First, p means the ratio of the intensity of the peak of interest (hkl) to the sum of all peak intensities of diamond, and f (hk
l) is an index of the ratio of the peak (hkl) of interest oriented to the non-oriented powdered diamond. Therefore, the larger the value of f, the stronger the peak intensity. Further, when this value is negative, it means that the peak is lower than the intensity that the peak should originally have (the intensity in the case of no orientation). The present inventors formed a hard carbon film having various values of f at the X-ray diffraction peak by changing the conditions for forming the hard carbon film in various ways, and the value of f and the characteristics of the hard carbon film When the value of f (111) was large, it was found that the film had excellent abrasion resistance but lacked the smoothness of the film.

The hard carbon film obtained by the conventional method is
The peak intensity of (111) of diamond is usually the highest, and most of such films have a diamond crystal with its crystal shape clearly exposed on the surface. Since the (111) plane of diamond has a higher density of atoms than other planes, it should be hard and excellent in abrasion resistance, but the problem is that impurity atoms are more likely to be taken in than the other planes. There is also. For example, in the evaluation by cathodoluminescence, the boron atom of the impurity is (1).
11) It is generally known that blue light is emitted when the light is captured by the surface. Such impurities can have various adverse effects on the properties of diamond.

On the other hand, the hard carbon film of the present invention
The feature is that the peak of (220) is stronger than the other peaks. This makes it possible to increase the wear resistance and thermal conductivity of the hard carbon film, and to form a film having a controlled texture and high smoothness. The peak of (220) is (11)
This is attributed to the (0) plane, but since this plane contains less impurity atoms than the (111) plane, it is considered that the plane exhibits rather high wear resistance.

Considering the crystal growth direction, (11)
In the case of the 1) plane, one crystal grain grows widely around the periphery, and as a result, the surface of the film after the growth tends to be a rough surface having large irregularities composed of large crystal grains. On the other hand, in the present invention, the growth of the (220) plane is mainly performed, but this growth is less widespread than the (111) plane, so that the crystal grains grow in a certain direction, and a smooth film is formed. It seems to be easy to obtain.

The reason why f (111) ≦ −0.1 is satisfied is that f (111) is larger than 0, as described above, because the smoothness of the tissue is lost. . More desirably, excellent characteristics are best exhibited at -0.5 or less.

Further, the reason for satisfying 0.2 ≦ f (220) ≦ 0.9 is that if it is smaller than 0.2, the effect of wear resistance and smoothness is hardly exhibited, and if it is larger than 0.9, DLC (diamond-like) is not obtained. It is preferable to be within this range, because the properties of the carbon) become close to the wear resistance. f (220)
Exhibits its best characteristics when it is desirably in the range of 0.4 to 0.75.

Then, | f (311) + f (400) +
The reason for setting f (331) | ≦ 0.1 is that, when the value is larger than 0.1, the surface causing these peaks appears on the film surface and starts to grow in different directions. Will not be maintained. In addition, since these surfaces have different atomic densities, there is a problem that unevenness is likely to occur during polishing. Therefore, f (311), f (4
00), f (331) needs to be +0.1 or less. However, when these values are too low and the sum of f (311), f (400), and f (331) is smaller than -0.1, these peaks should have the original intensity (unoriented powder). Strength in the case of diamond), in which case excessive strain is applied to the crystal lattice of the diamond in the hard carbon film, and the crystallinity of the diamond decreases. It tends to decrease. Therefore, for these reasons, the absolute value of the sum of the peak intensities of f (311), f (400), and f (331) needs to be 0.1 or less, particularly 0.05 to 0.1. It is desirable that

Next, in the present invention, the average size of crystal grains on the surface of the hard carbon film in the major axis direction is 2 μm.
It is desirable that this is the case. Usually in X-ray diffraction,
In the case where (220) is oriented, the particles constituting the film are usually very fine, several hundred angstroms. Although such a film is rich in the smoothness of the film, it has poor abrasion resistance in abrasion-resistant applications due to particles falling off. In addition, since the proportion of the grain boundaries in the film is high, the phonons contributing to heat conduction are scattered by impurities present at the grain boundaries, and the heat conduction characteristics are deteriorated. At present it was not possible to make use of the characteristics. However, according to the present invention, since the particles constituting the film are grown while being oriented to (220),
The excellent characteristics of diamond can be utilized while maintaining the smoothness of the film. In the present invention, it is important that the average size of the crystal grains on the surface of the film in the major axis direction is 2 μm or more. If it is less than 2 μm, the excellent characteristics of diamond cannot be sufficiently utilized as described above. Particularly, it is desirable that the average size of the crystal grains is 5 μm or more. Here, the size in the major axis direction means the maximum width of the crystal grains exposed on the surface of the film, and it is desirable that the average is 2 μm or more.

Next, when the surface of the hard carbon film according to the present invention was subjected to Raman spectroscopy by microscopic Raman spectroscopy, when the half-value width of the diamond peak at 1333 ± 5 cm ^-1 was 10 cm ^-1 or less. It is necessary to be. The peak half width of this diamond means that as its value increases, the integrity of the diamond as a crystal becomes disordered, and conversely, as its value decreases, the crystal integrity improves. Is what it means. As described above, in the diamond film in which the (220) is normally oriented, individual particles constituting the film are fine,
When the Raman spectrum was measured, the peak was likely to be broad and weak due to a phenomenon called the size effect of the Raman spectrum.

However, the crystal grains constituting the hard carbon film according to the present invention are made of diamond having a grain size larger than a region where the size effect of the Raman spectrum occurs (crystal grain size of 1 μm or less), and therefore suffer from this size effect. Nothing. Therefore, the hard carbon film according to the present invention can be obtained such that the diamond peak half width is 10 cm ^-1 or less. In the present invention, when the half width is larger than 10 cm ⁻¹ , since the crystal lattice of diamond is disordered,
The thermal conductivity decreases, the permeability of the membrane decreases,
The superior properties of diamond cannot be fully utilized. Therefore, it is necessary to be 10 cm ^-1 or less, and when it is preferably 8 cm ^-1 or less, the excellent properties of diamond are best exhibited.

Further, it is important that the thermal conductivity of the hard carbon film in the present invention is 800 W / (m · K) or more. Usually, in a diamond film in which (220) is oriented, individual particles constituting the film become fine, so that phonons contributing to heat conduction are easily scattered at crystal grain boundaries, and the thermal conductivity is usually low. . However, since the hard carbon film according to the present invention has a large particle size, the proportion occupied by the grain boundaries in the film is small, and a high thermal conductivity can be obtained. In the present invention, when it is smaller than 800 W / (m · K),
In particular, the characteristics cannot be sufficiently exhibited in applications utilizing high thermal conductivity. The thermal conductivity is especially 100
It is desirable that it be 0 W / (m · K) or more.

In order to synthesize a hard carbon film according to the present invention, for example, a method of decomposing a raw material gas containing carbon into a plasma to form a film on a substrate is used. Synthesis can be performed by using conditions such that the electron temperature is 8 eV or less, the electron density is 1 × 10 ¹¹ cm ⁻³ or more, and the temperature of the substrate surface is 800 ° C. or more.

The electron temperature is the temperature of the electrons existing in the plasma, and is a parameter for determining the sheath potential in the low-pressure non-equilibrium plasma.
If it is larger than V, the ion impact energy increases,
Since the damage to the hard carbon film increases, diamond in the film becomes amorphous or lattice defects occur, so that the film deteriorates and loses wear resistance. The electron density is a major factor that determines the density of active species contributing to film formation. In the present invention, the electron density is 1 × 10 ¹¹
cm ^-3 or more to increase the density of active species,
The nucleus generation density is dramatically increased, and the crystal can be grown while being oriented (220). As will be described later in detail, if the electron density is smaller than 1 × 10 ¹¹ cm ^−3, the tendency of the (111) orientation is increased. Further, the temperature of the substrate surface is an index of how much the active species contributing to the diamond synthesis in the plasma reach the substrate surface and move around (migration can be performed).
When they reach the substrate, they cannot move sufficiently, and are frozen immediately upon arrival. In such a case,
Insufficient crystal growth results in fine particles. By maintaining the substrate temperature at 800 ° C. or higher, it is possible to promote the growth of particles and to prevent fineness.
It is desirable that the electron temperature is 5 eV or less, the electron density is 3 × 10 ¹¹ cm ⁻³ or more, and the substrate temperature is 900 ° C. or more.

As a film forming method using plasma for forming a hard carbon film, a general microwave plasma C is used.
A VD method, a high-frequency plasma CVD method, a thermal plasma CVD method and the like are known, but it is difficult to form the hard carbon film of the present invention by such a method. The reason is that these methods generate plasma in a high pressure range of several torr to atmospheric pressure, so the plasma concentrates in a small region, and even if the film forming conditions are changed, the plasma itself changes. This is because it is difficult to change the electron temperature and electron density of the plasma. Furthermore, it is difficult to measure the plasma itself because the space where the plasma is generated is narrow, and when the probe is inserted into the plasma to measure the electron temperature and density, the plasma is affected and the state changes. There are also problems.

Therefore, in order to synthesize the hard carbon film in the present invention, it is desirable to employ an electron cyclotron plasma CVD method (hereinafter, referred to as an ECR plasma method) as a film forming method. According to this method, a uniform and high-density plasma can be generated in a wide space at a low pressure, so that many members can be generated while maintaining the growth rate of a normal microwave plasma CVD method. A hard carbon film can be grown with a uniform film thickness. Further, there is an advantage that the plasma region is wide, is not easily affected by the plasma measurement, and the control of parameters such as electron temperature and electron density is relatively easy. A manufacturing method using the ECR plasma method will be described with reference to FIG. A base material 2 on which a carbon film is formed is installed in a reaction furnace 1. A microwave generator 3 for generating plasma in the reactor and an electromagnetic coil 4 for generating a magnetic field are arranged around the reactor.

When a film is formed by using such an apparatus, a gas introduction furnace 5 containing at least a raw material gas containing at least carbon such as methane as a gas for forming a carbon film and optionally a carrier gas such as hydrogen in a reaction furnace. Through the furnace. Then, while keeping the inside of the reaction furnace at a low pressure of 1 torr or less, a microwave of 2.45 GHz is introduced into the furnace through the waveguide 6. At the same time, the electromagnetic coil 4
To apply a magnetic field of a level of about 875 gauss or more.
As a result, the electrons move to the cyclotron frequency f = eB / 2.
Cyclotron motion is generated based on πm (e: electron charge, B: magnetic flux density, m: electron mass). When this frequency coincides with the microwave frequency (2.45 GHz), that is, when the magnetic flux density B becomes 875 Gauss, electron cyclotron resonance occurs. As a result, the electrons are remarkably absorbed by the microwave energy, accelerated, collide with neutral molecules and cause ionization, and generate high-density plasma even at a low pressure. By maintaining the temperature of the substrate at 100 to 1200 ° C. at this time, a hard carbon film can be formed on the surface of the substrate.

In the present invention, when a hard carbon film having the above-mentioned predetermined characteristics is formed, the substrate temperature is set to about 800 ° C. to 1100 ° C., and the raw material gas concentration is set to 1% to 30 ° C.
% And the furnace pressure may be set in the range of 1 × 10 ⁻³ to 1 torr. This substrate temperature can be measured by measuring infrared rays emitted from the substrate surface during film formation.

Since the substrate temperature changes depending on the power, pressure, source gas concentration, etc. of the microwave to be supplied,
It is necessary to measure in advance under the same conditions as the film formation conditions.

The electron temperature of the plasma on the substrate surface is 8 eV or less, and the electron density is 1 × 10 ¹¹ cm ^−3.
It is important to place the substrate at a position as described above, but in order to achieve this, the electron temperature and electron density of the plasma are measured in advance under the same conditions as those used for film formation. It is necessary to investigate an area that satisfies the condition of This measurement is preferably performed using a known plasma diagnostic method, for example, the Langmuir probe method. These electron temperature and electron density depend on the power of microwave input, pressure,
It can be controlled by magnetic field configuration. For example, when the microwave power is increased or the pressure is decreased, the electron temperature tends to increase, and the electron density tends to increase. It is necessary to properly balance these factors and determine the film forming conditions.

The mixing ratio and type of these gases are not affected by the effects of the present invention by using any of the known methods disclosed in JP-A-60-19197 and JP-A-61-183198. Has no effect.

The carbon-containing raw material gas used in the above-mentioned production method includes, in addition to hydrocarbon gases such as methane, ethane and propane, organic compounds such as CxHyOz (x, y and z are at least one). Gases such as CO and CO ₂ can also be used.

The base material for coating the hard carbon film in the present invention is not particularly limited,
For example, in addition to ceramic materials such as silicon nitride and silicon carbide, WC-Co cemented carbides, cermets containing TiC and TiCN as main components, and materials such as metals and plastics can be used. When used for applications in the field of wear resistance, silicon nitride and silicon carbide are particularly preferable because of their close linear thermal expansion coefficient to diamond, which is the main component of the hard carbon film, and high adhesion to the film. In addition, when used for heat conduction and optical applications, the substrate is often removed and only diamond is used. Therefore, a material that can easily remove the substrate by acid treatment or the like is used, or a difference in linear expansion coefficient from diamond is used. It is desirable to use a base material having a large diameter to facilitate the peeling of diamond by thermal stress. In order to promote the generation of diamond nuclei on the surface of the substrate, the surface of the substrate may be previously damaged by diamond abrasive grains or the like before film formation.

The hard carbon film obtained by the above-mentioned method is mainly composed of diamond, and has a characteristic almost similar to diamond. However, it is mixed with a slight amount of amorphous carbon component, gas, film forming apparatus, base material and the like. Unavoidable impurities.

If the film is formed so as to satisfy the above conditions, a very smooth film can be obtained. Therefore, the surface roughness of the hard carbon film is almost the same as or slightly different from the surface roughness of the formed substrate. Will be more than Therefore, it is preferable to appropriately finish the surface roughness of the base body to a necessary surface roughness in advance according to the application actually used. If the required surface roughness exceeds the required value after the film formation, the film may be finish-polished using fine diamond abrasive grains. The membrane itself,
Since it is very smooth from the beginning, a little polishing is often sufficient.

[0045]

The hard carbon film according to the present invention has a high nucleation density (22
(311), (400), (3)
31) Since the crystal is grown to be large crystal grains while suppressing the growth of the crystal plane which causes the peak of 31),
The surface of the film is very smooth and has high abrasion resistance, high slidability, high thermal conductivity, and high light transmission characteristics. Since the growth of the diamond crystal is mainly performed on the (220) plane instead of the (111) plane, the crystal growth is mainly performed in the two-dimensional direction, and crystal growth controlled in a certain direction becomes possible. It seems to be. Due to such large crystal grains oriented in the (220) plane, the half-value width of the diamond peak in the Raman spectrum is reduced, and high thermal conductivity is exhibited.

In synthesizing the hard carbon film of the present invention, the electron temperature of the plasma on the surface of the substrate on which the film is formed is set to 8 eV or less, thereby suppressing ion bombardment of the film and having high wear resistance. High quality film can be synthesized. Further, by setting the electron density of the plasma on the substrate surface to 1 × 10 ¹¹ cm ⁻³ or more, the active species are increased in density and the degree of supersaturation on the substrate surface is increased, so that the nucleation density is dramatically increased. It is possible to obtain a smooth film made of crystals whose (220) plane is oriented. Further, since the substrate temperature is set to 800 ° C. or higher, the size of the crystal grains becomes large, and it is possible to prevent a decrease in thermal conductivity and abrasion resistance due to miniaturization of the film. On the other hand, since the electron density of plasma generated by a general microwave plasma CVD method is at most 10 ¹⁰ cm ⁻³ , the active species density is low and the nucleation density is also low. Individual crystals are likely to be rough and highly rough with large irregularities.

Under these conditions, the reason why the (220) plane of the diamond crystal in the hard carbon film grows preferentially as compared with the (111) plane cannot be speculated at present. In the crystal growth of diamond, the growth of the (111) plane becomes dominant when the degree of supersaturation of the active species is low, and the growth of the (220) plane becomes opposite when the degree of supersaturation of the active species is low. It is thought to be dominant. In the present invention, since a high active species is obtained by a high plasma density of 1 × 10 ¹¹ cm ⁻³ or more,
The (220) plane seems to grow. Further, since the electron temperature is suppressed to 8 eV or less, high crystallinity is maintained during the growth of the (220) plane, and (311), (400), and (3)
It is considered that the generation of secondary nuclei causing the peak of 31) is suppressed, and only the growth of pure (220) plane is promoted.

[0048]

【Example】

Example 1 A silicon wafer was installed as a substrate in a reaction furnace in an ECR plasma apparatus as shown in FIG. 1, a magnetic field having a maximum intensity of 2 kG was applied, and a substrate temperature of 900 ° C. was used under a microwave power of 4 kW. Film formation was performed on the substrate surface under the conditions of an internal pressure of 0.3 torr. In addition, methane gas, carbon dioxide, and hydrogen gas were
A mixture obtained at a flow rate ratio of 0 sccm, 20 sccm, and 270 sccm was used. Under these conditions, a hard carbon film of about 10
It was manufactured to have a thickness of 0 μm.

Regarding the installation position of the substrate, before the film formation, plasma measurement was carried out with an electrostatic probe under the condition of synthesizing the hard carbon film without the substrate, and the electron temperature was 6.3 eV and the electron temperature was 6.3 eV. It was confirmed that the density was 2.8 × 10 ¹¹ cm ⁻³ .

When the obtained carbon film was subjected to X-ray diffraction of the film, diamond peaks were detected, and the value of f of each peak was calculated.
= −0.7, f (220) = 0.43, | f (311)
+ F (400) + f (331) | = 0.01.
Note that the X-ray diffraction was measured by both the bulk measurement method and the thin film measurement method which were usually performed, but no change was observed in the peak intensity ratio.

When the surface of the carbon film was observed by SEM, it was found that the carbon film was composed of oriented particles having a smooth crystal plane, and the average value of the particles in the major axis direction was 21.1 μm. No voids are observed on the surface,
It was very smooth. When the surface roughness was measured with a stylus-type surface roughness meter, Rmax (hereinafter, surface roughness was Rmax
It was found to be 0.25 μm.

The surface of the carbon film was subjected to spectral measurement by micro-Raman spectroscopy. As a result, a diamond peak was observed at 1334 cm ⁻¹ , and the half width was 5.
It was 5 cm ^-1 . In addition, Raman spectroscopy shows A of 488 nm.
The laser beam was narrowed down to a diameter of about 10 μm. Half width of the peak is to draw oblique lines between positions 1100 cm ^-3 and 1700 cm ^-3, performs a peak separation of the observed peak as the baseline as the Lorentz type, to determine the half width.

When the thermal conductivity of this carbon film was measured by the AC calorimetry method, it was found to be 1530 W / (m · K). The value obtained by this method is
It is not the thermal conductivity itself but the thermal diffusivity. The thermal conductivity is given by a formula of thermal conductivity = heat capacity per unit volume × heat diffusivity. Here, the heat capacity per unit volume (=
Specific heat × density) is calculated using the reference value of diamond as 1.
The calculation was performed using 80 J / (K · cm ³ ). Also,
The measurement is performed by peeling the film from the base of the silicon wafer, and by measuring the two-layer material of silicon and carbon film without peeling, obtaining the measurement value of the silicon wafer alone, and subtracting the effect And the method of calculating the value of the carbon film alone was used, but both values were the same.

Next, a disk-shaped article made of high-density silicon nitride ceramics having a diameter of 40 mm
After finishing to a thickness of μm, a hard carbon film was formed using this as a substrate under exactly the same conditions as those described above. Thereafter, a sliding test was performed by a pin-on-disk method using this and a pin having a radius of 3/16 inch at the tip. The pin was made of an aluminum-18% silicon alloy, the load was 19.6 N, the sliding speed was 1 m / s, and the sliding distance was 100 km. During the test, the coefficient of friction was about 0.11, showing a very low value. Further, no metal deposition was observed on the surface of the film after the test. Further, since slight sliding traces were observed on the film, a change in the surface shape was examined. The specific wear amount was 1.4 × 10 ⁻¹⁹ m ^3.
/ (N · m), very low, hardly worn,
It was found that the sliding only further reduced the surface roughness of the film. Wear of the alloy pins was also very low.

Further, a hard carbon film was coated on a single-crystal Si wafer to a thickness of 200 μm under exactly the same conditions as described above, and then the Si wafer was immersed in a solution of hydrofluoric nitric acid and etched to form a hard carbon film. I got my own solid. This was cut into 25 × 25 fragments by laser processing, and the light transmission characteristics were measured in the range from ultraviolet to visible light. FIG. 2 shows the chart. 220 to 23 corresponding to a band gap
Light began to be transmitted from the region of 0 nm, and exhibited a uniform transmission characteristic of nearly 60% over almost the entire visible light region.

Next, for comparison, a hard carbon film was formed on a silicon wafer by the conventional microwave plasma CVD method in the same manner as described above. In this case, the plasma temperature is 6e
V, the plasma density was 3 × 10 ¹⁰ cm ⁻³ . Other conditions were the same except that no magnetic field was applied and the pressure was 35 torr.

When the obtained carbon film was evaluated in the same manner as in the above example, the value of f at each peak was determined from the peak intensity of the diamond by X-ray diffraction. However, f (111) = 0.6
3, f (220) = − 0.1, | f (311) + f (4
00) + f (331) | = 0.1. The half width at half maximum of the diamond peak in Raman spectroscopy was 12 cm ⁻¹ , and the thermal conductivity of the film was about 660 W / (m · K).

When the surface of this carbon film was observed by SEM, it was found that the crystal had grown largely and had an irregular surface with severe irregularities. The surface roughness was very large, 2.8 μm.

When a pin-on-disk sliding test was conducted in the same manner as described above, the coefficient of friction was 0.51, which was clearly higher than that of the above example. Then, at a point where the sliding distance was about 50 km, the pin of the alloy was scraped at the tip by the unevenness of the film surface and was worn away, and it became impossible to continue the test.
Partial adhesion of the alloy was observed.

FIG. 3 shows the results of measuring the transmission characteristics in the range from ultraviolet to visible light in exactly the same manner as described above. Light transmittance of less than 10% was obtained over almost all regions.

Example 2 A carbon film was formed on the surface of a silicon wafer in exactly the same manner as in Example 1 except that the conditions for forming the carbon film were as shown in Tables 1 and 2, and the obtained film was analyzed by X-ray diffraction. F of each peak
The values, the half width of the diamond peak by micro-Raman spectroscopy, the thermal conductivity, the particle diameter in the major axis direction (average particle diameter), and the surface roughness were evaluated by SEM observation. Furthermore, a sliding test by the pin-on-disk method and a measurement of light transmittance were performed.
The results are also shown.

[0062]

[Table 1]

[0063]

[Table 2]

These evaluations were performed under the same conditions as those shown in Example 1. For the sake of simplicity, the light transmittance of visible light having a wavelength of 600 nm is shown. The examples and comparative examples shown in the above Example 1 are No. 1 in Table 1, respectively. 1 and No. It is shown in FIG. Note that NO. All samples other than 2 were prepared by ECR plasma CVD.

As is clear from Tables 1 and 2, the sample No. 1 and No. 3-No. At 16,
Because the surface roughness of the film is small and has good smoothness,
Processing as a sliding member is easy. From the results of the pin-on-disk sliding test, it showed a low friction coefficient of 0.2 or less and a specific wear amount of 5 × 10 ⁻¹⁸ m ³ / (N · m) or less, and exhibited high wear resistance. You can see that it is. Also,
The light transmittance also shows a value of 40% or more in all the samples, which indicates that the sample is also useful as an optical window. In addition, since high transmittance means that impurities other than diamond are small in the film, even when used as a microwave transmission window, the heat conductivity is high without induction heating by microwaves. It means that it is suitably used in combination with the above.

On the other hand, the sample N outside the scope of the present invention
o. 2 and No. For Nos. 17 to 23, either the film was large in surface roughness and lacked smoothness, or the film was smooth but lacked abrasion resistance. In the case of a film lacking smoothness, a problem occurs in that a pin of a mating material is cut and damaged during a sliding test, and in the case of a film lacking abrasion resistance even when the film is smooth, 10 ^-17. m ³ / (N ·
m) The specific wear amount was low. The light transmittance also showed only a low value of about 25% or less.

[0067]

As described above in detail, the hard carbon film according to the present invention can synthesize diamond crystal particles having high crystallinity by synthesizing in a plasma in which the electron temperature, the electron density and the substrate temperature are controlled. Since the film is grown while being oriented in a certain direction at a nucleation density, the surface of the film is very smooth and has high slidability, high thermal conductivity, and high light transmittance. Therefore, when this hard carbon film is used as a coating material, its life can be greatly extended if it is used as a wear-resistant sliding component whose surface is mechanically slid. In addition, even when the hard carbon film is peeled off from the substrate and used alone, it exhibits excellent characteristics as a heat sink or a power device mounting substrate utilizing the high thermal conductivity.
Furthermore, it is also useful as an optical window, a microwave window, an X-ray window, etc. utilizing high light transmission characteristics.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an electron cyclotron plasma CVD method.

FIG. 2 is a graph showing light transmission characteristics in the range of ultraviolet to visible light in Sample No. 1.

FIG. 3 is a graph showing light transmission characteristics in the range of ultraviolet to visible light in Sample No. 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Reaction furnace 2 ... Base material 3 ... Microwave generator 4 ... Electromagnetic coil 5 ... Gas introduction path 6 ... Waveguide

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-7-215795 (JP, A) JP-A-6-316492 (JP, A) JP-A-64-52699 (JP, A) JP-A-4- 92896 (JP, A) JP-A-7-276106 (JP, A) JP-A-63-307196 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C30B 1/00-35 / 00

Claims (4)

(57) [Claims] In a hard carbon film containing diamond, the intensity of a diamond peak in X-ray diffraction is calculated as follows: f = (p-p ₀ ) / (1-p ₀ ) Peak intensity) /
(Sum of all peak intensities) and p ₀ is (peak intensity of interest) /
(Sum of all peak intensities)) f (hkl) at each peak when f (111) ≦ −0.1 0.2 ≦ f (220) ≦ 0.9 | f (311) + f (400) + f (331) | ≦ 0.1 and the major axis of the crystal grains on the surface of the film
A hard carbon film having a size in the direction of 2 μm or more on average . 2. When the Raman spectrum of the surface of the hard carbon film is measured by micro-Raman spectroscopy, 1333 ± 5c
The half-value width of the diamond peak present at m ^{- 1} is 10c
2. The hard carbon film according to claim 1, wherein the hardness is not more than m ^{- 1} . 3. The hard carbon film according to claim 1, wherein the heat conductivity of the film is 800 W / mk or more. 4. A obtained by forming a hard carbon film on the surface of the substrate the hard carbon film-coated member, the hard carbon film is a hard carbon film containing diamond, rigid carbon film,請
The hard carbon film according to any one of claims 1 to 3,
Hard carbon film-coated member characterized by that.