JPH1192934A - Hard carbon thick film and method of manufacturing the same - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To achieve a film thickness of 1 μm without a decrease in adhesion.
The present invention provides a hard carbon thick film capable of forming a sound thick film exceeding m on a base material and having excellent hardness and durability, and a method for producing the same. SOLUTION: The input power, the flow rate of raw material gas and the like are changed continuously or stepwise during the film formation to change the hydrogen content and / or the content of the third element such as nitrogen contained in the hard carbon thick film. By doing so, a film having a small internal stress is formed on the base material side, a film having a large internal stress is sequentially laminated thereon, and a film having the highest internal stress is formed on the outermost surface. The internal stress generated in the thick film is provided with a continuous or step-like inclination with respect to the film thickness direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a plasma CVD.
Hard carbon film formed on a substrate by a sputtering method, a sputtering method or the like, and a method for producing the same, particularly, abrasion resistance of tools, automobile parts, magnetic heads, magnetic disks, magnetic tapes, electrical contacts, lenses, etc. The present invention relates to a hard carbon thick film used as a coating film for components, sliding components, optical components, and the like, and a method for producing the same.

[0002]

2. Description of the Related Art A hard carbon film is an amorphous carbon film which does not show a clear crystal structure by X-ray diffraction, or a hydrogenated carbon film in which hydrogen is bonded to dangling bonds of carbon existing in the film. Yes, a-C: H, i-C, DLC (diamond-like carbon). Hard carbon film has excellent mechanical strength, thermal conductivity, electrical insulation, infrared transmission and chemical resistance. Therefore, expectations for a coating film that can apply the characteristics of diamond to various devices are increasing.

[0003] In particular, the hardness of a hard carbon film is lower than that of a diamond thin film but higher than that of other hard thin films, so that it has excellent wear resistance, but does not excessively damage a mating material when used as a wear-resistant member. There is an advantage.

Further, while the diamond thin film has a surface roughness of 5 to 10 μm due to a structure in which fine crystal grains are accumulated, the hard carbon film is amorphous, so that the surface roughness after the film formation is 1 nm. It has the following characteristics: excellent surface smoothness and low friction coefficient. Therefore, the hard carbon film is particularly excellent as a coating film for wear-resistant parts, sliding parts, infrared optical parts and the like.

[0005]

However, since a hard carbon film has an extremely large internal stress generated in the film after the film is formed, it is a combination with a base material which is expected to have a strong interfacial bonding force in principle. Also, as the film thickness increases, the stress concentrates on the interface between the film and the substrate, causing a decrease in adhesion, and furthermore, when the internal stress exceeds the interface bonding force,
There was a problem that cracks and peeling occurred in the film.

On the other hand, in order to compensate for such a defect, for example, Japanese Patent Laid-Open Publication No.
A hard carbon laminated film in which the thickness is indirectly increased by alternately laminating a hard carbon thin film of μm and a buffer layer of 0.03 to 2.0 μm and the outermost surface is a hard carbon thin film has been proposed. .

However, according to the method disclosed in Japanese Patent Application Laid-Open No. 5-65625, 0.2 to 0.2% are formed on the outermost surface.
When the hard carbon thin film having a thickness of 0.6 μm is worn away, a soft buffer layer appears on the outermost surface, resulting in a decrease in abrasion resistance and poor durability.

An object of the present invention is to provide a hard carbon film which can form a sound thick film having a film thickness of more than 1 μm on a substrate without lowering the adhesion, and which is excellent in hardness and durability. It is to provide a thick film and a manufacturing method thereof.

[0009]

Means for Solving the Problems In order to solve the above problems, a hard carbon thick film according to the present invention is a hard carbon thick film formed directly or via an intermediate layer on a base material. The gist is to provide a continuous or step-like inclination of the internal stress in the thick film so that the internal stress in the thick film increases from the material side toward the surface of the thick film.

According to the hard carbon thick film having the above structure,
A thin film having a small internal stress is formed on the substrate side, and a thin film having a large internal stress is sequentially stacked thereon, and a thin film having the largest internal stress is formed on the outermost surface. , An internal stress generated in the thick film is inclined. As a result, the strain energy stored in the entire thick film can be reduced as compared with the case where the entire thick film is in a state where the internal stress is large, so that even when the thickness is increased, the stress concentration at the interface can be reduced, Cracking and peeling of the thick film can be prevented.

Further, there is a correlation between the hardness of the hard carbon film and the internal stress, and the hardness tends to increase as the internal stress of the hard carbon film increases. According to the hard carbon thick film of the present invention, Since the internal stress of the outermost surface of the thick film, that is, the hardness can be maintained high, it is possible to obtain a thick film having high wear resistance. Further, since the entire thick film can be formed of a hard carbon film having higher hardness than other hard thin films, it is possible to obtain a hard carbon thick film having high durability which has not been achieved conventionally.

Here, as the base material for forming the hard carbon thick film according to the present invention, various metal materials such as steel, copper, aluminum, titanium alloy and cemented carbide, silicon carbide, silicon nitride, nitride Ceramic materials such as aluminum, boron nitride, glass, alumina, quartz, AlTiC (Al ₂ O ₃ + TiC), semiconductor materials such as Si, Ge, and GaAs;
Examples include optical materials such as ZnS and ZnSe, and plastic materials such as polyethylene terephthalate (PET), but are not particularly limited thereto, and can be applied to any material.

Further, a hard carbon film may not be expected to have a high adhesion due to a low interfacial bonding force to many base materials. In between, an intermediate layer with a high interfacial bonding force with the hard carbon thick film,
For example, it is preferable to interpose Si, Ge, or the like.

The term "internal stress" refers to a stress generated in a thin film when a thin film of a different material is formed on a substrate, and a thermal stress caused by a difference in thermal expansion coefficient between the thin film and the substrate. It is divided into intrinsic stress generated in connection with the growth mechanism of the thin film and the film forming process. The latter intrinsic stress does not occur in relation to the base material, but is the remaining stress even when only the film is taken out.

The method for inclining the internal stress provided in the thickness direction of the thick film is a step-like inclination in which a plurality of thin films having different internal stresses are stacked discontinuously, or a gradient in which the internal stress is continuously changed. It is not particularly limited. Also, as means for providing a gradient in internal stress,
As a result, it is sufficient that the internal stress in the thick film has a gradient, and there is no particular limitation.

However, it is particularly desirable that the means for inclining the internal stress changes the hydrogen content in the thick film continuously or stepwise from the substrate side toward the thick film surface side. The internal stress of the hard carbon film has the property of changing according to the hydrogen content in the film, and by laminating thin films so that the hydrogen content changes continuously or stepwise, the internal stress toward the film thickness surface increases. This is because the stress can be increased continuously or stepwise.

Here, it is known that the relationship between the hydrogen content in the film and the internal stress varies depending on the film forming method. For example, in a hard carbon film formed by a sputtering method, it is reported that the internal stress increases as the hydrogen content increases, but in the plasma CVD method, the internal stress increases as the hydrogen content decreases. This is thought to indicate the existence of a hydrogen content at which the internal stress is maximized, but details are unknown. In short, since the correspondence between the internal stress and the hydrogen content is different depending on the film forming method, the internal stress on the base material side is small according to the film forming method, and the internal stress is increased such that the internal stress increases toward the surface. May be controlled.

Further, the internal stress gradient means changes the content of the third element other than carbon and hydrogen in the thick film continuously or stepwise from the base material side to the thick film surface side. There may be. The internal stress of the hard carbon film has the property of changing according to the content of the third element bonded to the dangling bonds of carbon present in the film, and the content of the third element to be bonded is inclined with respect to the film thickness direction. By doing so, it is possible to provide a gradient in the internal stress generated in the thick film.

The third element to be added to the hard carbon thick film is not particularly limited as long as it is an element capable of bonding to dangling bonds in the hard carbon thick film. is there. For example, in the case of using the plasma CVD method, it is necessary to decompose the raw material gas in the reaction vessel. Therefore, as the third element, a gas containing the element or a liquid or a solid capable of easily generating a gas by a vaporizer is supplied. It needs to be something that can be done. Specifically, SiH ₄ , B ₂ H ₆ ,
Si in which a hydride such as PH ₃ is a liquid or a gas,
Examples include B, P, and Ti, Ge, and the like, in which a halide such as TiCl ₄ or GeF ₄ exhibits a liquid or gas.

However, the third element is particularly preferably nitrogen. Nitrogen-containing raw materials include nitrogen gas, ammonia, and the like, which are inexpensive, have low toxicity, and are easy to handle.

The third element contained in the hard carbon thick film may have a constant hydrogen content, and only the third element content may be inclined in the film thickness direction. Both of the element contents may be inclined toward the film thickness direction, and an optimal combination may be appropriately selected according to the film thickness, hardness, durability, and the like required for the hard carbon thick film.

The method for producing a hard carbon thick film according to the present invention includes a plasma CVD method in which a hydrocarbon gas is decomposed by plasma to form a film, a dual ion beam sputtering method combining graphite sputtering and ion acceleration, Various manufacturing methods such as an ion plating method in which graphite is evaporated with an electron beam, ionized, and accelerated vapor deposition can be used.

Examples of the carbon source used for forming the hard carbon thick film include hydrocarbons, graphite, alcohols, acetone, carbon monoxide, carbon tetrachloride, C ₂ H ₅ Cl and the like. In addition, the hydrogen source may not be necessary when a hydrogen-containing substance such as a hydrocarbon is used as the carbon source, but may be unnecessary when a substance that does not contain hydrogen such as graphite is used as the carbon source or when hydrogen in the film is used. If it is desired to further increase the content, it may be supplied separately as hydrogen gas.

In order to incline the content of hydrogen and / or the third element in the hard carbon thick film in the film thickness direction, the film forming conditions such as the input power and the supply amount of the raw material gas are continuously or in the course of film formation. What is necessary is just to change in step shape. This makes it possible to easily obtain a hard carbon thick film provided with a slope such that the internal stress increases toward the surface of the thick film.

In particular, after the substrate is placed on the electrode provided in the reaction vessel and the inside of the reaction vessel is evacuated to a predetermined degree of vacuum, carbon and hydrogen and / or a third element other than carbon and hydrogen are removed. One or two or more kinds of raw material gases are introduced into the reaction vessel, and the raw material gas is decomposed by applying a high frequency to the electrode, and ions generated by decomposition of the raw material gas are accelerated by a self-bias potential by the high frequency. Using a so-called plasma CVD method of forming a thick film by colliding with a substrate, power when applying a high frequency to an electrode, a flow rate of a source gas per unit time introduced into a reaction vessel, and forming a thick film Any one selected from the group of the temperature of the substrate at the time of the discharge and the OFF time of the discharge when performing the pulse discharge during the film formation discharge
It is preferable to change one or more film forming conditions continuously or stepwise during film formation.

In the plasma CVD method, the third element can be easily doped into the dangling bonds present in the amorphous carbon film, and the reaction is promoted by adjusting the gas pressure as compared with the PVD method. Because it is possible. Furthermore, the plasma CVD method can be synthesized at a low temperature and can reduce the thermal stress component caused by the difference in thermal expansion between the substrate and the film, so that the internal stress in the thick film is reduced and the adhesion between the thick film and the substrate is reduced. It is because it becomes possible to improve.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail. FIG. 1 shows a plasma CVD (PE-CVD) for producing a hard carbon thick film according to the present invention.
1 shows a schematic configuration diagram of the device. In FIG.
The plasma CVD apparatus 1 includes a reaction vessel 2. The reaction vessel 2 is connected to an exhaust system (not shown) so that the inside of the reaction vessel 2 can be maintained at a predetermined degree of vacuum.

An electrode 3 is provided inside the reaction vessel 2. The electrode 3 is connected to a high frequency power supply 5 via a matching box 4 so that a predetermined high frequency can be applied to the electrode 3. Further, the inside of the electrode 3 is hollow so that cooling water can be circulated. The cooling of the electrode 3 is performed not only to prevent the electrode from being damaged by eddy current generated when a high frequency is applied, but also to maintain the substrate temperature at a desired temperature. . Further, on the upper surface of the electrode 3, a substrate 6 for forming a hard carbon thick film can be placed.

The reaction vessel 2 is connected to one end of a mass flow control 8 via an electromagnetic valve 7, and the other end of the mass flow control 8 is connected to a source gas supply source (not shown). The raw material gas supply source includes a gas cylinder when the substance to be a raw material of the hard carbon thick film is a gas, and a vaporizer and a carrier gas supply source when the substance is formed of a liquid or a solid.

Next, a process of manufacturing a hard carbon thick film using the above-described manufacturing apparatus will be described. First, a substrate for forming a hard carbon thick film is prepared, and the surface of the substrate is wrapped to have a surface roughness Ra of 10 nm or less. When the substrate is made of a material having a large interfacial bonding force with the hard carbon film, for example, in the case of a Si wafer or the like, the hard carbon thick film may be manufactured as it is according to the following process.

However, when the substrate is made of a material having a small interfacial bonding force with the hard carbon film, for example, alumina or the like, a material having a large interfacial bonding force with the hard carbon film, for example, Si, is formed on the substrate surface. , Ge or the like is preferably formed in advance. As a method for forming the intermediate layer, there are various methods such as vapor deposition, sputtering, and ion plating. The thickness of the intermediate layer is usually formed to be 0.2 μm or less, though it depends on the application. I do.

Next, the substrate 6 is placed on the electrode 3 provided in the reaction vessel 2 and the reaction vessel 2 is sealed. Then, exhaust means (not shown) is used until the inside of the reaction vessel 2 reaches a predetermined degree of vacuum. Exhaust). When the inside of the reaction vessel 2 reaches a predetermined degree of vacuum, the solenoid valve 7 is opened, and a raw material gas consisting of hydrocarbons and, if necessary, hydrogen gas or carbon and other materials other than hydrogen are supplied from a raw material gas supply source (not shown). A source gas containing a third element is introduced into the reaction vessel 2. The supply amount of raw gas is
The gas pressure in the reaction vessel 2 is maintained at a predetermined value by controlling the mass flow control 8 and balancing the introduction speed of the raw material gas and the exhaust speed by the exhaust system.

When the raw material gas is introduced into the reaction vessel 2, a high frequency is applied to the electrode 3 by the high frequency power supply 5 via the matching box 4 while cooling the electrode 3. When a high frequency is applied to the electrode 3, a discharge occurs in the source gas introduced into the reaction vessel 2, and the source gas is decomposed by the input electric energy, and C ⁺ , CH ⁺ , CH ₂ ⁺ ,
It is ionized into ions containing carbon such as CH ₃ ⁺ , H ⁺ , ions of a third element added as necessary, and electrons, and becomes a plasma state.

In a state where a high frequency is applied, first, only electrons from the plasma reach the electrodes due to the mass difference from the ions. Therefore, electrons are accumulated in the electrodes, and the electrodes are accordingly negatively biased. As a result, cations and the like containing carbon in the plasma receive acceleration of the negative bias and collide with the substrate, and a hard carbon film is formed on the substrate.

The hydrocarbon used as the carbon source for the hard carbon thick film may be a gas or a liquid or solid substance that can be easily vaporized, such as methane, ethane, propane, ethylene, propylene, and the like. Examples include aliphatic hydrocarbons such as acetylene, alicyclic hydrocarbons such as cyclopropane and cyclobutane, and aromatic hydrocarbons such as benzene, toluene, and xylene. In particular, when an aromatic hydrocarbon such as benzene, toluene, or xylene is used as the carbon source, there is an advantage that the film formation rate can be increased.

Next, a method for providing a gradient in the internal stress of the hard carbon thick film using the above-described manufacturing apparatus will be described. The hard carbon thick film formed by the plasma CVD method is a mixture of dense amorphous carbon and hydrogen, and has a property that when the amount of hydrogen is reduced, the internal stress in the film increases.

Here, the growth of the hard carbon thick film proceeds when carbon ions in the plasma are bonded to carbon having dangling bonds existing on the film surface, and hydrogen is attached to the dangling bonds. If the number of dangling bonds is reduced, carbon-carbon bonds no longer occur at that portion, and hydrogen is still taken up.

In the plasma CVD method, H ⁺ in simultaneously generated plasma reacts with hydrogen or carbon on the film surface,
The film formation proceeds while being removed as a gas such as H ₂ or CH ₄ .

Therefore, in the initial stage of film formation, the film is formed under the condition that a large amount of hydrogen remains on the film surface, and as the film thickness increases, the reaction between the film surface and H ⁺ in the plasma is promoted to increase the film surface. If the film is formed while changing the film forming conditions continuously or stepwise so that the amount of hydrogen gradually decreases, the internal stress in the hard carbon thick film can have a gradient in the film thickness direction.

Plasma CVD shown in FIG. 1 as a film forming means
When the method is used, for example, among the film forming conditions, for example, an increase in the high-frequency power supplied to the electrode 3, a decrease in the flow rate of the raw material gas introduced into the reaction vessel 2, an increase in the temperature of the substrate 6, and during the film forming discharge, The increase in the OFF time of the discharge when performing the pulse discharge for temporarily stopping the high-frequency discharge acts to reduce the hydrogen content in the film.

The decrease in the hydrogen content in the film due to an increase in the high-frequency power applied to the electrode 3 or a decrease in the flow rate of the source gas per unit time is due to an increase in the input energy per unit molecule. This is because they are decomposed into discrete states, and the amount of generated H ^{+ in} the plasma increases, thereby promoting the etching reaction between the film surface and H ⁺ in the plasma.

The decrease in the hydrogen content in the film due to an increase in the substrate temperature is due to an increase in the kinetic energy of the film surface, thereby improving the reaction efficiency with H ⁺ in the plasma,
This is because the etching reaction proceeds even with a small amount of H ⁺ .

Further, when a pulse discharge is performed so as to apply or stop a high frequency to the electrode, the hydrogen content in the film is reduced because, in the continuous discharge, the film is formed by the balance between the etching reaction and the deposition reaction. In the pulse discharge, the lifetime of H ⁺ contributing to the etching reaction is longer than the lifetime of carbon or carbon compound molecules contributing to the deposition reaction in the high-frequency stop state. This is because the etching reaction is still performed even if the deposition reaction is stopped.

The same applies to the case where the content of the third element in the film is changed. A source gas containing a third element such as nitrogen is introduced into a reaction vessel together with a source gas serving as a carbon source, and the input power,
By changing the film formation conditions such as gas flow rate, substrate temperature, pulse discharge OFF time, etc. continuously or stepwise,
A gradient can be provided in the third element content in the film, so that the internal stress increases toward the film thickness surface,
It is possible to provide a gradient in the internal stress.

Example 1 A hard carbon thick film was formed using the plasma CVD apparatus shown in FIG. As the substrate 6, an Si wafer having a diameter of 6 inches and a thickness of 0.8 mm was used, and its surface was lapped to a surface roughness Ra of 10 nm or less. This was placed on the electrode 3 in the reaction vessel 2, and after evacuation of the inside of the reaction vessel 2 to 1 × 10 ⁻⁵ Torr, xylene was introduced into the reaction vessel 2 as a carbon source, and the substrate temperature was set at 27 ° C. 13.56
MHz and the xylene flow rate is 100 SCCM at the beginning of film formation.
From the initial stage of film formation to 300 W at the end of film formation, while simultaneously decreasing the power applied to the electrode 3 linearly from 25 W to 25 SCCM at the end of film formation. A hard carbon thick film was formed.

The hydrogen content, Vickers hardness Hv, and internal stress of the obtained hard carbon thick film were measured. The hydrogen content in the thick film was measured by the HFS (hydrogen forward scattering) method. The Vickers hardness Hv was measured by setting the load to 25 g, stopping the film formation when the film thickness reached a predetermined value, and measuring the hardness of the film surface.

The internal stress σ of the hard carbon thick film, like the Vickers hardness Hv, stops the film formation when the thickness of the hard carbon thick film 9 reaches a predetermined value, and as shown in FIG.
The amount of warpage H of the substrate 6 was measured and found by the following equation (1).

[0048]

(Equation 1)

[0049] However, E _s is Young's modulus of the substrate 6, [nu _s is Poisson's ratio of the substrate 6, L is the diameter of the substrate 6, D _s is the thickness of the substrate 6, d _f is the hard carbon thick film 9 thickness , R is the substrate 6 after film formation.
Is the radius of curvature of FIG. 3 shows the obtained results.

FIG. 3A shows a change in the hydrogen content contained in the hard carbon thick film in the thickness direction. The vertical axis indicates the film thickness (μm), and the horizontal axis indicates the hydrogen content (atm%). In the vicinity of the interface where the high-frequency power supplied to the electrode was set to 300 W and the xylene gas flow rate was set to 100 SCCM, the hydrogen content was 45 atm%. The hydrogen content decreases monotonously with an increase in the high-frequency power applied to the electrode and a decrease in the xylene gas flow rate. On the outermost surface of the thick film where the high-frequency power is set to 600 W and the xylene gas flow rate is set to 25 SCCM, the hydrogen content is reduced. 25 atm%.

FIG. 3B shows the change of the Vickers hardness Hv in the film thickness direction. The vertical axis is the film thickness (μm),
The horizontal axis is Vickers hardness Hv. 300 W high frequency power applied to the electrode, 100 SCCM xylene gas flow rate
The Vickers hardness Hv near the interface set to is 800, whereas at a position 1 μm from the substrate surface, 1000,
1400 at the position of 2 μm and 2220 at the position of 3 μm
And the high frequency power is set to 600 W and the xylene gas flow rate is set to 25 SCCM.
And the Vickers hardness Hv monotonously increased in response to the decrease in the hydrogen content.

FIG. 3 (c) shows the change of the internal stress generated in the hard carbon thick film in the direction of the thick film. The vertical axis represents the film thickness (μm), and the horizontal axis represents the internal stress (GPa). Similarly, for the internal stress, the high-frequency power applied to the electrode is 300
W and 0.4 GPa near the interface where the xylene gas flow rate was set to 100 SCCM, whereas the high-frequency power was 6
00W, the outermost surface of the thick film with the xylene gas flow rate set to 25 SCCM was 1.6 GPa, and increased linearly from the vicinity of the interface to the outermost surface of the thick film in response to the decrease in the hydrogen content. . No cracking or peeling was observed in the obtained hard carbon thick film having a thickness of 4 μm.

(Example 2) The flow rate of xylene gas in the reaction vessel 2 and the electric power supplied to the electrode 3 were each set to 20 SCC.
M and 600W, and 200 SC at the beginning of film formation.
A nitrogen gas of CM was introduced into the reaction vessel, and the nitrogen gas flow rate was linearly reduced so that the nitrogen gas flow rate became 0 at the time of the film thickness of 2.5 μm.
In the range from to 4.0 μm, a film having a thickness of 4
A μm thick hard carbon film was formed.

The hydrogen content, Vickers hardness Hv, and internal stress of the obtained hard carbon thick film were measured in the same procedures as in Example 1. Further, the nitrogen content in the thick film is determined by RB
It was measured by the S (Rutherford backscattering) method. The results obtained are shown in FIG.

FIG. 4A shows changes in the hydrogen content and the nitrogen content in the hard carbon thick film in the thickness direction. The vertical axis represents the film thickness (μm), and the horizontal axis represents the hydrogen content and the nitrogen content (atm%). The xylene gas flow rate is
Since it was maintained at 20 SCCM throughout the entire film formation process, the hydrogen content in the film was 24 irrespective of the distance from the interface.
Atm% was a constant value, and no inclination was observed in the film thickness direction.

On the other hand, the nitrogen content was 10 atm near the interface where nitrogen gas of 200 SCCM was introduced into the reaction vessel.
%, On the other hand, the nitrogen content in the thick film also decreases monotonously with the decrease in the nitrogen gas flow rate. there were.

FIG. 4B shows the change in the Vickers hardness Hv in the thickness direction. The vertical axis is the film thickness (μm),
The horizontal axis is Vickers hardness Hv. 24 atm% hydrogen,
While the Vickers hardness Hv near the interface containing 10 atm% of nitrogen is 1200, the Vickers hardness Hv monotonically increases with a decrease in the nitrogen content, and the film thickness becomes 2.5 μm.
The position was 2400 at the position, and 2500 at the outermost surface of the thick film.

FIG. 4 (c) shows the change of the internal stress generated in the hard carbon thick film in the direction of the thick film. The vertical axis represents the film thickness (μm), and the horizontal axis represents the internal stress (GPa). Similarly, the internal stress is 0.68 GPa near the interface where 200 SCCM of nitrogen gas is introduced into the reaction vessel 2, whereas the internal stress is 1.53 GPa at a position of 2.5 μm in thickness where the nitrogen gas introduction amount is zero. And 1.6 at the outermost surface of the thick film.
0 GPa, and monotonically increased from the vicinity of the interface toward the outermost surface of the thick film in response to the decrease in the nitrogen content. No cracking or peeling was observed in the obtained hard carbon thick film having a thickness of 4 μm.

(Embodiment 3) A 150 m diameter substrate was used.
m, an alumina substrate having a thickness of 2.8 mm, and a surface roughness R
After lapping the surface so that a is 10 nm or less, a thickness of 0.1 mm is applied to the lap surface by sputtering.
A μm Si film was formed.

Next, this was placed on the electrode 3 in the reaction vessel 2 and the inside of the reaction vessel 2 was evacuated to 1 × 10 ⁻⁵ Torr.
M, the substrate temperature was 27 ° C., the high frequency used was 13.56 MHz, and the power supplied to the electrode 3 was 300 W.
atm%, Vickers hardness Hv is 800, thickness 6μ
m of hard carbon film was formed.

Further, the electric power applied to the electrode 3 is set to 600 W
And the xylene gas flow rate was reduced to 20 SCCM to continue film formation. On the hard carbon film, the hydrogen content was 25 atm% and the Vickers hardness Hv was 2500.
By forming a 4 μm thick hard carbon film,
A hard carbon thick film having a total thickness of 10 μm in which the internal stress was increased stepwise was formed on an alumina substrate.

The adhesion and abrasion resistance of the obtained hard carbon thick film were measured. The adhesive force has a radius of curvature of 200 μm at the tip.
Was measured by a scratch test using a diamond stylus, and the magnitude of the adhesion was expressed by the limit needle load (N) when the film was peeled from the substrate. The wear resistance is
It was measured by a dry lap method using a new hard disk medium having no Ra of 6 to 9 nm and having a lubricant every time, and expressed as a wear volume per unit time (μm ³ / min).
Table 1 shows the results.

[0063]

[Table 1]

No cracking or peeling was observed in the obtained hard carbon thick film having a thickness of 10 μm. The adhesion between the hard carbon thick film and the substrate was 38 to 43 N, and the average wear amount of the hard carbon thick film was 200 μm ³ / min.

(Comparative Example 1) The procedure was performed except that the hydrogen content in the thick film was not inclined and the high-frequency power and the flow rate of xylene gas were adjusted so that the Vickers hardness Hv became a constant value of 2500. According to the same procedure as in Example 3, a hard carbon thick film having a thickness of 10 μm was formed on an alumina substrate. The adhesion and abrasion resistance of the obtained hard carbon thick film were evaluated in the same procedure as in Example 3. Table 1 shows the results.

The obtained hard carbon thick film having a thickness of 10 μm
30 to 50% of the film formation surface was peeled off. When the remaining portion was measured as a reference measurement, the average wear amount was 178.
μm ³ / min, which was equal to or higher than that of the hard carbon thick film having a gradient in the hydrogen content prepared in Example 3, but showed a low value of adhesion of 24 N or less.

Comparative Example 2 A film was formed by adjusting the high-frequency power and the flow rate of xylene gas so that the hydrogen content in the thick film was not inclined and the Vickers hardness Hv of the thick film was a constant value of 1500. Formed a hard carbon thick film having a thickness of 10 μm on an alumina substrate in the same procedure as in Example 3.
The adhesion and abrasion resistance of the obtained hard carbon thick film were evaluated in the same procedure as in Example 3. Table 1 shows the results.

No cracking or peeling was observed in the obtained hard carbon thick film having a thickness of 10 μm.
It was 40 N, which was almost the same value as the hard carbon thick film prepared in Example 3 with a gradient in the hydrogen content. But,
The average wear amount was 392 μm ³ / min.
Approximately twice the value of the hard carbon thick film prepared in the above.

Comparative Example 3 A film was formed by adjusting the high-frequency power and the flow rate of xylene gas so that the hydrogen content in the thick film was not inclined and the Vickers hardness Hv of the thick film was constant at 800. Formed a hard carbon thick film having a thickness of 10 μm on an alumina substrate in the same procedure as in Example 3. The adhesion and abrasion resistance of the obtained hard carbon thick film were measured in Example 3.
The evaluation was performed according to the same procedure as described above. Table 1 shows the results.

No cracking or peeling was observed in the obtained hard carbon thick film having a thickness of 10 μm.
8 to 54 N, which was higher than that of the hard carbon thick film having a gradient in the hydrogen content prepared in Example 3. But,
The average wear amount was 451 μm ³ / min.
The value was about 2.25 times that of the hard carbon thick film prepared in the above.

From the above results, by changing the hydrogen content or the content of the third element such as nitrogen, the internal stress in the vicinity of the interface is reduced, and the internal stress is increased in the film so as to be closer to the surface. It has been found that if a slope is provided for the internal stress, a sound hard carbon thick film having a thickness exceeding 1 μm can be formed on the substrate without lowering the adhesion and the wear resistance.

The present invention is not limited to the above-described embodiment at all, and various modifications can be made without departing from the gist of the present invention. For example, in the above embodiment, as a means for providing a gradient in the internal stress in the thick film, a gradient is provided for the hydrogen content or the nitrogen content, but other third elements, for example, Si, B, P, The content of the third element may be changed by doping the hard carbon thick film alone or in combination of two or more kinds of Ti, Ge, or the like, thereby providing a gradient in the internal stress.

In the above embodiment, a disc-shaped Si wafer or alumina is used as a substrate and a hard carbon thick film is formed on its flat surface. However, irregularities or curved surfaces of tools, optical lenses, magnetic heads and the like are used. The same effect can be obtained by applying the present invention to various parts having the above or various materials made of metal, plastic and the like.

[0074]

According to the present invention, the internal stress in the film is inclined so that the internal stress near the interface on the substrate side is small and the internal stress on the outermost surface side of the thick film is large. Can reduce the stress concentrated on the interface as compared with the case where the internal stress is large, so that a healthy thick film having a film thickness exceeding 1 μm can be formed on the base material without lowering the adhesion. There is.

Further, since the entire thick film can be formed as a hard carbon film having a higher hardness than other materials, and the outermost surface can be maintained in a high hardness state, the durability is unprecedented. This has the effect that a hard carbon thick film having excellent properties can be formed.

[Brief description of the drawings]

FIG. 1 shows plasma CVD for producing a hard carbon thick film.
It is a schematic structure figure of an apparatus.

FIG. 2 is a diagram showing a relationship between an internal stress generated in a film and an amount of warpage of a substrate.

FIG. 3 is a diagram showing changes in hydrogen content, Vickers hardness and internal stress of a hard carbon thick film in the thickness direction.

FIG. 4 is a diagram showing changes in the film thickness direction of hydrogen content, nitrogen content, Vickers hardness and internal stress of a hard carbon thick film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plasma CVD apparatus 2 Reaction vessel 3 Electrode 4 Matching box 5 High frequency power supply 6 Substrate 7 Solenoid valve 8 Mass flow control 9 Hard carbon film

Claims (5)

[Claims] 1. A hard carbon thick film formed directly or via an intermediate layer on a substrate, such that internal stress in the thick film increases from the substrate side toward the thick film surface side. A hard carbon thick film, wherein a continuous or step-like inclination is provided for internal stress in the thick film. 2. The method according to claim 1, wherein the means for inclining the internal stress changes the hydrogen content in the thick film continuously or stepwise from the substrate side toward the thick film surface side. 2. The hard carbon thick film according to 1. 3. The internal stress inclining means changes the content of a third element other than carbon and hydrogen in the thick film continuously or stepwise from the base material side to the thick film surface side. The hard carbon thick film according to claim 1 or 2, wherein: 4. The hard carbon thick film according to claim 3, wherein the third element is nitrogen. 5. A substrate is placed on an electrode provided in a reaction vessel, and the inside of the reaction vessel is evacuated to a predetermined degree of vacuum, and then contains carbon and hydrogen and / or a third element other than carbon and hydrogen. 1
A source or two or more source gases are introduced into a reaction vessel, and the source gas is decomposed by applying a high frequency to the electrode, and ions generated by the decomposition of the source gas are accelerated by a self-bias potential by the high frequency to form a substrate. A method of manufacturing a hard carbon thick film that forms a thick film by colliding with a gas, comprising: power for applying a high frequency to an electrode, a flow rate of a source gas per unit time introduced into a reaction vessel, and formation of a thick film. At least one of the film forming conditions selected from the group of the temperature of the substrate at the time of the discharge and the OFF time of the discharge when the pulse discharge is performed during the film discharge is changed continuously or stepwise during the film formation. A method for producing a hard carbon thick film.