JPH10130865A - Substrate with hard carbon film and its forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a substrate coated with a hard carbon film having excellent adhesion property of the film to the substrate and excellent peeling resistance by forming an intermediate layer comprising Al, Cr or oxide, nitrides, carbides of these on a substrate and then forming a hard carbon film thereon. SOLUTION: An intermediate layer 32 essentially comprising at least one kind of Al, Cr, Sn, Co and B or oxides, nitrides or carbides of these is formed on a substrate 31. This intermediate layer 32 is formed by sputtering to 50 to 8000Å thickness while high frequency voltage is applied on the substrate 31 to produce <=-20V self bias voltage. Then a hard carbon film 33 having a diamond structure is formed by CVD or the like to 50 to 5000Å thickness on the intermediate layer 32. As for the substrate 31, a metal essentially comprising Ni or Al used for a blade of an electric shaver, stainless steel, cast iron for sliding member, steel, iron alloy, nonferrous metal material, ceramics, noble metal material and carbon can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hard carbon coating substrate having a hard carbon coating formed on its surface and a method for forming the same, and more particularly, to an outer blade and an inner blade of an electric shaver, a magneto-optical disk, a thin-film magnetic head, and the like. And surface acoustic waves (S
AW) A protective film used for devices and the like, an antireflection film for lithography, a protective film used for sliding parts such as a compressor, a constituent layer of a solar cell, a decorative article, and a hard carbon film used for optical parts and the like, and formation thereof. It is about the method.

[0002]

2. Description of the Related Art Conventionally, it has been known that if a diamond-like coating is formed directly on a substrate, the adhesion between the diamond-like coating and the substrate is not good. It has been proposed to provide a layer between the diamond-like coating and the substrate (Japanese Patent Laid-Open No. Hei 2-
182880, JP-A-3-115572,
JP-A-1-138611, etc.).

In addition, N used for electric shaver blades and the like
Si, Ru, Ge can also be applied to a metal or alloy containing i or Al as a main component, or a substrate such as stainless steel.
It is disclosed that the adhesion is improved by forming a hard carbon film through an intermediate layer such as that described in Japanese Patent Application Laid-Open No.
-41386, JP-A-7-316818).

[0004]

By providing the intermediate layer of the prior art described above between the substrate and a hard carbon coating such as a diamond-like carbon coating, the adhesion can be increased and the peeling resistance can be improved. However, in view of enrichment of technology and application in various technical aspects, it is required to use other materials as an intermediate layer to improve adhesion to a substrate and improve peel resistance.

An object of the present invention is to satisfy such a demand, and to provide a hard carbon coating substrate with improved adhesion of the hard carbon coating to the substrate and improved peel resistance, and a method of forming the same. is there.

[0006]

According to the present invention, there is provided a hard carbon coated substrate according to the present invention, comprising: a substrate; and Al, Cr, S
an intermediate layer mainly composed of at least one selected from the group consisting of n, Co, and B, and oxides, nitrides, and carbides thereof; and a hard carbon coating provided on the intermediate layer. .

The method of forming the intermediate layer in the present invention is not particularly limited, but it can be formed by, for example, a sputtering method. When the intermediate layer is formed by a sputtering method, it is preferable to apply a high-frequency voltage to the substrate and generate a self-bias on the substrate to form the intermediate layer on the substrate. The self-bias voltage generated on the substrate is preferably -20V or less. By setting the self-bias voltage at the time of forming the intermediate layer to −20 V or less, the adhesion of the hard carbon coating to the substrate can be further increased.

Further, the intermediate layer in the present invention may be formed by other physical vapor deposition, chemical vapor deposition, or the like. When forming an intermediate layer made of a simple metal,
The intermediate layer may be formed by plating.

The hard carbon coating in the present invention includes an amorphous diamond coating and a diamond coating containing a crystalline portion, and further includes a crystalline diamond coating.

In the present invention, the method of forming the hard carbon film is not particularly limited, but it can be formed by, for example, a CVD method. For example, it can be formed using a plasma CVD method. Also in the formation of the hard carbon film, it is preferable to apply a high-frequency voltage to the substrate and generate the self-bias voltage on the substrate, as in the formation of the intermediate layer, to form the hard carbon film. The self-bias voltage is preferably −20 V or less. Examples of the plasma generating means in the plasma CVD method include, for example,
An electron cyclotron resonance (ECR) plasma CVD apparatus or the like can be used. By using such an apparatus, the density of the plasma can be further increased, and a high-quality hard carbon film can be formed at a low temperature.

The hard carbon coated substrate of the present invention can be applied to, for example, an outer blade and an inner blade of an electric shaver. The outer blade and the inner blade of the electric shaver are often made of a metal or alloy mainly containing Ni or Al,
Or it is formed from stainless steel or the like. Therefore,
In the present invention, a substrate made of these materials can be used as the substrate.

Further, the substrate is not limited to the outer blade and inner blade of the electric shaver, but can be applied to a magneto-optical disk, a thin-film magnetic head, and a surface acoustic wave (SAW) device. A hard carbon film can be formed as a film. Further, a hard carbon film may be formed as an antireflection film at the time of exposure in the lithography method. Further, a hard carbon film may be formed as a protective film on a sliding part of a compressor such as a rotary compressor, a constituent layer such as a protective film in a solar cell, or a part of an optical part or a decorative article.

Therefore, the material of the substrate in the present invention includes cast iron such as monicro cast iron, steel such as high speed tool steel, and the like.
Examples include stainless steel such as SUS304, ferrous alloys, non-ferrous metal materials, ceramics, precious metal materials, and carbon. As non-ferrous metal materials and ceramics,
Ti, Al, Zr, Si, W, Mo, In, Ta, F
e, Ni, Co, Mn, Cr, and Zn alone or in the form of an alloy or sintered body, and their oxides, nitrides, and carbides. As the noble metal materials, Au, Ag,
Pt, Ru, and Pd. The carbon includes aluminum-impregnated carbon.

[0014]

FIG. 1 is a sectional view showing a hard carbon coated substrate according to an embodiment of the present invention. Referring to FIG. 1, an intermediate layer 32 is formed on a substrate 31,
A diamond-like coating 33 which is a hard carbon coating is formed on the intermediate layer 32. As the thickness of the intermediate layer 32,
It is preferably 50 to 8000 °, more preferably 50 to 8000 °.
４4000４. The thickness of the diamond-like coating 33 is preferably about 50 to 5000 °, and more preferably about 50 to 3000 °.

FIG. 2 is a sectional view showing an embodiment in which the present invention is applied to an outer blade and an inner blade of an electric shaver. Referring to FIG. 2, an intermediate layer 42 is provided on substrate 41 of the outer cutter, and a diamond-like coating 43 which is a hard carbon coating is provided on intermediate layer 42. FIG. 3 is a plan view showing the planar shape of the substrate 41 of the outer blade. As shown in FIG. 3, a hole 41a for catching a beard is formed in the substrate 41 of the outer blade.
Are formed.

Returning to FIG. 2, inside the substrate 41 of the outer blade,
An inner blade is provided. An intermediate layer 52 is provided on the inner blade substrate 51, and a diamond-like coating 53, which is a hard carbon coating, is provided on the intermediate layer 52. FIG. 4 is a front view showing the substrate 51 of the inner blade, as viewed from a direction along the plane of FIG. As shown in FIG. 4, an inclined surface 51 a having a tapered inclination (see FIG. 2) whose cross section increases toward the distal end is formed at the distal end portion of the substrate 51 of the inner blade. Returning to FIG. 2, when the inner blade slides inside the outer blade in the direction shown by the arrow, the hole 41a is formed.
Cut the beard caught in the.

FIG. 5 is a schematic sectional view showing a thin film forming apparatus capable of forming an intermediate layer and a hard carbon film in one apparatus. Referring to FIG. 5, the vacuum chamber 8 includes:
A plasma generation chamber 4 is provided. Plasma generation chamber 4
Has one end of the waveguide 2 attached thereto.
At the other end, a microwave supply means 1 is provided.
The microwave generated by the microwave supply means 1 passes through the waveguide 2 and the microwave introduction window 3 and passes through the plasma generation chamber 4.
It is led to. The plasma generation chamber 4 includes a plasma generation chamber 4
A discharge gas introduction pipe 5 for introducing a discharge gas such as an argon (Ar) gas therein is provided therein. A plasma generation magnetic field generator 6 is provided around the plasma generation chamber 4. A high-density plasma is formed in the plasma generation chamber 4 by applying a high-frequency magnetic field generated by a microwave and a magnetic field from the plasma magnetic field generator 6.

A cylindrical substrate holder 12 is provided in the vacuum chamber 8. This cylindrical substrate holder 12
Is rotatably provided around an axis (not shown) provided perpendicular to the wall surface of the vacuum chamber 8. A plurality of substrates 13 are mounted on the peripheral surface of the substrate holder 12 at equal intervals. The high frequency power supply 10 is connected to the substrate holder 12.

Around the substrate holder 12, a metal cylindrical shield cover 14 is provided at a predetermined distance. This shield cover 14 is connected to a ground electrode. The shield cover 14 is provided to prevent a discharge from occurring between the substrate holder 12 and the vacuum chamber 8 other than the portion where the film is formed due to the RF voltage applied to the substrate holder 12 when the film is formed. ing. The gap between the substrate holder 12 and the shield cover 14 is arranged to have a distance equal to or less than the mean free path of the gas molecules. The mean free path of a gas molecule is equal to or less than the average distance that ions and electrons generated for some reason can be accelerated by an electric field and move without collision. Therefore, by setting the gap between the substrate holder 12 and the shield cover 14 to be equal to or less than the mean free path of the gas molecules, the probability of collision of ions and electrons with the gas molecules is reduced, and ionization is prevented from progressing in a chain. ing. The gap between the substrate holder 12 and the shield cover 14 is preferably set to a distance of 1/10 or less of the mean free path of gas molecules. In the apparatus of the present embodiment, the gap between the substrate holder 12 and the shield cover 14 is set to about 5 mm, which is 1/10 or less of the mean free path of gas molecules.

Above the shield cover 14, a first opening 15 is formed. The plasma extracted from the plasma generation chamber 4 is emitted to the substrate 13 mounted on the substrate holder 12 through the first opening 15. A reaction gas introduction pipe 16 is provided in the vacuum chamber 8. The tip of the reaction gas introduction pipe 16 is located above the first opening 15.

FIG. 6 is a plan view showing the vicinity of the tip portion of the reaction gas introduction pipe 16. Referring to FIG. 6, a reaction gas introduction pipe 16 includes a gas introduction section 16a for introducing CH ₄ gas from the outside into the vacuum chamber, and a gas introduction section 16a.
And a gas discharge portion 16b connected in the vertical direction. The gas releasing portion 16b is disposed perpendicular to the rotation direction A of the substrate holder 12, and is provided so as to be located upstream of the first opening 15 in the rotation direction. The gas discharge part 16b has a downward
A plurality of holes 21 are formed in a direction of 5 °. In this embodiment, eight holes 21 are formed. The space between the holes 21 is formed so as to gradually decrease from the center toward both sides. By forming the holes 21 at such intervals, the CH ₄ gas introduced from the gas introduction unit 16a is almost uniformly discharged from each hole 21.

Referring to FIG. 5 again, a second opening 17 is formed below shield cover 14 opposite to first opening 15. Below the second opening 17,
A target 18 made of material atoms constituting the intermediate layer is provided. The target 18 includes a target 1
A high frequency power supply 19 for sputtering 8 is connected. The target 18 and the high-frequency power supply 19 constitute a means for forming an intermediate layer. Therefore,
In the apparatus shown in FIG. 5, a hard carbon film is formed at the position of the first opening 15 by the plasma CVD method, and an intermediate layer is formed at the position of the second opening 17 by the sputtering method. By using an apparatus as shown in FIG. 5, a thin film can be formed on a plurality of substrates at once.

Example 1 (Intermediate layer: B) An intermediate layer and a diamond-like film were formed using the apparatus shown in FIG. The partial pressure of Ar gas in the vacuum chamber 8 was set to 1.5 × 10 ⁻³ Torr,
And an intermediate layer made of B was formed on the Ni substrate 13 while applying a high frequency voltage to the substrate holder so that the power applied to the target 18 was 200 W and the bias voltage generated on the substrate was -50 V. . By forming for 30 minutes, an intermediate layer having a thickness of about 0.05 μm was formed. Note that 24 Ni substrates 13 are mounted on the peripheral surface of the substrate holder 12 at equal intervals. While rotating the substrate holder 12 at a speed of about 10 rpm,
An intermediate layer was formed on No.3.

Next, a diamond-like film as a hard carbon film was formed on the Ni substrate 13 on which the intermediate layer was formed. The inside of the vacuum chamber 8 is adjusted to 10 ^-5 to 10 ^-7 Torr, and Ar gas is supplied at 5.7 × 10 ^-4 Torr from the discharge gas introduction pipe 5 of the ECR plasma generator, and from the microwave supply means 1. 2.45 GHz, 100
By supplying a microwave of W, Ar plasma formed in the plasma generation chamber 4 was radiated to the surface of the substrate 13. At the same time, the self-bias generated on the substrate 13 is -50V
An RF voltage of 13.56 MHz was applied to the substrate holder 12 from the high frequency power supply 10 so that CH ₄ gas was supplied from the reaction gas introduction pipe 16 at 1.3 × 10 ⁻³ Torr. This process is continued for about 15 minutes, and the substrate 13
A diamond-like film having a thickness of 1000 ° was formed on the surface of.

Example 2 (Intermediate layer: nitride of B) As in Example 1, the apparatus shown in FIG. 5 was used, and the partial pressure of Ar gas was 1.5 × 10 ⁻³ Torr, and the partial pressure of N ₂ gas was 5. 0x10
^-4 Torr, B was used as the target, and the target input power was set to 200 W.
Was formed. Note that an RF voltage was applied to the substrate holder so that the bias voltage generated on the substrate was -50 V. By forming the intermediate layer for 40 minutes, an intermediate layer made of BN having a thickness of about 0.05 μm was formed. Next, a film thickness of 1000
A diamond-like film of Å was formed thereon.

Example 3 (Intermediate layer: oxide of Al) As in Example 1, the apparatus shown in FIG. 5 was used, and the partial pressure of Ar gas was 1.5 × 10 ⁻³ Torr, and the partial pressure of O ₂ gas was 1. 0x10
^-3 Torr, Al as a target, and a target input power of 400 W.
An intermediate layer made of Al oxide was formed. Note that an RF voltage was applied to the substrate holder so that the bias voltage generated on the substrate was -50 V. An intermediate layer having a thickness of about 0.04 μm was formed by forming the intermediate layer for 30 minutes.
Next, a diamond-like film having a thickness of 1000 ° was formed thereon in the same manner as in Example 1.

Example 4 (Intermediate layer: nitride of Cr) As in Example 1, the apparatus shown in FIG. 5 was used, and the partial pressure of Ar gas was 1.5 × 10 ⁻³ Torr, and the partial pressure of N ₂ gas was 1. 0x10
^-3 Torr, Cr was used as the target, and the target input power was 400 W.
An intermediate layer made of Cr nitride was formed. Note that an RF voltage was applied to the substrate holder so that the bias voltage generated on the substrate was -50 V. An intermediate layer having a thickness of about 0.05 μm was formed by forming the intermediate layer for 30 minutes.
Next, a diamond-like film having a thickness of 1000 ° was formed thereon in the same manner as in Example 1.

Example 5 (Intermediate Layer: Sn Oxide) As in Example 1, the apparatus shown in FIG. 5 was used, and the partial pressure of Ar gas was 1.5 × 10 ⁻³ Torr, and the partial pressure of O ₂ gas was 1. 0x10
^-3 Torr, Sn as a target, and a target input power of 400 W.
An intermediate layer made of Sn oxide was formed. Note that an RF voltage was applied to the substrate holder so that the bias voltage generated on the substrate was -50 V. An intermediate layer having a thickness of about 0.04 μm was formed by forming the intermediate layer for 30 minutes.
Next, a diamond-like film having a thickness of 1000 ° was formed thereon in the same manner as in Example 1.

Example 6 (Intermediate layer: Co) In the same manner as in Example 1, an apparatus shown in FIG. 5 was used, an Ar gas partial pressure was set to 1.5 × 10 ⁻³ Torr, and Co was used as a target.
And an intermediate layer made of Co was formed on the Ni substrate 13 at a target input power of 400 W. In addition,
An RF voltage was applied to the substrate holder so that the bias voltage generated on the substrate became -50V. An intermediate layer having a thickness of about 0.05 μm was formed by forming the intermediate layer for 30 minutes. Next, in the same manner as in the first embodiment, a film thickness of 1000
Was formed thereon.

Comparative Example As a comparison, a diamond-like coating was formed directly on a Ni substrate without forming an intermediate layer. The conditions for forming the diamond-like coating were the same as in Example 1.

The adhesiveness of each of Examples 1 to 6 and Comparative Examples obtained as described above was evaluated. The evaluation of adhesion is
The test was performed by a pushing test using a Vickers indenter under a constant load (load = 1 kg). With 50 samples, N
The number of peeled diamond-like films on the i-substrate was counted and evaluated. Table 1 shows the results.

[0032]

[Table 1]

As is clear from the results shown in Table 1, in Examples 1 to 6 in which the intermediate layer was formed according to the present invention, the number of occurrences of peeling was significantly smaller than in Comparative Examples. Therefore, it can be seen that the adhesion of the diamond-like coating is improved by providing the intermediate layer according to the present invention.

FIG. 7 is a schematic sectional view showing a general structure of a rotary compressor. In FIG. 7, 101 is a closed container,
Reference numeral 102 denotes a crankshaft driven by an electric motor (not shown), and reference numeral 103 denotes a roller attached to an eccentric portion of the crankshaft 102, and the roller 103 is made of monochrome cast iron.

Reference numeral 104 denotes a cylindrical cylinder containing the roller 103, and this cylinder 104 is made of cast iron. Reference numeral 105 denotes a cylinder groove provided for reciprocating a vane 106 described later. Reference numeral 106 denotes a vane for partitioning a space in the cylindrical cylinder 104 into a high-pressure part and a low-pressure part. SKH5
1).

Reference numeral 107 denotes a spring for urging the vane 106 toward the roller 103. 108 is a cylindrical cylinder 1
A suction pipe 109 for supplying the refrigerant into the inside of the cylinder 04 and a discharge pipe 109 for discharging the refrigerant compressed inside the cylindrical cylinder 104 and having an increased pressure and temperature to the outside of the compressor.

The operation of the rotary compressor configured as described above will be described below. The electric motor drives the crankshaft 102
Is driven, and the roller 103 attached to the eccentric portion of the crankshaft 102 rotates inside the cylindrical cylinder 104 along the circumference. Vane 106 is a high pressure gas and spring 10
7, the vane 106 reciprocates in the cylinder groove 105 while constantly contacting the outer peripheral surface of the roller 103 with the rotation of the roller 103.

By repeating this movement continuously, the refrigerant sucked into the cylindrical cylinder 104 via the suction pipe 108 is compressed inside the cylindrical cylinder 104, and after the pressure and temperature rise, the discharge pipe The fluid is discharged to the outside of the rotary compressor via the compressor 9.

FIG. 8 is a schematic cross-sectional view of the vane 106 having the hard carbon film formed thereon according to the first aspect of the present invention. An intermediate layer 161 is formed on the vane 106, and a hard carbon coating 162 is formed on the intermediate layer 161.

FIG. 9 is a schematic sectional view of roller 103 having a hard carbon film formed thereon according to the first aspect of the present invention. An intermediate layer 131 is formed on the roller 103, and a hard carbon coating 132 is formed on the intermediate layer 131.

FIG. 10 is a schematic sectional view of cylinder groove 105 having a hard carbon film formed thereon according to the first aspect of the present invention. An intermediate layer 151 is formed on the inner surface of the cylinder groove 105, and a hard carbon coating 152 is formed on the intermediate layer 151.

Next, an evaluation test of the adhesion was performed on the hard carbon film formed on the vane 106 shown in FIG.
Using the apparatus shown in FIG. 5, the partial pressure of Ar gas is 1.5 × 10 ⁻³ T
The intermediate layer made of Cr was formed on the vane 106 at orr, Cr was used as the target, and the power supplied to the target was 400 W. Note that RF power was applied to the substrate holder so that the bias voltage generated on the substrate was -50 V. By forming the intermediate layer for 30 minutes,
An intermediate layer having a thickness of about 0.05 μm was formed.

Next, a diamond-like film 162 having a thickness of about 5000 ° was formed on the intermediate layer 161 for 75 minutes in the same manner as in Example 1 described above. The obtained hard carbon film was subjected to an adhesion evaluation test. The evaluation of the adhesion was performed by an indentation test under a constant load (load = 500 g) using a diamond spherical indenter having a tip radius of 0.1 mm. The number of samples was set to 50, and the number of peeled hard carbon films 162 on the vanes 106 was counted and evaluated. For comparison, the self-bias voltage −5 was directly applied on the vane 106 without forming the intermediate layer 161 made of Cr.
A hard carbon film was formed while applying an RF voltage to the substrate holder so that the voltage became 0 V, and an evaluation test of adhesion was similarly performed on the hard carbon film. Table 2 shows the evaluation results.

[0044]

[Table 2]

As is apparent from Table 2, when the intermediate layer 161 made of Cr is not formed on the vane 106, the hard carbon coating 16
2 is as large as 45, while an intermediate layer 161 made of Cr is formed on the vane 106, and a hard carbon film 162 is formed on the intermediate layer 161 at a self-bias voltage of -50V.
Was formed, the number of occurrences of peeling of the hard carbon coating 162 was reduced to five.

In each of the above embodiments, the intermediate layer is formed by sputtering. However, the present invention is not limited to such a forming method, and other physical thin film forming methods such as a vapor deposition method and a CVD method can be used. Alternatively, it may be formed by a chemical vapor deposition method such as, or a plating method. Further, the present invention is not limited to the apparatus shown in FIG. 5, and the intermediate layer and the hard carbon coating may be formed by different apparatuses.

[0047]

By providing the intermediate layer according to the present invention between the substrate and the hard carbon coating, the adhesion of the hard carbon coating is improved and the peel resistance is improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment according to the present invention.

FIG. 2 is a sectional view showing an embodiment in which the present invention is applied to an outer blade and an inner blade of an electric shaver blade.

FIG. 3 is a plan view showing a planar shape of an outer blade of the electric shaver blade.

FIG. 4 is a front view showing an inner blade of the electric shaver blade.

FIG. 5 is a schematic configuration diagram showing an apparatus for forming an intermediate layer and a hard carbon film in an embodiment according to the present invention.

FIG. 6 is a plan view showing the vicinity of the tip of a reaction gas introduction pipe in the apparatus shown in FIG. 5;

FIG. 7 is a schematic sectional view showing a general structure of a rotary compressor.

FIG. 8 is a schematic sectional view showing a vane on which a hard carbon coating according to the present invention is formed.

FIG. 9 is a schematic sectional view of a roller on which a hard carbon film is formed according to the present invention.

FIG. 10 is a schematic sectional view showing a cylinder groove on which a hard carbon coating according to the present invention is formed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 31 ... Substrate 32 ... Intermediate layer 33 ... Hard carbon coating 41 ... Outer blade substrate of electric shaver blade 42 ... Intermediate layer 43 ... Hard carbon coating 51 ... Inner blade substrate of electric shaver blade 52 ... Intermediate layer 53 ... Hard carbon coating 103: Roller 105: Cylinder groove 106: Vane 131, 151, 161: Intermediate layer 132, 152, 162: Hard carbon coating

Claims (7)

[Claims] 1. A substrate, provided on the substrate, wherein Al,
An intermediate layer mainly composed of at least one selected from the group consisting of Cr, Sn, Co, and B, and oxides, nitrides, and carbides thereof; and a hard carbon coating provided on the intermediate layer. Hard carbon coated substrate. 2. The hard carbon coated substrate according to claim 1, wherein said substrate is a substrate made of a metal or alloy containing Ni or Al as a main component, or stainless steel. 3. The hard carbon coated substrate according to claim 1, wherein the substrate is an electric shaver blade substrate. 4. The method according to claim 1, wherein the substrate is cast iron, steel, stainless steel,
Ferrous alloys, non-ferrous metal materials, ceramics, precious metal materials,
2. The hard carbon coated substrate according to claim 1, which is a substrate made of carbon. 5. The hard carbon-coated substrate according to claim 1, wherein the substrate is a substrate of a sliding component. 6. The hard carbon coated substrate according to claim 1, wherein the intermediate layer is an intermediate layer formed by a sputtering method. 7. The method for forming a hard carbon-coated substrate according to claim 1, wherein the high-frequency voltage is adjusted so that a self-bias voltage generated on the substrate is −20 V or less. A method for forming a hard carbon-coated substrate, wherein the intermediate layer is formed on the substrate by a sputtering method while being applied to the substrate.