JPH11117068A - Formation of hard carbon film on inside peripheral surface of cylindrical member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a hard carbon film, capable of forming a hard carbon film on a cylindrical member with superior adhesion. SOLUTION: This method has the following treatment stages: (1) a treatment stage where a cylindrical member 11 is disposed in a vacuum tank 13 in such a manner that an auxiliary electrode 23 connected to with a ground potential is inserted into the inside of the opening of the cylindrical member and then the inside of the vacuum tank 13 is evacuated to the initial ultimate pressure; (2) a treatment stage where a D.C. voltage is applied to the cylindrical member 11 and also a D.C. voltage is applied to an anode 31 and an A.C. voltage is applied to a filament 33; (3) a treatment stage where a carbon-containing gas is introduced via a gas-introducing hole into the vacuum tank 31 to produce plasma and a hard carbon film is formed on the cylindrical member 11 at a film formation pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a hard carbon film on the inner peripheral surface of a cylindrical member having a center opening, and particularly to various bushings, chucks, cylinders such as piston rings and linear bearings. The present invention relates to a method of forming a hard carbon film formed on the inner peripheral surface of a member.

[0002]

2. Description of the Related Art This hard carbon film is a black film.
It has properties very similar to diamond. In other words, the hard carbon film has excellent properties such as high mechanical hardness, low coefficient of friction when coming into contact with other members, high electrical insulation, high thermal conductivity, and high corrosion resistance. ing. Therefore, it has been proposed to coat a hard carbon film on decorative articles, medical equipment, magnetic heads, tools, and the like.

[0003] The hard carbon film is a hydrogenated amorphous carbon film, and has properties similar to diamond as described above, and is therefore called a diamond-like carbon film (DLC) or i-carbon. Also called a membrane.

Therefore, various bushes such as a guide bush mounted on an automatic lathe and slidably and rotatably supporting a rod-shaped workpiece, a chuck, a piston ring,
By forming this hard carbon film on the inner peripheral surface of a cylindrical member having a center opening such as a linear bearing, the wear resistance of the inner peripheral surface that comes into contact with other members can be drastically increased.

A method for forming a hard carbon film on the inner peripheral surface of a cylindrical member by using the conventional plasma enhanced chemical vapor deposition method will be described with reference to FIG. FIG. 10 is a cross-sectional view for explaining a method of forming a hard carbon film according to a conventional technique.

As shown in FIG. 10, an inner peripheral surface 11 is provided inside a vacuum chamber 13 having a gas introduction port 15 and an exhaust port 17.
The cylindrical member 11 for forming the hard carbon film is disposed at b. Then, the inside of the vacuum chamber 13 is evacuated by evacuation means (not shown in FIG. 10) so that the degree of vacuum becomes 3 × 10 ⁻⁵ torr or less. The pressure reached by evacuation at the beginning is hereinafter referred to as “initial pressure reached”.

After that, a gas containing carbon is introduced into the vacuum chamber 13 through the gas inlet 15 to adjust the pressure inside the vacuum chamber 13 to 5 × 10 ⁻³ torr.

[0008] A DC voltage is applied to the cylindrical member 11 from a DC power supply 25. Further, a DC voltage is applied from an anode power supply 27 to an anode 31 arranged to face the cylindrical member 11, and an AC voltage is applied from a filament power supply 29 to the filament 33. At this time, the DC voltage applied from the DC power supply 25 to the cylindrical member 11 is −3 kV, and the anode power supply 27
A positive DC voltage of 50 V is applied to the anode 31 from the power supply. Further, the voltage applied from the filament power supply 29 to the filament 33 is set so that a current of 30 A flows.
An AC voltage of 0 V is applied.

Thus, plasma is generated inside the vacuum chamber 13 including the central opening 11a of the cylindrical member 11, and a hard carbon film is formed on the entire surface including the inner peripheral surface 11b of the cylindrical member 11. . At this time, the pressure inside the vacuum chamber 13 forms a hard carbon film at 5 × 10 ⁻³ torr, and the pressure at which the hard carbon film is formed is hereinafter referred to as “film formation pressure”. .

[0010]

In the method of forming a hard carbon film by the plasma chemical vapor deposition method described with reference to FIG. 10, plasma generated in a region around the cylindrical member 11 is mainly used. The gas containing carbon is decomposed to form a hard carbon film. For this reason, the cylindrical member 1
The hard carbon film formed on the inner peripheral surface of the cylindrical member 11 has poor adhesion and the film quality such as hardness is inferior, although a hard carbon film can be formed on the outer peripheral portion with good uniformity. There is a point.

This is because the central opening 1 of the cylindrical member 11
This is because 1a is a space in which electrodes of the same potential are opposed to each other, and the plasma in the center opening 11a generates a discharge more than what is called hollow discharge.

The hard carbon film formed by the hollow discharge is a polymer-like film having poor adhesion, and is easily peeled from the inner peripheral surface 11b of the cylindrical member 11 and has a low hardness.

In the above-described method for forming a hard carbon film, the DC power supply 25 applies a negative voltage of 3 kV to the cylindrical member 11 at a film forming pressure of 5 × 10 ⁻³ torr.
DC voltage is applied.

The pressure in the vacuum chamber 13 is 5 × 10
^In a state of about ^-3 torr, a large amount of charges such as electrons are present in the space in the vacuum chamber 13, and the spatial impedance is low. Therefore, an arc discharge, which is an abnormal discharge, is likely to occur in the cylindrical member 11 at the moment when the plasma discharge starts.

Further, the start of the plasma discharge is also at the initial stage of the formation of the hard carbon film. Therefore, the adhesion to the cylindrical member 11 depends on the quality of the film formed at the initial stage of the film formation.

As described above, when an arc discharge, which is an abnormal discharge, occurs at the initial stage of the plasma discharge, the quality of the hard carbon film is deteriorated and the adhesion is reduced, and the hard carbon film is separated from the inner peripheral surface 11b of the cylindrical member 11. The problem occurs.

[Object of the Invention] An object of the present invention is to solve the above problems and to provide a method of forming a hard carbon film capable of forming a hard carbon film with good adhesion on the inner peripheral surface of a cylindrical member. It is to provide.

[0018]

Means for Solving the Problems In order to achieve the above object, the following means is employed in the method of forming a hard carbon film on a cylindrical member according to the present invention.

In the method for forming a hard carbon film on the inner peripheral surface of a cylindrical member according to the present invention, the cylindrical member is arranged in a vacuum chamber having an exhaust port and a gas inlet port and having an anode and a filament therein. A first step of arranging an auxiliary electrode to be connected to a ground potential into the central opening of the cylindrical member, and thereafter, a step of evacuating the vacuum chamber to an initial ultimate pressure of a predetermined degree of vacuum or less. Step 2 is followed by applying a DC voltage to the cylindrical member, applying a DC voltage to the anode, and applying an AC voltage to the filament.
After that, a gas containing carbon is introduced into the vacuum chamber from the gas inlet to generate plasma, and while forming a hard carbon film on the inner peripheral surface of the cylindrical member, the pressure in the vacuum chamber is increased. And a fourth step of controlling the film formation pressure to be higher than the initial attained pressure.

In the method for forming a hard carbon film on the inner peripheral surface of a cylindrical member according to the present invention, the cylindrical member is disposed in a vacuum chamber having an exhaust port and a gas inlet, and the cylindrical member is disposed in the center opening of the cylindrical member. A first step of arranging the auxiliary electrode to be connected to the ground potential, followed by a second step of evacuating the vacuum chamber to an initial ultimate pressure equal to or lower than a predetermined degree of vacuum; A third step of applying high-frequency power to the
Thereafter, a gas containing carbon is introduced from the gas inlet into the vacuum chamber to generate plasma, and while forming a hard carbon film on the inner peripheral surface of the cylindrical member, the pressure in the vacuum chamber is increased to an initial ultimate pressure. And a fourth step of controlling the film forming pressure to be higher.

In the method for forming a hard carbon film on the inner peripheral surface of a cylindrical member according to the present invention, the cylindrical member is disposed in a vacuum chamber having an exhaust port and a gas inlet, and the cylindrical member is disposed in a central opening of the cylindrical member. A first step of arranging the auxiliary electrode to be connected to the ground potential, followed by a second step of evacuating the vacuum chamber to an initial ultimate pressure equal to or lower than a predetermined degree of vacuum; A third step of applying a DC voltage to the substrate, and thereafter, a gas containing carbon is introduced into the vacuum chamber through a gas inlet to generate plasma, and a hard carbon film is formed on the inner peripheral surface of the cylindrical member. A fourth step of controlling the pressure in the vacuum chamber to a film forming pressure higher than the initial attained pressure.

In the method for forming a hard carbon film on the inner peripheral surface of a cylindrical member according to the present invention, the cylindrical member is disposed in a vacuum chamber having an exhaust port and a gas inlet port and having an anode and a filament therein. A first step of inserting an auxiliary electrode connected to a DC positive voltage into the center opening of the cylindrical member so as to be inserted thereinto, and thereafter, the inside of the vacuum chamber is evacuated to an initial ultimate pressure equal to or lower than a predetermined degree of vacuum. A second step, and thereafter, a third step of applying a DC voltage to the cylindrical member, applying a DC voltage to the anode, and applying an AC voltage to the filament, and further including carbon from the gas inlet. A gas is introduced into the vacuum chamber to generate plasma, and while forming a hard carbon film on the inner peripheral surface of the cylindrical member, the pressure in the vacuum chamber is controlled to a film forming pressure higher than the ultimate pressure. 4th Characterized by a step.

In the method for forming a hard carbon film on the inner peripheral surface of a cylindrical member according to the present invention, the cylindrical member is disposed in a vacuum chamber having an exhaust port and a gas inlet, and the cylindrical member is disposed in a central opening of the cylindrical member. A first step of arranging the auxiliary electrode to be connected to the DC positive voltage, followed by a second step of evacuating the vacuum chamber to an initial ultimate pressure equal to or lower than a predetermined degree of vacuum; A third step of applying high-frequency power to the member, and thereafter, a gas containing carbon is introduced into the vacuum chamber from a gas inlet to generate plasma, and a hard carbon film is formed on the inner peripheral surface of the cylindrical member. And a fourth step of controlling the pressure in the vacuum chamber to a film forming pressure higher than the initial attained pressure.

In the method for forming a hard carbon film on the inner peripheral surface of a cylindrical member according to the present invention, the cylindrical member is disposed in a vacuum chamber having an exhaust port and a gas inlet, and the center of the cylindrical member is opened. A first step of arranging an auxiliary electrode to be connected to a DC positive voltage, and a second step of evacuating the vacuum chamber to an initial ultimate pressure of a predetermined degree of vacuum or less; A third step of applying a DC voltage to the cylindrical member, and thereafter, a gas containing carbon is introduced into the vacuum chamber from a gas inlet to generate plasma, and a hard carbon film is formed on the inner peripheral surface of the cylindrical member. A fourth step of controlling the pressure in the vacuum chamber to be a film forming pressure higher than the ultimate pressure while forming.

[Operation] In the method for forming a hard carbon film on a cylindrical member according to the present invention, a DC negative voltage or a high-frequency power is applied to the cylindrical member before introducing a gas containing carbon into the vacuum chamber. Adopt means. In such a means, plasma discharge starts at a pressure lower than the film formation pressure.

That is, since the plasma discharge starts at a state where the spatial impedance is higher than the film forming pressure, the arc discharge which is an abnormal discharge does not occur. As described above, the arc discharge which is an abnormal discharge does not occur at the initial stage of the formation of the hard carbon film at the start of the plasma discharge. Therefore, when the initial film quality of the plasma discharge is affected, the arc discharge which is an abnormal discharge does not occur in the cylindrical member, and the adhesion of the hard carbon film does not decrease. Therefore, in the method for forming a hard carbon film of the present invention, the phenomenon that the hard carbon film is separated from the cylindrical member does not occur.

Further, in the method for forming a hard carbon film on a cylindrical member according to the present invention, an auxiliary electrode connected to a ground potential is disposed at the center of the opening on the inner surface of the cylindrical member to form the hard carbon film. I do. Then, a negative DC voltage or a high-frequency voltage is applied to the cylindrical member.

As a result, an auxiliary electrode connected to the ground potential is provided on the inner surface of the opening of the cylindrical member where the electrodes of the same potential face each other, so that the same potentials do not face each other. Such a potential state is the most desirable state for plasma-enhanced chemical vapor deposition, and a hollow discharge, which is an abnormal discharge, does not occur. Therefore, a hard carbon film having good adhesion can be formed on the cylindrical member.

Further, in the method of forming a hard carbon film on a cylindrical member according to the present invention, the auxiliary electrode is disposed on the inner surface of the opening of the cylindrical member as described above, and the inner surface of the opening in the longitudinal direction of the cylindrical member is formed. And the potential characteristics become uniform. As a result, there is no occurrence of a film thickness distribution of the hard carbon film formed on the inner surface of the opening of the cylindrical member, and there is also an effect that a uniform film thickness can be formed between the opening end surface and the back side of the opening.

Further, in the method of forming a hard carbon film on a cylindrical member according to the present invention, a means for forming a hard carbon film by applying a DC positive voltage to an auxiliary electrode disposed on the inner surface of the opening of the cylindrical member is employed. I do. When a DC positive voltage is applied to the auxiliary electrode in this manner, an effect of collecting electrons in a region around the auxiliary electrode occurs, and the region around the auxiliary electrode has a high electron density.

When the electron density is increased as described above, the probability of collision between the gas containing carbon and the electrons is inevitably increased, ionization of gas molecules is promoted, and the plasma density in the region around the auxiliary electrode is increased. . For this reason, the film formation speed of the hard carbon film is higher than when no DC positive voltage is applied to the auxiliary electrode.

Further, when the opening dimension of the cylindrical member is reduced and the gap dimension between the inner surface of the opening and the auxiliary electrode is reduced,
If the hard carbon film is formed without applying a DC positive voltage to the auxiliary electrode, no plasma is generated on the inner surface of the opening of the cylindrical member, and the hard carbon film cannot be formed.

On the other hand, according to the present invention, in which a DC positive voltage is applied to the auxiliary electrode to form a hard carbon film, a positive voltage is applied from a DC power source to the auxiliary electrode disposed on the inner surface of the opening to forcibly generate electrons. Can be collected in the surrounding area,
Plasma can be generated around the auxiliary electrode. Therefore, the hard carbon film can be formed by applying the forming method of the present invention to a cylindrical member having a small opening size where a hard carbon film cannot be formed without applying a DC positive voltage.

Furthermore, the hard carbon film formed on the inner peripheral surface of the cylindrical member is a black film, and has properties very similar to diamond. That is, the hard carbon film is
It has the excellent properties of high mechanical hardness, low coefficient of friction, good electrical insulation, high thermal conductivity and high corrosion resistance.
For this reason, the cylindrical member of the present invention can suppress the abrasion of the inner peripheral surface that comes into contact with other members, and can suppress the occurrence of scratches.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for forming a hard carbon film on the inner peripheral surface of a cylindrical member according to a preferred embodiment of the present invention will be described below with reference to the drawings.

[First Embodiment: FIGS. 1 and 7] A first embodiment of a method for forming a hard carbon film on the inner peripheral surface of a cylindrical member 11 will be described with reference to FIGS. FIG. 1 is a cross-sectional view showing a method for forming a hard carbon film on a cylindrical member according to an embodiment of the present invention, and FIG. 7 is a graph showing the relationship between the pressure inside the vacuum chamber and time in the embodiment of the present invention. is there. Hereinafter, description will be made with reference to FIGS. 1 and 7 alternately.

As shown in FIG. 1, a cylindrical member 11 for forming a hard carbon film on its inner peripheral surface 11b is placed in a vacuum chamber 13 having a gas inlet 15 and an exhaust port 17.
At the center of the opening 11a of the cylindrical member 11, an auxiliary electrode 23 connected to the ground potential is provided so as to be inserted.
At this time, the auxiliary electrode 23 is disposed so as to be at the center of the opening of the cylindrical member 11.

Thereafter, as shown in FIG.
The inside is evacuated from the exhaust port 17 by exhaust means (not shown in FIG. 1) so that the degree of vacuum becomes an initial ultimate pressure of 3 × 10 ⁻⁵ torr or less.

Thereafter, the DC power supply 25 is connected to the cylindrical member 11.
, A DC voltage is applied to the anode 31 from the anode power supply 27, and an AC voltage is applied to the filament 33 from the filament power supply 29. At this time, a DC voltage applied from the DC power supply 25 to the cylindrical member 11 is −3 kV, and a DC voltage applied from the anode power supply 27 to the anode 31 is +50 V. Further, as a voltage applied from the filament power supply 29 to the filament 33, an AC voltage of 10V is applied so that a current of 30A flows.

Thereafter, benzene (C 6 H 6) as a gas containing carbon is introduced into the vacuum chamber 13 through the gas inlet port 15 so that the pressure in the vacuum chamber 13 becomes a film forming pressure of 5 × 10 ^-3 torr. To control. Then, a plasma discharge was started in a region around the cylindrical member 11 in the vacuum chamber 13 at a pressure of 1 × 10 ⁻³ torr lower than a film formation pressure of 5 × 10 ⁻³ torr. Then, the inner peripheral surface 1 of the cylindrical member 11
The hard carbon film 15 is formed on the cylindrical member 11 by a plasma-enhanced chemical vapor deposition method utilizing the action of plasma formed between the electrode 1b and the auxiliary electrode 23.

As described above, in the method for forming a hard carbon film on a cylindrical member according to the present invention, the gas containing carbon is supplied to the vacuum chamber 13.
A means for applying a DC negative voltage to the cylindrical member 11 before introducing it into the interior is employed.

In such a means, the plasma discharge starts at a pressure lower than the film forming pressure. That is, since the start of the plasma discharge is in a state where the spatial impedance is higher than the pressure at which the film is formed, the arc discharge which is an abnormal discharge does not occur. As described above, an arc discharge which is an abnormal discharge does not occur at the initial stage of the formation of the hard carbon film 15 at the start of the plasma discharge. Therefore, when the initial film quality of the plasma discharge is affected, the arc discharge which is an abnormal discharge does not occur in the cylindrical member, and the adhesion of the hard carbon film does not decrease. For this reason, in the method for forming a hard carbon film of the present invention, the phenomenon that the hard carbon film is separated from the cylindrical member does not occur.

Further, in the method of forming a hard carbon film on a cylindrical member according to the present invention, an auxiliary electrode 23 connected to a ground potential is arranged at the center 11a of the opening of the cylindrical member 11 to form a hard carbon film 15. ing. Then, a negative DC voltage is applied to the cylindrical member 11. As a result, the auxiliary electrode 23 connected to the ground potential is provided on the inner surface of the opening of the cylindrical member 11 where the electrodes of the same potential face each other, so that the same potential does not face each other. Such a potential state is the most desirable state for plasma-enhanced chemical vapor deposition, and a hollow discharge, which is an abnormal discharge, does not occur. Therefore, a hard carbon film having good adhesion can be formed on the cylindrical member.

In addition, in the method of forming a hard carbon film on a cylindrical member according to the present invention, the auxiliary electrode 23 is disposed at the center of the opening 11a of the cylindrical member 11 as described above.
On the inner surface of the opening in the longitudinal direction of the cylindrical member 11, the potential characteristics become uniform. As a result, there is no occurrence of a film thickness distribution of the hard carbon film 15 formed on the inner surface of the opening of the cylindrical member 11, and there is also an effect that a uniform film thickness can be formed between the opening end face and the back side of the opening.

The auxiliary electrode 23 may have a size smaller than the opening size of the inner peripheral surface 11b of the cylindrical member 11, and preferably has a plasma forming region having a gap of about 4 mm. It is desirable that the dimensional ratio between the diameter of the auxiliary electrode 23 and the diameter of the inner peripheral surface 11b of the cylindrical member 11 be 1/10 or less. When the auxiliary electrode 23 is made thinner, it may be made linear. it can. The auxiliary electrode 23 is made of a metal material such as stainless steel (SUS) or a high melting point metal material such as tungsten (W) or tantalum (Ta).

Further, the cross-sectional shape of the auxiliary electrode 23 is circular, and when the auxiliary electrode 23 is inserted into the cylindrical member 11, the auxiliary electrode 23 has a length such that the auxiliary electrode 23 is aligned with the opening end face of the cylindrical member 11. Of the auxiliary electrode 23 protrudes from the opening end face of the cylindrical member 11 or from 1 mm to 2 mm from the opening end face without protruding from the opening end face of the cylindrical member 11.
mm.

[Second Embodiment: FIGS. 2 and 8] Next, a second embodiment of a method for forming a hard carbon film on the inner peripheral surface of a cylindrical member will be described with reference to FIGS. 2 and 8. explain. FIG. 2 is a cross-sectional view showing a method for forming a hard carbon film on a cylindrical member according to the embodiment of the present invention, and FIG. 8 is a graph showing the relationship between the pressure inside the vacuum chamber and time in the embodiment of the present invention. is there. Hereinafter, description will be made with reference to FIGS. 2 and 8 alternately.

As shown in FIG. 2, a cylindrical member 11 for forming a hard carbon film on its inner peripheral surface 11b is disposed in a vacuum chamber 13 having a gas inlet 15 and an exhaust port 17.
At the center of the opening 11a of the cylindrical member 11, an auxiliary electrode 23 connected to the ground potential is provided so as to be inserted.
At this time, the auxiliary electrode 23 is disposed so as to be at the center of the opening of the cylindrical member 11.

Thereafter, as shown in FIG.
The inside is evacuated from the exhaust port 17 by exhaust means (not shown in FIG. 2) so that the degree of vacuum becomes an initial ultimate pressure of 3 × 10 ⁻⁵ torr or less.

Thereafter, an oscillation frequency of 13.56 MHz is applied to the cylindrical member 11 via a matching circuit 19.
And a high frequency power of 400 W is applied from a high frequency power supply 21 having

Thereafter, methane gas (CH 4) as a gas containing carbon is introduced into the vacuum chamber 13 through the gas inlet 15 to adjust the degree of vacuum to a film forming pressure of 0.5 torr. Then, the cylindrical member 1 inside the vacuum chamber 13
First, the plasma discharge started at 0.2 torr, which was lower than the film forming pressure of 0.5 torr. And
The hard carbon film 15 is formed on the cylindrical member 11 by a plasma chemical vapor deposition method utilizing the action of plasma formed between the inner peripheral surface 11b of the cylindrical member 11 and the auxiliary electrode 23.

As described above, in the method for forming a hard carbon film on a cylindrical member according to the present invention, the gas containing carbon is supplied to the vacuum chamber 13.
Means for applying high-frequency power to the cylindrical member 11 before introduction into the inside is employed.

In such a film forming means, plasma discharge starts at a pressure lower than the film forming pressure. That is, since the start of the plasma discharge is in a state where the spatial impedance is higher than the pressure at which the film is formed, the arc discharge which is an abnormal discharge does not occur. As described above, an arc discharge which is an abnormal discharge does not occur at the initial stage of the formation of the hard carbon film 15 at the start of the plasma discharge. Therefore, when the film quality in the initial stage of the plasma discharge is affected, the arc discharge which is an abnormal discharge does not occur in the cylindrical member, and the adhesion of the hard carbon film does not decrease. Therefore, in the method for forming a hard carbon film of the present invention, the phenomenon that the hard carbon film is separated from the cylindrical member 11 does not occur.

Further, in the method of forming a hard carbon film on a cylindrical member according to the present invention, an auxiliary electrode 23 connected to a ground potential is arranged at the center of the inner surface of the opening of the cylindrical member 11 to form the hard carbon film 15. Has formed. Then, high-frequency power is applied to the cylindrical member 11.

As a result, the auxiliary electrode 23 connected to the ground potential is provided on the inner surface of the opening of the cylindrical member 11 where the electrodes of the same potential face each other, so that the same potential does not face each other. Such a potential state is the most desirable state for plasma-enhanced chemical vapor deposition, and a hollow discharge, which is an abnormal discharge, does not occur. Therefore, a hard carbon film having good adhesion can be formed on the cylindrical member.

In addition, in the method of forming a hard carbon film on a cylindrical member according to the present invention, the auxiliary electrode 23 is disposed at the opening center 11a of the cylindrical member 11 as described above.
On the inner surface of the opening in the longitudinal direction of the cylindrical member 11, the potential characteristics become uniform. As a result, there is no occurrence of a film thickness distribution of the hard carbon film 15 formed on the inner surface of the opening of the cylindrical member 11, and there is also an effect that a uniform film thickness can be formed between the opening end face and the back side of the opening.

The auxiliary electrode 23 may be smaller than the opening size of the inner peripheral surface 11b of the cylindrical member 11, and is preferably provided with a plasma forming region having a gap of about 4 mm. It is desirable that the dimensional ratio between the diameter of the auxiliary electrode 23 and the diameter of the inner peripheral surface 11b of the cylindrical member 11 be 1/10 or less. When the auxiliary electrode 23 is made thinner, it may be made linear. it can. The auxiliary electrode 23 is made of a metal material such as stainless steel (SUS) or a high melting point metal material such as tungsten (W) or tantalum (Ta).

Further, the sectional shape of the auxiliary electrode 23 is circular, and when the auxiliary electrode 23 is inserted into the cylindrical member 11, the auxiliary electrode 23 has a length such that the auxiliary electrode 23 is aligned with the opening end face of the cylindrical member 11. Of the auxiliary electrode 23 protrudes from the opening end face of the cylindrical member 11 or from 1 mm to 2 mm from the opening end face without protruding from the opening end face of the cylindrical member 11.
mm.

[Third Embodiment: FIGS. 3 and 8] Next, a third embodiment of a method of forming a hard carbon film on the inner peripheral surface of the cylindrical member 11 will be described with reference to FIGS. explain. FIG. 3 is a cross-sectional view illustrating a method for forming a hard carbon film on a cylindrical member according to the embodiment of the present invention.
FIG. 8 is a graph showing the relationship between the pressure inside the vacuum chamber and time in the embodiment of the present invention. Hereinafter, description will be made with reference to FIGS. 3 and 8 alternately.

As shown in FIG. 3, a cylindrical member 11 for forming a hard carbon film on its inner peripheral surface 11b is disposed in a vacuum chamber 13 having a gas inlet 15 and an exhaust port 17.
At the center of the opening 11a of the cylindrical member 11, an auxiliary electrode 23 connected to the ground potential is provided so as to be inserted.
At this time, the auxiliary electrode 23 is disposed so as to be at the center of the opening of the cylindrical member 11.

After that, as shown in FIG.
The inside is evacuated from the exhaust port 17 by exhaust means (not shown in FIG. 3) so that the degree of vacuum becomes an initial ultimate pressure of 3 × 10 ⁻⁵ torr or less.

Thereafter, a DC voltage of −600 V is applied to the cylindrical member 11 from the DC power supply 25.

Thereafter, methane gas (CH 4) as a gas containing carbon is introduced into the vacuum chamber 13 through the gas inlet 15 to adjust the degree of vacuum to a film forming pressure of 0.5 torr. Then, the cylindrical member 1 inside the vacuum chamber 13
First, the plasma discharge started at 0.2 torr, which was lower than the film forming pressure of 0.5 torr. And
The hard carbon film 15 is formed on the cylindrical member 11 by a plasma chemical vapor deposition method using plasma formed between the inner peripheral surface 11b of the cylindrical member 11 and the auxiliary electrode 23.

As described above, in the method of forming a hard carbon film on a cylindrical member according to the present invention, a gas containing carbon is supplied to the vacuum chamber 13.
A means for applying a DC negative voltage to the cylindrical member 11 before introducing it into the interior is employed. In such a means, plasma discharge starts at a pressure lower than the film formation pressure.

That is, since the start of the plasma discharge is in a state where the spatial impedance is higher than the film forming pressure, the arc discharge which is an abnormal discharge does not occur. As described above, an arc discharge which is an abnormal discharge does not occur at the initial stage of the formation of the hard carbon film 15 at the start of the plasma discharge. Therefore, when the initial film quality of the plasma discharge is affected, the arc discharge which is an abnormal discharge does not occur in the cylindrical member, and the adhesion of the hard carbon film does not decrease. For this reason, in the method for forming a hard carbon film of the present invention, the phenomenon that the hard carbon film is separated from the cylindrical member does not occur.

Further, in the method of forming a hard carbon film on a cylindrical member according to the present invention, an auxiliary electrode 23 connected to a ground potential is disposed at the center of the inner surface of the opening of the cylindrical member 11 to form the hard carbon film 15. Has formed. Then, a negative DC voltage is applied to the cylindrical member 11.

As a result, the auxiliary electrode 23 connected to the ground potential is provided on the inner surface of the opening of the cylindrical member 11 where the electrodes of the same potential face each other, so that the same potential does not face each other. Such a potential state is the most desirable state for plasma-enhanced chemical vapor deposition, and a hollow discharge, which is an abnormal discharge, does not occur. Therefore, a hard carbon film having good adhesion can be formed on the cylindrical member.

In addition, in the method of forming a hard carbon film on a cylindrical member according to the present invention, the auxiliary electrode 23 is disposed at the opening center 11a of the cylindrical member 11 as described above.
On the inner surface of the opening in the longitudinal direction of the cylindrical member 11, the potential characteristics become uniform. As a result, there is no occurrence of a film thickness distribution of the hard carbon film 15 formed on the inner surface of the opening of the cylindrical member 11, and there is also an effect that a uniform film thickness can be formed between the opening end face and the back side of the opening.

The auxiliary electrode 23 may be smaller than the opening size of the inner peripheral surface 11b of the cylindrical member 11, and is preferably provided with a plasma forming region having a gap of about 4 mm. It is desirable that the dimensional ratio between the diameter of the auxiliary electrode 23 and the diameter of the inner peripheral surface 11b of the cylindrical member 11 be 1/10 or less. When the auxiliary electrode 23 is made thinner, it may be made linear. it can. The auxiliary electrode 23 is made of a metal material such as stainless steel (SUS) or a high melting point metal material such as tungsten (W) or tantalum (Ta).

Further, the auxiliary electrode 23 has a circular cross section, and has a length such that when the auxiliary electrode 23 is inserted into the cylindrical member 11, the auxiliary electrode 23 is aligned with the opening end face of the cylindrical member 11. Of the auxiliary electrode 23 protrudes from the opening end face of the cylindrical member 11 or from 1 mm to 2 mm from the opening end face without protruding from the opening end face of the cylindrical member 11.
mm.

[Fourth Embodiment: FIGS. 4, 7 and 9] A fourth embodiment of a method for forming a hard carbon film on the inner peripheral surface of a cylindrical member will be described with reference to the drawings. I do. FIG. 4 is a sectional view showing a method for forming a hard carbon film on a cylindrical member according to the embodiment of the present invention.
FIG. 9 is a graph showing the relationship between the pressure inside the vacuum chamber and time in the embodiment of the present invention. FIG. 9 shows the relationship between the DC positive voltage applied to the auxiliary electrode and the hard carbon film thickness formed on the inner surface of the opening of the cylindrical member. FIG. Hereinafter, FIGS. 4 and 7
And FIG. 9 will be described alternately.

As shown in FIG. 4, a cylindrical member 11 for forming a hard carbon film on its inner peripheral surface 11b is disposed in a vacuum chamber 13 having a gas inlet 15 and an exhaust port 17.
The auxiliary electrode 23 connected to the DC positive voltage from the auxiliary electrode power supply 35 is provided on the inner surface of the opening of the cylindrical member 11. At this time, the auxiliary electrode 23 is
1 so that it is located at the center of the opening.

After that, as shown in FIG.
The inside of the chamber is evacuated from the exhaust port 17 by exhaust means (not shown) so that the degree of vacuum becomes an initial ultimate pressure of 3 × 10 ⁻⁵ torr or less.

Thereafter, the DC power supply 25 is connected to the cylindrical member 11.
, A DC voltage is applied to the anode 31 from the anode power supply 27, and an AC voltage is applied to the filament 33 from the filament power supply 29.
A DC positive voltage is applied to the auxiliary electrode 23 from an auxiliary electrode power supply 35. At this time, a DC voltage applied from the DC power supply 25 to the cylindrical member 11 is −3 kV, and a DC voltage applied from the anode power supply 27 to the anode 31 is +50 V. Further, as a voltage applied from the filament power supply 29 to the filament 33, an AC voltage of 10V is applied so that a current of 30A flows. Furthermore,
A DC voltage of plus 20 V is applied to the auxiliary electrode 23.

Thereafter, benzene (C 6 H 6) as a gas containing carbon is introduced into the vacuum chamber 13 from the gas inlet port 15 so that the pressure in the vacuum chamber 13 becomes a film forming pressure of 5 × 10 ⁻³ torr. To control. Then, a plasma discharge was started in a region around the cylindrical member 11 in the vacuum chamber 13 at a pressure of 1 × 10 ⁻³ torr lower than a film formation pressure of 5 × 10 ⁻³ torr. Then, the inner peripheral surface 1 of the cylindrical member 11
The hard carbon film 15 is formed on the cylindrical member 11 by a plasma chemical vapor deposition method using plasma formed between the first electrode 1b and the auxiliary electrode 23.

As described above, in the method of forming a hard carbon film on a cylindrical member according to the present invention, a gas containing carbon is supplied to the vacuum chamber 13.
A means for applying a DC negative voltage to the cylindrical member 11 before introducing it into the interior is employed. In such a means, plasma discharge starts at a pressure lower than the film formation pressure.

That is, since the start of the plasma discharge is in a state where the spatial impedance is higher than the pressure at which the film is formed, the arc discharge which is an abnormal discharge does not occur. As described above, an arc discharge which is an abnormal discharge does not occur at the initial stage of the formation of the hard carbon film 15 at the start of the plasma discharge. Therefore, when the initial film quality of the plasma discharge is affected, the arc discharge which is an abnormal discharge does not occur in the cylindrical member, and the adhesion of the hard carbon film does not decrease. For this reason, in the method for forming a hard carbon film of the present invention, the phenomenon that the hard carbon film is separated from the cylindrical member does not occur.

FIG. 9 is a graph showing the relationship between the DC positive voltage applied to the auxiliary electrode 23 using the auxiliary electrode power supply 35 and the thickness of the hard carbon film formed on the inner peripheral surface 11b of the cylindrical member 11. Show. In the graph of FIG. 9, when the DC positive voltage applied to the auxiliary electrode 23 is changed from zero V to 30 V and the gap between the inner peripheral surface 11 b of the cylindrical member and the auxiliary electrode 23 is 3 mm and 5 mm Shows the thickness of the hard carbon film. Note that a curve 37 indicates the characteristic when the gap between the inner surface of the opening of the cylindrical member 11 and the auxiliary electrode 23 is 3 mm, and a curve 39 indicates that the gap between the inner surface of the opening of the cylindrical member 11 and the auxiliary electrode 23 is 5 mm. The characteristic at the time of is shown.

As shown by the curves 37 and 39 in FIG. 9, when the DC positive voltage applied from the auxiliary electrode power supply 35 to the auxiliary electrode 23 is increased, the film formation speed of the hard carbon film is improved. Furthermore, the larger the gap size between the inner peripheral surface 11b of the cylindrical member 11 and the auxiliary electrode 23, the higher the film forming speed of the hard carbon film. When the curve 37, that is, the gap between the inner surface of the opening of the cylindrical member 11 and the auxiliary electrode 23 is 3 mm, the inner peripheral surface of the cylindrical member 11 is not applied when the potential applied to the auxiliary electrode 23 is zero V. 11b
Does not generate plasma and a hard carbon film cannot be formed.

However, the inner peripheral surface 1 of the cylindrical member 11
Even when the gap between 1b and the auxiliary electrode 23 is 3 mm,
When the DC positive voltage from the auxiliary electrode power supply 35 applied to the auxiliary electrode 23 is increased, plasma is generated on the inner surface of the opening around the auxiliary electrode 23, and a hard carbon film can be formed.

In the method of forming a hard carbon film shown in FIG. 4, the center of the opening
A hard carbon film is formed on the inner peripheral surface 11b of the cylindrical member 11 by an auxiliary electrode 23 which is arranged so as to be inserted in 1a and which applies a positive DC voltage. The auxiliary electrode 23, which is arranged to be inserted into the inner surface of the opening of the cylindrical member 11 and is connected to a positive DC voltage, prevents the same potential from being opposed to the inner surface of the opening. Therefore, there is no occurrence of hollow discharge, which is abnormal discharge, and the adhesion of the hard carbon film is improved.

Furthermore, the auxiliary electrode 23 disposed in the opening makes the potential characteristics uniform on the inner surface of the opening in the longitudinal direction of the cylindrical member 11, and the thickness distribution of the hard carbon film formed on the inner surface of the opening is eliminated. In addition, a uniform film thickness can be formed between the opening end face and the back side of the opening.

Further, in the embodiment of the method for forming a hard carbon film of the present invention, a DC positive voltage from an auxiliary electrode power supply 35 is applied to the auxiliary electrode 23 provided at the center of the inner surface of the opening of the cylindrical member 11. To form a hard carbon film. This produces an effect of collecting electrons in a region around the auxiliary electrode 23 to which a DC positive voltage is applied, and the region around the auxiliary electrode 23 has a high electron density.

As described above, when the electron density is increased, the collision probability between the gas molecules containing carbon and the electrons is inevitably increased, the ionization of the gas molecules is promoted, and the plasma intensity in the inner surface area of the opening of the cylindrical member 11 is reduced. Get higher. Therefore, the auxiliary electrode 2
In the method for forming a hard carbon film of the present invention in which a DC positive voltage is applied to 3, the film formation speed of the hard carbon film is:
It is higher than when no DC positive voltage is applied to the auxiliary electrode 23.

The auxiliary electrode 23 has only to be smaller than the opening size of the inner peripheral surface 11b of the cylindrical member 11, and preferably has a plasma forming region which is a gap of about 4 mm. The dimensional ratio between the diameter of the auxiliary electrode 23 and the diameter of the inner peripheral surface 11b of the cylindrical member 11 is desirably 1/10 or less. When the auxiliary electrode 23 is made thinner, it can be made linear. The auxiliary electrode 23 is made of a metal material such as stainless steel (SUS) or a high melting point metal material such as tungsten (W) or tantalum (Ta).

Further, the sectional shape of the auxiliary electrode 23 is circular, and when the auxiliary electrode 23 is inserted into the cylindrical member 11, the auxiliary electrode 23 has a length such that the auxiliary electrode 23 is aligned with the opening end face of the cylindrical member 11. Of the auxiliary electrode 23 protrudes from the opening end face of the cylindrical member 11 or from 1 mm to 2 mm from the opening end face without protruding from the opening end face of the cylindrical member 11.
mm.

[Fifth Embodiment: FIGS. 5, 8 and 9] A fifth embodiment of a method for forming a hard carbon film on the inner peripheral surface of a cylindrical member will be described with reference to the drawings. I do. FIG. 5 is a sectional view showing a method for forming a hard carbon film on a cylindrical member according to the embodiment of the present invention.
FIG. 9 is a graph showing the relationship between the pressure inside the vacuum chamber and time in the embodiment of the present invention. FIG. 9 shows the relationship between the DC positive voltage applied to the auxiliary electrode and the hard carbon film thickness formed on the inner surface of the opening of the cylindrical member. FIG. Hereinafter, FIGS. 5 and 8
And FIG. 9 will be described alternately.

As shown in FIG. 5, a cylindrical member 11 for forming a hard carbon film on its inner peripheral surface 11b is disposed in a vacuum chamber 13 having a gas inlet 15 and an exhaust port 17.
The auxiliary electrode 23 connected to the DC positive voltage from the auxiliary electrode power supply 35 is provided at the center of the opening 11a of the cylindrical member 11. At this time, the auxiliary electrode 23 is disposed so as to be at the center of the opening of the cylindrical member 11.

After that, as shown in FIG.
The inside is evacuated from the exhaust port 17 by exhaust means (not shown in FIG. 5) so that the degree of vacuum becomes an initial ultimate pressure of 3 × 10 ⁻⁵ torr or less.

Thereafter, an oscillation frequency of 13.56 MHz is applied to the cylindrical member 11 via a matching circuit 19.
And a high frequency voltage of 400 W is applied from a high frequency power supply 21 having Furthermore, a DC voltage of plus 20 V is applied to the auxiliary electrode 23.

Thereafter, methane gas (CH 4) as a gas containing carbon is introduced into the vacuum chamber 13 through the gas inlet 15 to adjust the degree of vacuum to a film forming pressure of 0.5 torr. Then, the cylindrical member 1 inside the vacuum chamber 13
First, the plasma discharge started at 0.2 torr, which was lower than the film forming pressure of 0.5 torr. And
The hard carbon film 15 is formed on the cylindrical member 11 by a plasma chemical vapor deposition method utilizing the action of plasma formed between the inner peripheral surface 11b of the cylindrical member 11 and the auxiliary electrode 23.

As described above, in the method of forming a hard carbon film on a cylindrical member according to the present invention, a gas containing carbon is supplied to the vacuum chamber 13.
Means for applying high-frequency power to the cylindrical member 11 before introduction into the inside is employed. In such a means, plasma discharge starts at a pressure lower than the film formation pressure.

That is, since the start of the plasma discharge is in a state where the spatial impedance is higher than the pressure at which the film is formed, the arc discharge which is an abnormal discharge does not occur. As described above, in the initial stage of the formation of the hard carbon film 15 at the start of plasma discharge, arc discharge, which is abnormal discharge, does not occur in the cylindrical member. Therefore, when the initial film quality of the plasma discharge is affected, an arc discharge which is an abnormal discharge does not occur, and the adhesion of the hard carbon film does not decrease. For this reason, in the method for forming a hard carbon film of the present invention, the phenomenon that the hard carbon film is separated from the cylindrical member does not occur.

FIG. 9 is a graph showing the relationship between the DC positive voltage applied to the auxiliary electrode 23 using the auxiliary electrode power supply 35 and the thickness of the hard carbon film formed on the inner surface of the opening of the cylindrical member. In the graph of FIG. 9, when the DC positive voltage applied to the auxiliary electrode 23 is changed from zero V to 30 V and the gap between the inner peripheral surface 11 b of the cylindrical member and the auxiliary electrode 23 is 3 mm and 5 mm Shows the thickness of the hard carbon film. Note that a curve 37 indicates the characteristic when the gap between the inner surface of the opening of the cylindrical member 11 and the auxiliary electrode 23 is 3 mm, and a curve 39 indicates that the gap between the inner surface of the opening of the cylindrical member 11 and the auxiliary electrode 23 is 5 mm. The characteristic at the time of is shown.

As shown by the curves 37 and 39 in FIG. 9, when the DC positive voltage applied from the auxiliary electrode power supply 35 to the auxiliary electrode 23 is increased, the film forming speed of the hard carbon film is improved. Furthermore, the larger the gap size between the inner peripheral surface 11b of the cylindrical member 11 and the auxiliary electrode 23, the higher the film forming speed of the hard carbon film. When the curve 37, that is, the gap between the inner surface of the opening of the cylindrical member 11 and the auxiliary electrode 23 is 3 mm, the inner peripheral surface of the cylindrical member 11 is not applied when the potential applied to the auxiliary electrode 23 is zero V. 11b
Does not generate plasma and a hard carbon film cannot be formed.

However, the inner peripheral surface 11 of the cylindrical member 11
Even when the gap between the electrode b and the auxiliary electrode 23 is 3 mm, when the DC positive voltage from the auxiliary electrode power supply 35 applied to the auxiliary electrode 23 is increased, plasma is generated on the inner surface of the opening around the auxiliary electrode 23. A hard carbon film can be formed.

In the method of forming a hard carbon film shown in FIG. 5, as described above, the auxiliary electrode 23 which is disposed so as to be inserted into the inner surface of the opening of the cylindrical member 11 and which applies a positive DC voltage is used. Inner peripheral surface 11b of cylindrical member 11
To form a hard carbon film. This cylindrical member 11
The auxiliary electrode 23 arranged to be inserted into the inner surface of the opening and connected to the positive DC voltage prevents the same potential from being opposed to the inner surface of the opening. Therefore, there is no occurrence of hollow discharge, which is abnormal discharge, and the adhesion of the hard carbon film is improved.

Further, the potential characteristics of the inner surface of the cylindrical member 11 in the longitudinal direction of the opening are made uniform by the auxiliary electrode 23 disposed in the opening, and the thickness distribution of the hard carbon film formed on the inner surface of the opening is not generated. A uniform film thickness can be formed between the end face of the opening and the back side of the opening.

Furthermore, in the embodiment of the method for forming a hard carbon film of the present invention, a DC positive voltage from an auxiliary electrode power supply 35 is applied to the auxiliary electrode 23 provided at the center of the inner surface of the opening of the cylindrical member 11. To form a hard carbon film. This produces an effect of collecting electrons in a region around the auxiliary electrode 23 to which a DC positive voltage is applied, and the region around the auxiliary electrode 23 has a high electron density.

When the electron density is increased as described above, the probability of collision between electrons and gas molecules containing carbon is inevitably increased, ionization of gas molecules is promoted, and plasma intensity in the inner surface area of the opening of the cylindrical member 11 is reduced. Get higher. Therefore, the auxiliary electrode 2
In the method for forming a hard carbon film of the present invention in which a DC positive voltage is applied to 3, the film formation speed of the hard carbon film is:
It is higher than when no DC positive voltage is applied to the auxiliary electrode 23.

The auxiliary electrode 23 has only to be smaller than the opening size of the inner peripheral surface 11b of the cylindrical member 11, and is preferably provided with a plasma forming region having a gap of about 4 mm. The dimensional ratio between the diameter of the auxiliary electrode 23 and the diameter of the inner peripheral surface 11b of the cylindrical member 11 is desirably 1/10 or less. When the auxiliary electrode 23 is made thinner, it can be made linear. The auxiliary electrode 23 is made of a metal material such as stainless steel (SUS) or a high melting point metal material such as tungsten (W) or tantalum (Ta).

Further, the sectional shape of the auxiliary electrode 23 is circular, and when the auxiliary electrode 23 is inserted into the cylindrical member 11, the auxiliary electrode 23 has a length such that the auxiliary electrode 23 is aligned with the opening end face of the cylindrical member 11. Of the auxiliary electrode 23 protrudes from the opening end face of the cylindrical member 11 or from 1 mm to 2 mm from the opening end face without protruding from the opening end face of the cylindrical member 11.
mm.

[Sixth Embodiment: FIGS. 6, 7 and 9] Next, a sixth embodiment of a method for forming a hard carbon film on the inner peripheral surface of a cylindrical member will be described with reference to the drawings. I do. FIG. 6 is a sectional view showing a method for forming a hard carbon film on a cylindrical member according to the embodiment of the present invention.
FIG. 9 is a graph showing the relationship between the pressure inside the vacuum chamber and time in the embodiment of the present invention. FIG. 9 shows the relationship between the DC positive voltage applied to the auxiliary electrode and the hard carbon film thickness formed on the inner surface of the opening of the cylindrical member. FIG. Hereinafter, FIGS. 6 and 7
And FIG. 9 will be described alternately.

As shown in FIG. 6, a cylindrical member 11 for forming a hard carbon film on its inner peripheral surface 11b is disposed in a vacuum chamber 13 having a gas inlet 15 and an exhaust port 17.
An auxiliary electrode 2 connected to a DC positive voltage from an auxiliary electrode power supply 35 is provided at an opening center 11a of the cylindrical member 11.
3 to be inserted. At this time, the auxiliary electrode 23 is disposed so as to be at the center of the opening of the cylindrical member 11.

After that, as shown in FIG.
The inside is evacuated from the exhaust port 17 by exhaust means (not shown in FIG. 6) so that the degree of vacuum becomes an initial ultimate pressure of 3 × 10 ⁻⁵ torr or less.

Thereafter, a DC voltage of −600 V is applied to the cylindrical member 11 from the DC power supply 25. Further, the auxiliary electrode 23 is connected to the auxiliary electrode
A DC voltage of 0 V is applied.

Thereafter, methane gas (CH 4) as a gas containing carbon is introduced into the vacuum chamber 13 from the gas inlet 15 to adjust the degree of vacuum to a film forming pressure of 0.5 torr. Then, the cylindrical member 1 inside the vacuum chamber 13
First, the plasma discharge started at 0.2 torr, which was lower than the film forming pressure of 0.5 torr. And
The hard carbon film 15 is formed on the cylindrical member 11 by a plasma chemical vapor deposition method utilizing the action of plasma formed between the inner peripheral surface 11b of the cylindrical member 11 and the auxiliary electrode 23.

As described above, in the method for forming a hard carbon film on a cylindrical member according to the present invention, a gas containing carbon is supplied to the vacuum chamber 13.
A means for applying a DC negative voltage to the cylindrical member 11 before introducing it into the interior is employed. In such a means, plasma discharge starts at a pressure lower than the film formation pressure.

That is, since the start of the plasma discharge is in a state where the spatial impedance is higher than the pressure at which the film is formed, the arc discharge which is an abnormal discharge does not occur. Thus, at the beginning of the formation of the hard carbon film 15 at the start of the plasma discharge,
Arc discharge, which is abnormal discharge, does not occur in the cylindrical member.
Therefore, the arc discharge which is an abnormal discharge does not occur when the initial film quality of the plasma discharge is affected, and the adhesion of the hard carbon film does not decrease. For this reason, in the method for forming a hard carbon film of the present invention, the phenomenon that the hard carbon film is separated from the cylindrical member does not occur.

FIG. 9 is a graph showing the relationship between the DC positive voltage applied to the auxiliary electrode 23 using the auxiliary electrode power supply 35 and the thickness of the hard carbon film formed on the inner surface of the opening of the cylindrical member. In the graph of FIG. 9, when the DC positive voltage applied to the auxiliary electrode 23 is changed from zero V to 30 V and the gap between the inner peripheral surface 11 b of the cylindrical member and the auxiliary electrode 23 is 3 mm and 5 mm Shows the thickness of the hard carbon film. Note that a curve 37 indicates the characteristic when the gap between the inner surface of the opening of the cylindrical member 11 and the auxiliary electrode 23 is 3 mm, and a curve 39 indicates that the gap between the inner surface of the opening of the cylindrical member 11 and the auxiliary electrode 23 is 5 mm. The characteristic at the time of is shown.

As shown by the curves 37 and 39 in FIG. 9, when the DC positive voltage applied from the auxiliary electrode power supply 35 to the auxiliary electrode 23 is increased, the film formation speed of the hard carbon film is improved. Furthermore, the larger the gap size between the inner peripheral surface 11b of the cylindrical member 11 and the auxiliary electrode 23, the higher the film forming speed of the hard carbon film. When the curve 37, that is, the gap between the inner surface of the opening of the cylindrical member 11 and the auxiliary electrode 23 is 3 mm, the inner peripheral surface of the cylindrical member 11 is not applied when the potential applied to the auxiliary electrode 23 is zero V. 11b
Does not generate plasma and a hard carbon film cannot be formed.

However, the inner peripheral surface 1 of the cylindrical member 11
Even when the gap between 1b and the auxiliary electrode 23 is 3 mm,
When the DC positive voltage from the auxiliary electrode power supply 35 applied to the auxiliary electrode 23 is increased, plasma is generated on the inner surface of the opening around the auxiliary electrode 23, and a hard carbon film can be formed.

In the method for forming a hard carbon film shown in FIG. 6, as described above, the hard carbon film is arranged so as to be inserted into the inner surface of the opening of the cylindrical member 11, and furthermore, the auxiliary electrode 23 for applying a DC positive voltage is used. Inner peripheral surface 11b of cylindrical member 11
To form a hard carbon film.

The auxiliary electrode 23 arranged to be inserted into the inner surface of the opening of the cylindrical member 11 and connected to the positive DC voltage prevents the inner surface of the opening from facing the same potential. Therefore, there is no occurrence of hollow discharge, which is abnormal discharge, and the adhesion of the hard carbon film is improved.

Further, the potential characteristics of the inner surface of the cylindrical member 11 in the longitudinal direction are made uniform by the auxiliary electrode 23 disposed in the opening, and the thickness distribution of the hard carbon film formed on the inner surface of the opening does not occur. A uniform film thickness can be formed between the end face of the opening and the back side of the opening.

Further, in the embodiment of the method for forming a hard carbon film of the present invention, a DC positive voltage from an auxiliary electrode power supply 35 is applied to the auxiliary electrode 23 provided at the center of the inner surface of the opening of the cylindrical member 11. To form a hard carbon film. This produces an effect of collecting electrons in a region around the auxiliary electrode 23 to which a DC positive voltage is applied, and the region around the auxiliary electrode 23 has a high electron density.

When the electron density increases as described above, the probability of collision between electrons and gas molecules containing carbon inevitably increases, ionization of the gas molecules is promoted, and the plasma intensity in the inner surface area of the opening of the cylindrical member 11 is reduced. Get higher. Therefore, the auxiliary electrode 2
In the method for forming a hard carbon film of the present invention in which a DC positive voltage is applied to 3, the film formation speed of the hard carbon film is:
It is higher than when no DC positive voltage is applied to the auxiliary electrode 23.

The auxiliary electrode 23 has only to be smaller than the opening size of the inner peripheral surface 11b of the cylindrical member 11, and is preferably provided with a plasma forming region which is a gap of about 4 mm. The dimensional ratio between the diameter of the auxiliary electrode 23 and the diameter of the inner peripheral surface 11b of the cylindrical member 11 is desirably 1/10 or less. When the auxiliary electrode 23 is made thinner, it can be made linear. The auxiliary electrode 23 is made of a metal material such as stainless steel (SUS) or a high melting point metal material such as tungsten (W) or tantalum (Ta).

Further, the auxiliary electrode 23 has a circular cross-section, and has a length such that when the auxiliary electrode 23 is inserted into the cylindrical member 11, the auxiliary electrode 23 is aligned with the opening end face of the cylindrical member 11. Of the auxiliary electrode 23 protrudes from the opening end face of the cylindrical member 11 or from 1 mm to 2 mm from the opening end face without protruding from the opening end face of the cylindrical member 11.
mm.

In the embodiment of the method for forming a hard carbon film according to the present invention described above, the embodiment using methane gas or benzene gas as the carbon-containing gas has been described. A vapor containing a gas or a liquid containing carbon such as hexane can also be used.

Further, an intermediate layer may be provided between the hard carbon film and the cylindrical member. In this case, the intermediate layer may be made of silicon (Si) or germanium (Ge) belonging to Group IVa of the periodic table, or a compound of silicon or germanium. Alternatively, a compound containing carbon such as silicon carbide (SiC) or titanium carbide (TiC) may be used as the intermediate layer. Further, the intermediate layer may have a two-layer film structure of titanium (Ti) or chromium (Cr) and silicon, germanium, or a carbide of silicon or germanium. In this case, titanium and chromium in the lower layer of the intermediate layer have a role of maintaining adhesion to the cylindrical member, and silicon, germanium, or silicon or germanium carbide in the upper layer of the intermediate layer is covalently bonded to the hard carbon film to form the hard carbon. It has a role to strongly bind to the membrane.

[0122]

As is apparent from the above description, in the method for forming a hard carbon film on a cylindrical member according to the present invention,
Before introducing the gas containing carbon into the vacuum chamber, a means for applying a DC negative voltage or a high-frequency power to the cylindrical member is employed. In such a means, plasma discharge starts at a pressure lower than the film formation pressure.

That is, since the plasma discharge starts at a state where the spatial impedance is higher than the film formation pressure, the arc discharge which is an abnormal discharge does not occur. As described above, the arc discharge which is an abnormal discharge does not occur at the initial stage of the formation of the hard carbon film at the start of the plasma discharge. Therefore, when the initial film quality of the plasma discharge is affected, the arc discharge which is an abnormal discharge does not occur in the cylindrical member, and the adhesion of the hard carbon film does not decrease. Therefore, in the method for forming a hard carbon film of the present invention, the phenomenon that the hard carbon film is separated from the cylindrical member does not occur.

Further, in the method of forming a hard carbon film on a cylindrical member according to the present invention, an auxiliary electrode connected to a ground potential is disposed at the center of the opening on the inner surface of the cylindrical member to form the hard carbon film. I do. Then, a negative DC voltage or a high-frequency voltage is applied to the cylindrical member.

As a result, an auxiliary electrode connected to the ground potential is provided on the inner surface of the opening of the cylindrical member where the electrodes of the same potential face each other, so that the same potentials do not face each other. Such a potential state is the most desirable state for plasma-enhanced chemical vapor deposition, and a hollow discharge, which is an abnormal discharge, does not occur. Therefore, a hard carbon film having good adhesion can be formed on the cylindrical member.

In addition, in the method of forming a hard carbon film on a cylindrical member according to the present invention, the auxiliary electrode is disposed on the inner surface of the opening of the cylindrical member as described above, and the inner surface of the opening in the longitudinal direction of the cylindrical member is formed. And the potential characteristics become uniform. As a result, there is no occurrence of a film thickness distribution of the hard carbon film formed on the inner surface of the opening of the cylindrical member, and there is also an effect that a uniform film thickness can be formed between the opening end surface and the back side of the opening.

Further, the method of forming a hard carbon film on a cylindrical member according to the present invention employs means for forming a hard carbon film by applying a DC positive voltage to an auxiliary electrode disposed on the inner surface of the opening of the cylindrical member. I do. When a DC positive voltage is applied to the auxiliary electrode in this manner, an effect of collecting electrons in a region around the auxiliary electrode occurs, and the region around the auxiliary electrode has a high electron density.

As described above, when the electron density increases, the collision probability between the gas containing carbon and the electrons inevitably increases, and ionization of gas molecules is promoted, so that the plasma density in the region around the auxiliary electrode increases. . For this reason, the film formation speed of the hard carbon film is higher than when no DC positive voltage is applied to the auxiliary electrode.

When the size of the opening of the cylindrical member is further reduced and the size of the gap between the inner surface of the opening and the auxiliary electrode is reduced,
If the hard carbon film is formed without applying a DC positive voltage to the auxiliary electrode, no plasma is generated on the inner surface of the opening of the cylindrical member, and the hard carbon film cannot be formed.

On the other hand, according to the present invention, in which a DC positive voltage is applied to the auxiliary electrode to form a hard carbon film, electrons are forcibly applied to the auxiliary electrode by applying a positive voltage from a DC power supply to the auxiliary electrode disposed on the inner surface of the opening. Can be collected in the surrounding area,
Plasma can be generated around the auxiliary electrode. Therefore, the hard carbon film can be formed by applying the forming method of the present invention to a cylindrical member having a small opening size where a hard carbon film cannot be formed without applying a DC positive voltage.

Furthermore, the hard carbon film formed on the inner peripheral surface of the cylindrical member is a black film, and has properties very similar to diamond. That is, the hard carbon film is
It has the excellent properties of high mechanical hardness, low coefficient of friction, good electrical insulation, high thermal conductivity and high corrosion resistance.
For this reason, the cylindrical member of the present invention can suppress the abrasion of the inner peripheral surface that comes into contact with other members, and can suppress the occurrence of scratches.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a method for forming a hard carbon film on an inner peripheral surface of a cylindrical member according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a method for forming a hard carbon film on an inner peripheral surface of a cylindrical member according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a method for forming a hard carbon film on an inner peripheral surface of a cylindrical member according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a method for forming a hard carbon film on the inner peripheral surface of a cylindrical member according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a method for forming a hard carbon film on the inner peripheral surface of the cylindrical member according to the embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a method for forming a hard carbon film on the inner peripheral surface of the cylindrical member according to the embodiment of the present invention.

FIG. 7 is a graph showing a method of forming a hard carbon film on the inner peripheral surface of a cylindrical member according to an embodiment of the present invention, and showing a relationship between pressure inside a vacuum chamber and time.

FIG. 8 is a graph showing a method of forming a hard carbon film on the inner peripheral surface of a cylindrical member according to an embodiment of the present invention, and showing a relationship between pressure inside a vacuum chamber and time.

FIG. 9 is a graph showing a method of forming a hard carbon film on an inner peripheral surface of a cylindrical member according to an embodiment of the present invention, and is a graph showing a relationship between an auxiliary electrode voltage and a film thickness of a hard carbon film to be formed.

FIG. 10 is a cross-sectional view showing a method of forming a hard carbon film on the inner peripheral surface of a cylindrical member according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Cylindrical member 11a Opening center 11b Inner peripheral surface 13 Vacuum tank 15 Gas inlet 17 Exhaust port 19 Matching circuit 21 High frequency power supply 23 Auxiliary electrode 25 DC power supply 27 Anode power supply 29 Filament power supply 31 Anode 33 Filament 35 Auxiliary electrode power supply

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Toida 840 Takeno, Shimotomi, Tokorozawa-shi, Saitama Citizen Watch Co., Ltd. No. 12 Citizen Watch Co., Ltd. Tanashi Factory

Claims (18)

[Claims] 1. A cylindrical member is disposed in a vacuum chamber having an exhaust port and a gas inlet port, in which an anode and a filament are provided, and an auxiliary electrode connected to a ground potential is provided in a central opening of the cylindrical member. A first step of arranging for insertion, followed by a second step of evacuating the vacuum chamber to an initial attainable pressure equal to or lower than a predetermined degree of vacuum, and then applying a DC voltage to the cylindrical member, A third step in which a DC voltage is applied to the anode and an AC voltage is applied to the filament; and further, a gas containing carbon is introduced into the vacuum chamber through a gas inlet to generate plasma. A fourth step of controlling the pressure in the vacuum chamber to a film forming pressure higher than the initial attainable pressure while forming the hard carbon film on the peripheral surface. Hard carb to Film formation method. 2. The gas containing carbon in the fourth step is methane or benzene.
A method for forming a hard carbon film on an inner peripheral surface of a cylindrical member according to the above. 3. The inner periphery of a cylindrical member according to claim 1, wherein a hard carbon film is formed on an inner peripheral surface of the cylindrical member via an intermediate layer for improving adhesion of the hard carbon film. A method for forming a hard carbon film on a surface. 4. A first arrangement in which a cylindrical member is disposed in a vacuum chamber having an exhaust port and a gas inlet, and an auxiliary electrode connected to a ground potential is inserted into a central opening of the cylindrical member. A second step of evacuating the inside of the vacuum chamber to an initial pressure not higher than a predetermined degree of vacuum, a third step of applying high-frequency power to the cylindrical member, and a further step of introducing gas. A gas containing carbon is introduced into the vacuum chamber through the mouth to generate plasma, and while forming a hard carbon film on the inner peripheral surface of the cylindrical member, the pressure in the vacuum chamber is increased to a film forming pressure higher than the ultimate pressure. A method for forming a hard carbon film on the inner peripheral surface of a cylindrical member. 5. The gas containing carbon in the fourth step is methane or benzene.
A method for forming a hard carbon film on an inner peripheral surface of a cylindrical member according to the above. 6. The inner periphery of a cylindrical member according to claim 4, wherein a hard carbon film is formed on an inner peripheral surface of the cylindrical member via an intermediate layer for improving the adhesion of the hard carbon film. A method for forming a hard carbon film on a surface. 7. A first arrangement in which a cylindrical member is disposed in a vacuum chamber having an exhaust port and a gas inlet, and an auxiliary electrode connected to a ground potential is inserted into a central opening of the cylindrical member. A second step of evacuating the inside of the vacuum chamber to an initial pressure equal to or lower than a predetermined degree of vacuum; a third step of applying a DC voltage to the cylindrical member; A gas containing carbon is introduced into the vacuum chamber through the mouth to generate plasma, and while forming a hard carbon film on the inner peripheral surface of the cylindrical member, the pressure in the vacuum chamber is increased to a film forming pressure higher than the ultimate pressure. A method for forming a hard carbon film on the inner peripheral surface of a cylindrical member. 8. The method according to claim 7, wherein the gas containing carbon in the fourth step is methane or benzene.
A method for forming a hard carbon film on an inner peripheral surface of a cylindrical member according to the above. 9. The inner periphery of a cylindrical member according to claim 7, wherein a hard carbon film is formed on an inner peripheral surface of the cylindrical member via an intermediate layer for improving the adhesion of the hard carbon film. A method for forming a hard carbon film on a surface. 10. An auxiliary electrode having an exhaust port and a gas inlet port, a cylindrical member disposed in a vacuum chamber having an anode and a filament therein, and a DC positive voltage connected to a central opening of the cylindrical member. And a second step of evacuating the inside of the vacuum chamber to an initial ultimate pressure equal to or lower than a predetermined degree of vacuum, and then applying a DC voltage to the cylindrical member and A third step of applying a DC voltage to the anode and applying an AC voltage to the filament; and further, introducing a gas containing carbon into the vacuum chamber from a gas inlet to generate plasma, thereby forming a cylindrical member. A fourth step of controlling the pressure in the vacuum chamber to a coating pressure higher than the ultimate pressure while forming a hard carbon film on the inner peripheral surface. Hard mosquito on the surface Method of forming a carbon film. 11. The method for forming a hard carbon film on an inner peripheral surface of a cylindrical member according to claim 10, wherein the gas containing carbon in the fourth step is methane or benzene. 12. The inner periphery of a cylindrical member according to claim 10, wherein a hard carbon film is formed on the inner peripheral surface of the cylindrical member via an intermediate layer for improving the adhesion of the hard carbon film. A method for forming a hard carbon film on a surface. 13. A first arrangement in which a cylindrical member is disposed in a vacuum chamber having an exhaust port and a gas inlet, and an auxiliary electrode connected to a DC positive voltage is inserted into a central opening of the cylindrical member. A second step of evacuating the vacuum chamber to an initial ultimate pressure equal to or lower than a predetermined degree of vacuum; a third step of applying high-frequency power to the cylindrical member; A gas containing carbon is introduced into the vacuum chamber from the inlet to generate plasma, and while forming a hard carbon film on the inner peripheral surface of the cylindrical member, the pressure in the vacuum chamber is higher than the initial pressure. A method for forming a hard carbon film on the inner peripheral surface of a cylindrical member. 14. The method according to claim 1, wherein the gas containing carbon in the fourth step is methane or benzene.
4. The method for forming a hard carbon film on an inner peripheral surface of a cylindrical member according to 3. 15. The inner peripheral surface of a cylindrical member according to claim 13, wherein a hard carbon film is formed on the inner peripheral surface of the cylindrical member via an intermediate layer for improving the adhesion of the hard carbon film. A method for forming a hard carbon film on a surface. 16. A first arrangement in which a cylindrical member is arranged in a vacuum chamber having an exhaust port and a gas inlet, and an auxiliary electrode connected to a DC positive voltage is inserted into a central opening of the cylindrical member. A second step of evacuating the vacuum chamber to an initial pressure not higher than a predetermined degree of vacuum; a third step of applying a DC voltage to the cylindrical member; A gas containing carbon is introduced into the vacuum chamber from the inlet to generate plasma, and while forming a hard carbon film on the inner peripheral surface of the cylindrical member, the pressure in the vacuum chamber is higher than the initial pressure. A method for forming a hard carbon film on the inner peripheral surface of a cylindrical member. 17. The method according to claim 1, wherein the gas containing carbon in the fourth step is methane or benzene.
7. The method for forming a hard carbon film on the inner peripheral surface of a cylindrical member according to 6. 18. The inner periphery of a cylindrical member according to claim 16, wherein a hard carbon film is formed on the inner peripheral surface of the cylindrical member via an intermediate layer for improving the adhesion of the hard carbon film. A method for forming a hard carbon film on a surface.