JP2002327271A - Electroconductive hard carbon film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electroconductive hard carbon film having adequate abrasion resistance, oxidation resistance, and corrosion resistance, and being used for an application and a production process in which electroconductive members contact each other, or in a corrosive environment, and a coated member therewith. SOLUTION: The electroconductive hard carbon film has a structure in which at least one part of SP<2> connective crystals continuously ranges to a film thickness direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive hard carbon film and a covering member thereof, and more specifically, to a conductive member that is electrically connected when a plurality of conductive members come into contact with each other.
Alternatively, the present invention relates to a conductive member used in a corrosive environment.

[0002]

2. Description of the Related Art Conventionally, ordinary metals, organic conductive materials such as carbon, and noble metal materials have been used for contact portions of conductive members that are brought into electrical conduction by being brought into contact with each other.

[0003]

However, when a metal is used, there is a problem that the metal is easily oxidized to form an insulator, and has low strength and is easily worn, so that its life is short. In addition, when an organic conductive material is used, the strength of the organic conductive material is low, and the organic conductive material is liable to wear. In addition, noble metal materials have been used as conductive materials that are not easily oxidized, but have a problem that they are easily worn due to low strength, have a short life, and are expensive.

Further, these noble metals and organic conductive materials are
When assembling to the final product, the members may come into contact with each other, and the damage caused by the contact may cause the member not to be used, thereby lowering the yield of the final product.

On the other hand, in a corrosive environment, a noble metal material is mainly used as a conductive material. When a pinhole is present, corrosion proceeds from the pinhole as a starting point. This is supported by increasing the thickness of the noble metal material (at least 10 μm). For this reason, it becomes expensive.

[0006] Even when there is no pinhole, there is a case where members come into contact with each other when assembling to a final product, and damage due to the contact sometimes becomes a corrosion starting point.

Accordingly, the present invention provides a conductive hard carbon film having good abrasion resistance, oxidation resistance and corrosion resistance and used in applications or processes where conductive members come into contact with each other or in a corrosive environment, and a coated member thereof. The purpose is to provide.

[0008]

The present invention solves the above-mentioned problems by using a conductive hard carbon film having a structure in which at least a part of the SP ² bonding crystal is continuously connected in the film thickness direction. It was done.

[0009] Since at least a part of the SP ² bonding crystal has a structure continuously connected in the film thickness direction, high conductivity can be maintained. Further, since the conductive hard carbon film is used, it has good wear resistance, oxidation resistance and corrosion resistance.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The conductive hard carbon film according to the present invention has a structure in which at least a part of the SP ² bonding crystal is continuously connected in the film thickness direction.

The above-mentioned SP ² -bonded crystal is a crystal having carbon as a main component, having SP ² -bonded carbon in at least a part of the crystal, and having a periodic structure in macroscopic view. Specific examples of those having such a structure include fullerenes such as graphite, carbon nanotubes, and onion clusters.

In the above SP ² -bonding crystal, the carbon has a six-membered ring,
A plane or curved surface (hereinafter, referred to as a five-membered ring)
Referred to as "SP ² bond flat or curved." ) Is formed, and the plane or the curved surface has a single or plural stacked structure. Also, in this SP ² coupling plane or curved surface, S
It is rare that a P ² binding crystal exists alone,
Graphite structures and various types of fullerene group structures are mixed and often connected to each other.

The above-mentioned "mainly containing carbon" means that in addition to carbon, unavoidable elements such as argon and nitrogen used as atmosphere gas and hydrogen contained in the raw material gas are mixed as impurities. But does not include other metal elements. It is preferable that the number of unavoidable impurities is small, and that carbon is 80 at. % Or more, 100 at. % Or less, and 90 at. % Or more is more preferable. Note that “at.%” Refers to a percentage based on the number of atoms.

A structure in which at least a part of the SP ² bonding crystal is continuously connected in the film thickness direction is described in FIG.
As shown in FIG. ² , a structure in which a plurality of SP ² binding crystals 30 are connected from the lowermost layer (substrate side) to the uppermost layer (surface side) of the hard carbon film. Specifically, when the coating 27 is provided on the base material 29 via the intermediate layer 28 as necessary, the coating 27 extends from the surface of the coating 27 in contact with the intermediate layer 28 or the base material 29 to a surface opposite to the surface. , SP ² binding crystals 30 in a row. At this time, the film 27 is continuous with SP ²
If it has a bonding crystal, it is not necessary to have the same structure as the structure shown in FIG. 4 regardless of its structure.

The organic hard carbon film according to the present invention, as having the thickness direction SP ² bond crystal, which are arranged in this sequential structure, a structure in which SP ² bond crystal, which are arranged in this continuously in the thickness direction Compared to the case without, the hardness is higher even with the same conductivity,
Shows high wear resistance.

The hard carbon film according to the present invention is SP ²
It has conductivity in the part of the bonding crystal, and the other parts are
Has wear resistance. Increasing the content of SP ² -bonded crystals leads to lower hardness of the film and lowers abrasion resistance. Also, the corrosion resistance is reduced by increasing the content of the SP ² -binding crystals. Therefore, achieving high conductivity while reducing the content of the SP ² -bonding crystal is important from the viewpoint of wear resistance and corrosion resistance. Therefore, the fact that the SP ² bonding crystal is present continuously from the film surface to the lowermost layer of the film is effective in increasing the conductivity in the film thickness direction of the film, and as a result, the SP ² bonding crystal Is desirable because the content of the compound can be reduced.

It is desirable that at least a part of the SP ² -bonding crystal has a graphite structure, because it can achieve high electrical conductivity while having higher wear resistance and higher corrosion resistance.

Further, the angle formed between the SP ² bonding plane or curved surface constituted by at least a part of the SP ² bonding crystal and the substrate surface, more preferably, the SP ² bonding crystal continuously connected in the film thickness direction. S constituted by a part of
The angle between the P ² bonding plane or curved surface and the substrate surface is 60
When it has a structure of not less than 120 ° and not more than 120 °, the obtained hard carbon film has an advantage that it can achieve high electrical conductivity while having higher wear resistance and higher corrosion resistance. When the above angle is specifically described, as shown in FIG.
When the cross section is observed in a direction in which the layer structure of the SP ² -bonded crystal can be observed, it is formed by the carbon atoms 31 bonded by the SP ² bond among the carbon atoms 31 in the film on the base material 29 or the intermediate layer 28. Plane or curved, ie SP
^{It is} preferable that the angle 33 formed by the ^two bonding planes or curved surfaces 32 and the surface of the substrate 29 is not less than 60 ° and not more than 120 °. That is, the axis perpendicular to the SP ² coupling plane or the curved surface 32, the C-axis 35 in FIG. 5, has 0 ° or more, 30 ° or less, or 150 ° or more and 180 ° or less with respect to the surface of the substrate 29. Is synonymous with

In a hard carbon film as shown in FIG.
The conductivity of the SP ² coupling plane or the curved surface 32 in the plane direction or the curved surface direction is high, and the conductivity in the C-axis direction, which is a direction perpendicular to the plane direction, is low. Therefore, when the C axis 35 of the SP ² bonding crystal is 30 ° or less or 150 ° or more with respect to the substrate,
This is desirable when it is desired to increase the conductivity from the coating surface, which is the thickness direction of the coating 27, to the coating lowermost layer direction. Even with the same electrical conductivity, when the C axis 35 is 30 ° or less or 150 ° or more with respect to the substrate, high hardness and high wear resistance can be obtained in a state where the content of the SP ² bonding crystal is lower. And the energy of ions reaching the substrate can be increased as compared with the conventional method.

When at least a part of the SP ² bonding crystal having such a structure has a structure that is continuous in the film thickness direction, high conductivity and high hardness can be obtained while having higher hardness and higher wear resistance. This is a desirable structure that can be achieved.

The interlayer distance 34 between the SP ² bonding plane or the curved surface and the adjacent SP ² bonding plane or the curved surface included in the hard carbon film according to the present invention is preferably 2.4 ° or more and 3.9 ° or less. . The interlayer distance refers to the distance between planes or curved surfaces where the SP ² coupling planes or curved surfaces are coupled by van der Waals force, and refers to the distance between stacked SP ² coupling planes or curved surfaces. is there. In graphite, half of the C-plane distance corresponds to this. The hard carbon film having the above interlayer distance has high hardness and high electrical conductivity.

The existence and structure of the above-mentioned SP ² binding crystal can be confirmed by observation with a transmission electron microscope, electron beam diffraction and X-ray diffraction.

The hard carbon film of the present invention has the above SP ²
The portion other than the bonding crystal is amorphous. In the nano order, a cluster structure with SP ³ bonding may be observed, but in X-ray diffraction and transmission electron diffraction using CuK line, the crystal structure other than the peak relating to the SP ² bonding crystal is changed. No suggestive peak is observed.

Further, the hard carbon film according to the present invention comprises:
The presence of the SP ² -bonding crystal can also be confirmed by evaluation by electron energy loss spectroscopy, and the peak shape is such that the peak height (I285) near 285 eV and 293
Ratio of peak height (I293) near eV (= I293 /
I285) is preferably 0.9 or more and 1.6 or less. The peak around 285 eV is due to the π-π ^* transition,
Suggesting the presence of SP ² bonds. On the other hand, the peak near 293 eV is due to the σ-σ ^* transition. I293 / I
When 285 is 0.9 or less, the proportion of SP ² -bonding crystals becomes too high, and the film hardness becomes too low. May be inferior. On the other hand, I293 / I285 was 1.6.
Above the above, the proportion of the SP ² -bonding crystal may be too low, and the conductivity may be low.

Further, the hard carbon coating according to the present invention preferably has a Knoop hardness of 1,000 or more and 3000 or less from the viewpoint of abrasion resistance. The Knoop hardness is measured by using a diamond Knoop indenter and pressing a load of 15 g for 10 seconds.

When these hard carbon films are formed on a member, the member only needs to be formed on at least a part of the member that comes into contact with a solid, gas, or liquid. That is, it is not always necessary to cover the entire surface of the member. For example, the effect can be exerted even when the member is formed on a surface of each member that is in contact with a plurality of members or is used in a corrosive environment and particularly requires corrosion resistance.

Further, it is not necessary to form them directly on the member. For example, 4a,
A nitride comprising at least one of metals belonging to the group 5a and 6a;
A sufficient effect can be obtained even if a carbide or carbonitride film is used as an intermediate layer and formed between the member and the hard carbon film of the present invention. In this case, the continuity of the SP ² bonding crystal described above is from the surface of the hard carbon film to immediately above the intermediate layer.

The conductive hard carbon film according to the present invention comprises:
It can be formed by using an evaporation method such as a sputtering evaporation method or a vacuum arc evaporation method.

In any of the above vapor deposition methods, at least a part of the SP ² -bonded crystal is continuously connected in the film thickness direction by increasing the energy of carbon ions reaching the substrate. Can be formed. As a method of increasing the energy of the carbon ions reaching the substrate, there is a method of increasing the substrate bias of each vapor deposition device to the negative side. Hereinafter, the substrate bias value is expressed as an absolute value, but all the signs are negative. The substrate bias is preferably 400 to 1000 V,
400-600V is preferred. If the absolute value of the bias voltage is smaller than 400 V, the ratio of the amorphous carbon component increases, and the SP ² bonding crystal may not be continuous.
On the other hand, if the absolute value of the bias voltage is larger than 1000 V, the deposited film is etched, and it is difficult to form a dense film, and the hardness may decrease.

The conductive hard carbon film according to the present invention comprises:
When used for a conductive member used in a corrosive environment such as a solid electrolytic chamber type fuel cell separator, various battery electrodes, and plating electrodes, the effect of improving corrosion resistance can be exerted. Or
It can also be used as a key contact, a plug electrode, a wiring board contact, a brush feed contact, etc., and a sliding contact. In addition, the member forming the conductive hard carbon film of the present invention is not limited to the members listed here, and a conductive member that is electrically conductive when a plurality of conductive members come into contact with each other, or in a corrosive environment. The present invention can be applied not only to the conductive member to be used but also to various tools, parts and the like that simply require wear resistance.

[0031]

The present invention will be described more specifically below with reference to examples and comparative examples. In the following examples and comparative examples, the substrate bias value is indicated by an absolute value, but the signs are all negative. (Example 1) The high frequency plasma CVD apparatus shown in FIG. 1 was used. The apparatus includes a horizontal plate-shaped substrate holder 2 in a vacuum chamber 1, and a high-frequency power supply 3 and a DC power supply 4 are connected to the substrate holder 2. The vacuum chamber 1 has a gas inlet 5 and a gas outlet 6.

Next, an ion irradiation method and a method of forming a conductive hard carbon film when the above high-frequency plasma CVD apparatus is used will be described below. First, after setting the substrate 7 on the substrate holder 2 in the vacuum chamber 1, the inside of the apparatus is evacuated to 0.002 Pa or less from the gas exhaust port 6. As atmosphere gas, A
r is introduced from the gas introduction port 5 so that the inside of the vacuum chamber 1 has a predetermined pressure. Then, a high frequency power of 500 W is applied to the substrate holder 2 by the high frequency power supply 3 and a DC voltage is applied by the DC power supply 4 to apply a predetermined negative bias to the substrate holder. As a result, the ions of the atmospheric gas having a positive charge, which have been ionized by the high-frequency plasma, collide with the substrate 7, thereby removing the dirt and the oxide layer on the substrate surface by etching.

Then, after the inside of the vacuum chamber 1 is evacuated,
Gas inlet 5 so that the pressure in vacuum chamber 1 is 10 Pa.
Methane gas is introduced into the base material holder 2 by the high-frequency power supply 3 and the high-frequency power is 300 to 800 W, and the DC voltage is 5
A voltage of 0 V to 200 V was applied to form a conductive hard carbon film. The conductive hard carbon film could be produced by setting the absolute value of the DC voltage to be larger than the normal condition for forming the hard carbon film. These conductive hard carbon films are SP
The portions other than the ^two- bond crystals were amorphous.

Example 2 A hard carbon film was formed by using a sputter deposition apparatus shown in FIG. This apparatus includes a horizontal disk-shaped rotary table 9 in a vacuum chamber 8 and a substrate holder 10 fixed vertically to the rotary table 9.
Sputter evaporation sources 11 are installed on opposing vacuum chamber side walls sandwiching the base material holder 10, and each sputter evaporation source 11 is connected to a high frequency power supply 12. A target 13 is mounted on the sputter evaporation source 11. T on one target 13
i, Cr, and V are set, and solid carbon is set on the other target 13. Also, the substrate holder 1
0 is a pulse DC power supply 14 connected to the turntable 9.
Thus, a predetermined negative bias voltage can be applied.

After evacuating the vacuum chamber 8, the vacuum chamber 8 is evacuated.
An N ₂ gas and an Ar gas are introduced from the gas inlet 15 so that the inside pressure is 1 Pa or less. The ratio of N ₂ gas to Ar gas is N ₂ / Ar = 1/2 to 1/10. A high-frequency power of 4 is applied to the sputtering evaporation source 11 equipped with a solid carbon target.
With a power of 00 W, a bias voltage of 50 V was applied to the substrate holder 10 and the nitride of Cr, Ti, and V was formed as an intermediate layer while rotating the rotary table 9 at 5 rpm.

Next, after the inside of the vacuum chamber 8 is evacuated, the gas inlet port 1 is controlled so that the inside of the vacuum chamber 8 has a pressure of 1 Pa or less.
From step 5, CH ₄ gas and Ar gas are introduced. CH ₄ gas and A
The ratio of r gas is CH ₄ / Ar = 1/2 to 1/10.
A high-frequency power of 400 W is applied to the sputter evaporation source 11 equipped with a solid carbon target, and 200 V is applied to the substrate holder 10.
While applying a bias voltage of ８００800 V and rotating the rotary table 9 at 5 rpm, a conductive hard carbon film was formed. By setting the DC voltage to the substrate holder to be larger in absolute value than the normal condition for forming a hard carbon film, a conductive hard carbon film could be produced. In these conductive hard carbon films, portions other than the SP ² binding crystals were amorphous.

Example 3 A hard carbon film was formed by using a vacuum arc evaporation apparatus shown in FIG. This apparatus includes a horizontal disk-shaped rotary table 19 in a vacuum chamber 18, and a substrate holder 20 fixed vertically to the rotary table 19.
With. An arc discharge evaporation source having targets 21 is provided on the opposite vacuum chamber side walls with the substrate holder 20 interposed therebetween, and each target 21 is connected to a DC power supply 22. One target 21 is set with Ti, Cr and V metals, and the other target 21 is set with solid carbon. Further, a predetermined negative bias voltage can be applied to the substrate holder 20 by the DC power supply 23 connected to the turntable 19. The vacuum chamber 18 has a gas inlet 24 and a gas outlet 25.

After setting the substrate 26 in the substrate holder 20, the inside of the apparatus is evacuated to 0.002 Pa or less from the gas exhaust port 25. N ₂ gas is introduced from the gas inlet 24 so that the inside of the vacuum chamber 18 has a pressure of 2 Pa. A bias voltage of 50 V to 150 V is applied to the substrate holder 20, and T
An arc discharge is generated by applying a cathode current of 60 A to the i, Cr, V metal target, and the rotating table 19 is rotated at 5 rpm.
While rotating at m, an intermediate layer was formed.

Next, Ar gas is introduced from the gas inlet 24 so that the pressure in the vacuum chamber 18 becomes 1 Pa. Alternatively, with the inside of the apparatus kept at 0.002 Pa or less, a bias voltage of 150 V to 800 V is applied to the base material holder 20, a cathode current of 50 A flows through the solid carbon target to generate arc discharge, and the rotary table 19 is rotated at 5 rpm. While rotating at, a conductive hard carbon film was formed. The absolute value of the DC voltage applied to the substrate holder was set to be larger than the normal condition for forming the hard carbon film, and a conductive hard carbon film could be produced. In these conductive hard carbon films, portions other than the SP ² binding crystals were amorphous.

Comparative Examples 1 to 3 Films in which the substrate bias voltage during film formation was set outside the range of Examples 1 to 3 were formed.

[Evaluation] Measurement of Coating Strength Using a Knoop indenter made of diamond, a load of 15 g and a load application time of 10 seconds were used, and an average value of 10 measured values was adopted. When the unevenness of the coating surface was so large that the shape of the indentation was difficult to see, buffing was performed with a # 8000 diamond paste so that the indentation shape could be observed.

The presence of the above SP ² bond crystal, orientation of the angle of the C axis, the presence of the graphite crystal, the continuity of the SP ² bond crystal, and the interlayer distance is observed and electron diffraction by transmission electron microscopy, It was examined by X-ray diffraction.

Key contact performance after 50,000 contacts The conductive hard carbon film formed by each of the above-described film forming methods is applied to a SUS305 substrate on the surface of a coned disc spring and a receiving-side contact constituting a key contact for a mobile phone. , Formed. For these contacts, the contact resistance at the key contact after 50,000 contact operations was measured.

Carbon content Carbon was quantified by Rutherford backscattering, hydrogen was quantified by an elastic recoil particle detection method, and the carbon content was calculated.

I293 / I285 Using electron energy loss spectroscopy, the ratio (= I293 / I285) of the peak height (I285) around 285 eV and the peak height (I293) around 293 eV was calculated.

Conductivity Electrodes were provided at two points on the sample, a constant current was passed between them, the potential drop between the two electrodes was measured, and the resistance was calculated to calculate the conductivity. The results are shown in Table 1.

[0047]

[Table 1]

From the results shown in Table 1, it was found that the member having the conductive hard carbon film according to the present invention formed on the contact portion exhibited good contact performance without deterioration such as oxidation. On the other hand, Comparative Examples outside the scope of the present invention are Comparative Examples 1, 2,
For No. 3, the conductivity of the film itself is not sufficient and it is useless. In this example, the increase in the contact resistance after 50,000 times was suppressed within three times the initial value.

[0049]

The conductive hard carbon film according to the present invention has a structure in which at least a part of the SP ² bonding crystal has a continuous structure in the film thickness direction, so that high conductivity can be maintained.

Also, since a conductive hard carbon film is used,
Has good wear resistance, oxidation resistance and corrosion resistance.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a high-frequency plasma CVD apparatus.

FIG. 2 is a schematic diagram showing a sbutter evaporation apparatus.

FIG. 3 is a schematic diagram showing a vacuum arc evaporation apparatus.

FIG. 4 is a schematic view showing a state in which SP ² bonded crystals are continuously connected in the film thickness direction.

FIG. 5 is an explanatory view of an angle formed by an SP ² bonded crystal and a substrate plane.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Vacuum tank 2 Substrate holder 3 High frequency power supply 4 DC power supply 5 Gas inlet 6 Gas exhaust port 7 Substrate 8 Vacuum tank 9 Rotation table 10 Substrate holder 11 Sputtering evaporation source 12 High frequency power supply 13 Target 14 DC power supply 15 Gas introduction Port 16 Gas exhaust port 17 Substrate 18 Vacuum tank 19 Rotary table 20 Substrate holder 21 Target 22 DC power supply 23 DC power supply 24 Gas inlet 25 Gas exhaust port 26 Substrate 27 Coating 28 Intermediate layer 29 Substrate 30 SP ² bonded crystal 31 angle 34 interlayer distance formed by carbon atoms 32 SP ² bond flat or curved 33 SP ² bond flat or curved and the substrate surface

Continued on the front page (72) Inventor Hisanori Ohara 1-1-1, Kunyo-Kita, Itami City F-term in Sumitomo Electric Industries, Ltd. Itami Works 4G046 CA02 CB00 CB03 CB09 CC06 4K029 BA02 BA07 BA17 BA34 BB02 BB07 BC03 BD03 CA01 CA05 CA06 DB05 DB17 DC05 DD06 4K030 AA10 BA27 BB01 FA03 KA20 LA01 LA11

Claims (11)

[Claims] 1. The method according to claim 1, wherein at least a part of the SP ² binding crystal is
A conductive hard carbon film having a structure continuously connected in the film thickness direction. 2. The conductive hard carbon film according to claim 1, wherein at least a part of the SP ² bonding crystal has a graphite structure. 3. An angle formed by an SP ² bonding plane or a curved surface constituted by at least a part of the SP ² bonding crystal and a substrate surface is 60 ° or more and 120 ° or less. The conductive hard carbon film according to the above. 4. An angle formed by an SP ² bonding plane or a curved surface constituted by a part of an SP ² bonding crystal continuously connected in a film thickness direction and a substrate surface is 60 ° or more and 120 ° or more. The conductive hard carbon film according to claim 2, which is as follows. 5. The SP ² adjacent to the SP ² bond flat or curved
The distance between the bonding plane and the curved surface is 2.4 ° or more and 3.9 or more.
The conductive hard carbon film according to any one of claims 1 to 4, wherein 6. The conductive hard carbon film according to claim 1, wherein a portion other than the SP ² binding crystal is amorphous. 7. 285 in electron energy loss spectroscopy
Ratio of peak height (I285) near eV to peak height (I293) near 293 eV (= I293 / I285)
The conductive hard carbon film according to any one of claims 1 to 6, wherein is not less than 0.9 and not more than 1.6. 8. The conductive hard carbon film according to claim 1, which has a Knoop hardness of 1000 or more and 3000 or less. 9. The method according to claim 9, wherein the composition of carbon is 80 at. % Or more, 100 at. %. The conductive hard carbon film according to any one of claims 1 to 8, which is not more than 10%. 10. A member formed on a surface of a member in contact with a plurality of members or a member used in a corrosive environment.
10. The conductive hard carbon film according to any one of items 1 to 9. 11. The conductive hard carbon film according to claim 1, which is formed by using a sputter deposition method or a vacuum arc deposition method.