JP2017101279A - Arc type film deposition apparatus and film deposition method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an arc type film deposition technique capable of stably depositing a smooth DLC film by suppressing discharge of pulverized particles from a cathode during arc discharge when depositing a DLC film using an arc type film deposition apparatus.SOLUTION: An arc type film deposition apparatus for sublimating carbon from an arc spot 31 formed on a cathode surface by arc discharge using a cathode material having carbon used as a principal component to deposit a carbon film having carbon used as a principal component on the surface of a base material comprises: cathode holding means for holding a cathode 4; base material holding means for holding the base material; a vacuum chamber having the housed cathode holding means and base material holding means; and means for setting the temperature of a region in the vicinity of the arc spot of the cathode 4 to a temperature of at least 500-3000°C during film deposition.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an arc type film forming apparatus for forming a thin film mainly composed of carbon on the surface of a substrate such as a mold, an automobile part, or a tool, and a film forming method using the arc type film forming apparatus.

  In general, a hard carbon film mainly composed of carbon called a DLC (diamond-like carbon) film has attracted attention as a material excellent in low friction and welding resistance. Such DLC films are roughly classified into hydrogen-containing DLC films formed using hydrocarbon gas as a carbon material and hydrogen-free DLC films formed using solid carbon as a carbon material. Among these, in particular, the hydrogen-free DLC film has high hardness and high heat resistance, and also has a small coefficient of friction in oil, so that it can be used for base materials such as molds for lens molding, automobile parts, and tools. Used as a surface treatment film.

  Such a hydrogen-free DLC film is generally formed by using a sputtering method or an arc method, but it is difficult to increase productivity by the sputtering method, and the film quality of the formed DLC film is sufficient. In recent years, film formation using the arc method has been preferably performed (see, for example, Patent Document 1).

JP 2014-62326 A

  However, when a DLC film is formed on the surface of a substrate using an arc type film forming apparatus, large particles (pulverized particles) having a diameter of several μm to several hundred μm are discharged from the cathode during arc discharge during film formation. In some cases, the surface of the DLC film to be smooth is roughened by being taken into the DLC film being formed.

  If a lens is molded using a mold for molding a lens on which a DLC film incorporating such pulverized particles is formed, a pinhole may be formed in the molded lens, which may reduce the quality of the lens. is there. For this reason, the FVA (Filtered Vacuum Arc) method has been developed and put into practical use as a technique for suppressing the incorporation of pulverized particles into the DLC film using a duct or a magnetic field. The provision of the apparatus increases the cost of the apparatus and slows the film formation rate to about 1/5 that of the conventional arc method.

  In addition, when pulverized particles are taken in when a DLC film is formed on automobile parts and tools such as piston rings, valve lifters, and piston pins, the pulverized particles become the starting point of peeling, and the quality of automobile parts and tools, etc. There is a risk of lowering.

  Further, generally, a process of removing the pulverized particles by lapping or the like is also performed, but there is a problem that an extra man-hour (cost) is required.

  Therefore, the present invention stably forms a smooth DLC film by suppressing the release of pulverized particles from the cathode during arc discharge when forming the DLC film using an arc type film forming apparatus. It is an object of the present invention to provide an arc type film forming technique capable of forming a film.

  In examining the solution of the above problems, the present inventor first examines in detail the release mechanism of pulverized particles, and the pulverized particles are between the arc spot and the surrounding portion at the cathode during arc discharge. It was found that this occurred due to a large temperature difference.

  FIG. 7 is a cross-sectional view schematically showing the vicinity of an arc spot formed on the cathode of a conventional arc type film forming apparatus. As shown in FIG. 7, in general, in the vacuum arc deposition method, an arc spot 31 is formed on the surface of the cathode 4 by arc discharge, and carbon is sublimated by the high temperature of the arc spot 31, and the sublimated carbon 44 is formed on the base material. A DLC film is formed by vapor deposition on the surface (not shown).

  At this time, in the arc method, since a relatively large current (30 to 200 A) is concentrated on the arc spot 31, the temperature of the cathode 4 is sublimated at a high temperature exceeding 3000 ° C. Is normally cooled with water from the back side of the cathode 4, the temperature around the arc spot nearest portion 41 generally remains at 500 ° C. or less, and a large temperature difference with the arc spot 31 occurs.

  When such a large temperature difference occurs in the adjacent region of the arc spot closest portion 41 and its surroundings 42, a large thermal distortion occurs in the region, causing cracks. The occurrence of such cracks causes the cathode 4 to be pulverized, and the pulverized carbon is released as pulverized particles 43, so that sparks are generated around the arc spot 31.

  Based on the above findings, the present inventor has found that if the temperature of the entire cathode 4 is high, the temperature difference generated between the arc spot closest portion 41 and the surrounding 42 is reduced, and the generation of pulverized particles 43 and sparks ( Hereinafter, it is considered that the generation of the pulverized particles 43) can be suppressed, and various experiments are conducted to determine how much the temperature at the cathode 4 is specifically set to suppress the generation of the pulverized particles 43. Study was carried out.

  As a result, at least the portion where the pulverized particles 43 have been generated, that is, the region in the vicinity of the arc spot 31, is at a high temperature of 500 to 3000 ° C, preferably 1000 to 3000 ° C. When the arc spot 31 is formed, a large temperature difference does not occur between the portion 41 immediately adjacent to the arc spot and the surrounding 42, the generation of the pulverized particles 43 is suppressed, and a smooth DLC film, specifically, surface roughness. It was found that a DLC film having a (ten-point average roughness) of 0.5 μm or less can be stably formed. Then, the inventor has studied an arc type film forming apparatus capable of setting the temperature of the region near the arc spot of the cathode 4 during film formation to 500 to 3000 ° C.

  Further, as described above, when an arc type film forming apparatus capable of increasing the temperature of at least the area near the arc spot 31 in the cathode 4 is used, the carbon near the arc spot 31 is easily sublimated in a short time by arc discharge. Therefore, it has been found that the arc spot 31 can be moved smoothly, and that the carbon of the cathode 4 is evenly consumed and the utilization efficiency of the cathode 4 can be increased.

  Here, the region near the arc spot is a place where pulverization occurs unless heated, and varies depending on the cathode material and arc discharge conditions. However, as shown in FIG. It is an area within a radius of 3 mm and a depth of 3 mm.

  However, since the arc spot moves according to the magnetic field and the surface state of the cathode, it is preferable that the new destination is already at a high temperature, and it is preferable that the high temperature region is large. Most preferably, the substantial entire discharge surface is hot.

The inventions according to claims 1 and 2 are based on the above knowledge, and the invention according to claim 1
By performing arc discharge using a cathode material mainly composed of carbon, the carbon is sublimated from the arc spot formed on the cathode surface, and a carbon film mainly composed of carbon is formed on the substrate surface. Arc type film forming apparatus
Cathode holding means for holding the cathode;
Substrate holding means for holding the substrate;
A vacuum chamber containing the cathode holding means and the substrate holding means,
An arc type film forming apparatus comprising means for setting a temperature of at least a region near the arc spot of the cathode to 500 to 3000 ° C. during film formation.

And the invention of Claim 2 is
2. The arc type film forming apparatus according to claim 1, further comprising means for setting a temperature of at least a region of the cathode near the arc spot during film formation to 1000 to 3000 ° C. 3.

  Next, the present inventor conducted experiments and studies on specific means for setting the temperature of the region near the arc spot of the cathode 4 to the above-described temperature, and broadly divided, the following two means can be preferably adopted. I found.

  First, as a first means, a heating means for heating the cathode from the outside is provided. That is, if at least the area near the arc spot of the cathode is heated to a high temperature during arc discharge by external heating, the temperature difference between the immediate vicinity of the arc spot and the surrounding area is reduced in the cathode during film formation. The generation of pulverized particles can be suppressed.

Invention of Claim 3 is based on said knowledge,
The arc-type film formation according to claim 1 or 2, further comprising heating means for heating at least a region of the cathode in the vicinity of the arc spot to bring the temperature of the cathode to 500 to 3000 ° C. Device.

  As a specific heating means for heating the above-described cathode from the outside, it has been found that heating by a heater is most suitable. However, the same effect can be obtained in an induction heating device, an electron beam heating device, and a laser heating device. I can expect.

That is, the invention described in claim 4
4. The arc type film forming apparatus according to claim 3, wherein the heating means is a heater for heating the cathode from the outside.

  When a heater is used as the heating means, it is preferable because temperature control of the cathode can be easily performed. Moreover, both heater heating and arc discharge can be performed with one power source by connecting the heater and the cathode and causing the current flowing through the heater to flow through the cathode.

The invention according to claim 5
4. The arc-type film forming apparatus according to claim 3, wherein the heating means is an induction heating apparatus that induction-heats the cathode.

  Since the induction heating apparatus can heat the cathode even from a remote position, the degree of freedom of the installation position becomes high, and it can be preferably used even when it is difficult to provide the heater described above.

The invention according to claim 6
4. The arc type film forming apparatus according to claim 3, wherein the heating means is an electron beam heating apparatus that irradiates the cathode with an electron beam to heat the cathode.

  Similar to the induction heating device described above, the electron beam heating device can also heat the cathode from a remote location.

The invention according to claim 7
The arc heating film forming apparatus according to claim 3, wherein the heating means is a laser heating apparatus that irradiates the cathode with laser light to heat the cathode.

  As for the laser heating device, the cathode can be heated from a distant position as in the induction heating device and the electron beam heating device.

  Although the heating of the cathode from the outside of the first means described above is easy, the provision of the heating means tends to increase the size and cost of the arc type film forming apparatus. Therefore, the present inventor then, as a second means, does not heat the cathode from the outside, but at least the arc spot of the cathode by self-heating of the cathode which heats the cathode with the heat generated in the cathode itself by arc discharge. A means for setting the temperature in the nearby region to 500 to 3000 ° C. was considered.

  For example, since the cathode 4 is heated to a temperature higher than or equal to the sublimation temperature of carbon (about 3500 ° C.) in the vicinity 41 of the arc spot near the arc spot 31, the entire cathode 4 is heated by the heat in the portion 41 near the arc spot. Furthermore, the whole of the cathode 4 is also heated by resistance heating due to the arc current.

  If the cathode 4 can be heated to 500 to 3000 ° C. by keeping the heat generated by self-heating of the cathode 4 at least in the vicinity of the arc spot of the cathode 4, the arc spot can be obtained without providing new heating means outside. It becomes possible to heat the periphery 42 of the nearest part 41 to high temperature, and the enlargement of an apparatus is not caused.

The invention according to claims 8 to 10 is based on the above knowledge, and the invention according to claim 8
The arc type composition according to claim 1 or 2, wherein a temperature of at least a region in the vicinity of the arc spot of the cathode is 500 to 3000 ° C by self-heating of the cathode. It is a membrane device.

The invention according to claim 9 is:
9. The arc type film forming apparatus according to claim 8, wherein the self-heating of the cathode is performed by heat generated in the arc spot.

The invention according to claim 10 is
The arc-type film forming apparatus according to claim 8, wherein the self-heating of the cathode is performed by resistance heating generated by an arc current.

  As a specific method for setting the temperature of the region near the arc spot of the cathode to 500 to 3000 ° C. by self-heating of the cathode described above, it is first considered to use a cathode that is thinner than a conventional general cathode. It is done. When such a thin cathode is used, the heat generated at the arc spot is accumulated in the thin cathode, so that the cathode can be sufficiently heated only by the heat generated at the arc spot. In addition, since the resistance increases in the case of a thin cathode, the cathode can be sufficiently heated by resistance heating due to an arc current. As a result of the experiment, it was found that a columnar cathode having a diameter of 20 mm or less should be used as the cathode in order to set the temperature of at least the region near the arc spot of the cathode to 500 to 3000 ° C.

That is, the invention according to claim 11
The arc type film forming apparatus according to any one of claims 8 to 10, wherein the cathode is a columnar cathode having a diameter of 20 mm or less.

  In addition, when a porous cathode is used as the cathode, the actual volume of the cathode is reduced even if the cathode has the same thickness due to the presence of the pores, and the heat generated at the arc spot is a cathode with a small actual volume. On the other hand, since the resistance increases due to the presence of the holes, the cathode can be sufficiently heated by the resistance heat generated by the arc current. In addition, since the heat conduction at the cathode is reduced due to the presence of the holes, it is difficult for the heat generated at the arc spot to escape into the cathode material, and the generated heat can be used effectively.

That is, the invention according to claim 12
The arc type film forming apparatus according to any one of claims 8 to 10, wherein the cathode is a porous cathode.

  Also, a general arc type film forming apparatus has a cooling means for cooling the cathode in order to prevent the entire cathode from melting or sublimating due to temperature rise during arc discharge and falling off from the cathode holding means. Is provided. However, when the DLC film is formed as in the present invention, since the sublimation temperature of the cathode is high, the necessity for cooling the cathode is low.

  For this reason, if the cooling means is controlled to make the cooling of the cathode weaker than before, the temperature of the cathode itself can be made higher than before, and at least the temperature in the vicinity of the arc spot of the cathode is set to 500 to It can be 3000 degreeC.

The invention according to claim 13 is based on the above knowledge,
A cooling means for cooling the cathode, and a cooling control means for controlling the cooling means so that a temperature of at least a region in the vicinity of the arc spot of the cathode is 500 to 3000 ° C. The arc-type film forming apparatus according to any one of Items 8 to 10.

  The first means for raising the temperature of the cathode by providing a heating means for heating the cathode from the outside and the second means for raising the temperature of the cathode by self-heating of the cathode can be used in combination.

That is, the invention according to claim 14
By combining the heat generated by the heating means for heating the cathode and the heat generated by the self-heating of the cathode, the temperature of at least the area near the arc spot of the cathode is set to 500 to 3000 ° C. An arc type film forming apparatus according to claim 1 or 2, wherein

The invention according to claim 15 is:
The heating means for heating the cathode is any one of a heater, induction heating, electron beam heating, laser heating,
15. The arc type film forming apparatus according to claim 14, wherein the self-heating of the cathode is performed by heat generated at the arc spot and / or resistance heating of the cathode.

  Next, from the viewpoint of improving the utilization efficiency of the cathode, it is preferable to provide a magnetic field generating means for generating a magnetic field around the cathode to generate the magnetic field in a predetermined direction. Specifically, in general, in the case of an arc type film forming apparatus using a columnar cathode, as shown in FIG. 6, the arc spot 31 during arc discharge extends from the tip T of the cathode 4 to the root (not shown). The side surface of the cathode 4 is moved spirally. At this time, only the portion of the carbon through which the arc spot 31 has passed is sublimated and used for forming the DLC film, and the portion of the carbon that has not passed through is not sublimated and is not used for forming the DLC film. For this reason, in the case of an arc-type film forming apparatus using the columnar cathode 4, the utilization efficiency of the cathode 4 remains low.

  On the other hand, as shown in FIG. 5, a coil 12 as a magnetic field generating means is provided in the arc type film forming apparatus, and the angle θ formed between the axial direction of the cathode 4 and the magnetic force lines M is an acute angle on the tip T side of the cathode 4. When the magnetic field is generated so that the arc spot has a characteristic that the arc spot moves in a direction in which the angle θ is an acute angle, the arc spot stays at the tip T of the cathode 4 and the tip T side of the cathode 4 Carbon is consumed sequentially. As a result, the utilization efficiency of the cathode 4 can be improved as compared with the prior art. In FIG. 5, the coil 12 is used as the magnetic field generating means. However, the present invention is not limited to this, and a permanent magnet may be used.

The invention according to claim 16 is based on the above knowledge,
The cathode is a cylindrical cathode;
16. The magnetic field generating means for generating a magnetic field so that an angle formed between an axial direction of the columnar cathode and a line of magnetic force is an acute angle on the tip side of the cathode is provided. It is an arc type film-forming apparatus of any one item.

  Further, when a cylindrical cathode is used, it is preferable to provide a delivery mechanism that feeds the cathode toward the substrate. Thereby, when a cathode becomes short by arc discharge, a cathode can be sent out and stable arc discharge can be maintained for a long time.

That is, the invention according to claim 17
The arc-type film forming apparatus according to claim 16, further comprising a delivery mechanism that delivers the cylindrical cathode toward the base material.

The invention according to claim 18
An arc type in which a carbon film mainly composed of carbon is formed on the surface of a base material by evaporating the carbon from an arc spot formed on the surface of the cathode by performing arc discharge on the cathode mainly composed of carbon. A film forming method comprising:
In the film forming method, the carbon film is formed at a temperature of at least 500 to 3000 ° C. in the vicinity of the arc spot of the cathode.

The invention as set forth in claim 19
Using the arc-type film forming apparatus according to any one of claims 1 to 17,
In the film forming method, the carbon film is formed at a temperature of at least 500 to 3000 ° C. in the vicinity of the arc spot of the cathode.

  In the inventions according to claims 18 and 19, as described above, since the generation of pulverized particles is suppressed during film formation, a smooth DLC film can be stably formed. Moreover, the utilization efficiency of a cathode can also be raised.

  According to the present invention, when a DLC film is formed using an arc type film forming apparatus, a smooth DLC film is stably formed by suppressing the release of pulverized particles from the cathode during arc discharge. An arc-type film forming technique capable of forming a film can be provided.

It is the schematic which shows the basic composition of the arc type film-forming apparatus which concerns on one embodiment of this invention. It is sectional drawing which shows typically the mode of the arc spot vicinity in the arc type film-forming apparatus which concerns on one embodiment of this invention. It is the schematic which shows the arc type film-forming apparatus which concerns on other embodiment of this invention. It is a perspective view which shows typically an example of the cathode of the arc type film-forming apparatus which concerns on one embodiment of this invention. It is a figure explaining the magnetic field generation | occurrence | production means of the arc type film-forming apparatus which concerns on other embodiment of this invention. It is a figure explaining the movement of the arc spot in the conventional arc type film-forming apparatus. It is sectional drawing which shows typically the mode of the arc spot vicinity in the conventional arc type film-forming apparatus. It is a figure explaining the area | region of an arc spot vicinity.

  Hereinafter, based on an embodiment, the present invention will be described with reference to the drawings. Specifically, first, the basic configuration of the arc-type film forming apparatus will be described, then the temperature of the cathode during film forming, which is a characteristic part of the present invention, will be described, and then the film forming method will be described. .

[1] Arc type film forming apparatus Basic Configuration First, the basic configuration of the arc type film forming apparatus according to the present embodiment will be described. FIG. 1 is a schematic diagram showing a basic configuration of an arc type film forming apparatus according to the present embodiment.

  The basic configuration of the arc type film forming apparatus 10 used in the present invention is the same as that of the conventional arc type film forming apparatus. Specifically, the arc type film forming apparatus 10 includes a vacuum chamber 1, a substrate holding means 2, a cathode holding means 3, a cathode 4, power supplies 6 and 7, and a trigger electrode 8. In FIG. 1, reference numeral 5 denotes a shutter and 9 denotes a resistor.

(1) Vacuum chamber The vacuum chamber 1 is provided with an exhaust port 11, and the inside of the vacuum chamber 1 is evacuated by an exhaust means (not shown) such as a turbo molecular pump or a rotary pump connected to the exhaust port 11. be able to. The vacuum chamber 1 is electrically grounded.

(2) Base material and base material holding means The base material holding means 2 is accommodated in the vacuum chamber 1 and holds the base material 20 as a film formation target. The substrate holding means 2 is insulated from the vacuum chamber 1. In addition, in FIG. 1, although the base material holding means 2 which hold | maintains the one base material 20 is shown, the base material holding means which can hold | maintain a some base material can also be used.

(3) Cathode and cathode holding means The cathode holding means 3 is accommodated in the vacuum chamber 1 and is configured to hold the cathode 4 so as to face the base material 20 held by the base material holding means 2. ing. The cathode 4 is made of a material mainly composed of carbon, and isotropic graphite, anisotropic graphite, porous graphite, C / C composite, or the like can be used. Further, glassy carbon or pyrocarbon may be used instead of these powder aggregates. By using such glassy carbon or pyrocarbon, the generation of sparks and pulverized particles can be more appropriately suppressed.

(4) Power source In this arc type film forming apparatus 10, a power source 6 is connected to the base material holding means 2, and a negative voltage can be applied to the base material 20 through the base material holding means 2. ing. Similarly, a power source 7 is also connected to the cathode holding means 3 so that a negative voltage can be applied to the cathode 4 via the cathode holding means 3.

(5) Trigger electrode The trigger electrode 8 is attached so that the tip thereof faces the tip of the cathode 4. The trigger electrode 8 is made of, for example, molybdenum (Mo), and an arc discharge is generated between the cathode 4 and the vacuum chamber 1 by bringing the tip of the trigger electrode 8 into contact with the cathode 4 to which a negative voltage is applied. Can be generated.

(6) Magnetic field generating means In order to control the movement of the arc spot, it is preferable to provide a magnetic field generating means, for example, the coil 12 shown in FIG. The coil 12 is configured to generate a magnetic field around the cathode 4 such that an angle θ formed between the magnetic lines of force M and the side surface of the cathode 4 is an acute angle on the tip T side of the cathode 4.

  As described above, when the magnetic field generating means for generating such a magnetic field is provided, the arc spot moves in the direction in which the magnetic lines of force M are at an acute angle, so the arc spot is at the tip of the cathode 4. The carbon can be consumed sequentially from the tip T side of the cathode 4, and the utilization efficiency of the cathode 4 can be improved as compared with the conventional case.

2. Next, the temperature of the cathode during film formation, which is a feature of the present invention, will be described. FIG. 2 is a cross-sectional view schematically showing a state in the vicinity of an arc spot in the arc type film forming apparatus according to the present embodiment.

  In the arc-type film forming apparatus according to the present embodiment, the temperature at least in the portion where the pulverized particles 43 are conventionally generated, that is, in the region near the arc spot 31 of the cathode 4 is 500 to 3000 ° C. (preferably 1000 ° C.). -3000 ° C.). Thereby, the temperature difference between the arc spot closest portion 41 in the vicinity of the arc spot 31 shown in FIG. 2 and its surrounding 42 can be reduced, and the thermal strain generated in the periphery 42 of the arc spot closest portion 41 can be reduced. As a result, generation of cracks due to thermal strain can be prevented, and generation of pulverized particles 43 (see FIG. 7) can be suppressed. In consideration of the carbon sublimation temperature (about 3500 ° C.) of the cathode 4, the temperature of the cathode 4 during film formation is set to 3000 ° C. or lower.

  In the present embodiment, as means for reducing the temperature difference between the arc spot closest portion 41 and its surroundings 42, means for providing a heating means for heating the cathode 4 from the outside, and means for raising the temperature of the cathode 4 by self-heating. Using at least one of the above means, the temperature of at least the area near the arc spot of the cathode 4 during film formation is set to 500 to 3000 ° C. Hereinafter, specific examples of each means will be described.

(1) In the case of heating means First, a specific example of means for providing a heating means for heating the cathode 4 from the outside so that the temperature of at least the region near the arc spot 31 of the cathode 4 is 500 to 3000 ° C will be described.

(A) Heater Examples of the heating means for heating the cathode 4 from the outside include a heater. As this heater, for example, a heater using a heating wire can be used. Since such a heater has a simple structure and easy temperature control, at least a region in the vicinity of the arc spot 31 of the cathode 4 can be reliably heated to 500 to 3000 ° C. and can be preferably used. In addition, when using a heater as a heating means, the method of heating the cathode 4 via the cathode holding means 3 by incorporating a heater in the cathode holding means 3 is mentioned, for example.

(B) Induction heating apparatus Next, an induction heating apparatus can also be used as a heating means. As this induction heating device, a known induction heating device can be used. When an induction heating apparatus is used as the heating means, even if the heating means is installed at a position away from the cathode 4, at least a region in the vicinity of the arc spot 31 of the cathode 4 can be heated to 500 to 3000 ° C. 10 can be preferably used when it is difficult to provide a heater or the like.

(C) Electron Beam Heating Device Next, an electron beam heating device can be used as the heating means. In the case of using an electron beam heating device, an electron gun is provided in a vacuum chamber, and the cathode is heated by irradiating the cathode with an electron beam from the electron gun. As with the induction heating device, this electron beam heating device can also heat the cathode 4 from a distant position, and thus has a high degree of freedom in installation position.

(D) Laser heating device A laser heating device is also preferably used as the heating means because the cathode can be heated from a distant position as described above.

(2) Case of Self-Heating of Cathode Next, a means for setting the temperature of the cathode 4 to 500 to 3000 ° C. by self-heating of the cathode 4 without separately providing a heating means as described above will be described. In this means, the cathode 4 itself is heated by heat generated at the cathode 4 during arc discharge, such as heat generated at the arc spot 31 and resistance heat generation of the cathode 4 due to arc current, and at least near the arc spot 31 of the cathode 4. The region temperature is 500-3000 ° C. Hereinafter, specific means will be described.

(A) Use of a cathode having a small diameter In a conventional arc-type film forming apparatus, when a cylindrical cathode 4 as shown in FIG. 4 is used, the diameter D of the cathode 4 is set to 50 to 70 mm. However, if the cathode 4 is made thinner than the conventional one and the diameter D is 20 mm or less, the heat generated at the arc spot is accumulated in the thin cathode, so that at least the area near the arc spot 31 of the cathode 4 due to the heat generated at the arc spot. The temperature can be set to 500 to 3000 ° C.

  Specifically, when a general cathode 4 having a diameter D of 50 to 70 mm is used as in the prior art, the heat generated at the arc spot 31 (see FIG. 7) is dispersed in a wide range of the cathode 4, so that the cathode 4 It is difficult to raise the temperature. For this reason, the temperature of the cathode 4 becomes 500 ° C. or less, and a large temperature difference is generated between the arc spot closest portion 41 and its periphery 42, and cracks are likely to occur.

  On the other hand, when the thin cathode 4 having a diameter D of 20 mm or less is used, the heat generated at the arc spot is accumulated in the thin cathode as described above, so that at least the heat generated at the arc spot 31 (see FIG. 2) The region near the arc spot 31 of the cathode 4 can be heated to 500 to 3000 ° C. In addition, the diameter D of the cathode 4 is more preferably 5 mm or less, and further preferably 3 mm or less.

  In addition, when the thin cathode 4 having a diameter D of 20 mm or less is used, the cross-sectional area when the arc current flows is small, so that the resistance is higher than when a conventional cathode having a thickness is used. Thereby, when the arc current flows to the cathode 4, the cathode 4 can sufficiently generate heat.

  As described above, by using the thin cathode 4 having a diameter D of 20 mm or less, the temperature of the entire cathode 4 can be increased by the heat generated in the arc spot 31 and the resistance heat generation of the cathode 4, and the temperature can be easily increased to 500 to 3000 ° C. .

  When the thin columnar cathode 4 is used, a cathode holding unit 3 (see FIG. 3) that holds one end of the columnar cathode 4 is used, and the columnar cathode 4 is used as the cathode holding unit 3 at this time. It is preferable to provide a delivery mechanism that sequentially feeds the substrate toward the substrate 20. As a result, when the cathode is shortened, it can be sent out appropriately, and the number of times of replacing the cathode 4 can be reduced, and stable arc discharge can be sustained for a long time.

(B) Use of Porous Cathode As a means for bringing the cathode to 500 to 3000 ° C. by self-heating of the cathode, it is also preferable to use a porous cathode for the cathode 4. When such a porous cathode is used, even if it is the same thickness, the actual volume of the cathode is reduced by the pores. In addition, the temperature of the cathode 4 can be raised by both resistance heating due to the arc current, and the temperature of at least the region in the vicinity of the arc spot 31 of the cathode 4 can be easily set to 500 to 3000 ° C.

(C) Control of cooling means In place of each of the above-described means, the cooling means for the cathode provided in a general arc type film forming apparatus is controlled so that at least the area near the arc spot 31 of the cathode 4 is controlled. Setting the temperature to 500 to 3000 ° C is one means.

  Specifically, in a general arc type film forming apparatus, in order to prevent the entire cathode from being melted or sublimated due to temperature rise during arc discharge and falling off from the cathode holding means, Cooling means are provided.

  However, as described above, such a dropout of the cathode occurs when a metal material (such as Ti) having a relatively low melting point is used for the cathode, and a DLC film is formed as in the present invention. In this case, since a cathode mainly composed of carbon having a high sublimation temperature is used, the necessity for cooling the cathode is low.

  For this reason, when the DLC film is formed, the temperature of the cathode can be made higher than before by controlling the degree of cooling by the cooling means to be weaker than before.

[2] Arc Type Film Forming Method Next, an arc type film forming method according to the present embodiment performed using the arc type film forming apparatus having the above configuration will be described. First, an outline of a film forming method using the arc type film forming apparatus as shown in FIG. 1 which is the same as the conventional film forming method will be described, and then the characteristic of the film forming method of the present invention will be described. The important part will be described.

1. Outline of Film Forming Method First, the cathode 4 is set in the cathode holding means 3 and the base material 20 is set in the base material holding means 2, and then the inside of the vacuum chamber 1 is evacuated to a predetermined degree of vacuum (10 ⁻⁴ to 10 ⁻³ Pa).

  Next, a negative bias voltage (0 to −300 V) is applied from the power source 6 to the substrate 20, and a negative voltage (−15 to −50 V) is applied from the power source 7 to the cathode 4.

  And after making the front-end | tip of the trigger electrode 8 contact the cathode 4, it leaves | separates. Thereby, arc discharge (about 80 A) is generated between the vacuum chamber 1 and the cathode 4. Thereby, an arc spot 31 is formed on the cathode 4, and the carbon of the cathode 4 is sublimated in the arc spot 31.

  In this state, when the shutter 5 is opened, the sublimated carbon is deposited on the surface of the substrate 20 to form a DLC film.

2. Features of Arc Type Film Forming Method According to the Present Embodiment In the present embodiment, the temperature of the region in the vicinity of the arc spot 31 of the cathode 4 during the film formation described above is set to 500 to 3000 ° C. As shown in FIG. 2, the temperature difference between the arc spot closest portion 41 in the vicinity of the arc spot 31 and the surrounding 42 is reduced to suppress the generation of cracks due to thermal distortion and to suppress the release of pulverized particles.

  For example, when the temperature of the cathode 4 is set to 500 to 3000 ° C. using the heating means such as the heater described above, the heating means is operated before the tip of the trigger electrode 8 is brought into contact with the cathode 4 to start arc discharge. Prior to this, the temperature of at least the area near the arc spot 31 of the cathode 4 is preliminarily raised to 500 to 3000 ° C. Thereby, since arc discharge can be performed in a state where the temperature difference between the arc spot closest portion 41 in the vicinity of the arc spot 31 and its surroundings 42 is reduced, the release of pulverized particles due to cracks can be suppressed.

  Further, when the temperature of at least the area near the arc spot 31 of the cathode 4 is set to 500 to 3000 ° C. by self-heating of the cathode 4, for example, a thin cathode 4 having a diameter D of 20 mm or less shown in FIG. Start discharging. The temperature of the entire cathode 4 is raised by the heat generated at the arc spot 31 and the resistance heat generated by the arc current. At this time, since the thin cathode is used, the generated heat stays at the thin cathode and is sufficiently heated. be able to.

  When the cathode 4 reaches 500 ° C. or higher, the shutter 5 is opened and film formation is started. Thereby, in the cathode 4 during film formation, it is possible to reduce the temperature difference between the arc spot closest portion 41 and its surroundings 42 and suppress the release of pulverized particles due to cracks.

  Further, since the smooth DLC film can be stably formed on the substrate by suppressing the release of the pulverized particles as described above, for example, in a lens mold, there are few pinholes. High quality lenses can be molded, and in automobile parts and tools such as piston rings, valve lifters, piston pins, etc., it is possible to prevent pulverized particles from starting from being taken in. It does not cause deterioration in quality over a long period of time.

[1] Experiment 1
In Experiment 1, a heater was provided as a heating means for heating the cathode, and the cathode during film formation was heated with the heater, and the temperature of the cathode capable of suppressing the release of pulverized particles was examined.

1. Experimental Examples 1-4
Specifically, Experimental Examples 1 to 4 were performed by installing a heater in a conventional arc type film forming apparatus and controlling the temperature so as to be the cathode temperature shown in Table 1. Specific film forming conditions other than the heater temperature were as follows.

Cathode: Length 30mm
Diameter 50mm
Base material: Base material for testing (made of high-speed tool steel)
Degree of vacuum: 1 × 10 ⁻³ Pa
Bias voltage: -50V
Arc voltage: -20V
Arc discharge current: 50A
Deposition time: 20 min

2. Evaluation (1) Cathode Temperature In each experimental example, the temperature of the cathode during film formation was measured using an infrared radiation thermometer. The results are shown in Table 1.

(2) Surface roughness of DLC film For the DLC film formed in each experimental example, the surface shape is measured using a surface roughness meter, and the surface roughness (ten-point average roughness) is determined based on the measurement result. Calculated. The results are shown in Table 1.

(3) Observation of spark discharge amount The amount of spark discharge from the periphery of the cathode arc spot during arc discharge was visually observed. The results are shown in Table 1.

  From Table 1, in Experimental Examples 2 to 4 in which the cathode was heated by a heater and the temperature of the cathode during film formation was 500 ° C. or higher, the surface roughness of the formed DLC film was 500 ° C. It turns out that it is smaller than the experimental example 1 made less. From this, it was confirmed that the release of pulverized particles due to cracks can be appropriately suppressed by setting the temperature of the cathode during film formation to 500 ° C. or higher using a heater. In consideration of the sublimation temperature of carbon, the upper limit of the temperature of the cathode 4 during film formation is 3000 ° C.

  It can also be seen that in Experimental Example 4 in which the temperature of the cathode was 1000 ° C., the surface roughness was significantly smaller than in Experimental Examples 2 and 3. This shows that the temperature of the cathode during film formation is preferably 1000 ° C. or higher.

  Further, in Experimental Examples 2 to 4 in which the cathode was heated to 500 ° C. or higher, the amount of sparks emitted was smaller than in Experimental Example 1, and it was confirmed that the occurrence of sparks could be suppressed.

[2] Experiment 2
In Experiment 2, an experiment was conducted as to whether the release of pulverized particles can be suppressed by self-heating of the cathode 4.

1. Experimental Examples 5-9
Specifically, a DLC film was formed using arc type film forming apparatuses having different diameters of the cathode 4 (Experimental Examples 5 to 9). Specifically, as shown in Table 2, five types of film formation were performed by varying the diameter of the cathode 4 in each of Experimental Examples 5 to 9.

Cathode: Sintered carbon with a length of 30 mm Base material: Base material for testing (made of high-speed tool steel)
Degree of vacuum: 1 × 10 ⁻³ Pa
Bias voltage: -50V
Arc voltage: -20V
Arc current: 50A
Deposition time: 5 min

2. Evaluation Using the same method as in Experiment 1, the cathode temperature and the surface roughness of the DLC film after film formation were measured, and the amount of sparks emitted was observed. The results are shown in Table 2.

  From Table 2, it can be seen that in Experimental Examples 5 to 7 where the cathode diameter is 20 mm or less, the cathode during film formation is heated to 500 ° C. or more, and as the cathode diameter decreases, film formation occurs. It can be seen that the temperature of the inside cathode is high.

  In Experimental Examples 5 to 7, the surface roughness of the formed DLC film is smaller than in Experimental Examples 8 and 9, and the surface of the formed DLC film has a smaller cathode diameter. It can be seen that the roughness is reduced. It can also be seen that the amount of sparks released is also reduced. From this, it was confirmed that by using a cathode having a diameter of 20 mm or less, the temperature of the cathode can be increased to 500 ° C. or more, and the release of pulverized particles due to cracks can be appropriately suppressed.

  While the present invention has been described based on the embodiments, the present invention is not limited to the above embodiments. Various modifications can be made to the above-described embodiments within the same and equivalent scope as the present invention.

DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Base material holding means 3 Cathode holding means 4 Cathode 5 Shutter 6, 7 Power supply 8 Trigger electrode 9 Resistance 10 Arc type film-forming apparatus 11 Exhaust port 12 Coil 20 Base material 31 Arc spot 41 Arc spot immediate part 42 Arc spot Around the nearest part 43 Grinding particles 44 Sublimated carbon D Cathode diameter M Magnetic field line T Cathode tip θ Angle between the axial direction of the cathode and the magnetic field line

Claims (19)

By performing arc discharge using a cathode material mainly composed of carbon, the carbon is sublimated from the arc spot formed on the cathode surface, and a carbon film mainly composed of carbon is formed on the substrate surface. Arc type film forming apparatus
Cathode holding means for holding the cathode;
Substrate holding means for holding the substrate;
A vacuum chamber containing the cathode holding means and the substrate holding means,
An arc type film forming apparatus comprising means for setting a temperature of at least a region of the cathode near the arc spot to 500 to 3000 ° C. during film formation.   2. The arc type film forming apparatus according to claim 1, further comprising means for setting a temperature in a region in the vicinity of the arc spot of the cathode at least 1000 to 3000 [deg.] C. during film formation.   The arc-type film formation according to claim 1 or 2, further comprising heating means for heating at least a region of the cathode in the vicinity of the arc spot to bring the temperature of the cathode to 500 to 3000 ° C. apparatus.   The arc-type film forming apparatus according to claim 3, wherein the heating means is a heater for heating the cathode from the outside.   The arc-type film forming apparatus according to claim 3, wherein the heating unit is an induction heating apparatus that induction-heats the cathode.   4. The arc type film forming apparatus according to claim 3, wherein the heating means is an electron beam heating apparatus that irradiates the cathode with an electron beam to heat the cathode.   The arc-type film forming apparatus according to claim 3, wherein the heating means is a laser heating apparatus that heats the cathode by irradiating the cathode with laser light.   The arc type composition according to claim 1 or 2, wherein a temperature of at least a region in the vicinity of the arc spot of the cathode is 500 to 3000 ° C by self-heating of the cathode. Membrane device.   The arc-type film forming apparatus according to claim 8, wherein the self-heating of the cathode is performed by heat generated in the arc spot.   9. The arc type film forming apparatus according to claim 8, wherein the self-heating of the cathode is performed by resistance heating generated by an arc current.   The arc type film forming apparatus according to any one of claims 8 to 10, wherein the cathode is a columnar cathode having a diameter of 20 mm or less.   The arc type film-forming apparatus according to any one of claims 8 to 10, wherein the cathode is a porous cathode.   A cooling means for cooling the cathode, and a cooling control means for controlling the cooling means so that a temperature of at least a region in the vicinity of the arc spot of the cathode is 500 to 3000 ° C. The arc type film-forming apparatus of any one of Claims 8 thru | or 10.   By combining the heat generated by the heating means for heating the cathode and the heat generated by the self-heating of the cathode, the temperature of at least the area near the arc spot of the cathode is set to 500 to 3000 ° C. 3. An arc type film forming apparatus according to claim 1, wherein the arc type film forming apparatus is provided. The heating means for heating the cathode is any one of a heater, induction heating, electron beam heating, laser heating,
The arc-type film forming apparatus according to claim 14, wherein the self-heating of the cathode is performed by heat generated at the arc spot and / or resistance heating of the cathode. The cathode is a cylindrical cathode;
16. The magnetic field generating means for generating a magnetic field so that an angle formed between an axial direction of the columnar cathode and a line of magnetic force is an acute angle on the tip side of the cathode is provided. The arc-type film-forming apparatus of any one of Claims.   The arc-type film forming apparatus according to claim 16, further comprising a delivery mechanism that delivers the columnar cathode toward the substrate. An arc type in which a carbon film mainly composed of carbon is formed on the surface of a base material by evaporating the carbon from an arc spot formed on the surface of the cathode by performing arc discharge on the cathode mainly composed of carbon. A film forming method comprising:
A film forming method comprising forming the carbon film while maintaining a temperature of at least 500 to 3000 ° C. in a region near the arc spot of the cathode. Using the arc-type film forming apparatus according to any one of claims 1 to 17,
A film forming method comprising forming the carbon film while maintaining a temperature of at least 500 to 3000 ° C. in a region near the arc spot of the cathode.

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