JP2001158958A - Arc discharge ion plating equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for avoiding local heating and reducing droplets by suppressing abrupt current multiplication of arc current due to the growth of arc discharge and also forcing arc spots on the surface of a cathode to move, independently of an equipment running condition and an incidental condition such as the degree of target consumption while obviating the necessity of a large-scale magnetic field generating circuit in the periphery of the cathode. SOLUTION: This equipment is used for evaporating a cathode 3 material by vacuum arc discharge and ionizing the resultant evaporated atoms to form a film by vapor deposition on a material to be plated. The equipment has a magnetic field generating means 9 for generating a magnetic field penetrating an evaporation surface 3a of the cathode, and an anode electrode 4 is disposed in such a way that it intersects the lines of magnetic flux. The anode electrode 4 is provided in a state where it is divided into a plurality of pieces in a peripheral direction centering around the cathode 3 as a central axis. The resultant divided anode electrodes 4 are connected respectively at ground potential via circuit elements 16 with inductance components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tool, a mold, a bearing ball, a bearing, a spindle cylinder, a protective film for a magnetic head, and the like, which are required to have wear resistance, corrosion resistance, and self-lubrication. The present invention relates to a thin film forming apparatus (generally called an arc-type ion plating apparatus) for applying a cathode material and forming a thin film made of the cathode material or a nitride, an oxide, or the like of the cathode material.

[0002]

2. Description of the Related Art In an arc ion plating apparatus, the cathode material evaporated from a cathode by arc discharge contains a considerable proportion of cathode material ions ionized by arc plasma generated near the cathode.
The cathode material ions are attracted to the object by the bias electric field to form a thin film on the surface. The thin film has advantages such as good adhesion and a high deposition rate, and is widely used as a means for coating a metal film or a ceramic film on a surface of a tool or a mold.

[0003] The reason why the film has good adhesion is that cathode material ions contained in the cathode material are attracted to the object to be processed by an electric field due to a negative bias voltage or the like and collide therewith, so that an effect of ion mixing can be expected. is there. The high deposition rate is due to the action of instantaneously heating, melting, and evaporating the cathode surface using the large current of arc discharge. However, this advantage has the following side effects: That is, the cathode material generated from the cathode contains coarse particles called droplets or macroparticles, and when these particles enter and adhere to the thin film formed on the surface of the workpiece, the smoothness of the thin film is impaired and the tool is damaged. Etc., shorten the service life, or impair the appearance of the thin film.

[0004] The cause of the droplet is caused by excessive growth of the liquid pool due to local heating immediately below the arc spot on the cathode surface. It has been observed that the number of droplets increases rapidly due to an increase in arc current, concentration and localization of arc spots. The arc discharge phenomenon is essentially a positive feedback action in which the cathode surface heated by the discharge electrons turns the evaporated material into arc plasma, which becomes the discharge medium, lowers the equivalent resistance of the discharge space, and further increases the discharge current. Arc discharge,
Once generated, the arc current rapidly increases, and the arc discharge grows until it is suppressed by the self-pinch of the plasma or the voltage drop of the power supply system. Therefore, local heating and expansion of the liquid pool due to local heating are inevitable. (Prior Art A) Japanese Patent Application Laid-Open No. 10-46324 discloses a method for suppressing an instantaneous increase in arc current by inserting an inductor coil at an output terminal of a power supply circuit connected to a cathode. (Prior Art B) As another method, a relatively strong magnetic field (700 Oe or more) is generated near the cathode surface with a divergence angle of 0 to 30 ° with respect to the normal line, and the arc ion current and A method of moving the arc spot position on the cathode surface so as to orbit the evaporation surface slightly outward without concentrating on the center of the cathode by the electromagnetic interaction of the magnetic field is disclosed in Japanese Patent Application Laid-Open No. HEI 9-163568.
It is proposed in Japanese Patent Publication No. 11-36063. It is reported that, depending on the conditions, the arc spot moves at a considerably high speed, so that local heating is avoided and the expansion of the liquid pool, that is, the generation of droplets is suppressed.

[0005] Furthermore, this method has the effect of extending the life of the cathode because the entire evaporation surface of the cathode is almost uniformly consumed, or the outer periphery thereof is slightly consumed and the cathode surface is used evenly. (Prior art C) A method of reheating and disassembling another droplet is allowed, even if the generation of the droplet is allowed.
No. 1993. By forming a strong magnetic field near 1000 Oe near the front of the cathode and at the center of the cathode, the arc plasma generated near the surface of the cathode is confined, and the droplets generated in this plasma are reheated, re-melted, and re-heated. This is a method of reducing the diameter and the number of droplets by promoting the decomposition and reuse of the droplets by evaporation.

[0006]

SUMMARY OF THE INVENTION Arc voltage, degree of vacuum,
The rapid multiplication of the arc current due to the growth of the arc discharge does not depend on the equipment operating conditions such as the type of introduced gas and pressure, and the incidental conditions such as the degree of target depletion, and does not require a large magnetic field generating circuit around the cathode. Provided is a method for suppressing and forcibly moving the arc spot on the cathode surface to avoid local heating and thus reduce droplets. First, in the conventional method A, when the arc spot position is localized due to the consumption deformation of the cathode surface and the peripheral boundary structure, the discharge is frequently stopped with the multiplication of the arc current,
On average, the input power is low, and there is a fear that the productivity of film formation is sacrificed. Naturally, uniform consumption of the cathode surface cannot be expected.

Next, in the conventional method B, it is true that the arc spot orbits the cathode surface at a constant speed under a certain appropriate operating condition. However, the arc spot, the degree of vacuum, the type of introduced gas and the pressure, etc. The proposal is sensitive to the operating conditions and incidental conditions such as the degree of target consumption, and is not a proposal that can be used for practical operation. In fact, in the experiments of the present inventor, in accordance with the increase of the arc voltage applied to the cathode, a slight change was made in the order of random discharge → clockwise orbital movement → counterclockwise orbital movement. Sometimes it wasn't.

Further, it is not easy to equip a coil system or a permanent magnet system for producing a magnetic field of 700 Oe near a cathode holder which requires high voltage and large capacity water cooling.
Furthermore, there is an experimental result that did not lead to eradication of the droplet even when the condition that the arc spot circulates at the maximum speed ideally is found, and it is understood that this method is not a drastic solution. In the third conventional method C, it is important that a high-density arc plasma exists near the cathode. However, in an arc plasma that can be realized or obtained by an arc current and a magnetic flux density as operating conditions, droplets generated Is insufficient to reheat, re-melt and re-evaporate all of the.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to an apparatus for vaporizing and ionizing a cathode material by vacuum arc discharge and depositing a film on an object to be processed, wherein a magnetic field generating a magnetic field penetrating the evaporation surface of the cathode is provided. Means, and an anode electrode is provided so as to intersect the magnetic flux lines. The anode electrode is divided into a plurality in the circumferential direction with the cathode as a central axis, and each divided anode electrode has an inductance component. Are connected to the ground potential via circuit elements having

Since the orbit of the electron flow of the arc discharge is fixed by the magnetic flux lines, each part of the cathode surface (evaporation surface) and each of the divided anode electrodes where the electron flow is absorbed are separated by one.
It will be mapped to one-to-one. The arc discharge current generated in a part of the cathode is absorbed by the anode electrode corresponding to the part, and passes through the connected inductor (coil) circuit.
Reach ground potential. If the arc current grows rapidly,
The back electromotive force induced in the inductor results in changing the potential of the anode electrode in a direction that suppresses the arc current.

In this case, since the other anode electrodes are kept at the ground potential, when viewed from the cathode, the potential difference is high and the discharge is easy, and the arc spot moves to the corresponding cathode site. Will do. The above is
It is a time series description of microscopic discharge phenomena,
Actually, in this arc ion plating apparatus, a stable arc discharge occurs even at a high voltage and a large current, and an arc spot moves randomly or at a high speed on the cathode surface, so that a time-average uniform discharge occurs. Surface will be realized.

Further, according to the above configuration, the magnetic field penetrating the cathode is weak (10 gauss or more and 100 gauss or less at most;
01T to 0.01T), so that the configuration of the magnetic field generating means can be simplified. The magnetic field is preferably a divergent magnetic field that diverges parallel or forward through the evaporation surface of the cathode. Further, if the anode electrode is divided in a direction inclined in the circumferential direction, the arc spot can be rotated in one direction, and it is desirable to reduce dependence on operating conditions (film forming conditions).

In the above-mentioned apparatus, when the arc current is operated under a small condition, if it is difficult to move the arc spot only by the back electromotive force of the inductor circuit, the anode electrode is divided into an even number, The circuit elements connected to the adjacent anode electrodes are coupled to each other in an inductively opposite phase, so that the movement of the arc spot can be facilitated. That is, the current flowing into one anode electrode generates a counter electromotive force generated in the inductance connected to it, and acts on the inductors of both adjacent anodes to generate an electromotive force of a polarity that promotes (pulls in) discharge, This is for producing the anode electrodes on both sides.

The movement characteristics of the arc spot can be adjusted by adding a series pure resistance and / or a parallel capacitance component to the circuit element connected to the anode electrode of the device, in addition to the inductance component. In the present invention, the current is stable as described above, while realizing a uniform arc discharge on the cathode surface, and adopting magnetic lines of force that proceed or diverge in parallel in front of the evaporation surface of the cathode,
The region where the cathode material ions are radiated along the lines of magnetic force is widened, so that the effect of widening the film formation region with high film thickness uniformity can be expected.

Further, the movement of the arc spot causes the entire evaporating surface of the cathode to be consumed almost uniformly, or the entire evaporating surface is consumed while placing a specific gravity slightly outward. Since the surfaces are used evenly, the life of the cathode can be extended. As for the device, the required magnetic field is much weaker than that of the conventional technology, and an inexpensive magnetic field generator is sufficient.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an arc ion plating apparatus 1 according to a first embodiment of the present invention. This apparatus 1 includes a cathode (cathode) 3 as an evaporation source and an anode (anode) 4 in a vacuum chamber 2 constituting a processing chamber.
And The cathode 3 is connected to the negative pole of the arc power supply whose positive pole is grounded. Further, the vacuum chamber 2 itself is also grounded.

The vacuum chamber 2 is connected to a vacuum pump 6 and an introduction gas tank (introduction gas supply means) 7. In the vacuum chamber 2, there is further provided a magnetic field generating means 9 for generating a magnetic field in a region including the evaporation surface (front surface) 3a of the cathode 3. More specifically, the magnetic field generating means 9 is for generating a magnetic field in a region penetrating the evaporation surface and extending from the evaporation surface 3a to the front thereof. Here, the magnetic field generating means 9 comprises a cylindrical (more specifically, cylindrical) magnetic coil 10 wound around the evaporation surface 3a.

The magnetic coil 10 is excited by a coil power supply (not shown) to form the above-described magnetic field. FIG. 1 schematically shows an example of magnetic lines of force created by the magnetic coil 10. The lines of magnetic force are substantially orthogonal to the evaporation surface and diverge forward (upward in FIG. 1). In front of the cathode 3, a processing object 12 is provided with a space therebetween, and a negative electrode of a bias power supply 13 having a positive electrode connected to the vacuum chamber 2 is connected to the processing object 12. It is kept at a negative potential.

The anode electrode 4 is arranged so as to surround an object to be processed and to intersect (absorb) the magnetic field lines with a normal line to the evaporation surface 3a at the center of the cathode 3 as an axis. The anode electrode 4 is divided into a plurality (8: even number) in the circumferential direction, and is formed in a cylindrical shape as a whole. Note that this cylindrical shape is a shape in which the diameter is enlarged at the front. Each of the anode electrodes 4, 4,... Is connected to a ground potential (vacuum chamber 2) via an individual inductor (coil) circuit element 16.

The coil 10 according to the present embodiment has the cathode evaporation surface 3
In front of a, a line of magnetic force diverging outward in the traveling direction is generated, and has a maximum value on the evaporation surface 3a of the cathode 3 and a minimum value on the surface of the anode 4. At most 10 Oe near the anode
If a magnetic field of (Oersted) (about 790 A / m) or more is formed, the electron flow of the arc discharge starting from the cathode moves toward the anode electrode 4 along a line of magnetic force while drawing a spiral orbit. This can be understood from the fact that the orbital radius of the electron is given by the following equation. r [m] = 3.4 × 10 ⁻⁶ √T [eV] / B [T] Even if the plasma temperature is assumed to be 100 eV, at most 10 eV
Even in Gauss (0.001T), the orbit is only on the order of 1cm,
The picture that the electron current flows entangled with the lines of magnetic force is a good approximation.

Now, the mechanism of arc current multiplication and arc spot delocalization will be described with reference to the above embodiment. Since the orbit of the electron flow of the arc discharge is fixed by the divergent magnetic flux lines, each part of the cathode surface 3a and one of the divided anode electrode bodies 4, 4,. 1 will be mapped. Cathode 3
Is absorbed by the anode electrode body 4 corresponding to the portion and reaches the ground potential via the connected inductor (coil) circuit 16.

When the arc current multiplies rapidly, the back electromotive force induced in the inductor 16 changes the potential of the anode electrode 4 in such a direction as to suppress the arc current. In this case, since the other anode electrodes 4 remain at the ground potential, when viewed from the cathode 3, the potential difference is high and the discharge is easy, and the arc spot moves to the corresponding cathode site. Will be. As described above, when the ring-shaped anode electrode 4 divided into a plurality in the circumferential direction is used, a potential difference is generated between a certain divided anode electrode 4 and another adjacent divided anode electrode 4 to move the arc spot. be able to.

Although the microscopic discharge phenomenon is described in time series in the above description, in practice, in the arc ion plating apparatus 1, a stable arc discharge can be performed up to a high voltage and a large current. As well as the cathode surface 3
In a, the arc spot moves randomly or at a high speed to realize a uniform discharge surface on a time average. In the present embodiment, the current is stable as described above, and a uniform arc discharge is realized on the cathode surface 3a.
Due to the effect of the lines of magnetic force that travel in parallel or diverge in front of the evaporation surface 3a, the region where the cathode material ions are radiated along the lines of magnetic force is widened, so that the film formation region with high film thickness uniformity is also widened. Can be expected.

Furthermore, the movement of the arc spot depends on the cathode 3
Or the entire evaporating surface 3a is consumed almost uniformly, or the entire evaporating surface 3a is consumed while placing a specific gravity slightly outside. In any case, the evaporating surface 3a of the cathode 3 is used evenly. The life of the cathode 3 can be extended. The movement characteristic of the arc spot can be adjusted by adding a series pure resistance and / or a parallel capacitance component to the circuit element 6 connected to the anode electrode 4 in addition to the inductance component.

FIG. 2 shows an arc ion plating apparatus 1 according to a second embodiment of the present invention. This second
The embodiment is the same as the first embodiment except for the shape of the anode electrode 4, and other configurations are the same. In the first embodiment, the dividing direction of the anode electrode 4 is a radiation direction centering on the cathode 3, but in the present embodiment, the dividing direction of the anode electrode 4 is
Are divided in a direction inclined from the radial direction to the circumferential direction. That is, if attention is paid to the imaginary line X that divides the anode electrode 4, the spiral line as a whole is formed. In other words, the anode electrode 4 has a rotationally asymmetric shape with the cathode as the central axis, specifically, a shape like a blade of a fan (propeller shape). As a result, the arc spot can be rotated in one direction, and an effect of reducing dependence on operating conditions (film forming conditions) can be expected.

That is, due to the characteristic that the arc spot moves outward from the center of the cathode, a phenomenon occurs in which the mapped anode electrode 4 moves from the outside to the inside. If the movement from the outside to the inside is regulated so as to accompany the movement in the circumferential direction, the movement direction of the arc spot can be rotated in a fixed direction. The reason why the dividing direction of the anode electrode 4 is inclined in the circumferential direction is to pay attention to this point. Specifically, for example, if the anode electrode 4 is shaped like a blade of a fan, the shape of the anode electrode 4 may be changed depending on the shape. As a result, it is forcibly moved in the circumferential direction when going in from
In the example, the arc spot orbits counterclockwise.

FIG. 3 shows an arc ion plating apparatus 1 according to a third embodiment of the present invention, and FIG. 4 shows an arc ion plating apparatus 1 according to a fourth embodiment of the present invention. These devices 1 are intended to enable operation even under conditions where the arc current is small. When it is difficult to move the arc spot only by the back electromotive force of the inductor circuit due to the small arc current, the anode electrode 4 is divided into an even number and connected to the anode electrodes 4 adjacent in the circumferential direction. The circuit elements 16 are coupled in opposite phases in an electromagnetic induction manner to facilitate movement of the arc spot.

FIG. 3 shows an example in which the inductors 16 are connected by a common ring-shaped magnetic core 18, and the coils 16A and 16B adjacent to each other are wound in opposite directions. FIG.
A secondary coil 19 is provided on each inductor / coil 16 (the winding of each coil is in the same direction), and the adjacent secondary coil 1 is provided.
9A and 19B are connected in opposite phases to form a closed circuit. In FIG. 4, the secondary coils 19 may be connected in the same phase by reversing the winding method of the adjacent inductor coils 16. 3 and 4, the current flowing into one anode electrode 4 generates a back electromotive force generated in the inductance 16 connected to the anode electrode 4 and acts on the inductor 16 of the anode electrode 4 on both sides. An electromotive force having a polarity that promotes (pulls in) discharge is generated in the adjacent anode electrodes 4.

FIG. 5 shows a fifth embodiment of the present invention. In this device 1, the permanent magnet 2 is used as the magnetic field generating means 9.
1, a cylindrical permanent magnet 21 having a magnetic pole in the axial direction is arranged coaxially around the cathode 3, and can generate lines of magnetic force similar to those of the first embodiment. Note that the description of the second to fifth embodiments is omitted in the same manner as the first embodiment.

[0030]

According to the present invention, arc voltage, degree of vacuum,
The rapid multiplication of the arc current due to the growth of the arc discharge does not depend on the equipment operating conditions such as the type of introduced gas and pressure, and the incidental conditions such as the degree of target depletion, and does not require a large magnetic field generating circuit around the cathode. While suppressing, the arc spot can be forcibly moved over the cathode surface to avoid local heating and thus reduce droplets.

[Brief description of the drawings]

FIG. 1 is a plan view and a sectional view of an arc ion plating apparatus according to a first embodiment of the present invention.

FIG. 2 is a plan view of an arc ion plating apparatus according to a second embodiment.

FIG. 3 is a plan view of an arc ion plating apparatus according to a third embodiment.

FIG. 4 is a plan view of an arc ion plating apparatus according to a fourth embodiment.

FIG. 5 is a sectional view of an arc ion plating apparatus according to a fifth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Arc ion plating apparatus 2 Vacuum chamber 3 Cathode 4 Anode electrode 5 Arc power supply 9 Magnetic field generating means 12 Workpiece 16 Inductor circuit element (coil)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshiyuki Hosokawa 1-5-5 Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture Inside Kobe Research Institute, Kobe Steel Ltd. (72) Inventor: Adult Adachi Shinhama, Araimachi, Takasago City, Hyogo Prefecture 2-3-1 No. 1 in Kobe Steel, Ltd. Takasago Works F-term (reference) 4K029 DD06

Claims (4)

[Claims] An apparatus for evaporating and ionizing a cathode material by vacuum arc discharge and depositing a film on an object to be processed (12), comprising: a magnetic field generating means for generating a magnetic field penetrating an evaporation surface (3a) of the cathode. 9), and an anode electrode (4) is provided so as to intersect the magnetic flux lines. The anode electrode (4) is divided into a plurality in the circumferential direction with the cathode (3) as a central axis, and is arranged side by side. An arc ion plating apparatus wherein each of the divided anode electrodes (4) is connected to a ground potential via a circuit element (16) having an inductance component. 2. The device according to claim 1, wherein the anode electrode is divided in a direction inclined in a circumferential direction.
An arc ion plating apparatus as described in the above. 3. The anode electrode (4) is divided into an even number, and the circuit elements (16) connected to the anode electrodes (4) adjacent in the circumferential direction have opposite phases in electromagnetic induction. 3. The arc ion plating apparatus according to claim 1, wherein the apparatus is coupled. 4. The circuit element (16) includes a series pure resistance and / or a parallel capacitance component in addition to an inductance component.
The arc ion plating device according to any one of the above.