JP4878020B2 - Vacuum arc evaporation source - Google Patents

Description

  The present invention relates to a vacuum arc evaporation source used for wear-resistant coatings on cutting tools, machine parts and the like.

Conventionally, various methods have been proposed for reducing droplets (molten particles), which is a fatal drawback of the vacuum arc deposition method.
For example, Japanese Patent Publication No. 5-48298 (Patent Document 1) states that “a magnetic field having a magnetic field component parallel to the surface of the cathode (evaporated material) causes the arc to follow an endless path, or further generates the magnetic field. A method and apparatus characterized by moving the magnetic means relative to the cathode. ”, Reducing dissolved particles of evaporating material; The automatic re-ignition accompanying the arc extinguishing is considered unnecessary.

Japanese Patent Laid-Open No. 11-36063 (Patent Document 2) states that “a magnetic field of 700 Oe or more is formed on the evaporation surface of the arc evaporation source, and the magnetic field advances or diverges in front of the evaporation surface, An arc evaporation source in which the angle formed by the magnetic field lines is 0 to 30 degrees ”, which provides an arc evaporation source with reduced droplets and a long cathode life.
Further, JP-A-1-234562 (Patent Document 3) states that “a magnet generator is installed inside a hollow rotating body provided with a cathode evaporation material on the outer surface, and the evaporation material / magnet generator is rotated or moved. An apparatus that generates a discharge ", which was intended to accurately control the arc path and not create groove-like erosion on the cathode.
JP 2001-262218 A JP 11-343514 A Japanese Patent No. 3282865

According to Patent Document 1 described above, that is, according to a method of moving an arc in an endless path on the evaporation surface by applying a magnetic field parallel to the evaporation surface by a magnetic field generation source that generates a magnetic force of a level that is normally available. If the arc current is a relatively small value of 100 A or less, the trajectory is stable, but if the arc current is increased, the ratio of going off the trajectory increases, and if it exceeds 200 A, it is difficult to stably secure the trajectory. I grasped it experimentally.
Also, in order to secure a trajectory for a discharge current exceeding 200 A, the magnetic force must be increased, but then the discharge voltage rises due to the increase in the arc spot speed, and discharge is normally possible at a voltage of around 20V. It has been confirmed that a voltage exceeding 40V is required, and a voltage close to 100V is required by increasing the magnetic force and current, and a very special and expensive arc power source is required.

Further, if the magnetic means is not moved, the evaporated substance is consumed so as to be deeply swept along the endless path, and the movement of the magnetic means is essentially essential.
In the actual apparatus using the technique of Patent Document 2 described above, when the discharge current was operated at about 150 A, the arc spot was unevenly distributed on the evaporation surface and was locally consumed at the outer peripheral portion of the evaporation surface. .
Furthermore, it was found that cracks occurred on the entire evaporation surface. Further, in order to generate a magnetic field of 700 Oe on the evaporation surface by normal means, the diameter of the evaporation surface must be suppressed to 50 mm to 60 mm, and the current load (thermal load) for a small evaporation area is large. In actual discharge by this technique, a certain amount of gas such as nitrogen or argon has to be introduced, and there are significant process restrictions.

  In addition, as the evaporation material is consumed, the relationship between the magnetic field lines and the evaporation surface changes greatly, and because the consumption is fast due to the small evaporation area as described above, it is difficult to actually maintain the desired magnetic field form for a long time. is there. According to the embodiment, when the evaporation surface is retracted from the center of the coil as it is consumed, the magnetic field on the evaporation surface changes from the divergent shape to the convergent shape, and this prior art (Patent Document 2) does not hold. Furthermore, the arc spot pops out due to the consumption of the outer peripheral portion of the evaporation surface, which may cause abnormal discharge.

  According to the above-mentioned Patent Document 3, in reality, there are very large restrictions on stable discharge as described just by placing a magnet inside the hollow evaporation material. For example, the arc spot can be moved along the path as shown in the figure, or can be captured and controlled by the magnetic field lines as shown only when the discharge current is 100 A or less and the chamber pressure is 1 Pa or less. It is actually confirmed that the current and pressure conditions are completely uncontrollable. This is illustrated for the arc spot due to the general phenomenon in vacuum arc discharge where multiple arc spots are generated by increasing the arc current or the movement of the arc spot becomes wide when the pressure is increased. In addition to the above, the magnetic field lines that are actually generated will come into play, and this will inevitably occur.

  In the vacuum arc vapor deposition method, in order to obtain a film having a good roughness even during film formation at a production level, it is possible to stably confine and control the arc in a predetermined area on the evaporation surface by performing a large current discharge, Furthermore, it aims at providing the vacuum arc evaporation source which can control generation | occurrence | production of a droplet.

In order to achieve the above object, the present invention takes the following technical means.
That is, a vacuum arc evaporation source for discharging by forming a magnetic field in a region including the evaporation surface of the columnar evaporated substance, substantially elliptical discharge conductive region extending in the axial direction of the columnar evaporation material in the evaporation surface of the columnar evaporated substance In order to confine the arc spot, a magnetic field generating source for setting the angle of the magnetic lines of force and an arc power source for setting an arc current value of 200 A or more are provided.

Another vacuum arc evaporation source of the present invention is a vacuum arc evaporation source that discharges by forming a magnetic field in a region including the evaporation surface of the columnar evaporation substance, and in the circumferential direction of the columnar evaporation substance on the evaporation surface of the columnar evaporation substance. to confine the arc spot to the discharge collector region of quasi-strip extending, it is characterized in that it comprises a magnetic source for setting the angle of the magnetic field lines, and arc power supply for setting the 200A or more arc current value .
Furthermore, in a vacuum arc evaporation source, it is recommended that two permanent magnets be arranged such that the same magnetic poles face each other to repel magnetic lines of force.

  Further, it is recommended that the magnets arranged opposite to each other have different magnetic forces, and it is recommended that the magnets arranged opposite to each other be opposed to different poles. In addition, it is recommended that the strength of the magnetic field on the evaporation surface be 5 millitesla or more.

Furthermore, the anode part of the arc discharge can be moved parallel to the axis of the columnar evaporating substance, and a plurality of power feeding parts are provided for the columnar evaporating substance, and this feeding part is switched or the current value of each feeding part is changed. It can also be made. The magnetic field generation source may have a columnar shape, and may be arranged so that the magnetic pole of the magnetic field generation source faces a plane including the axis of the columnar evaporated substance.

  As described above in detail, according to the present invention, in order to obtain a coating film with good roughness even during film formation at a production level, large current discharge is performed to stably confine the arc in a predetermined area on the evaporation surface. And the generation of droplets can be controlled.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an embodiment according to claim 1, FIG. 1 (1) is a cross section of an evaporating substance and a magnetic field, FIG. 1 (2) shows the direction (angle) of a magnetic force line with respect to the normal line on the evaporation surface, 1 (3) is a perspective view showing a columnar evaporating substance and a magnetic field generation source, and FIG. 1 (4) is an arrow A in FIG. 1 (3), and is a substantially oval shape extending in the axial direction of the columnar evaporating substance. The discharge part of a shape is shown.
In FIG. 1, a magnetic field generation source 2 exemplified by a permanent magnet having an N pole and an S pole is arranged in a hollow portion (inside) of a columnar evaporation substance 1 exemplified by a cylindrical shape. The angle of the magnetic field lines and the arc current value are set on the evaporation surface 1A of the columnar evaporating substance 1 so as to confine the arc spot in a substantially oval discharge region (discharge part) 1B extending in the axial direction of the columnar evaporating substance 1. ing.

  That is, in a vacuum arc evaporation source in which the evaporating substance 1 is columnar, a magnetic field having a certain intensity or more in a region including the evaporating surface 1A of the evaporating substance 1 is formed, and the evaporation surface 1A on the evaporation surface 1A is The angle on the acute angle side (hereinafter referred to as α) formed by the normal line Q and the magnetic force line X is distributed in φ ≦ α ≦ θ (φ ≦ 20 °, θ ≧ 30 °), and the region where α = φ is α = θ The arc spot is confined in a region (substantially elliptical discharge portion 1B) inside α = θ centered around α = φ and surrounded by a region of It is designed to discharge.

Here, the angle φ is the minimum angle with respect to the normal, and the angle θ is also the maximum angle.
The principle of operation of the embodiment shown in FIG. 1 will be described. This principle is not definitive, but is thought to be as follows. In general, in the region of α = θ, the action of magnetic fields (Lorentz force) on the electrons and ion currents that form arc discharge is strong, so the movement of the arc spot is strongly constrained, the randomness is lost and the moving speed increases. The discharge voltage rises. The rise in discharge voltage becomes a factor that hinders discharge in that region. On the other hand, in the region of α = φ, the arc spot restraint force due to the Lorentz force is weak, but the discharge voltage is at a level almost unchanged from the normal voltage. Here, if the arc current is small, the acting force by the Lorentz force is superior to the discharge stopping force due to the increase of the discharge voltage, and the arc spot is constrained to a region near α = θ (in the case of θ = 90 ° in the prior art 1) ).

  However, when the arc current exceeds a certain value, the discharge blocking force due to the increase of the arc voltage is superior to the restraining force due to the Lorentz force, and the discharge voltage is lower than the region near α = θ, near α = φ. (See FIG. 8 showing a photograph of the discharge site observed from the side at φ = 0 °, magnetic force = 20 mT, discharge current = 600 A, nitrogen pressure = 2 Pa). As a result, the arc spot moves around at random around α = φ inside the region surrounded by α = θ. Therefore, the arc spot can be reliably confined inside α = θ, and the discharge region can be set at an appropriate position on the evaporation surface. In particular, by providing a portion where α = θ at the outer peripheral portion of the evaporation surface, the effective evaporation surface is effectively consumed while preventing abnormal discharge due to consumption of the outer periphery of the evaporation surface, which is a problem in the prior art 2. (Refer to FIG. 9 showing a photograph of an example of a substantially elliptical discharge region with a white line portion: α = 90 ° and a black line portion: α = 0 °).

Further, since the arc spot moves around in a plane inside α = θ, only the part of the endless circular trajectory as in the case of the static magnetic field of the prior art 1 digs deeply into a linear shape without moving the magnetic field generation source. Can be avoided.
Further, in the discharge region, the direction of the arc current in the vicinity of the evaporation surface is close to the direction of the magnetic field lines, and the electrons forming the discharge are wound around the magnetic field lines at the site with a small radius, thereby increasing the discharge current density. In order to exceed the current density that an individual can have, the arc spot is divided into a larger number than the normal number (for example, about 200 at 200 A on average). Therefore, the current value per arc spot is lowered, and the probability of occurrence of droplets generated at the arc spot and the diameter of the droplets can be greatly reduced.

Furthermore, the arc discharge plasma is activated along the magnetic field lines extending from the region having α = φ as the center, and the ionization of the evaporated evaporation substance is promoted, so that a dense film can be formed on the processed material. When a thick film of chromium nitride is formed by this technique, a film having a good roughness is obtained even if the film thickness is increased compared to a conventional standard film.
That is, FIG. 10 is a micrograph of the surface of the CrN film formed according to the present invention, where film thickness = 76 μm, Ra (average roughness) = 0.12 μm, and Rmax (maximum roughness) = 2.10 μm. On the other hand, FIG. 11 is a micrograph of a conventional standard CrN film surface, where film thickness = 30 μm, Ra = 0.75 μm, and Rmax = 8.2 μm.

The experimental conditions in FIG. 10 are a magnetic field strength of 30 mT, an arc current of 800 A, and a voltage of 25 v, and FIG. 11 is a magnetic field strength of 0 mT, an arc current of 800 A, and a voltage of 20 v. However, the target shape is a cylindrical shape of φ90 mm × L900 mm in both FIGS.
Further, in the present invention, it is not necessary to introduce gas to the arc discharge, and discharge can be performed in a pressure range completely including the pressure range normally required for a film forming process, for example, in the range of no gas introduction to a nitrogen pressure of 6 Pa or more. I have confirmed that there is. This is probably because a very high-density arc plasma is formed in front of the discharge region, and the arc plasma itself regulates the discharge form and is not affected by other discharge environments such as gas introduction.

Furthermore, in the present invention, even if the evaporated substance is consumed, the magnetic field form of this means can be maintained, so that the above effect can always be enjoyed.
In the vacuum arc evaporation source shown in FIG. 1, the strength of the magnetic field in the direction of the magnetic field on the evaporation surface is 5 mT (millitesla) or more. By setting the strength of such a magnetic field, the discharge voltage when the arc spot moves in the vicinity of α = θ is surely 40 V or more. Therefore, the arc spot is in a low discharge voltage region centering on α = φ. It is possible to move reliably and to restrain the arc spot stably by a desired evaporation surface area. In particular, when increasing the discharge current, it is desirable to increase the strength of the magnetic field. For example, 10 mT or more is desirable for 400A, and 20 mT or more is desirable for 800A.

FIG. 2 shows a vacuum arc vapor deposition apparatus using the evaporation source shown in FIG. 1. In FIG. 2, a work 3 is provided on a turntable 4, and the vacuum chamber 5 has a vertical axis around it. In this example, the chamber 5 is used as an anode.
In the vacuum arc evaporation source shown in FIG. 2, the arc current value is 200 A or more. With this configuration, α = θ is set by the repulsive force between spots due to the generation of a plurality of arc spots. Since the arc spot cannot stably exist in the center area, the arc spot surely moves to the area centering on α = φ and is stably restrained by the desired evaporation surface area.

Furthermore, in the above-described vacuum arc evaporation source, θ ≧ 60 ° is set, and with this configuration, the discharge voltage exceeds 40 V when there is an arc spot near α = θ. It is possible to reliably shift to a low discharge voltage region centered on α = φ, and to restrain the arc spot stably by a desired evaporation surface region.
FIG. 3 shows an example in which the magnetic field is moved in the above-described vacuum arc evaporation source. The magnetic field including the part of α = φ is parallel to the axis of the evaporating substance in FIG. ), The magnetic field generation source is configured to move so as to rotate and move about the axis.

FIG. 4 shows an example in which the anode part of arc discharge is moved in parallel with the axis of the evaporated substance in the vacuum arc evaporation source described above, and FIG. 4 (1) shows an example in which the anode itself is moved up and down. FIG. 4 (2) shows an example in which the part serving as the anode is moved up and down.
FIG. 5 is a plan view and a front view showing an example in which the magnetic field generating source and the anode are rotated synchronously. In the above-described vacuum arc evaporation source, the magnetic field and anode including the portion of α = φ are set to the axis of the evaporated substance. It is configured to rotate synchronously as the center.
FIG. 6 shows that a plurality (two in the figure) of power supply units (arc power supplies 1 and 2) are provided for the columnar evaporative substance. The power supply units are switched or the current value of each power supply unit is changed to a large or small value. FIG. 6 shows discharge current values I ₁ and I ₂ with I ₁ > I ₂ or I ₁ <I ₂ .

That is, if I ₁ <I _{2, the} arc spot moves downward, and if I ₁ > I _2, it moves upward.
FIG. 7 shows a modified example of the present invention, in which a magnetic field coil is adopted as a magnetic field generation source, and the columnar evaporation substance is provided in the constriction portion of the vacuum chamber with its axis oriented laterally, and this constriction portion is a magnetic field generation source. An electromagnetic coil is disposed, and other configurations are common to the above-described examples.
According to the embodiment shown in FIGS. 3 to 6, the evaporation surface can be more evenly consumed and the evaporation substance can be used effectively. In addition, the present invention is characterized by operation with a large current, the temperature rise of the evaporating material due to the arc current can be made uniform throughout the evaporating material, and cracks are generated by reducing the thermal stress of the evaporating material due to the uneven distribution of heat generation parts. To prevent. In particular, this is effective when the area where α = φ is very wide in a large area evaporation source.

In addition to the arc spot being distributed around α = φ, it can be used that the distribution tends to be closer to the anode or closer to the power supply unit for the evaporated substance.
FIG. 12 shows another example of a columnar evaporating substance, and FIG. 12 shows a prismatic evaporating substance having a circular hollow inside. Thus, the evaporating substance has a cylindrical shape, a rectangular tube shape, or a solid cylinder. (Refer FIG. 7), solid prisms, flat columnar shapes, etc. are arbitrary.
13 to 16 show an embodiment of the present invention according to claims 2 to 5.
That is, in FIG. 13, the angle of the magnetic field lines and the arc current value are set so that the arc spot is confined in the substantially strip-shaped (annular) discharge region extending in the circumferential direction of the columnar evaporated substance on the evaporation surface of the columnar evaporated substance. It has a magnetic field source.

More specifically, referring to FIG. 13, when the magnetic field generating source 2 shown as a pair of permanent magnets 2 having a donut shape and whose end face is a magnetic pole is placed so that the same magnetic poles face each other, A portion where α = 0 ° is formed at the intermediate position of the magnet, and α = 90 ° is formed on both sides (up and down in FIG. 13) in the circumferential direction of the evaporation source. In this case, it is possible to discharge at a band-like portion sandwiched between α = 0 ° and α = 90 °.
FIG. 14 shows an example in which the magnets arranged opposite to each other have different magnetic forces (in FIG. 14, the case where the upper part is strengthened but the case where the lower part is strengthened is also included).

In the embodiment shown in FIG. 14, as shown in FIG. 15, the main magnetic field direction (the sum of the components in the direction of the target surface of the magnetic field lines at the discharge site) is directed downward to generate an arc spot (specifically, generated from the arc spot). Since the Lorentz force acting on the metal ion flow) is determined in one counterclockwise direction when viewed from above, the arc spot makes a revolving motion in that direction at a substantially constant speed. However, since the Lorentz force acting here is weak, there is almost no increase in the discharge voltage as described above, and it does not become a factor that inhibits discharge.
Also, if the magnetic forces of the upper and lower magnets are equal, the main magnetic field direction is equal to the direction of the metal ion flow, and therefore the Lorentz force does not work, so the arc spot moves randomly in the left-right direction of the discharge site, but the anode (anode) Due to the asymmetry of the arrangement and the chamber structure, discharge may occur in a certain direction of the evaporated material.

By making the upper and lower magnets have different magnetic forces, the arc spot can be reliably discharged over the entire circumference of the evaporated substance.
FIG. 16 shows an embodiment in which magnets arranged opposite to each other are opposed to different poles. According to this, when an appropriate magnet size / arrangement is selected, the result is as shown in FIG. 16, and α = 90 ° appears at three points. It was. Although two discharge sites appear as expected, when the magnetic force at the center α = 90 ° is weak, the arc spot moves back and forth between the upper and lower discharge sites.
In addition, when the upper and lower magnets have different magnetic forces in this magnetic field form (the form shown in FIG. 16), if the vertical magnetic force difference is large, the discharge portion on the weak side disappears.

In FIG. 13 and FIG. 14, the discharge portion of the columnar evaporative substance has a band shape, so that it is not necessary to rotate the columnar evaporant and the magnetic field generation source synchronously as illustrated in FIG. 5. However, the anode can be moved as illustrated in FIG.
13 to 14, the above-described minimum angle φ and maximum angle θ are the same as described above, and the arc current value (200 A or more) and the magnetic field strength are 5 millitesla, 400 A is 10 mT or more, 800 A The same applies to 20 mT and the like.
Furthermore, in the present invention, the above-described embodiments can be arbitrarily combined.

1 shows an embodiment of the present invention, (1) shows a cross section of the evaporated substance and magnetic field, (2) shows the angle of the magnetic field lines with respect to the normal, (3) is a perspective view of the evaporation source, (4) FIG. 2 shows a vacuum arc vapor deposition apparatus using the evaporation source of FIG. An example in which a magnetic field is moved is shown, (1) is a plan view and a front view of axial translation (including relative movement), and (2) is rotational movement (including relative rotation) around the axis. An example of moving the anode is shown, wherein (1) is the vertical movement (including horizontal movement) of the anode itself, and (2) is the vertical movement (including horizontal movement) of the part serving as the anode. It is the top view and front view which rotate a magnetic field generation source and an anode synchronously. It is explanatory drawing which provided the several electric power feeding part in the evaporative substance. It is a block diagram which shows the other example of this invention. It is the photograph which observed the discharge part from the side. It is a photograph of the discharge area. It is a microscope picture of the CrN membrane | film | coat surface by this invention. It is a microscope picture of the conventional standard CrN film surface. It is sectional drawing of a prismatic evaporating substance. An embodiment according to claim 2 is shown, wherein (1) is a perspective view, (2) is a plan view, and (3) is a front view. An example in which the upper and lower magnets have different magnetic forces is shown, (1) is a perspective view, (2) is a plan view, and (3) is a front view. FIG. 15 is an operation explanatory diagram of FIG. 14. It is a half missing front view at the time of making an up-and-down magnet opposing a different pole.

Explanation of symbols

1 Columnar evaporation material 2 Magnetic field source

Claims (9)

A vacuum arc evaporation source that discharges by forming a magnetic field in an area including an evaporation surface of a columnar evaporation substance,
To confine the arc spot in a substantially elliptical discharge conductive region extending in the axial direction of the columnar evaporation material in the evaporation surface of the columnar evaporated substance set, and the magnetic field generation source for setting the angle of the magnetic field lines, the 200A or arc current value A vacuum arc evaporation source, comprising: an arc power source. A vacuum arc evaporation source that discharges by forming a magnetic field in an area including an evaporation surface of a columnar evaporation substance,
Arc set to confine the arc spot in a substantially belt-shaped discharge conductive region extending in the circumferential direction of the columnar evaporation material in the evaporation surface of the columnar evaporated substance, a magnetic source for setting the angle of the magnetic field lines, the 200A or arc current value A vacuum arc evaporation source comprising a power source.   3. The vacuum arc evaporation source according to claim 2, wherein the pair of permanent magnets is a magnetic field generating source for repelling the lines of magnetic force by arranging the same magnetic poles to face each other.   The vacuum arc evaporation source according to claim 3, wherein the magnets arranged opposite to each other have different magnetic forces.   The vacuum arc evaporation source according to claim 2, wherein the magnets arranged to face each other are opposed to different poles. 2. The vacuum arc according to claim 1, wherein the magnetic field generation source has a columnar shape, and is arranged so that a magnetic pole of the magnetic field generation source faces a plane including an axis of the columnar evaporated substance. Evaporation source.   The vacuum arc evaporation source according to any one of claims 1 to 6, wherein the strength of the magnetic field on the evaporation surface is 5 millitesla or more.   The vacuum arc evaporation source according to any one of claims 1 to 7, wherein the anode part of the arc discharge is moved in parallel with the axis of the columnar evaporation substance.   The vacuum arc evaporation source according to any one of claims 1 to 8, wherein a plurality of power supply units are provided for the columnar evaporating substance, and the power supply units are switched or the current value of each power supply unit is changed.

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