JP4827235B2 - Arc type evaporation source and method for manufacturing film-formed body - Google Patents

Description

  The present invention relates to an arc evaporation source for forming a hard carbon coating for improving wear resistance, reducing friction loss, or adding color to the outer surface of a substrate such as a tool, a mold, a decorative article, and a machine part. And a method for manufacturing a film-formed body.

An arc evaporation source that forms a coating on the outer surface of the substrate to melt and evaporate the cathode material by arc discharge to improve wear resistance and durability, reduce friction loss, and protect the surface shape. Is used.
In an arc evaporation source, much of the evaporated cathode material is ionized by arc plasma formed in the space in front of the cathode by arc discharge. Then, by applying a predetermined voltage to the deposition target substrate using arc plasma, the ionized cathode material is attracted to the substrate to form a coating on the substrate surface.

  Since the arc ion plating method has a high film forming speed and excellent adhesion between the coating and the substrate, the film forming apparatus by this method has excellent productivity, and a metal film or its carbide on the surface of machine parts or cutting tools. It is widely used as a film forming apparatus for nitride and the like. The reason why the film formation rate of the arc ion plating method is high is that the cathode material is melted by arc discharge and a large amount of vapor of the cathode material can be generated. It is necessary to replace the cathode after the discharge time has elapsed.

  Japanese Patent Laid-Open No. 5-17866 (Patent Document 1) discloses a technique for using a cathode that is longer in the axial direction than the diameter and uniformly consuming the cathode by arc discharge. In this technique, carbon is used for the cathode and a cathode delivery mechanism is provided. When the formed film thickness is large and the discharge time is long, or when it is desired to increase the cathode replacement period, the initial cathode length is increased in anticipation of the cathode consumption. Further, in this technique, in order to prevent atmospheric leakage from a hole through which the cathode is inserted into the vacuum vessel, the cathode and the cathode delivery mechanism are all covered with a vacuum cover.

In addition, as an arc evaporation source having a cathode having a long axial length with respect to the diameter and having a magnetic coil, Japanese Patent Application Laid-Open No. 2001-58266 (Patent Document 2) and Japanese Patent Application Laid-Open No. 2001-181829 ( Patent Document 3) is disclosed.
FIG. 5 shows a cross-sectional structure of an arc evaporation source described in Patent Documents 2 and 3. In this figure, the magnetic coil 42 'disposed outside the cathode 22' forms a magnetic field necessary for maintaining arc discharge on the cathode evaporation surface. In the same document, it is described that by optimizing the current value of the magnetic coil, it is possible to form a magnetic field that spreads substantially perpendicularly or outwardly with respect to the cathode evaporation surface and stably maintain the arc discharge. Yes.
In the case of the technique described in Patent Document 3, it has been proposed to provide a tapered ring 64 ′ made of a conductive material and having the same potential as the cathode 22 ′ at the tip of the cathode cooling mechanism. In this way, it is said that the arc discharge occurrence frequency in the vicinity of the cathode is suppressed, and the characteristics of limiting the movement of the arc spot within the cathode evaporation surface are improved.
In the techniques described in Patent Documents 2 and 3, a cathode delivery mechanism is also provided, and the cathode is forwarded according to wear, and the state of the magnetic lines of force on the cathode evaporation surface and the distance between the base material and the cathode evaporation surface are almost the same. It is possible to keep it constant.

  On the other hand, JP 2005-126737 A (Patent Document 4) is disclosed as a technique in which a magnetic field forming mechanism (magnet or electromagnet) is provided in the cathode together with the cathode delivery mechanism. FIG. 6 shows a cross-sectional structure of an arc evaporation source in this technique. A through-hole 132 ′ is provided along the central axis of the cathode 122 ′, and a magnetic field necessary for maintaining arc discharge on the cathode evaporation surface is formed by the magnetic field forming mechanism 142 ′ inserted therein. Since the position of the magnetic field forming mechanism 142 ′ can be determined independently of the cathode, even if the cathode is consumed, the magnetic field configuration on the cathode evaporation surface and the movement of the arc spot can be kept stable. Can be consumed evenly.

There are other techniques for optimizing the magnetic field configuration (arc spot motion) of the cathode evaporation surface. For example, as a technique of arranging a magnet (electromagnet) having a magnetic pole in the cathode axis direction so as to surround the cathode evaporation surface or the front of the evaporation surface, and forming a magnetic field configuration extending substantially perpendicular to the cathode evaporation surface or in the outer peripheral direction, Japanese Patent Laying-Open No. 2003-71610 (Patent Document 5) is disclosed.
Japanese Patent Application Laid-Open No. 11-269634 (Patent Document 6) discloses a technique in which a ring-shaped permanent magnet having an S-pole on the inner peripheral surface side and an N-pole on the outer peripheral surface side is arranged coaxially on the outer rear side of the cathode. It is disclosed. This magnet forms magnetic lines of force having a component parallel to the cathode evaporation surface around the cathode, and suppresses the distribution of arc spots in the outer peripheral region of the cathode evaporation surface.

JP-A-5-17866 JP 2001-58266 A JP 2001-181829 A JP 2005-126737 A JP 2003-71610 A JP-A-11-269634

In order to improve the use efficiency by reducing the film formation cost by using the cathode for a long time without replacing it, it is necessary to use a cathode that is long in the axial direction. Even if a long cathode is used for a long time, the following problems are required in order to ensure reproducibility (film quality, film thickness distribution, etc.) during film formation.
(1) The cathode is consumed evenly. (2) The arc spot shift to a portion other than the evaporation surface of the cathode, for example, the side surface of the cathode, is suppressed. The adhesion of objects can also be suppressed.

In addition to the cathode usage efficiency, it is important to improve the usage efficiency of the apparatus in order to reduce the film formation cost. The arc evaporation source has a large evaporation amount from the cathode, and the evaporated cathode constituent material adheres to and accumulates on the arc evaporation source. If the deposits are peeled off and mixed into the coating, the coating quality deteriorates. Therefore, equipment maintenance such as blasting is required periodically. Therefore, the following problems are required in order to facilitate the desorption of the evaporation source to improve the workability and to suppress the generation of deposits themselves.
(3) The evaporation source is small and lightweight (4) No structure is present in front of the cathode evaporation surface, or deposition on this part is reduced (5) A strong magnetic field is formed in the vicinity of the cathode Since deposits are deposited in the front of the surface in a short time, and the exfoliated material is mixed into the film and enters the film forming apparatus drive unit and the vacuum seal unit, causing the apparatus to stop and the degree of vacuum to be reduced. Countermeasures are required. Further, according to (5), deposition on the rear side of the cathode evaporation surface or in a region on the same surface as the evaporation surface is suppressed. This is due to the following reason. Normally, most of the evaporated cathode constituent material is ionized to form plasma, which is easily affected by a magnetic field. Therefore, when another magnetic field stronger than the magnetic field in the region where the plasma is generated is formed, the movement of the plasma along the magnetic field lines to the strong magnetic field region is suppressed by the so-called mirror effect. Therefore, if a strong magnetic field is formed around the cathode, deposition on this portion can be suppressed.

By the way, if the target formed film has the same composition as the cathode constituent material, an inert gas may be introduced into the apparatus, or the apparatus may be put into a high vacuum without introducing the gas. It is more preferable to employ the latter from the viewpoint that inert gas is not taken into the film. On the other hand, when the formed film is not the same as the cathode constituent material (such as nitride or oxide), a reactive gas that reacts with the cathode constituent material is introduced into the apparatus to form a compound film.
Thus, although the presence or absence of gas introduction into the apparatus differs depending on the target film, the following problems are required from the viewpoint of the stability of the apparatus.
(6) Arc discharge can be stably maintained regardless of the presence or absence of gas introduction.

  As described above, various problems are required for the arc evaporation source. However, the techniques described in Patent Documents 1 to 6 have the following problems.

<Technique described in Patent Document 1>
In the case of the technique described in Patent Document 1, an elongate rod-like cathode having a diameter of about 5 to 20 mm is used. However, since carbon is a brittle material, the cathode is damaged during the replacement operation and the productivity is lowered. Further, when the consumption volume is the same, the elongated cathode has a longer cathode consumption length than a cathode having a large diameter, and the cathode length needs to be longer in order to use for a long time. Therefore, in the case of this technology, in order to prevent atmospheric leakage from the hole through which the elongated cathode is inserted into the vacuum vessel, a large vacuum cover including the cathode length is required, which increases the size of the entire apparatus and causes the problem (3). Not satisfied.

<Techniques described in Patent Documents 2 and 3>
In the case of the techniques described in Patent Documents 2 and 3, there is a problem that the diameter of the magnetic coil increases. When the coil is in front of the evaporation surface of the cathode, in order to make the magnetic field configuration around the center of the cathode equal to that of the periphery, the coil length is made longer than the coil diameter or the coil is made larger than the cathode outer diameter. This is because the inner diameter needs to be sufficiently large. As a result, the entire arc evaporation source including the coil becomes long.
In addition, when the magnetic coil is provided, the magnetic field lines formed in the vicinity of the cathode evaporation surface are substantially parallel to the cathode central axis, and the directivity of the ionized cathode constituent material is increased. Become thicker. Therefore, in order to make the film thickness distribution uniform, it is necessary to install a plurality of evaporation sources facing the substrate. Therefore, in any case, in the case of the same technology, the above problem (3) is not satisfied.
Furthermore, in the case of the techniques described in Patent Documents 2 and 3, since a magnetic field having a substantially uniform strength is formed in the vicinity of the cathode, a part of the cathode constituent material evaporated and ionized by the arc discharge is hindered at all. It is also possible to reach the rear of the cathode. In addition, since the ionized cathode constituent material is present in a portion close to the cathode evaporation surface, these are deposited in a relatively short time, then peeled off, mixed into the film, and deposited on the film forming apparatus drive unit and vacuum seal unit. Intrusion occurs, leading to the stoppage of the apparatus and a decrease in the degree of vacuum, so the problem (5) is not satisfied.

Furthermore, in the case of the techniques described in Patent Documents 2 and 3, the following problems may occur. First, when a magnetic coil is used, a magnetic field having a uniform intensity is formed in the vicinity of the cathode evaporation surface, and ionized cathode constituent materials are bound to this magnetic field. These ions become high-density plasma and deposit on the inner wall of the device around the cathode. In the case of this technique, the cathode evaporation surface is located inside the magnetic coil, so that the deposition on the inner wall of the magnetic coil becomes significant. If this deposit is peeled off and mixed in the film being formed, the quality of the film is deteriorated, so that apparatus maintenance is frequently required. Thus, in the case of this technique, the above problem (4) is not satisfied.
If the inner diameter of the magnetic coil is not sufficiently larger than the outer diameter of the cathode (when the distance between the inner side of the coil and the outer side of the cathode is narrow), there are the following problems. That is, the magnetic field generated by the coil is stronger on the outside of the coil than on the inner center of the coil, so that a strong magnetic field is formed on the inner wall portion of the ring-shaped coil. Electrons and ions, especially electrons with a light mass, are easily affected by a magnetic field, and move along the magnetic field lines while performing a circular motion so that they wrap around the magnetic field lines. It is known that the radius of circular motion (Larmor radius) has a characteristic inversely proportional to the magnetic field strength. Therefore, electrons and ions that have jumped out of the cathode evaporation surface inside the coil where a weak magnetic field is formed are prevented from reaching the periphery of the inner wall of the coil where a strong magnetic field is formed. The directivity of ions increases, and the film thickness on the front side of the evaporation source increases. Therefore, as described above, it is necessary to install a plurality of evaporation sources, and the techniques described in Patent Documents 2 and 3 do not satisfy the problem (3).
The technique described in Patent Document 3 uses a tapered ring 64 '. When the arc spot is pushed back in the direction of the cathode evaporation surface, an arc spot is temporarily generated on the surface of the tapered ring, and the tip of the ring is caused by arc discharge. exhaust. Therefore, as the discharge time increases, the shape of the tapered ring changes from the initial conical surface, and the effect of the ring decreases. Therefore, it is necessary to periodically replace the tapered ring. Furthermore, in order to exhibit the effect of the tapered ring, the angle formed by the slope of the ring and the magnetic field lines needs to be an acute angle. However, if the tip angle of the tapered ring is reduced, the consumption rate due to arc discharge is increased, and the taper is reduced. The effect of the ring is reduced. For this reason, in the case of this technology, the problems (1) and (2) are not satisfied.
For these reasons, in this technology, it is actually difficult to adopt a magnetic field configuration in which the magnetic lines of force spread widely in the outer circumferential direction, and the ions of the cathode constituent material have a strong directivity in the tangential direction of the magnetic lines of force. . As a result, in order to make the film thickness distribution uniform, it is necessary to install a plurality of evaporation sources facing the substrate.

  By the way, normally, when the formed film is the same as the cathode material, when an inert gas is introduced, gas components are taken into the film and the film strength is reduced. Therefore, the film is formed under a high vacuum without using an inert gas. Is preferred. However, in the case of the techniques described in Patent Documents 2 and 3, if gas is not introduced into the apparatus (inside the vacuum vessel), arc discharge becomes unstable and the frequency of stopping arc discharge becomes high. I'm not satisfied. For this reason, a cylindrical coordinate system is taken with respect to the central axis of the magnetic coil and considered from the relationship between the magnetic field, the arc discharge current, and the direction of the force acting on the arc discharge current.

  First, at the midpoint (central part) in the length (axis) direction of the magnetic coil, the magnetic field intensity on the cathode surface is almost uniform regardless of the position, and the direction of the lines of magnetic force is almost the same as that of the magnetic coil (cathode axis). Match). If no gas is introduced into the vacuum vessel, the thermoelectrons emitted from the cathode by the arc discharge are affected by the electric field, so that the anode (vacuum vessel wall or coil storage vessel) close to the cathode, that is, movement around the cathode axis, is not affected. Arc discharge current tends to flow in the radial direction. However, since the magnetic coil forms a magnetic field in a direction substantially parallel to the central axis of the cathode, the electrons rotate in response to a force (so-called J × B force) in an azimuth direction perpendicular to both the current and the magnetic field lines. Therefore, the arc discharge current is prevented from flowing in the radial direction.

The current flowing through the cathode forms a magnetic field _Bθ having the above azimuth direction component around the cathode. As described above, arc discharge current tends to flow in the radial direction with respect to the cathode central axis, the influence of the magnetic field B _theta, the central axis both to the cathode of which is vertical and the magnetic field lines of the current and the magnetic field B _theta The pushing force (J × B _θ ) is also received. Both of these actions prevent the arc discharge current from flowing in the radial direction. Therefore, the arc discharge current is almost unaffected by the J × B force and the J × B _θ force, that is, both the magnetic field B mainly formed by the coil and B _θ formed by the discharge current are combined. It flows in the direction along the magnetic field lines. Of the magnetic field lines formed by the magnetic coil, the magnetic field lines that penetrate the cathode evaporation surface reach the vacuum vessel wall that acts as an anode outside the magnetic coil. As a result, since the current path between the cathode and the anode becomes long, it becomes difficult to maintain the arc discharge, and the frequency at which the arc discharge stops increases.
Therefore, if the magnetic field strength formed near the cathode evaporation surface by the magnetic coil is weakened in order to reduce the influence of the J × B force, the plasma holding capacity in front of the cathode evaporation surface is reduced, and the arc spot on the cathode evaporation surface is reduced. Motion control is also difficult. Therefore, arc discharge stops or the frequency of occurrence of arc discharge at a place other than the cathode evaporation surface increases. In this case, since the components near the cathode are melted, arc discharge must be stopped or the melt is mixed into the coating.

<Technique described in Patent Document 4>
On the other hand, in the case of the technique described in Patent Document 4, the magnetic field forming mechanism forms a magnetic force line extending outward with respect to the central axis of the cathode, and the arc discharge current flows along this magnetic force line. Since the arc discharge can be stably maintained, the problem (6) is satisfied.
However, in the case of this technology, it is necessary to provide a through hole for inserting a magnetic field forming mechanism in the cathode, and the volume of the cathode constituent material is reduced by the amount of the through hole, so that the efficiency of film formation is reduced. There is a problem that the film formation cost is increased.

<Technique described in Patent Document 5>
In the case of the technique described in Patent Document 5, the magnetic field is stronger toward the front and outside of the cathode evaporation surface. Therefore, the magnetic field from the cathode evaporation surface is closer to the anode electrode reaching the magnetic field lines penetrating the cathode evaporation surface and the device wall serving as the anode electrode. strong. For this reason, the movement of electrons to the anode electrode is hindered by the mirror effect, and the discharge becomes unstable. As a result, the amount of droplets (coarse particles) generated increases.
Further, in the case of this technique, the deposition of the cathode material on the magnet (electromagnet) located in front of the cathode evaporation surface becomes significant, so the problem (4) is not satisfied for the same reason as described above.

<Technique described in Patent Document 6>
In the case of the technique described in Patent Document 6, since the magnetic poles on the inner peripheral surface of the ring magnet have the same polarity, a circular cusp magnetic field is formed around the cathode evaporation surface. A circular cusp magnetic field has a strong magnetic field around its magnetic pole, but a weak magnetic field in the middle region of the opposite magnetic pole and the center of the magnetic field. It is known that the arc spot moves faster as the magnetic field strength is higher, particularly as the magnetic field strength parallel to the cathode surface is higher. Therefore, since the movement of the arc spot is slow in the central part of the cathode where the magnetic field strength is weak, the temperature of the cathode evaporation surface in this part rises locally and the amount of droplets generated increases.
Furthermore, in the case of this technique, a stronger magnetic field is formed as the distance from the central region of the cathode increases, so that the movement of the arc spot becomes faster as the distance from the central portion of the cathode increases. For this reason, the temperature of the cathode evaporation surface where the arc spot is located in the cathode peripheral region is lower than that of the inner cathode evaporation surface, and the amount of evaporation of the cathode material is reduced. As a result, the cathode consumption rate varies between the central part and the peripheral part of the cathode, and this technique does not satisfy the problem (1).

  In addition, in the case of this technique, since a circular cusp magnetic field is formed, the magnetic field lines are once gathered in the central region and then formed so as to spread vertically outward, and an arc discharge current flows along this. For this reason, the length that the discharge current flows becomes long, and if the gas is not introduced, the arc discharge becomes unstable and the frequency at which the arc discharge stops increases. Therefore, in the case of this technique, the problem (6) is not satisfied.

  As described above, the present invention can stably maintain arc discharge regardless of whether or not gas is introduced into the vacuum vessel, can stably form a film, and reduces the deposition of the cathode material other than the object. It is another object of the present invention to provide an arc evaporation source and a method for manufacturing a film-forming body that are easily consumed and maintained while the cathode is uniformly consumed.

The present invention has been made to solve the above problems, and in an arc evaporation source that evaporates a cathode material by arc discharge, magnetic field formation in which cylindrical magnetic poles having different polarities are arranged at both ends in the axial direction is provided. And a cathode delivery mechanism for moving the cathode disposed inside the magnetic field forming mechanism forward and backward in the axial direction of the magnetic field forming mechanism, the cathode being longer in the axial direction than the diameter, and the evaporation surface of the cathode being The relationship between the axial distance ΔL between the evaporation surface and the front end and the inner diameter D of the magnetic field formation mechanism is 0.1 × D ≦ ΔL ≦ 2.0 × D. It is characterized by.

Thus, when the magnetic field forming mechanism is arranged behind the evaporation surface of the cathode, magnetic lines of force extending along the cathode axis and extending outward from the cathode central axis are formed in front of the evaporation surface 23 (side closer to the vacuum chamber). Therefore, the effective distance between the cathode and the anode along the magnetic field lines is shortened. Therefore, arc discharge is maintained without introducing gas into the vacuum vessel. In addition, since the lines of magnetic force spread outward from the central axis of the cathode, the directivity of ions is reduced and the ions are emitted over a wide range.
If the magnetic field forming mechanism is disposed behind the evaporation surface of the cathode, a strong magnetic field is formed in the vicinity of the evaporation surface, and arc discharge is stably maintained at any position on the evaporation surface.
These effects become remarkable by defining the relationship between ΔL and D within a predetermined range.
When the magnetic field forming mechanism is disposed behind the evaporation surface of the cathode, an arc-type evaporation source having no structure (for example, a magnetic field forming mechanism) in front of the evaporation surface 23 (side close to the vacuum chamber) is taken. Thus, the deposition, separation and scattering of the cathode material on the structure in front of the evaporation surface 23 are suppressed. Furthermore, by using a magnetic field forming mechanism in which magnetic poles of different polarities are arranged at both ends in the axial direction, the magnetic field on the side surface of the cathode is almost parallel to the side surface of the cathode, and the magnetic field becomes stronger toward the rear from the evaporation surface. The arc discharge current from the evaporation surface to the rear is also suppressed. For this reason, the arc spot is prevented from accidentally moving to the side surface of the cathode.
Note that the present invention utilizes the property that in a magnetic field, the current flowing in the plasma tends to flow in a direction along the magnetic field lines as compared to the direction crossing the magnetic field lines.

The present invention also provides a magnetic field forming mechanism in which arc-shaped evaporation sources that evaporate a cathode material by arc discharge have cylindrical and different polarity magnetic poles disposed at both ends in the axial direction, and are disposed inside the magnetic field forming mechanism. A cathode delivery mechanism for advancing and retracting the cathode to be moved in the axial direction of the magnetic field forming mechanism, and causing an evaporation surface of the cathode to protrude from a front end of the magnetic field forming mechanism, and an axial distance ΔL between the evaporation surface and the front end A cathode position control mechanism that outputs or displays control information for controlling the cathode delivery mechanism such that the relationship with the inner diameter D of the magnetic field forming mechanism is 0.1 × D ≦ ΔL ≦ 2.0 × D And the cathode is longer in the axial direction than the diameter .

The present invention also provides a magnetic field forming mechanism in which arc-shaped evaporation sources that evaporate a cathode material by arc discharge have cylindrical and different polarity magnetic poles disposed at both ends in the axial direction, and are disposed inside the magnetic field forming mechanism. A cathode delivery mechanism for advancing and retracting the cathode to be moved in the axial direction of the magnetic field forming mechanism, and causing an evaporation surface of the cathode to protrude from a front end of the magnetic field forming mechanism, and an axial distance ΔL between the evaporation surface and the front end A cathode position control mechanism for controlling the cathode delivery mechanism so that the relationship with the inner diameter D of the magnetic field forming mechanism is 0.1 × D ≦ ΔL ≦ 2.0 × D, and the cathode is smaller than the diameter. It is long in the axial direction .

  It is preferable that the magnetic field forming mechanism includes a cylindrical permanent magnet. It is preferable that the magnetic field forming mechanism includes an electromagnet having a cylindrical iron core and a coil.

The manufacturing method of the present invention is a manufacturing method of a film-forming body that forms a film on a substrate surface using an arc evaporation source that evaporates a cathode material by arc discharge, wherein the arc evaporation source is cylindrical and A magnetic field forming mechanism in which magnetic poles of different polarities are arranged at both ends in the axial direction, and a cathode arranged inside the magnetic field forming mechanism, the cathode being longer in the axial direction than the diameter , and having an evaporation surface of the cathode Projecting from the front end of the magnetic field forming mechanism, and the relationship between the axial distance ΔL between the evaporation surface and the front end and the inner diameter D of the magnetic field forming mechanism is 0.1 × D ≦ ΔL ≦ 2.0 × D The film is formed as described above.

According to the present invention, arc discharge is maintained without introducing gas into the vacuum vessel, and the frequency of stopping arc discharge can be reduced and the smoothness of the coating surface can be improved. In addition, according to the present invention, the directivity of ions made of the cathode constituting material is lowered and released over a wide range, so that the film thickness distribution becomes uniform.
Further, according to the present invention, accidental migration of the arc spot to the side surface of the cathode is suppressed, and unnecessary vapor deposition on the device around the cathode can be prevented.
According to the present invention, it is possible to configure an arc evaporation source in which no structure exists in front of the cathode evaporation surface, so that the cathode material is deposited on the structure in front of the evaporation surface, or the deposit is It is possible to prevent the film strength and the smoothness of the film from being lowered due to peeling and scattering and being taken into the film.
Furthermore, according to the present invention, since the cathode is consumed uniformly, the usage efficiency of the cathode is high, and the cathode replacement frequency and the film formation cost can be reduced.

<First Embodiment>
Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 is a sectional view showing an example of a first embodiment of an arc evaporation source according to the present invention.
The arc evaporation source 20 is installed on the opening flange 4a of the vacuum chamber 4 (only a part of the container wall is shown in the figure), and constitutes an arc evaporation apparatus as a whole. The arc evaporation source 20 includes a magnetic field forming mechanism (cylindrical magnet) 116, a cathode holding flange 29, a cathode delivery mechanism (stepping motor) 38, and a cathode position control mechanism 92. The cathode position control mechanism 92 includes a trigger tip position measuring device 86, a trigger tip initial setting device 88, and a comparator 90.
The cathode position control mechanism 92 may be composed of, for example, a semiconductor circuit, or may be composed of computer software and a semiconductor circuit that estimate the amount of cathode consumption based on film forming conditions. In the latter case, the amount of cathode consumption corresponding to the film formation conditions (arc discharge current, discharge time, and atmospheric gas pressure) is accumulated in advance as empirical data, and the cathode consumption is estimated by inputting these conditions. Build software.
The cylindrical magnet is magnetized, for example, in the axial direction. For example, the cylindrical magnet is configured by arranging an S pole at the axial front end (side facing the vacuum chamber 4) and an N pole at the rear end.

The arc evaporation source 20 is fixed to the vacuum chamber 4 by fitting the cylindrical magnet 116 and the columnar cathode 22 inserted into the cylindrical magnet 116 into the opening flange 4 a of the vacuum chamber 4. Is called.
The tip of the cathode 22 protruding from the cylindrical magnet 116 into the vacuum chamber 4 is covered with a shield plate 10 that covers the inner wall of the vacuum chamber 4, and the evaporation surface 23 at the tip of the cathode 22 is exposed from the opening of the shield plate 10. Yes. The shield plate 10 is made of a conductive material, and is connected to the ground 2 via the resistor 60. From the viewpoint of workability, cost, and heat resistance, an iron-based material is suitable as the shield plate 10.

Between the inner surface of the base side of the opening flange 4 a and the outer surface of the cathode 22, a ring-shaped insulator 25 with a flange at one end is interposed with the flange side facing the vacuum chamber side. It comes to slide against. The insulator 25 is electrically connected between the cathode 22 and the vacuum chamber (container wall) 4 or between the shield plate 10 and the vacuum chamber (container wall) 4 due to conductive dust that has fallen from the cathode 22 and the shield plate 10. To prevent short circuit.
A substantially ring-shaped insulator 46 is interposed between the inner surface of the end edge of the opening flange 4 a and the outer surface of the cylindrical magnet 116. The insulator 46 also performs a vacuum seal between the vacuum chamber 4 (opening flange 4a) and the arc evaporation source 20 (cathode 22 and cylindrical magnet 116).

  A cathode holding flange 29 is coaxially attached to the rear end of the cathode 22 and both are electrically connected. An arc discharge current source 14 is connected between the cathode holding flange 29 and the ground 2, and the cathode 22, the anode (which is grounded) in the vacuum chamber 4, and the shield plate 10 (which is grounded via a resistor). The ionized cathode material jumps out from the evaporation surface 23 toward the anode, and a film is formed on the substrate surface in the vacuum chamber 4. In addition, the code | symbol 24 of FIG. 1 shows the flow of the evaporated ion, and the code | symbol 44 shows a magnetic force line.

The cathode holding flange 29 includes a columnar flange portion 29a and a rod-shaped shaft portion 29b. With the flange portion 29a at the head (on the vacuum chamber side in FIG. 1), the flange 29 is coaxial with the cylindrical magnet 116. It is inserted. A concave portion is formed in the radial direction of the side wall of the flange portion 29a, and the O-ring seal 70 fitted in the concave portion contacts the inner wall of the cylindrical magnet 116, whereby the flange 29 and the cylindrical magnet 116 are vacuum-sealed. .
The cathode mounting screw 18 protrudes from the center of the front end surface of the flange portion 29 a, and the cathode 22 is mounted to the flange 29 by tightening the screw 18 in the center hole on the rear surface of the cathode 22. On the other hand, the shaft portion 29 b of the flange 29 is attached to the cathode delivery mechanism 38 via the delivery shaft 36, and the flange 29 and the cathode 22 advance and retreat in the cylindrical magnet 116 in the axial direction according to the advance and retreat of the cathode delivery mechanism 38. To do.

  A circulation path for the refrigerant 30 is formed inside the cathode holding flange 29 to cool the flange 29 and the cathode 22. In addition, a magnet cooling mechanism (jacket) 120 through which the refrigerant 122 circulates is provided on the outer periphery of the cylindrical magnet 116 to cool the cylindrical magnet 116 to suppress a temperature rise and prevent a decrease in magnetic field strength. If it does in this way, the film-forming speed | rate will be maintained constant and the film thickness reproducibility of a film will improve further.

  As the cathode, for example, a cylindrical and solid normal shape can be used. It is preferable to use a conductive material that is not a ferromagnetic material as the cathode, because even if the protruding amount of the cathode or the cathode length changes, the magnetic field configuration by the magnetic field forming mechanism is not affected. Examples of the material include metals, alloys, metalloid materials such as carbon, and semiconductor materials such as InAs. In particular, it is preferable to use a material composed of at least one of non-ferromagnetic metals and metal carbides, metal nitrides, metal borides, and metal sulfides as the cathode. As such metals, Ti, V , Cr, Al, Nb, Zr, Mo, W, Hf, Ta or more.

In each embodiment of the present invention, the magnetic field forming mechanism is “cylindrical”. However, the present invention is not limited to this, and a cylindrical shape having, for example, a polygonal cross section is possible. May be. On the other hand, the shape of the cathode is not limited, and may be a polygonal columnar shape in addition to the columnar shape described above. In addition, the cross-sectional shape of the cylinder of the magnetic field forming mechanism and the cross-sectional shape of the cathode may be similar or different, but usually the cross-sectional shapes of both are similar (for example, from the point of symmetry of the formed magnetic field) When the magnetic field forming mechanism is a cylinder, the cathode is also preferably a column).
Furthermore, the axis of the magnetic field forming mechanism and the axis of the cathode may be coaxial or different, but from the viewpoint of the symmetry of the magnetic field to be formed, both axes should be coaxial. preferable.

<Cathode position control>
With a long-term use, the cathode is consumed, and the evaporation surface 23 is retracted toward the outside of the vacuum chamber. Therefore, it is necessary to stabilize the evaporation of the cathode 22 and keep the film formation rate and quality constant by sending the cathode 22 forward using the cathode delivery mechanism 38. The cathode position is controlled using, for example, the following trigger.

The trigger 16 has a rod shape whose tip is bent in a U-shape, and is inserted into a small hole in the vacuum chamber (container wall) 4. The tip of the trigger 16 faces the evaporation surface 23 of the cathode 22, and the other end of the trigger 16 is connected to a trigger driving mechanism (stepping motor or pneumatic cylinder) 84 that is outside the vacuum chamber 4. Then, the trigger 16 moves in the axial direction of the cathode 22 in accordance with the advance / retreat of the trigger drive mechanism 84. When the tip of the trigger 16 comes into contact with the evaporation surface 23, the trigger driving mechanism 84 stops, and the trigger tip position measuring device 86 acquires the stop position at that time. The tip position of the stopped trigger 16 coincides with the position L1 of the exhausted cathode evaporation surface 23. The tip of the trigger 16 comes out of the evaporation surface 23 after contacting the cathode evaporation surface 23 for a certain time.
The comparator 90 compares the position information with the initial value preset in the trigger tip initial setting device 88 (tip position of the trigger 16 that is the position of the cathode evaporation surface 23 at the start of film formation), and wears out. The position L1 of the subsequent cathode evaporation surface 23 is calculated and output. The cathode delivery mechanism 38 acquires the output result and sends the cathode 22 forward according to the output. Thereby, even if the position of the cathode evaporation surface 23 is consumed, it is returned to the preset initial position.

  When the film formation time is long or when film formation is performed with a large discharge current, the amount of consumption of the cathode increases, so that the position of the cathode evaporation surface and the cylindrical magnet, which will be described later, does not satisfy the predetermined relationship with time. become. In some cases, it is desired to control the movement of the arc spot to a constant state during film formation. In these cases, it is necessary to feed the cathode forward during the film forming process and control the cathode evaporation surface position so as to satisfy a predetermined condition. In order to control the cathode evaporation surface position, re-ignition at the time of arc discharge misfire or trigger operation when returning from discharge continuation (abnormal discharge) at a portion other than the cathode evaporation surface 23 is used. It is preferable to measure the position and return it to the initial position before the cathode is consumed (or a position in a range satisfying the above positional relationship). Furthermore, even when the above-described trigger operation does not occur, it is preferable to force the trigger to operate at a predetermined time interval, measure the position of the cathode evaporation surface, and return to the initial position before the cathode is consumed.

The trigger driving mechanism 84 operates at the start of arc discharge, reignition at the time of arc discharge misfire, and at the time of return from continuing discharge (abnormal discharge) at a portion other than the evaporation surface 23 of the cathode. Arc discharge is started between. Except when performing the above operation, the trigger 16 is preferably housed around the shield plate or the vacuum vessel wall 4 in order to reduce the adhesion of the cathode material to the trigger 16.
The trigger drive mechanism 84 is not limited to the one that reciprocates as described above. For example, a trigger drive mechanism that drives the trigger tip to draw an arc may be used. In this case, the trigger tip position measuring device 86 measures the tip position from the angle of the circular motion of the trigger. Further, without using a trigger or a trigger driving mechanism, an ultrasonic transmitter and a receiver are provided behind the cathode 22, and the cathode length (position) is calculated from the time when the ultrasonic pulse reciprocates the cathode. Good.
In the above-described example, the cathode delivery mechanism 38 operates in conjunction with the output information of the comparison calculator 90. However, the cathode delivery mechanism 38 may be manually operated based on the output value of the comparison calculator 90. In the case of using commonly used Cr, Ti, or the like as the cathode, the amount of cathode consumption corresponding to the film forming conditions (arc discharge current, discharge time, atmospheric gas pressure) is accumulated as empirical data. Therefore, if these conditions are known, the amount of cathode consumption can be estimated. Therefore, in such a case, it is not necessary to measure the position L1 of the cathode evaporation surface using a trigger or the like, and the amount of cathode consumption (L1) is estimated according to the film forming conditions. Based on the estimated L1, The cathode delivery mechanism 38 may be operated automatically or manually.

<Control of relative position of cathode and cylindrical magnet>
In the present invention, the relative position between the cylindrical magnet 116 and the evaporation surface 23 of the cathode is controlled as follows in order to appropriately form a magnetic field, which will be described later, as well as advancement of the cathode according to wear.
In FIG. 1, the axial distance between the position L1 of the cathode evaporation surface 23 and the position L2 of the front end (end closer to the vacuum chamber) of the cylindrical magnet 116 is denoted by ΔL. However, it is essential to position L1 in front of L2 (side closer to the vacuum chamber). The inner diameter of the cylindrical magnet 116 is D.

At this time, Formula 1
0.1 × D ≦ ΔL ≦ 2.0 × D (1)
The cathode position is controlled to satisfy this relationship. This control is performed by the cathode position control mechanism 92 in the same manner as described above. Here, D and L2 are set in the trigger tip initial setting device 88 in advance. The comparison calculator 90 compares L1 acquired by the trigger tip position measuring device 86 with D and L2 acquired from the trigger tip initial setting device 88, and determines whether or not these satisfy the relationship of Expression 1. To do. When 0.1 × D> ΔL, the comparison calculator 90 outputs a value for sending the cathode forward. When 2.0 × D <ΔL, the comparison arithmetic unit 90 outputs a value for returning the cathode backward. The cathode delivery mechanism 38 controls the cathode position based on the output result. Based on the output result, an operator may manually operate the cathode delivery mechanism 38 to control the cathode position. In the latter case, the cathode position control mechanism 92 includes a display unit that displays the output result of the comparator 90 (cathode position control information) so that the operator can recognize the control amount of the cathode position.

L2 and D indicate positions of portions of the cylindrical magnet 116 that effectively generate magnetic force. For example, when the cylindrical magnet 116 is covered with a cover or the like, the position of the cover is not included.
Further, the cylindrical magnet 116 is not limited to the one composed entirely of magnets. For example, a cylinder made of a ferromagnetic material may be arranged coaxially with the cathode, and a ring-shaped (cylindrical) magnet may be provided coaxially behind the cylinder. In this case, the magnetic field generated at the end of the ferromagnetic material by the cylindrical magnet forms a magnetic pole at the other end of the ferromagnetic material. The end portion of the cylindrical magnet and the end portion of the ferromagnetic material as a whole function substantially equivalent to the cylindrical magnet. At this time, L2 is the front end of the ferromagnetic material (the end on the side close to the vacuum chamber and the end opposite to the end in contact with the cylindrical magnet).
Furthermore, the magnetic field strength may be adjusted by adding a magnet (not shown) to the outer periphery and / or rear of the cylindrical magnet 116. The cylindrical magnet may have a structure that can be divided into two or more so as to be easily attached and detached, and a small-diameter columnar or prismatic bar magnet may be arranged in a cylindrical shape.

<Formation of magnetic field>
Next, the magnetic field formed by the arc evaporation source of this embodiment will be described with reference to FIG. FIG. 2 shows the lines of magnetic force in Formula 1 obtained by magnetic field analysis when 0.5 × D = ΔL, and reference numeral 44 indicates the lines of magnetic force. In this analysis, the inner diameter (D) of the cylindrical magnet 116 is 64 mm, the outer diameter is 76 mm, the axial length of the cylindrical magnet 116 is 30 mm, and the cathode diameter is 60 mm.
In FIG. 2, the cylindrical magnet 116 is magnetized in the axial direction, has a south pole at the front end, has a north pole at the rear end, and a position L2 of the front end of the magnet 116 is a position L1 of the evaporation surface 23 of the cathode. Located rearward.

<Operation of placing the cylindrical magnet behind the evaporation surface>
As described above, when the cylindrical magnet is disposed behind the evaporation surface 23, magnetic force lines extending along the cathode axis and outward from the cathode central axis can be formed in front of the evaporation surface 23 (side closer to the vacuum chamber). it can. Electrons emitted from the arc spot on the cathode evaporation surface 23 are captured by the magnetic field lines and transported along the magnetic field lines. Furthermore, the ions of the cathode constituent material ionized by arc discharge also diverge in a wide angular direction along the magnetic field lines.
Since the arc discharge current can reach the anode (shield plate or inner wall of the vacuum vessel) along the magnetic field lines, the effective distance between the cathode and the anode along the magnetic field lines is shortened. In this way, even if gas is not introduced into the vacuum vessel, arc discharge is maintained, and it is possible to reduce the frequency of stopping arc discharge and the amount of droplets generated. As a result, the coating surface is smoothed, and a decrease in the mechanical strength of the coating can be suppressed. In addition, since the restraint force of the magnetic field becomes weaker as it moves away from the evaporation surface 23, electrons and ions move freely to form a film. However, since the magnetic field lines spread outward from the cathode central axis, the directivity of ions is low. Since it is released in a wide range, the film thickness distribution becomes uniform.

Further, by arranging the cylindrical magnet behind the evaporation surface, a strong magnetic field can be formed in the vicinity of the evaporation surface 23 of the cathode, and arc discharge is stably maintained at any position on the evaporation surface 23. As already described, since the plasma generated by the arc discharge is captured as the magnetic field is stronger, high-density plasma is formed in the vicinity of the evaporation surface 23. And since the sheath (Sheath) formed between a cathode evaporation surface and plasma becomes thin, so that it becomes high density plasma, it becomes easy to maintain arc discharge.
In addition, by arranging the cylindrical magnet behind the evaporation surface 23, the weight of the cathode material which has no components in front of the cathode evaporation surface 23 and adheres to the inner wall of the vacuum vessel other than the film formation substrate and other parts. Can be reduced. Further, since a stronger magnetic field is formed toward the rear of the cathode evaporation surface 23, the cathode constituent material evaporated and ionized by the arc discharge is restrained from moving backward along the magnetic field lines due to the mirror effect. Thus, the proportion of the cathode constituent material that is scattered forward of the cathode evaporation surface and is consumed for forming the coating is improved.

<Action to control relative position of cathode and cylindrical magnet>
The action of disposing the cylindrical magnet behind the evaporation surface becomes remarkable by controlling the relative position of the cathode and the cylindrical magnet within the range of Equation 1. In other words, if 0.1 × D> ΔL, the cylindrical magnet is not arranged sufficiently behind the evaporation surface, so that part of the lines of magnetic force returns to the cathode evaporation surface and a magnetic field configuration is formed toward the cathode rear. . That is, since the magnetic lines of force that close within the cathode evaporation surface are formed, it is difficult for the magnetic lines of force to reach the vacuum vessel wall and the shield plate serving as the anode. And since the arc discharge current hardly flows in the direction crossing the magnetic field lines, the arc discharge becomes unstable, and the frequency at which the discharge stops increases. On the other hand, if 2.0 × D <ΔL, the distance between the magnet and the evaporation surface is too large, so that a strong magnetic field cannot be formed in the vicinity of the evaporation surface 23 of the cathode, and the movement of the arc spot becomes slow. As the temperature of the cathode evaporation surface rises, the amount of droplets generated increases and the cathode is not evenly consumed.
Preferably, 0.3 × D ≦ ΔL ≦ 1.5 × D. It is preferable that 0.3 × D ≦ ΔL ≦ 1.5 × D because the magnetic field lines spread outward and the movement of the arc spot becomes faster, so that the arc evaporation source can be further downsized.

<Operation using cylindrical magnets with magnetic poles with different polarities at both ends in the axial direction>
When cylindrical magnets having N and S poles arranged at both ends in the axial direction are used, as shown in FIG. 2, the magnetic field on the cathode side surface is parallel or acute with respect to the cathode side surface and parallel to the cathode side surface. Ingredients become stronger. As described above, since the arc discharge current flows along the magnetic field lines and it is difficult to cross the magnetic field lines, it is difficult to maintain the arc discharge on the cathode side surface. Further, when the cylindrical magnet is used, the magnetic field becomes stronger toward the rear from the evaporation surface 23, so that the electrons are pushed back by the mirror effect, and the arc discharge current from the cathode evaporation surface to the rear is also suppressed. As described above, since it is difficult to maintain the arc discharge on the cathode side surface, accidental migration of the arc spot to the cathode side surface is suppressed, and unnecessary deposition on the device around the cathode is prevented.

  If the cylindrical magnet is disposed behind the cathode evaporation surface 23, the influence of the center of the cylindrical magnet (the portion where no magnet is present) decreases as the distance from the magnet evaporates, and the magnetic field line formed by the disc-shaped magnet approaches. Therefore, a uniform magnetic field similar to a disk magnet is generated on the cathode evaporation surface, and the arc spot can move evenly on the cathode evaporation surface. This effect occurs sufficiently even when a long cathode is used in the axial direction, so that the cathode is evenly consumed, and a long cathode in the axial direction can be suitably used. As a result, it is possible to improve the production efficiency by reducing the frequency and time during which the cathode is replaced. Also, with the above configuration, magnetic field lines substantially parallel to the axial direction are formed in the vicinity of the central portion of the cylindrical magnet in the axial direction, so that a magnetic field similar to the magnetic field configuration formed by the coil can be formed. .

<Second Embodiment>
In the present invention, an electromagnet may be used as the magnetic field forming mechanism. FIG. 3 is a sectional view showing a second embodiment of the arc evaporation source of the present invention.
3, since it is the same as that of 1st Embodiment except having used the electromagnet 114 instead of the cylindrical magnet 116, description of the structure of the same part is abbreviate | omitted. The electromagnet 114 includes a cylindrical iron core 112 and a coil provided on the outer periphery thereof, and is connected to an electromagnet excitation power source 108. The magnetic field strength can be adjusted by changing the current applied to the electromagnet 114. In this embodiment, the inner diameter of the iron core 112 is D. The iron core 112 may be made of a ferromagnetic material such as Ni, Co, or ferrite.

  In the case of the first embodiment, since a permanent magnet is used, an electromagnet current source is unnecessary, the configuration of the evaporation source can be simplified, and a strong magnetic field can be formed with a relatively small magnet, so that the apparatus is compact. become. On the other hand, in the case of the second embodiment, if the current of the electromagnet is controlled, it is easy to adjust the magnetic field strength so that arc discharge is stabilized.

Next, the magnetic field formed by the arc evaporation source 20B of the second embodiment will be described with reference to FIG. FIG. 4 shows the lines of magnetic force in Formula 1 obtained by magnetic field analysis when 0.5 × D = ΔL, and reference numeral 44B indicates the lines of magnetic force. In this analysis, the inner diameter (D) of the iron core 112 is 64 mm, the outer diameter is 74 mm, the length is 40 mm, the inner diameter of the coil 114 is 74 mm, the outer diameter is 79 mm, the length is 40 mm, and the cathode diameter is 60 mm. To do.
In FIG. 4, as in FIG. 2, magnetic lines of force extending outward from the cathode central axis are formed in front of the cathode evaporation surface 23.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

<Example 1-1>
A hard chromium nitride film was formed using the arc evaporation source 20 shown in FIG. This is Example 1-1. A mirror-polished carburized shim (outer diameter 30 mm, thickness 2 mm, surface roughness Ra 0.02 μm or less) was used as the film-forming substrate, and this was fixed 500 mm away from the front of the cathode evaporation surface. This is designated as Sample 1. Further, in order to investigate the spread state of carbon evaporated from the cathode, another carburized shim shim was fixed at a position 200 mm away from the sample 1 in the lateral direction (the direction parallel to the cathode evaporation surface) (hereinafter referred to as sample 2). ).
As the cathode, a chromium cathode (purity 99.9%) having an outer diameter of 60 mm and an axial length of 200 mm was used. A cylindrical carbon steel magnet having an inner diameter of 64 mm and an outer diameter of 78 mm was used as the magnetic field forming mechanism. The relative position of the front end of the magnet and the cathode evaporation surface was adjusted so that D = ΔL.

First, an ion bombardment process was performed prior to film formation. In the ion bombardment treatment step, the inside of the vacuum vessel is evacuated to 2.7 × 10 ⁻³ Pa (2 × 10 ⁻⁵ Torr) or less by a vacuum exhaust pump (not shown), and then Ar gas is supplied at a flow rate of 1 from a gas introduction hole (not shown). 7 × 10 ⁻² Pam ³ / s (10 sccm (standard cc / min)) was introduced, and the inside of the vacuum vessel was maintained at about 1.3 Pa (10 mTorr). Then, high frequency power having a frequency of 13.56 MHz and a power of 100 W was applied to the film formation substrate through an impedance matching device (not shown) for 10 minutes to perform high frequency plasma discharge. The film-deposited substrate is negatively self-biased by electron attachment from plasma, Ar ions that are positive ions are accelerated, the substrate surface is sputtered, and the surface is cleaned.

  Subsequent to the ion bombardment process, a film forming process was performed. Nitrogen gas is introduced into the vacuum vessel, and the inside of the vacuum vessel is maintained at 2.6 Pa (20 mTorr). Then, an arc current of 100 A was applied to the cathode to perform arc discharge, and at the same time, a DC voltage (-100 V) was applied to the film formation substrate. When this state was maintained and film formation was performed for 30 minutes, a hard chromium nitride film having a thickness of about 1 μm was formed on the surface of the base material.

<Example 1-2>
Film formation was performed in exactly the same manner as in Example 1-1 except that the arc evaporation source 20B shown in FIG. 3 was used. This is Example 1-2. Also in this example, the relative position of the front end of the magnet and the cathode evaporation surface was adjusted so that D = ΔL, and D was the inner diameter of the iron core.

<Comparative Example 1-1>
Using an arc evaporation source described in Patent Document 3 (corresponding to the configuration of FIG. 5 of the present specification), film formation was performed under the conditions described in the Example of Patent Document 3. This is designated as Comparative Example 1-1. However, a chromium cathode 32 (purity: 99.9%) having a diameter of 50 mm and a length of 120 mm, and a chromium tapered ring 74 (purity: 99.9%) having an inner diameter of 50 mm, an outer diameter of 90 mm, and an angle of the inclined surface 76 of 45 degrees. ) Was applied. The film forming conditions were the same as those in Example 1-1. However, nitrogen gas was introduced using a gas spray mechanism. As a result, a hard chromium film having a thickness of about 1 μm was formed on the substrate surface.

<Evaluation>
The following evaluation was performed about each Example and the comparative example.
1. Electricity amount The film forming process was performed 30 times, and a value (average value) obtained by dividing the total electric energy amount of arc discharge by the number of times of film formation was evaluated.
2. Deposit weight Measure the total weight of the deposit attached to the structure (shield plate, magnet (or electromagnet) inner wall, vacuum vessel inner wall, accessory attached to the inner wall of Fig. 1) located in front of the cathode evaporation surface. The value divided by the number of film formations was evaluated.
3. Smoothness of coating (surface roughness Ra)
Of the samples subjected to the film forming process 30 times, the surface roughness Ra of the last three samples was measured using a stylus type surface roughness meter. The surface roughness was measured at five locations per sample, and the average value was evaluated.
4). Thickness uniformity (film thickness of sample 2) / (film thickness of sample 1) was evaluated. The closer this value is to 1, the more uniform the film thickness is regardless of the position of the equipment.

  The obtained results are shown in Table 1.

As is clear from Table 1, in the case of Example 1-1 and Example 1-2, the amount of power consumed for the operation of the arc evaporation source was low.
In each of the examples, the evaporation surface of the cathode was positioned in front of the magnet, so that chromium and chromium nitride did not adhere to the inner wall of the magnet, and the weight of the deposit on the shield plate surface was small. In each example, since the coating did not peel off, the cathode material can be used effectively for forming the coating, and the peeled off material is mixed into the coating to reduce the coating quality (surface smoothness). I did not let it.
Furthermore, in each example, the film thickness uniformity was high, and the film thickness did not decrease much even at a position away from the front of the cathode. From this, it can be seen that in each example, the cathode material was released from the evaporation surface at a wide angle.

  On the other hand, in the case of Comparative Example 1-1, since an electromagnet (coil) was used to form a magnetic field, the electric power consumed for the operation of the arc evaporation source increased. Furthermore, in the case of Comparative Example 1-1, the structure (magnetic coil inner wall, vacuum vessel inner wall) located in front of the cathode evaporation surface was covered with chromium or chromium nitride, and the weight of the deposit increased.

Film formation was performed in the same manner as in Example 1 except that the following conditions were changed. However, carbon having a purity of 99.9% or more was used as the cathode, and a single crystal silicon plate (a length of 15 mm on one side and a thickness of 1 mm) was used as the film formation substrate. In addition, the relative position between the front end of the magnet and the cathode evaporation surface before the start of film formation was adjusted as shown in Table 2 between 0.1 × D ≦ ΔL ≦ 2.0 × D. The cathode position was not changed during film formation. Further, in the film formation process, the film was formed in a high vacuum environment (2.6 × 10 ⁻³ Pa or less) without introducing gas into the vacuum vessel.
As described above, a hard carbon film having a thickness of about 1 μm was formed on the substrate surface. The time required for film formation was 30 min. One film formation was completed when the film thickness reached about 1 μm.
As shown in Table 2, a case where ΔL is 0.7 times D (0.7 × D = ΔL) is referred to as Example 2-1, and hereinafter, ΔL is 0.1 times D, 0. The cases of 3 times, 1.0 times, 1.5 times, 2.0 times, 0.05 times, and 3.0 times are shown in Example 2-2, Example 2-3, and Example 2-, respectively. 4, Example 2-5, Example 2-6, Comparative Example 2-1, and Comparative Example 2-2.

<Evaluation>
5). Abnormal discharge occurrence number In order to evaluate the movement of the arc spot on the cathode evaporation surface during film formation, the voltage across the resistor installed on the shield plate 10 of FIG. 1 was measured. As a result, when arc discharge continues normally on the cathode evaporation surface, the voltage is in the range of 0.1V to -10V, but when abnormal arc discharge occurs between the cathode periphery and the shield plate, The voltage was less than -40V.
Therefore, the case where the time during which the voltage is less than −40 V continues for 1 second or more during one film formation is regarded as abnormal discharge, and the number of times abnormal discharge occurred in one film formation process was evaluated. When the occurrence of abnormal discharge was confirmed, arc discharge was temporarily stopped, the trigger was operated to return to a state where arc discharge continued normally, and film formation was continued.
If the number of abnormal discharge occurrences is less than 10 during the discharge for 30 minutes, it can be said to be good.

6). Impurity amount in the coating The amount of the constituent material (Fe) of the shield plate mixed as an impurity in the hard carbon coating was evaluated. The obtained coating film was analyzed with EDX (fluorescence X-ray analyzer) to determine the Fe / Si signal intensity ratio. The smaller this ratio is, the less impurities are mixed. The Fe content in the cathode was below the EDX detection limit.
Here, since the quantitative analysis accuracy of carbon, which is a light element, is low in EDX analysis, the composition ratio of carbon and Fe is not directly determined, but is set to the ratio of Si. In order to obtain the amount of impurities in the film more accurately, SIMS (secondary ion mass spectrometer), which is a destructive analysis method, may be used. However, EDX is a nondestructive analysis method and is convenient.
7). Coating smoothness (surface roughness Ra)
The surface roughness Ra of each sample was measured using a stylus type surface roughness meter. The surface roughness was measured at five locations per sample, and the average value was evaluated.

  The obtained results are shown in Table 2.

  As apparent from Table 2, in each of the examples, the number of abnormal discharges was small, the amount of impurities in the film was small, and the smoothness of the film was excellent. In particular, in the case of Example 2-1, Example 2-3, Example 2-4, and Example 2-5, the number of abnormal discharge occurrences was further reduced, and the smoothness of the coating was further improved. Furthermore, the cathode evaporation surface after film formation was consumed almost uniformly at the center and the periphery, and the shield plate did not melt.

  On the other hand, in the case of Comparative Example 2-1 where 0.1 × D> ΔL and the case of Comparative Example 2-2 where 2.0 × D <ΔL, the number of abnormal discharge occurrences exceeded 10 times, The amount of impurities was large, the number of droplets on the surface of the film was large, and the smoothness of the film was also deteriorated. Furthermore, in the case of each comparative example, the amount of consumption at the peripheral portion was larger than that near the center of the cathode evaporation surface, and a part of the shield plate adjacent to the cathode was melted.

It is sectional drawing which shows the arc type evaporation source of the 1st Embodiment of this invention. It is a figure which shows the magnetic field formed with the arc type evaporation source of 1st Embodiment. It is sectional drawing which shows the arc type evaporation source of the 2nd Embodiment of this invention. It is a figure which shows the magnetic field formed with the arc type evaporation source of 2nd Embodiment. It is sectional drawing which shows the structural example of the conventional arc type evaporation source. It is sectional drawing which shows the other structural example of the conventional arc type evaporation source.

Explanation of symbols

2 Ground 4 Vacuum chamber (vacuum vessel wall)
DESCRIPTION OF SYMBOLS 10 Shield plate 14 Arc discharge current source 16 Trigger 18 Cathode attachment screw 20 Arc type evaporation source 22 Cathode 23 Evaporation surface 24 Film forming substance 25 Insulator 29 Cathode holding flange 30 Refrigerant 36 Delivery shaft 38 Cathode delivery mechanism 44 Magnetic field line 46 Insulator 60 Resistor 62 Arc spot 70 O-ring seal 84 Trigger drive mechanism 86 Trigger tip position measuring device 88 Trigger tip position initial setting device 90 Comparison calculator 108 Electromagnet excitation power source 112 Cylindrical iron core 114 Electromagnet 116 Cylindrical magnet 120 Magnet cooling mechanism 122 Refrigerant

Claims (6)

In an arc evaporation source that evaporates a cathode material by arc discharge, a magnetic field forming mechanism in which cylindrical and magnetic poles of different polarities are arranged at both ends in an axial direction, and a cathode arranged inside the magnetic field forming mechanism are connected to the magnetic field. A cathode delivery mechanism that advances and retreats in the axial direction of the forming mechanism, the cathode is longer in the axial direction than the diameter, the evaporation surface of the cathode protrudes from the front end of the magnetic field forming mechanism, and the evaporation surface and the front end An arc evaporation source characterized in that the relationship between the axial distance ΔL and the inner diameter D of the magnetic field forming mechanism is 0.1 × D ≦ ΔL ≦ 2.0 × D. In an arc evaporation source that evaporates a cathode material by arc discharge, a magnetic field forming mechanism in which cylindrical and magnetic poles of different polarities are arranged at both ends in an axial direction, and a cathode arranged inside the magnetic field forming mechanism are connected to the magnetic field. A cathode delivery mechanism that advances and retreats in the axial direction of the forming mechanism, and causes the evaporation surface of the cathode to protrude from the front end of the magnetic field forming mechanism, and the axial distance ΔL between the evaporation surface and the front end and the inner diameter of the magnetic field forming mechanism A cathode position control mechanism that outputs or displays control information for controlling the cathode delivery mechanism so that the relationship with D is 0.1 × D ≦ ΔL ≦ 2.0 × D, and the cathode has a diameter of Arc type evaporation source characterized in that it is longer in the axial direction than In an arc evaporation source that evaporates a cathode material by arc discharge, a magnetic field forming mechanism in which cylindrical and magnetic poles of different polarities are arranged at both ends in an axial direction, and a cathode arranged inside the magnetic field forming mechanism are connected to the magnetic field. A cathode delivery mechanism that advances and retreats in the axial direction of the forming mechanism, and causes the evaporation surface of the cathode to protrude from the front end of the magnetic field forming mechanism, and the axial distance ΔL between the evaporation surface and the front end and the inner diameter of the magnetic field forming mechanism A cathode position control mechanism for controlling the cathode delivery mechanism so that the relationship with D is 0.1 × D ≦ ΔL ≦ 2.0 × D, and the cathode is longer in the axial direction than the diameter. A characteristic arc evaporation source. 4. The arc evaporation source according to claim 1, wherein the magnetic field forming mechanism includes a cylindrical permanent magnet. 4. The arc evaporation source according to claim 1, wherein the magnetic field forming mechanism includes an electromagnet having a cylindrical iron core and a coil. A method of manufacturing a film-forming body that forms a film on a substrate surface using an arc evaporation source that evaporates a cathode material by arc discharge, wherein the arc evaporation source has a cylindrical shape and magnetic poles of different polarities in an axial direction. And a cathode disposed inside the magnetic field forming mechanism. The cathode is longer in the axial direction than the diameter, and the evaporation surface of the cathode is longer than the front end of the magnetic field forming mechanism. In addition, the film is formed so that the relationship between the axial distance ΔL between the evaporation surface and the front end and the inner diameter D of the magnetic field forming mechanism is 0.1 × D ≦ ΔL ≦ 2.0 × D. A method for producing a film-forming body, comprising: