JP5081320B2 - Arc type evaporation source - Google Patents

Description

  The present invention relates to an arc evaporation source of a film forming apparatus for forming a thin film such as a ceramic film such as a nitride and an oxide or an amorphous carbon film, which is used for improving wear resistance of a machine part or the like. Is.

Conventionally, arc ion plating and sputtering methods have been used to coat thin films on the surface of substrates such as machine parts, cutting tools and sliding parts for the purpose of improving wear resistance, sliding characteristics and protective functions. The physical vapor deposition method such as the above is widely known, and in the arc ion plating method, a cathode discharge arc evaporation source is used.
The cathode discharge type arc evaporation source generates an arc discharge on the surface of a target that is a cathode, instantaneously dissolves and evaporates the material constituting the target, and ionizes the material that is ionized on the substrate to be processed. A thin film is formed by drawing into the surface. Since this arc evaporation source has a high evaporation rate and a high ionization rate of the evaporated substance, a dense film can be formed by applying a bias to the substrate during film formation. For this reason, it is industrially used for the purpose of forming a wear-resistant film on a cutting tool or the like.

However, in the arc discharge generated between the cathode (target) and the anode, when the target evaporates around the electron emission point (arc spot) on the cathode side, the molten target before evaporation is emitted from the vicinity of the arc spot. Sometimes. The adhesion of the molten target to the object to be processed becomes a cause of reducing the surface roughness of the thin film.
The amount of molten target material (macro particles) released from the arc spot tends to be suppressed when the arc spot moves at a high speed, and the moving speed of the arc spot may be affected by the magnetic field applied to the target surface. Are known.

In addition, it is known that target atoms that evaporate by arc discharge are highly ionized and ionized in the arc plasma, and the trajectory of ions from the target toward the substrate is affected by the magnetic field between the target and the substrate. There are problems such as.
In order to solve such a problem, the following techniques for applying a magnetic field to the target surface and controlling the movement of the arc spot have been proposed.

  Patent Document 1 discloses a vacuum arc evaporation source in which a ring-shaped magnetic field generation source is provided around a target and a magnetic field perpendicular to the target surface is applied. Patent Document 2 discloses an arc evaporation source in which a magnet is disposed on the back surface of a cathode.

JP-A-11-269634 JP-A-08-199346

However, according to the vacuum arc evaporation source disclosed in Patent Document 1, since the magnetic field is applied to the target surface only from the periphery of the target, the magnetic field becomes weak near the center of the target surface. When discharging near the center where the magnetic field is weakened in this way, many particles are emitted.
This technique of weakening the magnetic field near the center is not only difficult to apply to an evaporation source that uses a large target, but also because the magnetic field lines from the target surface do not extend toward the substrate, evaporating and ionizing The target material thus formed cannot be efficiently guided toward the substrate. In order to avoid this problem, it is conceivable to increase the current value applied to the ring-shaped magnetic field generation source. However, relying only on the increase in current has problems such as heat generation and has a limit.

  Further, according to the arc evaporation source disclosed in Patent Document 2, a strong magnetic field can be applied to the cathode surface by the magnet on the back surface of the cathode, but the magnetic field lines extend in the direction from the center of the cathode surface toward the outer periphery (outside). (Diverging). In a situation where a vertical magnetic field is applied to the cathode surface, the arc spot tends to move in the direction in which the lines of magnetic force fall, so that during discharge, the arc spot moves to the outer peripheral portion and the discharge becomes unstable, and the outer peripheral portion Only a local discharge will occur.

  In view of the above-described problems, the present invention increases the magnetic force between the target and the substrate, and makes the gradient of the magnetic force lines on the target surface vertical, or from the outer periphery of the cathode surface toward the center (inner side). It is an object of the present invention to provide an arc evaporation source that can be controlled to be

In order to achieve the above object, the present invention employs the following technical means.
An arc evaporation source according to the present invention includes a target and a magnetic field that is disposed in front of the target along a direction in which an axial center is substantially perpendicular to the front surface of the target and that is substantially perpendicular to the front surface of the target. An arc-type evaporation source having a ring-shaped magnetic field generating mechanism that is ring-shaped, the magnetization direction being along the radial direction of the ring shape, and surrounding the outer periphery of the target, and the magnetization An outer peripheral magnet arranged so that the direction is parallel to the front surface of the target is provided.

Preferably, the outer peripheral magnet may be arranged such that a front end portion and / or a rear end portion is located behind the front surface of the target and forward of the back surface.
The arc evaporation source according to the present invention is arranged such that the target and the axis in front of the target are along a direction substantially perpendicular to the front surface of the target, and are substantially perpendicular to the front surface of the target. An arc evaporation source having a ring-shaped magnetic field generating mechanism for generating a magnetic field, which is ring-shaped, the magnetization direction is along the radial direction of the ring shape, and the front end portion is behind the rear surface of the target And an outer peripheral magnet disposed so that the magnetization direction is along a direction parallel to the front surface of the target.

Preferably, in the arc-type evaporation source, the target is disk-shaped, and the outer peripheral magnet is a permanent magnet.
Preferably, the magnetic field generation mechanism is an electromagnetic coil.
Furthermore, preferably, the magnetic field on the front surface of the target is 100 gauss or more.

  According to the present invention, the magnetic force between the target and the substrate is strengthened, and the gradient of the magnetic force lines on the target surface is vertical or the direction from the outer periphery of the cathode surface toward the center side (inner side). Can be controlled.

(A) is a side view which shows schematic structure of the film-forming apparatus provided with the arc type evaporation source which concerns on embodiment of this invention, (b) is a top view which shows schematic structure of the film-forming apparatus. It is a figure which shows schematic structure of the arc type evaporation source which concerns on embodiment of this invention. It is a figure which shows the magnetic force line distribution of the arc type evaporation source by a prior art example. It is a figure which shows the magnetic force line distribution of the arc type evaporation source by an Example. It is a figure which shows schematic structure of the modification of the arc type evaporation source which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
An embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 shows a film forming apparatus 6 including an arc evaporation source 1 (hereinafter referred to as an evaporation source 1) according to this embodiment.
The film forming apparatus 6 includes a chamber 11, in which a turntable 12 that supports a base material 7 that is an object to be processed and an evaporation source 1 attached to the base material 7 are arranged. Yes. The chamber 11 is provided with a gas introduction port 13 for introducing a reaction gas into the chamber 11 and a gas exhaust port 14 for discharging the reaction gas from the chamber 11.

In addition, the film forming apparatus 6 is provided with an arc power source 15 that applies a negative bias to the target 2 of the evaporation source 1 to be described later, and a bias power source 16 that applies a negative bias to the substrate 7. The positive electrode side is grounded to the ground 18.
As shown in FIG. 1, the evaporation source 1 has a disk shape (hereinafter referred to as “disk shape”) having a predetermined thickness and disposed so that the evaporation surface faces the base material 7. And a magnetic field forming means 8 (consisting of an outer peripheral magnet 3 and a rear magnet 4) disposed in the vicinity of the target 2. In this embodiment, the chamber 11 functions as an anode. With such a configuration, the evaporation source 1 functions as a cathode discharge type arc evaporation source.

The configuration of the evaporation source 1 provided in the film forming apparatus 6 will be described below with reference to FIGS. FIG. 2 is a diagram showing a schematic configuration of the evaporation source 1 according to the present embodiment.
As described above, the evaporation source 1 includes the disk-shaped target 2 having a predetermined thickness and the magnetic field forming means 8 disposed in the vicinity of the target 2.
In the following description, the surface facing the base material 7 side (base material direction) that becomes the evaporation surface of the target 2 is referred to as “front surface”, and the surface facing the opposite side (direction opposite to the base material) is referred to as “back surface”. (See FIGS. 1 and 2).

The target 2 is made of a material selected according to the thin film to be formed on the base material 7. Examples of the material include metal materials such as chromium (Cr), titanium (Ti), and titanium aluminum (TiAl), and ionizable materials such as carbon (C).
The magnetic field forming means 8 includes an electromagnetic coil 9 as a magnetic field generating mechanism and a ring-shaped (annular or donut-shaped) outer peripheral magnet 3 disposed so as to surround the outer periphery of the target 2. The outer peripheral magnet 3 is composed of a permanent magnet formed of a neodymium magnet having a high coercive force.

The electromagnetic coil 9 is a ring-shaped solenoid that generates a magnetic field in a direction perpendicular to the front surface (evaporation surface) of the target 2. For example, the number of turns is about several hundreds (for example, 410 times). The coil is wound so that the coil has a diameter slightly larger than the diameter. In this embodiment, a magnetic field is generated with a current of about 2000 A · T to 5000 A · T.
As shown in FIG. 2, the electromagnetic coil 9 is provided on the front side of the target 2, and the projection of the electromagnetic coil 9 viewed from the radial direction does not overlap the projection of the target 2. At this time, the electromagnetic coils 9 are arranged so as to be arranged concentrically with the target 2. When the target 2 and the electromagnetic coil 9 arranged in this way are viewed from the base material 7 side, the circular target 2 is almost concentrically inside the annular electromagnetic coil 9.

A current is passed through the electromagnetic coil 9 arranged in this way, and a magnetic field is generated inside the electromagnetic coil 9 from the target 2 side toward the base material 7 side. At this time, the magnetic lines of force that have passed through the front surface of the target 2 can be passed through the electromagnetic coil 9.
As described above, the outer peripheral magnet 3 is a ring body and has a predetermined thickness in the axial direction. The thickness of the outer peripheral magnet 3 is substantially the same as or slightly smaller than the thickness of the target 2.

The appearance of such a ring-shaped outer peripheral magnet 3 is composed of two annular surfaces (annular surfaces) parallel to each other and two peripheral surfaces connecting the two annular surfaces in the axial direction. . The two peripheral surfaces are an inner peripheral surface formed on the inner peripheral side (diameter inner side) of the annular surface and an outer peripheral surface formed on the outer peripheral side (radial outer side) of the annular surface. The width of the inner peripheral surface and the outer peripheral surface is the thickness of the outer peripheral magnet 3.
As shown in FIG. 2, the outer peripheral magnet 3 is magnetized so that the inner peripheral surface is an N pole and the outer peripheral surface is an S pole. In the figure, an arrow heading from the S pole to the N pole is shown. Hereinafter, the direction of the arrow is referred to as a magnetization direction. The outer peripheral magnet 3 of the present embodiment is arranged so that the magnetization direction is along a direction parallel to the front surface of the target 2, that is, the magnetization direction faces the target 2.

The outer peripheral magnet 3 may be a ring-shaped or annular integrated shape, and columnar or rectangular parallelepiped magnets are arranged in a ring-shape or a ring-shape so that the magnetization direction is parallel to the surface of the target 2. Things can be used.
The outer peripheral magnet 3 is arranged so as to surround the outer periphery of the target 2, and is concentric with the target 2 in such an arrangement. At this time, the outer peripheral magnet 3 is disposed so as not to come out of the thickness range of the target 2. Therefore, the projection viewed from the radial direction of the outer peripheral magnet 3 is arranged to overlap the projection viewed from the radial direction of the target 2. That is, in the outer peripheral magnet 3, shadows formed when the outer peripheral magnet 3 and the target 2 are projected in a direction parallel to the evaporation surface of the target 2 overlap with each other, and the shadow of the outer peripheral magnet 3 completely overlaps the shadow of the target 2. It is arranged to be included in.

Thus, the outer peripheral magnet 3 has a front end portion that is an annular surface on the front surface side and / or a rear end portion that is an annular surface on the rear surface side on the back side (rear) from the front surface of the target 2 and on the front side from the back surface. The evaporation source 1 is provided so as to be disposed (front).
When the outer peripheral magnet 3 is provided in this way, the magnetic force lines near the target 2 can be converged and allowed to pass through the evaporation surface of the target 2 as compared with the case where only the electromagnetic coil 9 is used. Further, an effect is obtained that the direction of the magnetic field lines passing through the evaporation surface of the target 2 can be made substantially perpendicular to the evaporation surface.

  In the above-described configuration, the polarity of the electromagnetic coil 9 is the N pole on the substrate 7 side and the S pole on the target 2 side. Moreover, the polarity of the outer peripheral magnet 3 is the N pole on the inner peripheral surface side facing the target 2 and the S pole on the outer peripheral surface side. However, the direction of the current applied to the electromagnetic coil 9 is reversed, and the polarities of the inner peripheral surface and the outer peripheral surface are opposite to those of the outer peripheral magnet 3, so that the polarity is opposite to the above configuration. Even if it comprises, it can obtain the same magnetic field line distribution.

Next, a film forming method in the film forming apparatus 6 using the evaporation source 1 will be described.
First, the chamber 11 is evacuated and vacuumed, and then an inert gas such as argon gas (Ar) is introduced from the gas inlet 13 to remove impurities such as oxides on the target 2 and the substrate 7 by sputtering. To do. After removing the impurities, the inside of the chamber 11 is evacuated again, and the reaction gas is introduced into the chamber 11 that has been evacuated from the gas inlet 13.

When arc discharge is generated on the target 2 installed in the chamber 11 in this state, the substance constituting the target 2 is turned into plasma and reacts with the reaction gas. Thereby, a nitride film, an oxide film, a carbonized film, a carbonitride film, an amorphous carbon film, or the like can be formed on the substrate 7 placed on the turntable 12.
As the reaction gas, a hydrocarbon gas such as nitrogen gas (N ₂ ), oxygen gas (O ₂ ), or methane (CH ₄ ) may be selected according to the application, and the pressure of the reaction gas in the chamber 11 may be selected. May be about 1 to 7 Pa. During film formation, the target 2 may be discharged by flowing an arc current of 100 to 200 A, and a negative voltage of 10 to 30 V may be applied by the arc power supply 15. Further, a negative voltage of 10 to 200 V may be applied to the substrate 7 by the bias power supply 16.

Moreover, it is preferable that the outer peripheral magnet 3 and the electromagnetic coil 9 are configured and arranged so that the magnetic field on the front surface of the target 2 is 100 Gauss or more. Thereby, film formation can be performed reliably. More preferably, the magnetic field at the front surface of the target 2 is 150 gauss.
The distribution state of the magnetic lines of force when the film is formed using the evaporation source 1 of the present embodiment will be described in detail in the following examples.

With reference to FIG. 3 and FIG. 4, characteristics of magnetic field lines generated by the arc evaporation source 1 according to the embodiment of the present invention will be described.
3 and 4, the magnetic force line distribution diagram shown by (a) shows the magnetic force line distribution from the back side of the target 2 to the surface of the base material 7. 3A and 4A, the right end indicates the position of the surface of the base material 7. In FIG. Magnetic field line distribution diagrams shown in (b) in the lower part of FIGS. 3 and 4 are enlarged views around the target 2 in FIGS. 3 (b) and 4 (b), respectively.

Various experimental conditions in the conventional examples and examples described below are shown. For example, the target 2 has a dimension of (100 mmφ × 16 mm thickness) and is made of titanium aluminum (TiAl) having an atomic ratio of titanium (Ti) to aluminum (Al) of 1: 1.
The outer circumference magnet 3 has dimensions (outer diameter 170 mm, inner diameter 150 mmφ, thickness 10 mm), and is formed of a permanent magnet.
[Conventional example]
First, in order to deepen understanding, a conventional example, that is, a distribution of magnetic lines of force when only the electromagnetic coil 9 is used will be described with reference to FIG.

Referring to FIG. 3A, the magnetic field lines generated by the magnetic field formed by the electromagnetic coil 9 are introduced into the coil of the electromagnetic coil 9 while being converged from the target 2 side, and are diffused from the inside of the coil 7 while being diffused from the inside of the coil. To the surface.
Referring to FIG. 3B, the magnetic field lines passing through the front surface (evaporation surface) of the target 2 are inclined in the direction from the outer periphery to the inner periphery of the target 2, and converge from the back surface of the target 2 toward the front surface. Yes.
[Example]
With reference to FIG. 4, the magnetic field line distribution when the arc evaporation source 1 according to the embodiment of the present invention is used will be described.

Referring to FIG. 4A, among the magnetic lines of force generated by the magnetic field formed by the electromagnetic coil 9 and the outer peripheral magnet 2, almost all of the magnetic lines of force from the back side of the target 2 toward the substrate 7 are on the front surface (evaporation surface) of the target 2. It passes through and is introduced into the coil of the electromagnetic coil 9.
Compared with the conventional example shown in FIG. 3A, it can be seen that in the embodiment shown in FIG. 4A, the density of magnetic lines of force between the target 2 and the electromagnetic coil 9 is high. That is, it can be said that the magnetic force between the target 2 and the electromagnetic coil 9 is increased by using the outer peripheral magnet 2.

  Referring to FIG. 4B, it can be seen that the density of magnetic lines of force on the front surface (evaporation surface) of the target 2 is higher than that in the conventional example shown in FIG. Not only this, the lines of magnetic force that pass through the evaporation surface of the target 2 are substantially perpendicular to the evaporation surface of the target 2 (in other words, substantially parallel to the target normal), but only to the evaporation surface. In addition to being almost vertical, it can be said that the target 2 is slightly inclined in the direction from the outer periphery to the inner periphery.

Due to this inclination, the problem that the arc spot moves to the outer periphery during discharge and the discharge becomes unstable, and the problem that local discharge occurs only in the outer periphery are less likely to occur.
As described above, the following can be understood through the embodiments and examples of the present invention. That is, in order to efficiently extract the ionized target material from the evaporation surface of the target 2, if it is desired to increase the magnetic force between the target 2 and the electromagnetic coil 9, the current value to be added to the electromagnetic coil 9 if the outer peripheral magnet 3 is provided. Without increasing the magnetic field strength, the magnetic strength between the target 2 and the electromagnetic coil 9 can be increased.

The position where the outer peripheral magnet 3 is provided is not limited to the position disclosed in the above embodiment.
For example, the outer peripheral magnet 3 can be arranged at a position shifted from the back side of the target 2. By shifting the position of the outer peripheral magnet 3 in this way, the front side of the projection viewed from the radial direction of the outer peripheral magnet 3 overlaps the rear side of the projection viewed from the radial direction of the target 2. In other words, the outer peripheral magnet 3 has projections formed when the outer peripheral magnet 3 and the target 2 are projected in a direction parallel to the evaporation surface of the target 2 partially overlap each other, and the front side of the projection of the outer peripheral magnet 3 is the target. 2 are arranged so as to overlap the back side of the projection.

At this time, the center position in the thickness direction of the outer periphery magnet 3 indicated by the arrow in the outer periphery magnet 3 of FIG. 2, that is, the intermediate position between the front end portion and the rear end portion of the outer periphery magnet 3 is the width along the thickness direction of the target 2. And is disposed on the front side (front side) of the back side of the target 2.
Thus, the outer peripheral magnet 3 in the present embodiment is provided in the evaporation source 1 so that the front end portion is disposed in front of the back surface of the target 2. More specifically, the outer peripheral magnet 3 has a front end portion which is an annular surface on the front surface side of the target 2 and / or a rear end portion which is an annular surface on the rear surface side of the target 2 on the rear side from the front surface of the target 2. It can be said that the evaporation source 1 is provided so as to be arranged (rear) and on the front side (front side) with respect to the rear side.

  As described above, when the outer peripheral magnet 3 is shifted to the back side of the target 2, the magnetic field lines passing through the evaporation surface of the target 2 are more perpendicular to the evaporation surface of the target 2 (in other words, with respect to the target normal line). More parallel). In addition, even when the position of the evaporation surface changes due to consumption of the target 2, the uniformity of the magnetic field on the evaporation surface can be maintained in a good state.

As described above, it is desirable to arrange the outer peripheral magnet 3 so that the front end portion is in front of the back surface of the target 2.
However, as shown in FIG. 5, as a modified example of the arc evaporation source 1 according to the present embodiment, the outer peripheral magnet 3 does not surround the outer periphery of the target 2, and the front end portion is behind the rear surface of the target 2. May be placed in At this time, the front side of the projection viewed from the radial direction of the outer peripheral magnet 3 is located behind the rear side of the projection viewed from the radial direction of the target 2. That is, the projection formed when the outer peripheral magnet 3 and the target 2 are projected in a direction parallel to the evaporation surface of the target 2 does not overlap, and the front side of the projection of the outer peripheral magnet 3 is projected by the target 2. It can arrange | position so that it may become back rather than the back side.

  Needless to say, if the outer peripheral magnet 3 is separated too far from the rear surface of the target 2, the magnetic force on the front surface of the target 2 becomes weak and magnetic lines that diverge outside the target 2 are formed. Therefore, if the condition that the magnetic field lines on the front surface of the target 2 are about 100 Gauss or more and the magnetic field lines inclined toward the center of the target are formed on the outer peripheral part of the target 2 is satisfied, for example, the outer peripheral magnet Reference numeral 3 denotes a position where the axial center intersects the front surface of the target 2 substantially perpendicularly so that the front end portion is behind the rear surface of the target 2 and the magnetization direction is parallel to the front surface of the target 2. May be arranged. More preferably, the outer peripheral magnet 3 may be arranged so as to be substantially coaxial (concentric) with the target 2.

  By the way, it should be thought that embodiment disclosed this time is an illustration and restrictive at no points. In particular, in the embodiment disclosed this time, matters that are not explicitly disclosed, such as operating conditions and measurement conditions, various parameters, dimensions, weights, volumes, and the like of a component deviate from a range that is normally implemented by those skilled in the art. Instead, values that can be easily assumed by those skilled in the art are employed.

  The present invention can be used as an arc evaporation source of a film forming apparatus for forming a thin film.

1 Evaporation source (arc evaporation source)
DESCRIPTION OF SYMBOLS 2 Target 3 Perimeter magnet 6 Film-forming apparatus 7 Base material 8 Magnetic field formation means 9 Electromagnetic coil 11 Vacuum chamber 12 Turntable 13 Gas inlet 14 Gas exhaust 15 Arc power 16 Bias power 18 Ground

Claims (6)

A ring-shaped magnetic field generation mechanism that generates a magnetic field that is arranged in a direction substantially perpendicular to the front surface of the target, and the target is disposed along a direction in which the axial center is substantially perpendicular to the front surface of the target in front of the target; In an arc evaporation source having
It is ring-shaped, and is arranged so that the magnetization direction is along the radial direction of the ring shape, surrounds the outer periphery of the target, and the magnetization direction is along the direction parallel to the front surface of the target. An arc evaporation source characterized in that an outer peripheral magnet is provided.   2. The arc evaporation source according to claim 1, wherein the outer peripheral magnet is disposed such that a front end portion and / or a rear end portion is located behind the front surface of the target and forward of the back surface. A ring-shaped magnetic field generation mechanism that generates a magnetic field that is arranged in a direction substantially perpendicular to the front surface of the target, and the target is disposed along a direction in which the axial center is substantially perpendicular to the front surface of the target in front of the target; In an arc evaporation source having
In a ring shape, the magnetization direction is along the radial direction of the ring shape, the front end portion is behind the back surface of the target, and the magnetization direction is parallel to the front surface of the target An arc-type evaporation source comprising an outer peripheral magnet arranged along the arc.   The arc-type evaporation source according to any one of claims 1 to 3, wherein the target is disk-shaped and the outer peripheral magnet is a permanent magnet.   The arc-type evaporation source according to claim 1, wherein the magnetic field generation mechanism includes an electromagnetic coil.   The arc evaporation source according to any one of claims 1 to 5, wherein a magnetic field in front of the target is 100 gauss or more.