JP5648532B2 - Arc ion plating equipment - Google Patents

Description

  The present invention relates to an arc ion plating apparatus in which an evaporation source is ionized by arc discharge to form a film on a workpiece.

  An arc ion plating apparatus causes arc discharge in a vacuum using an evaporation source of a metal material or ceramic material as a cathode, thereby evaporating the evaporation source and simultaneously releasing it as ions. ) Is a device for forming a film by applying a negative bias voltage and accelerating and supplying ions to the work surface. As the evaporation source, titanium and chromium are widely used. For example, hard surfaces such as Ti, TiAl, and CrAl are used to improve wear resistance on the surface of a cutting tool made of high-speed steel, cemented carbide, cermet, or the like. It is used in technology for forming a film.

In this type of arc ion plating apparatus, when the arc current concentrates on a minute region on the surface of the evaporation source, the minute region becomes an arc spot to dissolve and evaporate the evaporation source. When this arc spot stays, the material in the vicinity of the staying portion melts and scatters without evaporating, so that a magnet is installed behind the evaporation source to promote the movement of the arc spot.
As the magnetic field, Patent Document 1 recommends that the strength of the magnetic field on the evaporation surface of the evaporation source is 5 mT (millitesla) or more and the arc current value is 200 A or more. Further, it is recommended that the maximum angle θ of the magnetic field lines with respect to the normal line on the evaporation surface is 60 ° or less.
Patent Document 2 discloses that the minimum value of the magnetic flux density on an arbitrary line segment from the center of the evaporation surface along the radial direction of the evaporation surface is 4.5 mT or more, the average value is 8 mT or more, and the standard deviation is 3 or less. It is described that the use efficiency of a cathode (cathode) can be improved by forming a certain magnetic field.
In Patent Document 3, a first magnet is centered on the back surface of the target, and six or more second magnets having a magnetic field opposite in polarity and 0.5 to 1 times the magnetic force of the first magnet on the outer periphery of the back surface are evenly spaced. And an annular electromagnetic coil coaxial with the second magnet and having the same outer diameter is arranged adjacent to each other, and the movable area of the arc spot is controlled to expand the erosion area and improve the target life. ing.

Japanese Patent No. 40345563 JP 2009-144236 A

However, there is a phenomenon that the arc spot enters other than the surface portion of the evaporation source during the discharge, resulting in a problem that the discharge cannot be stably performed, for example, the power supply is stopped.
Further, since the magnetic force in the central portion is smaller than that in the peripheral portion of the target, the arc spot is concentrated in the central portion, and droplets are easily generated, which causes the smoothness of the thin film surface to be impaired.
In order to solve this problem, if the magnetic force is increased, the magnetic force in the vicinity of the workpiece also increases, and the range of the ion particles from the evaporation source increases, during which the valence of the ion particles increases and the force that is drawn into the workpiece Tends to increase and the residual stress of the thin film tends to increase. In this case, it is considered that the bias voltage applied to the workpiece should be lowered. However, since the magnetic force is large, it is difficult to reduce the residual stress even if the bias voltage is lowered.

  The present invention has been made in view of such circumstances, preventing the phenomenon that the arc spot enters other than the surface portion of the evaporation source, causing stable discharge, improving the surface smoothness, and reducing the residual stress. An object of the present invention is to provide an arc ion plating apparatus capable of forming a thin film having high controllability.

The arc ion plating apparatus of the present invention is provided with a central magnet on the back surface of the evaporation source so as to increase the magnetic flux density of the surface of the evaporation source by concentrating from the peripheral portion to the central portion, and radially outside the evaporation source. In addition, a double ring-shaped magnet having opposite polarities is provided, and the polarities inside the central magnet and the double ring are reversed, and an end having a predetermined width is formed inward from the end face of the evaporation source. The magnetic flux density on the inner region surface excluding the part region is 10 to 15 mT, the magnetic flux density on the end region surface is larger than the magnetic flux density on the inner region surface, and the distance from the surface of the evaporation source to the workpiece is 120. The integrated value of the absolute value of the magnetic flux density during that distance is 260 mT · mm or less.

Since the arc spot generated on the evaporation surface is an emission point of electrons, it is important to make it possible to move around on the entire evaporation surface on average in order to improve the utilization efficiency of the evaporation source. In the present invention, the arc spot can move randomly at high speed on the surface of the inner region where the magnetic flux density on the evaporation surface is 10 to 15 mT. Further, in order to obtain the effect of confining the arc spot in the discharge region, the magnetic flux density needs to be 10 mT or more. If the magnetic flux density exceeds 15 mT, the presence of the arc spot itself is remarkably limited, and there is a problem that the film forming speed is remarkably reduced. Moreover, the problem that the voltage value of arc discharge rises from the normal time also occurs.
On the other hand, since the magnetic flux density is larger in the end region of the evaporation source than in the inner region surface, the arc spot on the inner region surface is bounced back by the strong magnetic field in the end region even if it goes to the end region. , Returned to the inner area. Therefore, it is possible to prevent the arc spot from entering the region other than the surface portion from the end region, and to move the arc spot while being confined in the inner region. The predetermined width is preferably 1 cm from the end face.
Thereby, the evaporation source can be uniformly evaporated in the surface, and the smoothness of the thin film surface can be enhanced.

  In addition, since the integrated value of the absolute value of the magnetic flux density between the evaporation source and the workpiece is reduced so that the magnetic flux density in the vicinity of the workpiece is reduced, the range of ion particles in the evaporation source can be shortened. it can. For this reason, an increase in the valence of ions can be suppressed, and the effect of drawing ions by the bias voltage with respect to the work can be reduced. As a result, the residual stress of the thin film can be easily controlled.

In addition, a central magnet is provided on the back surface of the evaporation source so that the magnetic flux density on the surface of the evaporation source is concentrated and concentrated in the central portion from the peripheral portion. Therefore, by increasing the magnetic flux density at the center of the evaporation source with the central magnet, the magnetic flux density on the surface of the evaporation source is made uniform in the surface, and the polarity of the ring magnet is reversed. Due to the heavy arrangement, it is possible to cancel the magnetic field in the space up to the workpiece and reduce the integrated value.

In the arc ion plating apparatus of the present invention, the magnetic flux density on the end region surface is preferably 3 mT or more larger than the magnetic flux density on the inner region surface.
In order to prevent the arc spot from moving out of the end region, it is important that the magnetic flux density on the end region surface be at least 3 mT greater than the magnetic flux density on the inner region surface. More preferably, the magnetic flux density on the inner region surface is 10 to 15 mT, and the magnetic flux density on the end region surface is 18 mT or more.

In the arc ion plating apparatus of the present invention, the magnetic field lines on the evaporation surface have an angle θ of 0 ° <θ <20 ° with respect to the normal line of the evaporation surface, and the surface of the end region is inclined toward the inner region. It is good to have.
When the line of magnetic force is set at the above angle with respect to the normal line of the evaporation surface, there is an effect of confining the arc spot on the evaporation surface.
In addition, the force that moves the arc spot is determined by the magnitude of each of the component parallel to the evaporation surface and the component perpendicular to the evaporation surface in the magnetic field, and the direction is a direction perpendicular to the component parallel to the evaporation surface. , The direction of synthesis of the parallel component and the same direction. Therefore, if the component parallel to the evaporation surface in the magnetic field is directed to the inner region of the evaporation surface, a force acts in the direction to return to the inner region of the evaporation surface even if the arc spot moves to the end region surface. Jumping out of the area is prevented.

In the arc ion plating apparatus of the present invention, the magnetic flux density in the inner region may have a standard deviation of 3 or less.
In the inner area of the evaporation surface, local concentration is eliminated and the arc spot moves evenly over the entire surface, so that the evaporation source is evenly consumed and utilization efficiency is improved.

  According to the arc ion plating apparatus of the present invention, the arc spot can be moved randomly at high speed on the surface of the evaporation source, and the phenomenon that the arc spot can enter other than the surface portion can be prevented to generate a stable discharge. And the smoothness of the thin film surface can be enhanced. In addition, since the integrated value of the absolute value of the magnetic flux density from the evaporation source to the work has been reduced, the effect of attracting ions by the bias voltage to the work can be reduced and the residual stress of the thin film can be easily controlled. it can.

It is the plane sectional view showing typically one embodiment of the arc ion plating apparatus of the present invention. It is a longitudinal cross-sectional view of FIG. It is a schematic diagram which shows the vector of the magnetic force line on an evaporation surface. It is a schematic diagram explaining the movement principle of the arc spot by the magnetic force line on an evaporation surface. It is a graph which shows distribution of the magnetic flux density on an evaporation surface, and the angle of a line of magnetic force.

Hereinafter, an embodiment of an arc ion plating apparatus of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the arc ion plating apparatus 1 of this embodiment is provided with a table 4 for holding a workpiece (coating object) 3 in a vacuum chamber 2, and through the table 4. On both sides, an evaporation source 5 as a cathode is provided. The table 4 has a mechanism in which a plurality of support bars 6 holding a plurality of workpieces 3 are erected on the upper surface of the table 4 at intervals in the circumferential direction, and the support bars 6 rotate horizontally as indicated by arrows in FIG. The turntable itself is a turntable that can be turned horizontally by a turning mechanism (not shown). And it is the structure which revolves while rotating the workpiece | work 3 hold | maintained at the support rod 6. As shown in FIG.
The vacuum chamber 2 is provided with a gas introduction port 7 for introducing a reaction gas into the interior and a gas discharge port 8 for exhausting the reaction gas from the inside, and on the table 4 behind the table 4. A heater 9 is provided to heat the workpiece 3 and increase the adhesion of the coating.

In the illustrated example, the evaporation source 5 is formed in a disk shape, and one surface of the evaporation source 5 faces the work 3 on the table 4 (perpendicular to the radial direction of the table 4). The arrangement is such that the evaporated surface 11 becomes the evaporation surface 11. Then, an anode electrode 12 is arranged with an appropriate position on the evaporation surface 11 of the evaporation source 5, the evaporation source 5 is a cathode, and an arc power source 13 that applies a negative bias voltage between the anode electrode 12 and the evaporation source 5. Is connected.
The table 4 is also connected to a bias power source 14 that applies a negative bias voltage to the work 3 held by the table 4.

In addition, a central magnet 15 is provided at the center of the back surface of the evaporation source 5, and two ring magnets 16 </ b> A and 16 </ b> B are provided at positions radially outside the evaporation source 5 so as to surround the outer peripheral surface of the evaporation source 5. Yes. These magnets 15, 16A, 16B are permanent magnets.
The central magnet 15 at the back of the evaporation source 5 is formed in a conical shape having a thickness at the central portion larger than that at the peripheral portion, and is disposed in a state where the conical surface faces the evaporation source 5. In other words, the pole surface (conical surface) of the central magnet 15 is arranged such that the central portion is closest to the back surface of the evaporation source 5 and gradually separated toward the peripheral portion. For this reason, the magnetic flux density on the surface of the evaporation source 5 increases in a concentrated manner from the peripheral part to the central part.

On the other hand, the pair of ring magnets 16A and 16B provided outside the evaporation source 5 are arranged in a double ring shape with respect to the center of the evaporation source 5 and have opposite polarities. Further, the magnet 16 </ b> A on the inner side is arranged so as to be opposite to the pole of the central magnet 15.
In the illustrated example, the pole on the side where the central magnet 15 faces the front of the evaporation source 5 is an N pole, and among the ring magnets, the inner magnet 16A has an S pole on the side facing the front of the evaporation source 5; The outer magnet 16 </ b> B is arranged such that the pole on the front side of the evaporation source 5 is an N pole.

  By adopting such a magnet arrangement, the central magnet 15 concentrates the magnetic lines of force at the center of the surface of the evaporation source 5 to increase the magnetic flux density at the center, and a part of the magnetic field of each magnet 15, 16A, 16B. Acts to overlap each other. The ring-shaped magnets 16A and 16B are concentrated at the outer peripheral portion of the evaporation source 5 and weaken toward the central portion of the evaporation source 5, but are arranged in double with opposite polarities. Are reversed and act to cancel each other.

  Then, by appropriately setting the magnetic flux density of such a plurality of magnets 15, 16 </ b> A, 16 </ b> B, these combined magnetic fields act on the surface of the evaporation source 5. The magnetic flux density on the surface of the evaporation source 5 is 10 to 15 mT (millitesla) on the surface of the inner region C excluding the ring-shaped end region E having a width of 1 cm inward from the outer peripheral end surface of the evaporation source 5, and the standard deviation is 3 On the surface of the ring-shaped end region E, the magnetic flux density of the surface of the inner region C is greater than 15 mT.

Further, the magnetic field lines passing through the evaporation source 5 have an angle θ with respect to the normal line of the evaporation surface 11 of 0 ° <θ <20 °, and the angle is directed toward the inner region C on the surface of the ring-shaped end region E. Are formed to be inclined.
As schematically shown in FIG. 3 by the vector of the magnetic field lines on the evaporation surface 11, the angle with respect to the normal line of the evaporation surface 11 is set to 0 ° <θ <20 ° in the inner region C as shown by the broken line. In the end region E, as shown by a solid line, the angle of the magnetic field lines having a magnetic flux density larger than that of the inner region C with respect to the normal line of the evaporation surface 11 is 0 ° <θ <20 °. It is formed in a state inclined toward C.

A method of forming a film on the workpiece 3 using the arc ion plating apparatus 1 configured as described above will be described.
First, the work 3 is held on the support rod 6 of the table 4 and the inside of the vacuum chamber 2 is evacuated. Then, Ar or the like is introduced from the gas introduction port 7, and oxides on the evaporation source 5 and the work 3 are removed. Impurities are removed by sputtering. Then, after evacuating the inside of the vacuum chamber 2 again, a reactive gas such as nitrogen gas is introduced from the gas introduction port 7, and an arc discharge is generated using the anode electrode 12 directed to the evaporation source 5 as a trigger. 5 is converted into plasma and reacted with a reactive gas, and a nitride film or the like is formed on the surface of the work 3 on the table 4.

During this film forming process, the discharge current is concentrated on a minute region on the evaporation surface 11 of the evaporation source 5, and an arc spot having a diameter of several μm that is extremely active at a high temperature is generated. While moving around at random speed, the evaporation source 5 is instantly dissolved and evaporated and released as ions.
At this time, a magnetic field is generated on the evaporation surface 11 of the evaporation source 5 by the magnets 15, 16A and 16B described above, and the movement of the arc spot is controlled by the action of the magnetic field.

Specifically, since the magnetic flux density is 10 to 15 mT on the surface of the inner region C excluding the end region E on the outer periphery of the evaporation source 5, the arc spot generated on the surface of the inner region C is , And is confined in the inner region C. Further, since the magnetic field lines on the evaporation surface 11 are set to 0 ° <θ <20 ° with respect to the normal line of the evaporation surface 11 due to the interaction of the two magnets 15 and 16 described above, the arc spot is converted into the evaporation surface. 11 acts to be confined.
The reason why the standard deviation of the magnetic flux density in the inner region C is 3 or less is to exhaust the evaporation source 5 evenly.

  On the other hand, since the magnetic flux density is set higher in the end region E of the evaporation source 5 than in the inner region C surface, even if the arc spot on the inner region C surface is directed toward the end region E, the end region E It is bounced back by the strong E magnetic field and returned to the inner region C. If the magnetic flux density in the end region E is set to be 3 mT or more larger than the magnetic flux density in the inner region C, the effect of returning the arc spot to the inner region C can be exhibited.

  In addition, since the angle of the magnetic force line with respect to the normal line of the evaporation surface 11 is formed so as to be inclined toward the inner region C in the end region E, there is an effect of returning the arc spot toward the inner region C. According to Robson et al. (Springer, Cathodic arcs, p. 140), the force applied to the arc spot by the magnetic field generated on the evaporation surface 11 is parallel to the evaporation surface 11 when the magnetic field indicated by B in FIG. 4 is taken as an example. The magnetic field component BH becomes a force AH in a direction inclined by 90 ° with respect to the magnetic field component, and the magnetic field component BV perpendicular to the evaporation surface 11 acts on the force AV in the same direction as the parallel magnetic field component BH. The arc spot A is moved by the combined force of the forces AH and AV acting from these magnetic fields. Therefore, the direction of the force AV acting on the arc spot A from the magnetic field can be directed to the inner region C by directing the angle θ of the magnetic force line with respect to the normal line of the evaporation surface 11 to the inner region C. Further, by increasing the magnetic field component BV perpendicular to the evaporation surface 11, the magnitude of the force AV can be increased, and the force for returning the arc spot A to the inner region C can be increased.

By increasing the magnetic flux density in these end regions E and inclining the magnetic field lines toward the inner region C, the arc spot A tends to move to the end regions E as indicated by arrows in FIG. Then, it is returned and returned to the inner area C.
Further, since the arc spot A is confined in the inner region C and restricted beyond the end region E in this way, the phenomenon that the arc spot enters other than the evaporation source surface portion is prevented, and stable discharge is maintained. be able to.

  Further, the central magnet 15 and the pair of ring magnets 16A and 16B provide a large magnetic flux density on the surface of the evaporation source 5, and the magnetic flux density decreases as the distance from the evaporation source 5 increases. The integrated value of the absolute value of the magnetic flux density between them can be reduced, particularly the magnetic flux density in the vicinity of the workpiece is reduced, and the range of the ion particles of the evaporation source 5 can be shortened. For this reason, an increase in the valence of ions can be suppressed, and the effect of drawing ions by the bias voltage with respect to the work can be reduced. As a result, the residual stress of the thin film can be easily controlled.

Examples carried out to confirm the effects of the present invention will be described.
TiAl (Ti: Al = 50: 50) having a diameter of 100 mm and a thickness of 16 mm was used as an evaporation source.
The pair of ring magnets outside the evaporation source and the central magnet on the back of the evaporation source were both permanent magnet neodymium magnets having a coercive force of 2000 kA / m and a surface magnetic flux density of 1150 mT. As a comparative example, on the outside of the evaporation source, a single ring magnet, a neodymium magnet, the coercive force was 2000 kA / m, and the surface magnetic flux density was 1150 mT. The magnet at the center of the back surface of the evaporation source was a ferrite magnet having a coercive force of 250 kA / m and a surface magnetic flux density of 350 mT.

When the evaporation source was arranged in the arc ion plating apparatus to which such a magnet was attached and the magnetic field on the evaporation surface was measured, it was as shown in FIG. In FIG. 5, a broken line is an Example and a continuous line is a comparative example. In both cases, the horizontal axis shows the center of the evaporation source as 0, the distance from the center is shown on the left and right, and both the left and right ends are the outer peripheral ends.
As shown in FIG. 5, in the example, there is a substantially constant region in a relatively wide range from the center of the evaporation source, and it is larger than 15 mT near the outer peripheral end. In the portion of the inner region excluding the end region, the magnetic flux density was 3 or less standard deviation. Further, the angle (inclination angle) formed between the magnetic force line and the normal line of the evaporation surface is in the range of 0 ° <θ <20 ° over the entire surface. Further, since the angle is relatively small, there is little difference between the absolute value of the magnetic flux density and the vertical component.

On the other hand, in the comparative example, the outer peripheral end of the evaporation source is 15 mT or more, but the magnetic field in the vicinity of the center is a very small value of 7 mT or less. There is a large variation in the magnetic flux density as a whole including the inner region. Further, the angle (tilt angle) formed between the magnetic force line and the normal line of the evaporation surface is in the range of 0 ° <θ <20 ° near the center of the evaporation surface, but exceeds 20 ° near the outer peripheral edge. .
The magnetic flux density was measured on a straight line passing through the center of the evaporation source surface at the evaporation source surface with a magnetometer. On the surface of the evaporation source, the measurement locations were set at 10 mm intervals, and the magnetic flux density in the vertical direction and parallel direction of the evaporation source surface was measured at each measurement point. Further, from these measured values, the magnetic flux density at each measurement point and the angle (tilt angle) formed by the lines of magnetic force and the normal line of the evaporation surface were calculated. The standard deviation of the magnetic flux density on the surface of the evaporation source was calculated from the numerical value of the magnetic flux density excluding the portion where the magnetic flux density in the end region was large.

Next, as shown in Table 1 and Table 2, the film was formed under various conditions, and the integrated magnetic force from the evaporation source to the workpiece and the residual stress of the film were measured. Nitrogen gas was used as the reaction gas.
The integrated magnetic force was obtained by obtaining the magnetic flux density at intervals of 10 mm on a straight line from the evaporation source surface center to the workpiece with a magnetometer, and integrating this from the evaporation source to the workpiece.
Residual stress was determined by 2θ-sin ² φ method using X-ray diffraction.
Table 1 shows a comparative example, and Table 2 shows an example.

  As is apparent from the results of Tables 1 and 2, in the example, by adjusting the bias voltage, the residual stress of the film varies greatly, and it can be seen that the control is easy.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, in the above embodiment, the central magnet is formed in a conical shape. However, any magnet can be used as long as the magnetic flux density of the evaporation source can be increased by concentrating on the central portion rather than the peripheral portion. The magnetic flux density may be distributed by providing a plurality of concentrated portions in the portion and dispersively arranging the peripheral portions.
In addition, although the evaporation source is formed in a disk shape, it can also be applied to a columnar shape, a cylindrical shape, etc. In this case as well, the magnetic field as described above is applied with a range of 1 cm width from the end face as an end region. You only have to set it.

DESCRIPTION OF SYMBOLS 1 Arc ion plating apparatus 2 Vacuum chamber 3 Work 4 Table 5 Evaporation source 6 Support rod 7 Gas introduction port 8 Gas discharge port 9 Heater 11 Evaporation surface 12 Anode electrode 13 Arc power supply 14 Bias power supply 15 Central magnet 16A, 16B Ring-shaped magnet

Claims (4)

A central magnet is provided on the back surface of the evaporation source so that the magnetic flux density on the surface of the evaporation source is concentrated and concentrated in the central portion from the peripheral portion. A magnetic flux density on the surface of the inner region excluding an end region having a predetermined width inward from the end surface of the evaporation source , wherein a ring-shaped magnet is provided and the inner magnet and the double ring have opposite polarities inside. 10 to 15 mT, the magnetic flux density on the surface of the end region is larger than the magnetic flux density on the surface of the inner region, and the distance from the surface of the evaporation source to the workpiece is 120 to 300 mm. An arc ion plating apparatus, wherein an integrated value of absolute values of magnetic flux density is 260 mT · mm or less. Arc ion plating apparatus according to claim 1, wherein the magnetic flux density in the end regions the surface is characterized by more 3mT greater than the magnetic flux density of the inner region surface. The magnetic field lines on the evaporation surface have an angle θ of 0 ° <θ <20 ° with respect to the normal line of the evaporation surface, and the surface of the end region is inclined toward the inner region. Or the arc ion plating apparatus of 2. The arc ion plating apparatus according to any one of claims 1 to 3 , wherein the magnetic flux density in the inner region has a standard deviation of 3 or less.

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