JPH05148641A - Sputtering device - Google Patents

Abstract

PURPOSE:To improve the cooling effect of the sputtering device using an indirect cooling system for a target and to decrease the thermal distortion and deformation of the target. CONSTITUTION:A cooling jacket 18 has an inner peripheral surface 18b which receives the stepped outer peripheral surface 20c of the target 20 and a base 18c which receives the rear surface 20b of the target 20 as cooling surfaces. An annular projecting surface part 18g for enhancing the cooling effect on the rear surface of the target is provided in the central part in the radial direction of the base 18c. The rear surface of the target 20 comes into contact with the projecting surface part 18g of the base 18c of the cooling jacket 18 when the target 20 is mounted to the cooling jacket 18. The rear surface 20b of the target 20 is brought into tight contact with the projecting surface part 18g of the base 18c of the cooling jacket near the plasma ring by a large pressure at the time of the sputtering, by which the target 20 is effectively cooled from the rear side as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering device,
More specifically, it relates to improvements in target cooling and retention mechanisms.

[0002]

2. Description of the Related Art In sputtering, plasma ions are made to collide with the surface of a target (evaporation material) on the cathode side, and the particles repelled from there are deposited on the object to be processed on the opposite anode side to form a film. It is a film forming technology. During sputtering, plasma ions collide with the target, causing the target surface to have a considerably high temperature. If the target is kept in a high temperature state, the target is deformed due to thermal strain, which affects the sputtering efficiency and film formation quality. Therefore, a normal sputtering apparatus is provided with a mechanism for cooling the target.

This type of cooling mechanism includes a direct cooling system and an indirect cooling system. The direct cooling method is a method in which cooling water is introduced close to the back side of the target via a heat conduction plate, and a large cooling efficiency can be obtained, but there is a drawback that the cooling water easily leaks. On the other hand, the indirect cooling method is a method in which cooling water is flowed through a target holding and cooling member called a cooling jacket to cool it, and the target is brought into contact with the cooled cooling jacket to cool the target. Is. Many sputter devices today employ an indirect cooling system. The cooling jacket generally has a cooling surface surrounding the outer peripheral surface and the back surface of the target, and the target is detachably mounted on the cooling surface.

[0004]

By the way, in the sputtering apparatus, the inside of the processing container is evacuated to a high vacuum, and no gas is present between the target and the cooling jacket.
If they do not adhere to each other, a good cooling effect cannot be obtained. However, the general cooling jacket contacts the target so as to wrap the outer peripheral surface and the back surface of the target, but the contact condition is not the same on the outer peripheral side and the back side, and on the outer peripheral side of the target, the target outer peripheral surface is generated due to the thermal expansion of the target. Contacts the inner peripheral surface of the cooling jacket, so the contact condition is good and the cooling effect is large, while on the back side of the target, the back surface of the target is pressed against the bottom surface of the cooling jacket by the temperature difference between the front side and the back side of the target. Although such a force acts, the contact pressure is small in the conventional sputtering apparatus, and thus the cooling effect is small.

As described above, in the conventional sputtering apparatus which employs the indirect cooling method, the target is easily deformed because the cooling from the back side of the target does not work.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a sputtering apparatus that improves the target cooling function by the indirect cooling method and reduces the thermal distortion / deformation of the target. And

[0007]

In order to achieve the above object, the sputtering apparatus of the present invention is a sputtering apparatus provided with a target holding and cooling means for holding and cooling a target, facing the back surface of the target. The target cooling and holding means is provided with a convex portion on the cooling surface.

[0008]

When the target is mounted on the target cooling and holding means, the back surface of the target comes into contact with the convex portion of the cooling surface of the target cooling and holding means. During sputtering, the target thermally expands in the radial direction, and the outer peripheral surface of the target is pressed against and closely adheres to the inner peripheral surface of the target cooling and holding means, so that the target is effectively cooled from the outer peripheral side. Further, a pressure from the front side to the back side is applied to the target due to the temperature difference between the target front surface side and the target back side, and the back surface of the target comes into pressure contact with the convex surface portion of the target cooling and holding means. Since the area of the convex surface is a part of the total area of the cooling surface facing the target, the contact pressure with the convex surface alone is larger than that with the entire outer cooling surface of the target. Is obtained, which in turn gives a large thermal conductivity. In this way, the back surface of the target is brought into close contact with the convex surface portion of the target cooling and holding means with a large pressure, so that the target is also effectively cooled from the back side.

Further, the magnetic field generating means for plasma confinement is rotationally moved at a high speed, for example, 100 rpm or more, and the high-density plasma is rotationally moved on the target surface at the same speed, so that the thermal strain in the target is made uniform. Therefore, the target cooling effect can be further enhanced, and the rotational movement of the target can be prevented.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows the configuration of an indirect cooling type planar magnetron sputtering apparatus according to an embodiment of the present invention.

In this magnetron sputtering apparatus,
The sputter gun 12 is attached downward (inwardly) to the upper surface of the processing container 10, and a semiconductor wafer 52, for example, a semiconductor wafer 52 is provided as an object to be processed on a mounting table of the heating mechanism 50 that is disposed below and facing the sputter gun 12. Placed. A plate 54 around the heating mechanism 50 is a cover plate. A shutter 56 is provided between the sputter gun 12 and the semiconductor wafer 52, and the shutter 56 is retracted from the front surface (sputter surface) of the sputter gun 12 during the sputtering period. Reference numeral 58 is a shutter drive shaft, and 60 is a shutter drive motor.

The sputter gun 12 is a cylindrical casing 1
Have four. A disc-shaped cooling jacket 18 is fixedly attached to the inner lower end portion of the casing 14 via a ring-shaped insulating material 16, and a dish-shaped target 20 is screwed to the cooling jacket 18 with the target surface 20a facing downward.
It is removably attached by. A water passage 18 a for passing cooling water is provided in the cooling jacket 18.

A disc-shaped insulating substrate 24 is attached to the upper portion of the casing 14 so as to close the upper end opening of the casing, and a cylindrical portion 26 is provided below the central portion of the insulating substrate 24 at a central portion of the wall thickness of the cooling jacket 18. It is fixed on the back side of. Inside the cylindrical portion 26, the power feeding rod 28 is provided with the cooling jacket 1.
8 is also passed through to the back surface of the central portion of the wall thickness. The power supply rod 28 is a negative voltage power source (not shown) of about 800 to 1000 volts.
The negative voltage is applied to the target 20 as a cathode voltage via the power feed rod 28 and the conductor in the cooling jacket 18.

A drive ring 32 is rotatably attached to the outer peripheral side of the cylindrical portion 26 via a bearing 30. The gear 34 on the upper part of the drive ring 32 meshes with the gear 38 connected to the output shaft of the drive motor 36, and the drive ring 32 is rotated by the rotation driving force of the drive motor 36 about the cylindrical portion 26 as a central axis. It is designed to rotate at speed. A magnet unit 44 is attached to a disk-shaped support plate 40 below the drive ring 32 via a support rod 42.

A gas supply system 100 for introducing a gas such as an inert gas and an exhaust system 110 for reducing the pressure inside the processing container 10 to a predetermined pressure are connected to the processing container 10.

As shown in FIG. 2, the magnet unit 44 is
Four permanent magnet pieces 44b are fixed to the inner peripheral surface of a ring-shaped pole piece 44a made of a magnetic material at intervals of approximately 90 °. A magnetic field B for confining the target is provided on the surface of the target 20 by the magnetic flux emitted from the magnet unit 44. An electric field E is applied in a substantially vertical direction near the surface of the target 20 which is a cathode electrode, and high-density plasma is confined in a place where the vector product E × B of the electric field E and the magnetic field B is closed in a loop. ,
A so-called plasma ring R as shown in FIG. 3 is formed. As the magnet unit 44 rotates, the plasma ring R traces the surface of the target and rotates in the direction of the arrow at a constant speed. As a result, the high-density plasma acts evenly on the surface (sputtering surface) of the target 20, and the sputtering surface is evenly sputtered.

Next, the construction and operation of the cooling jacket 18 in this embodiment will be described in detail with reference to the partially enlarged sectional view of FIG. 4 and the perspective view of FIG. The cooling jacket 18 is made of a copper alloy such as oxygen-free copper that has a high thermal conductivity and a low outgas in a vacuum, and has a stepped outer peripheral surface 20 of the target 20.
inner peripheral surface 18b receiving c and the back surface 20 of the target 20
It has a bottom surface 18c for receiving b as a cooling surface. Then, the recess 18 for mounting the target is formed in the center of the bottom surface 18c.
d is provided, a screw hole 18e is formed at the center of the bottom of the recess 18d, and a pair of pins 18f for preventing target rotation are provided on both sides of the screw hole 18e so as to project. Although the above-mentioned respective parts of the jacket are common to those of the conventional one, in the present embodiment, a ring-shaped convex surface part 18g for enhancing the cooling effect on the back side of the target is provided at the center part of the bottom surface 18c in the radial direction. When the target 20 is mounted on the cooling jacket 18, the back surface of the target 20 is cooled by the cooling jacket 18.
Contacts the convex surface portion 18g of the bottom surface 18c.

At the time of sputtering, the target 20 thermally expands in the radial direction, and the outer peripheral surface 20c of the target 20 is brought into pressure contact with the inner peripheral surface 18b of the cooling jacket 18 so as to be in close contact therewith. To be cooled.

Further, during sputtering, there is a large temperature difference between the target surface side where the plasma exists and the back side of the target where the cooling jacket 18 exists, so that the target 20 is under a pressure to press it toward the cooling jacket 18 side. Thus, the back surface 20b of the target 20 is brought into pressure contact with the convex surface portion 18g of the bottom surface 18c of the cooling jacket 18. The area of the convex portion 18g is approximately 1 of the total area of the bottom surface 18c.
Since it is about / 3, a larger (about three times) contact pressure is obtained when the back surface 20b of the target 20 is in contact with the back surface 20b of the target 20 only by the convex surface portion 18g than in the entire bottom surface 18c. As a result, large thermal conductivity can be obtained. In addition, it is cooled at the closest point to the plasma, and the cooling effect is great. In this manner, the back surface 20b of the target 20 is close to the plasma and is brought into close contact with the convex portion 18g of the cooling jacket bottom surface 18c with a large pressure, so that the target 20 is effectively cooled by the cooling jacket 18 from the back side as well.

As described above, the target 20 is firmly cooled by the cooling jacket 18 not only from the outer peripheral side but also from the back side, so that the heat distortion is less likely to occur and the target 20 is less likely to be deformed. In addition, in this embodiment, one ring-shaped convex surface portion 18g is provided, but the present invention is not limited to this form, and the convex surface portion can have an arbitrary shape and arrangement configuration. For example, as shown in FIG. The small convex surface portions 18h may be arranged discretely.

As described above, according to this embodiment, it is possible to improve the target cooling effect by improving the target holding and cooling mechanism and suppress the thermal strain / deformation of the target.

By the way, when rotating the plasma ring R on the surface of the target 20 as in the present embodiment, in the conventional magnetron sputtering apparatus, a strong rotational force acts on the target 20 and the anti-rotation pin 18f is bent. It may have been damaged. It is considered that the rotational force acting on the target 20 is due to the non-uniform thermal strain in the target 20 due to the rotation of the plasma ring R and the generation of the stress in the rotational direction. According to the cooling jacket 18 of the present embodiment as described above, the thermal strain in the target 20 can be reduced, so that the rotational stress can be reduced.

However, the present inventor has found another effective method for preventing target rotation. It is a method of rotating and moving the plasma confining magnetic field generating means (magnet unit) at a high speed. In the conventional magnetron sputtering apparatus of this type, the magnet unit is rotationally moved at a speed of about 30 rpm. On the other hand, in the magnetron sputtering apparatus of this embodiment, the magnet unit 44 is rotated at a rotational speed several times higher than the conventional speed, preferably 100 rpm or more. It has been found that when the magnet unit 44, and thus the plasma ring R, is rotationally moved at such a high speed, the thermal strain is made uniform in the target 20, and no stress in the rotational direction is generated.

The graph of FIG. 7 is an example of an experimental result showing the rotational movement amount of the target with respect to the rotational speed of the magnet unit. In this experiment, the target was made rotatable and the rotation speed of the magnet unit was changed in an ordinary magnetron sputtering apparatus. As can be seen from this figure, when the rotation speed of the magnet unit is increased to about 100 rpm, almost no rotational force acts on the target.

As described above, by rotating the magnet unit 44 at a high speed, the rotational deviation of the target 20 can be effectively prevented, so that the target rotation prevention pin 18f of the cooling jacket 18 is not likely to be bent or damaged. .. Further, since the thermal distortion in the target 20 can be made uniform by the high speed rotation of the magnet unit 44, the cooling effect by the cooling jacket 18 can be further enhanced.

The sputtering apparatus of the above-mentioned embodiment is
Although the planar type magnetron sputtering apparatus applies a DC bias, the present invention is also applicable to other types of sputtering apparatuses.

[0027]

As described above, according to the sputtering apparatus of the present invention, the cooling effect from the back side of the target is provided by providing the convex surface portion on the cooling surface of the target cooling and holding means facing the back surface of the target. It is possible to increase the temperature and reduce the thermal distortion and deformation of the target.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing the configuration of a planar magnetron sputtering apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the configuration of a magnet unit as a plasma confining magnetic field generating means in the sputtering apparatus of the embodiment.

FIG. 3 is a plan view showing a plasma ring on a target surface in the sputtering apparatus of the embodiment.

FIG. 4 is a partially enlarged cross-sectional view showing the configuration of a cooling jacket in the sputtering apparatus of the embodiment.

FIG. 5 is a perspective view showing a configuration of a cooling jacket in the sputtering apparatus of the embodiment.

FIG. 6 is a perspective view showing the configuration of a modified example of the cooling jacket in the sputtering apparatus of the embodiment.

FIG. 7 is a characteristic diagram showing a target rotation movement amount with respect to a rotation speed of a magnet unit.

[Explanation of symbols]

 12 Sputter gun 18 Cooling jacket 18c Cooling jacket bottom 18g Convex surface 18f Target rotation prevention pin 20 Target 44 Magnet unit

Claims (1)

[Claims] 1. A sputtering apparatus comprising a target holding and cooling means for holding and cooling a target, wherein a convex surface portion is provided on a cooling surface of the target holding and cooling means facing the back surface of the target. Sputtering equipment.