JP2008025001A - Magnetron sputtering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetron sputtering apparatus in which a thick target having a large thickness dimension (film thickness) can be used and a local erosion can be prevented and which is high in use efficiency. <P>SOLUTION: In the magnetron sputtering apparatus, a plasma is generated in a space between a cathode 1 on which a target 5 is placed and a substrate to be treated arranged to oppose to the cathode 1, and sputtering treatment is performed in a plasma space. The magnetron sputtering apparatus has such a cathode structure that the target 5 is formed of a ferromagnetic material, a couple of first and second magnets 2a, 2b, projecting to the plasma space side than the target 5, are provided, the couple of magnets 2a, 2b form a closed loop-like magnetic circuit including the target 5 and the plasma space as its parts, and the target 5 is provided at a position opposing to the magnetic circuit in the plasma space. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sputtering apparatus, and more particularly, to a structure of a magnetron sputtering apparatus related to manufacture of an electronic device and formation of a magnetic film on a magnetic sensor element or the like.

  Conventionally, sputtering apparatuses using magnets have been used for thin film deposition.

  A conventional general sputtering apparatus has a vacuum vessel provided with an inlet and an outlet for an inert gas such as argon (Ar). Inside the vacuum vessel, it is attached to a mounting plate that is grounded so as to have the same potential as the vacuum vessel, and a substrate to be processed that acts as an anode and a target that acts as a cathode are arranged to face each other. Yes.

  The target is attached to a backing plate made of stainless steel or the like, and the backing plate is electrically insulated and attached to the vacuum vessel so as to keep vacuum airtightness.

  A magnet is disposed on the back side of the backing plate, that is, on the target substrate side of the target. The backing plate is provided with a yoke for guiding a magnetic circuit of a magnet disposed on the target substrate side of the target onto the target in the vacuum vessel.

  In the sputtering apparatus configured as described above, an inert gas is introduced into a vacuum vessel, and a voltage of about −400 V is applied to the backing plate by a sputtering power source in a vacuum state.

  As a result, the electrons generated by the discharge generated between the target substrate acting as the anode and the target acting as the cathode are subjected to the magnetic action of the magnetic circuit, and the inert gas molecules Colliding and exciting or ionizing the inert gas to generate a high density plasma.

  Then, the plasma is densified near the upper surface of the target by a magnetic field, and gas ions in the plasma collide with the target and are sputtered with high efficiency. By attaching, a thin film can be formed (see, for example, Patent Documents 1 and 2).

Japanese Utility Model Publication No. 2-118751 Japanese Patent Laid-Open No. 2-194171

  Thus, the conventional sputtering apparatus is configured to obtain a magnetic field for capturing plasma in the vicinity of the upper surface of the target.

  However, when the target is a ferromagnetic material such as cobalt or iron, a magnetic field is drawn into the target and confined in the target, and is unlikely to leak near the upper surface of the target. Therefore, in order to obtain a sufficient leakage magnetic field on the target, the thickness of the target must be formed as thin as about 1 mm, the target material is used for a short period of time, and the sputtering apparatus is used for target replacement work. The frequency of stopping was increased, and there was a problem in mass productivity.

  Furthermore, if the leakage magnetic field is inappropriate, local erosion occurs on the target, and the frequency of target replacement increases more and more.

  Accordingly, the present invention provides a magnetron sputtering apparatus that can use a target having a large thickness dimension (film thickness) even when the target is a ferromagnetic material, prevents local erosion, and has good use efficiency. It is intended.

  The first feature of the magnetron sputtering apparatus of the present invention that achieves the above-described object is that plasma is generated in a space between a cathode on which a target is placed and a substrate to be processed facing the cathode, The target is made of a ferromagnetic material, and includes a first and a second pair of magnets projecting toward the plasma space from the target, and the pair of magnets includes: A closed loop magnetic circuit having the target and the plasma space as a part thereof is formed, and the target has a cathode structure in a position facing the magnetic circuit in the plasma space.

  The magnetron sputtering apparatus of the present invention having such a configuration can form a plasma generation space and a closed magnetic circuit having a part of the path in the target by the role of the target as a yoke material. it can.

  Therefore, the target does not attract and weaken the magnetic field in the plasma generation space, and a sufficient magnetic field strength can be obtained in the plasma generation space. Therefore, the thickness dimension of the target can be increased. Therefore, the use period of the target material can be extended, the frequency of stopping the magnetron sputtering apparatus for replacement is reduced, and the mass productivity can be improved.

  A second feature of the magnetron sputtering apparatus of the present invention is that the first magnet is disposed at the center of the cathode, and the target is disposed in an annular shape so as to surround the first magnet. The second magnet is disposed on the outer periphery of the target.

  According to the magnetron sputtering apparatus of the present invention having such a configuration, since the magnetic field is formed in an annular shape, electrons can be prevented from jumping out in the outer peripheral direction in plan view. That is, the magnetron sputtering apparatus of the present invention easily traps electrons and stabilizes the plasma.

  Furthermore, a third feature of the magnetron sputtering apparatus of the present invention is that the first and second magnets are placed on a yoke that forms a part of the magnetic circuit, and the target and the yoke are substantially the same. It is at a point on the surface.

  The magnetron sputtering apparatus of the present invention having such a configuration has less magnetic loss in the closed magnetic circuit, and as a result, the magnetic field in the plasma generation space becomes stronger.

  Still further, a magnetron sputtering apparatus according to a fourth aspect of the present invention has a backing plate that covers the entire area of the cathode including the first and second magnets and the yoke, and the backing plate includes the first An annular recess formed by recessing the gap between the magnet and the second magnet is formed, and the target is at least disposed in the recess.

  In the magnetron sputtering apparatus of the present invention having such a configuration, impurities other than the target material are not sputtered.

  A fifth feature of the magnetron sputtering apparatus according to the present invention is that the first magnet is rotatably arranged in an eccentric state with respect to the center of the cathode.

  According to the magnetron sputtering apparatus of the present invention having such a configuration, local erosion can be avoided more reliably by disposing the first magnet in a state of being eccentric with respect to the center of the cathode. can do.

  First, the cathode structure in the first embodiment of the magnetron sputtering apparatus of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of the main part showing the structure of the cathode which is the main part of the magnetron sputtering apparatus of the present invention. The configuration of the magnetron sputtering apparatus itself is the same as that of the previously used magnetron sputtering apparatus, and the description thereof is omitted.

  The magnetron sputtering apparatus of the present embodiment includes a first magnet 2a disposed in the center and a second magnet 2b disposed in an annular shape around the first magnet 2a. .

  The first magnet 2a and the second magnet 2b are placed on a disk-shaped first yoke 3a and an annular second yoke 3b, respectively. In the present embodiment, the first yoke 3a and the second yoke 3b are made of iron.

  A backing plate 4 made of stainless copper having a circular outer shape is disposed above the first magnet 2a and the second magnet 2b. In the present embodiment, the backing plate 4 is formed with an annular recess 4a in which a portion corresponding to a gap formed between the first magnet 2a and the second magnet 2b is recessed. . And, from the surface of the backing plate 4 including the concave portion 4a is formed in an annular shape, from a ferromagnetic material such as cobalt, iron, or an alloy thereof as a ferromagnetic material (a trace additive element may be present). A target 5 is provided. That is, in the present embodiment, an annular first target 5a that functions as a main target material is formed in the recess 4a of the backing plate 4 so as to surround the first magnet 2a disposed in the center of the cathode. The second magnet 2b is disposed on the outer periphery of the annular target.

  Here, the concave portion 4a positions the first target 5a on substantially the same plane as the first yoke 3a and the second yoke 3b, and the first magnet 2a and the second magnet 2b are connected to the first target 5a. It is formed to have a depth dimension that protrudes toward the space where plasma is generated (hereinafter referred to as plasma generation space).

  A circular second target 5b is provided at the center of the recess 4a corresponding to the first magnet 2a, and an annular third target is provided at the outer peripheral portion of the recess 4a corresponding to the second magnet 2b. 5c is arranged. Furthermore, a fourth target 5d for connecting the first target 5a and the third target 5c, and a first target 5a and a second target 5b are connected to the outer peripheral side wall and the inner peripheral side wall forming the recess 4a, respectively. A fifth target 5e is disposed.

  In the magnetron sputtering apparatus of the present embodiment configured as described above, the first magnet 2a and the second magnet 2b have a closed-loop magnetic structure in which the first target 5a and the plasma generation space are a part thereof. Form a circuit. At this time, the first target 5a is positioned opposite to the parallel magnetic field formed in the magnetic circuit in the plasma generation space.

  FIG. 2 shows the results of a magnetic field analysis simulation formed by the first magnet 2a and the second magnet 2b in the magnetron sputtering apparatus having such a cathode 1 structure.

  As shown in FIG. 2, in the cathode 1, the first target 5a made of a ferromagnetic material serves as a yoke, so that a magnetic circuit including the first target 5a in part is formed. It has been confirmed that a magnetic field (parallel magnetic field) parallel to the first target 5a is formed between the second target 5b and the third target 5c in the magnetic circuit.

  In addition, the thickness dimension of the 1st target 5a used for this simulation is 20 mm. As described above, in the magnetron sputtering apparatus of this embodiment, even when the first target 5 having a thickness of 20 mm is used, the first target 5 does not weaken the magnetic field, and the magnetic circuit can be formed. It was confirmed that he contributed as York.

  Moreover, the thickness dimension of the 4th target 5d and the 5th target 5e was 1 mm or less. As described above, it is desirable that the fourth target 5d and the fifth target 5e disposed perpendicular to the parallel magnetic field have a small thickness. If the fourth target 5d and the fifth target 5e are formed thick, a magnetic field parallel to the first target 5a cannot be formed. The outer peripheral side wall and the inner peripheral side wall of the backing plate 4 are not formed. This is because it is sufficient to cover the backing plate 4 so that the constituent material is not sputtered during the film formation of the main target material.

  In the magnetron sputtering apparatus having such a cathode 1 structure, the plasma generated in the parallel magnetic field generated at the position facing the first target 5a in the magnetic circuit is captured at high density and is opposed to the parallel magnetic field. The first target 5a serving as a cathode positioned at the same position is sputtered, and a material film of the first target 5a is formed on the surface of the substrate to be processed which is supported on the anode disposed to face the first target 5a. Film.

  At that time, since the parallel magnetic field formed in the magnetic circuit of the magnetron sputtering apparatus of the present embodiment is a wide parallel magnetic field, it is possible to sputter the substantially entire surface of the first target 5a as the main target material, Generation of local erosion can be avoided.

  Further, since the magnetic circuit forms a closed magnetic circuit through the first target 5a, the first yoke 3a, and the second yoke 3b, the magnetic strength is sufficient. Therefore, even if the thickness dimension of the first target 5a made of a ferromagnetic material is increased, a sufficient leakage magnetic field can be obtained on the target 5 and the usage period of the target material becomes longer. In addition, the frequency of stopping the magnetron sputtering apparatus is reduced, and the mass productivity can be improved.

  Since some gas ions in the plasma collide with the outer peripheral side wall and the inner peripheral side wall and are sputtered, the target 5 is disposed on the entire surface of the backing plate 4 as described above. Is preferred. However, if the material of the backing plate 41 is an appropriate material that does not adversely affect the characteristics of the material film formed on the substrate to be processed even if it is mixed into the target material by sputtering, as shown in FIG. The cathode structure in which the second target 5b to the fifth target 5e are omitted and only the first target 5a in the magnetic circuit formed by the magnet 2 is provided (second embodiment) may be employed.

  Further, the one pole made of the first magnet 2a constituting the magnet 2 may be rotatably arranged in a state of being eccentric with respect to the center of the magnet 2 (third embodiment).

  Specifically, as shown in FIG. 4, a circular first yoke 3a on which the first magnet 2a is eccentrically mounted is rotatable by a rotating shaft 6 positioned at the center of the first magnet 2a. The second magnet 2b is arranged with the same dimension from the center of the first magnet 2a.

  Thus, local erosion can be more reliably prevented by rotating one pole of the magnet 2.

  In addition, this invention is not limited to embodiment mentioned above, A various change is possible as needed.

Sectional perspective view which shows the structure of the cathode in 1st Embodiment of the magnetron sputtering apparatus of this invention. Simulation result of cathode magnetic field analysis in first embodiment of magnetron sputtering apparatus of the present invention (backing plate not shown) Sectional perspective view which shows the structure of the cathode in 2nd Embodiment of the magnetron sputtering apparatus of this invention. Schematic sectional view showing the configuration of the cathode in the third embodiment of the magnetron sputtering apparatus of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cathode 2a 1st magnet 2b 2nd magnet 3a 1st yoke 3b 2nd yoke 4 Backing plate 4a Recessed part 5a 1st target 5b 2nd target 5c 3rd target 5d 4th target 5e 5th target 6 Rotating shaft

Claims (5)

A magnetron sputtering apparatus for generating a plasma in a space between a cathode on which a target is placed and a substrate to be processed facing the cathode, and performing a sputtering process in the plasma space, wherein the target is made of a ferromagnetic material. Comprising a first and second pair of magnets protruding from the target toward the plasma space, and the pair of magnets includes a closed loop magnetic circuit having the target and the plasma space as a part thereof. A magnetron sputtering apparatus, wherein the magnetron sputtering apparatus is formed, and the target has a cathode structure located at a position facing a magnetic circuit in the plasma space. The first magnet is disposed at a central portion of the cathode, the target is disposed in an annular shape so as to surround the first magnet, and the second magnet is disposed at an outer peripheral portion of the target. The magnetron sputtering apparatus according to claim 1, wherein: 3. The magnetron according to claim 2, wherein the first and second magnets are placed on a yoke that is a part of the magnetic circuit, and the target and the yoke are on substantially the same plane. Sputtering equipment. A backing plate that covers the entire area of the cathode including the first and second magnets and the yoke, and the backing plate has a circle in which a gap between the first magnet and the second magnet is recessed; An annular recess is formed, the target is disposed at least in the recess, and portions other than the target of the backing plate are covered with the same material as the target. The magnetron sputtering apparatus according to claim 2 or 3. 5. The magnetron sputtering apparatus according to claim 2, wherein the first magnet is rotatably arranged in an eccentric state with respect to the center of the cathode. 6.

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