JP2008121077A - Magnetic circuit for magnetron sputtering - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic circuit for magnetron sputtering capable of attaining the elongation in the service life of a target. <P>SOLUTION: The magnetic circuit is provided with: a rectangular center yoke 21; an internal magnet 22 installed at the central part of the surface thereof to a long side direction and magnetized to a height direction; a first magnet body 2 having external magnets 23 with a polarity reverse to that of the internal magnet 22 installed on both the sides thereof; and second magnet bodies 3, 4 connected to both the end parts of the first magnet body 2. The second magnet body 3(4) includes: a first magnet unit 31 having a rectangular first yoke 311 adjacent to the center yoke 21, and an internal magnet 322 and an external magnet 323 installed in the surface thereof; and a second magnet unit 32 having a second yoke 321 adjacent to the first yoke, and an internal magnet 322 and an external magnet 323 arranged at the surface thereof. The second magnet body 3 is supported movably along the longitudinal direction of the center yoke 21 by a connection plate 5 whose one end side is fixed to the back face of the center yoke 21. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetic circuit incorporated in a magnetron sputtering apparatus used for forming a thin film on a substrate surface.

  In the manufacturing process of electronic components such as semiconductor ICs, since a thin film is formed on the surface of the substrate, the deposition rate of the film is high, and the collision of electrons with the substrate does not occur. Many magnetron sputtering apparatuses are used. According to the magnetron sputtering apparatus, a target disposed in a vacuum chamber so as to face the substrate on the anode side is connected to a high frequency power source to form a cathode, and an inert gas (eg, Ar gas) of 13.33 to 0.13 Pa is used. After the introduction, a voltage is applied between the anode and the cathode to cause glow discharge to ionize the inert gas, and secondary electrons emitted from the target are captured in a plane perpendicular to the magnetic field. The ionization is promoted by causing the cycloid motion to collide with gas molecules, and the target material is condensed (thinned) and deposited as neutral atoms on the substrate, thereby forming a thin film.

  In order to confine the plasma on the target surface and increase the efficiency of thin film generation, a magnetic circuit having a racetrack-like magnetic field distribution is arranged on the back side of the target. The film formation rate is faster than the other parts. As a result, erosion progresses in a region facing the corner portion is accelerated (locally sputtered), so that there is a disadvantage that the thickness of the thin film formed on the substrate becomes non-uniform. Furthermore, since the target is locally eroded, the use efficiency of the target is reduced, and the life of the target is shortened, leading to an increase in the cost for forming a thin film. Therefore, since the magnetic circuit is required to have a small variation in magnetic flux density, various magnetic circuit structures have been proposed.

  For example, Patent Document 1 discloses a magnetic flux density distribution of magnetic lines of force on a target by providing an outer peripheral magnet around a central magnet provided in a central portion of a rectangular target and making a corner portion of the outer peripheral magnet substantially horseshoe-shaped. It is described that can be made uniform. Therefore, in order to extend the life of the target, in addition to making the magnetic flux density distribution uniform, a magnetic field distribution according to the material of the target is required.

  In detail, the rate at which the target is eroded depends on the plasma density and the target material, which increase in proportion to the magnetic field strength, and a multilayer thin film is formed on the semiconductor substrate and the liquid crystal substrate. A suitable target is selected. Therefore, changing the magnetic circuit for each target is not practical in consideration of cost, so use a common magnetic circuit and adjust the distance between the entire magnetic circuit and the target surface as the target material changes. The magnetic field strength applied to the target surface is appropriately adjusted. However, when the distance between the entire magnetic circuit and the target surface is adjusted, the magnetic field strength at the corner portion is improved, but the magnetic field strength at the straight portion is reduced.

  Therefore, a magnetic circuit is divided into a straight portion and a corner portion, and the distance between the corner portion and the target surface is adjusted. For example, in Patent Document 2, a magnetron magnetic field generating magnet is divided into an upper magnet, a middle magnet, and a lower magnet, and their arrangement is changed according to the wear of the target. For example, the progress of wear on the upper and lower portions of the target is fast. Sometimes, it is described that the upper magnet and the lower magnet are separated from the target more than the middle magnet.

Japanese Patent Laid-Open No. 7-34244 (page 3-4, FIGS. 1 and 5) Japanese Patent Laid-Open No. 11-350129 (page 3-4, FIG. 1, FIG. 2, FIG. 3)

  In the structure described in Patent Document 2, it is possible to divide the magnetic circuit and selectively change the distance to the target for each divided part, but this is not sufficient to cope with an increase in the substrate size. That is, with the increase in the size of the magnetic circuit, it is difficult to obtain a uniform film thickness distribution simply by adjusting the distance between the magnetic circuit and the target surface. It is difficult to obtain a distribution.

  Accordingly, an object of the present invention is to provide a magnetic circuit for magtron sputtering that can extend the life of a target with respect to many types of targets of different materials.

  In order to achieve the above object, the magnetron sputtering magnetic circuit of the present invention is provided with a center yoke, an inner magnet installed in a predetermined direction at the center of the surface and magnetized in the height direction, and installed on both sides thereof. A first magnet body having an outer magnet having a polarity opposite to that of the inner magnet; and a second magnet body connected to both ends of the first magnet body, the second magnet body being adjacent to the center yoke. A first magnet, a first magnet unit having an inner magnet and an outer magnet installed on the surface of the first yoke, a second magnet unit having a second yoke adjacent to the first yoke and a magnet disposed on the surface of the first magnet unit. The magnet unit is supported by a connecting member whose one end is fixed to the back surface of the center yoke so as to be movable along the predetermined direction, and the racetrack-shaped magnetic field distribution can be adjusted. And it is characterized in and.

  In the magnetic circuit for magnetron sputtering of the present invention, the second magnet member further includes a third magnet unit adjacent to the second magnet unit, and a fourth magnet unit adjacent to the third magnet unit, Preferably, the magnet unit and the third magnet unit have an outer magnet having the same polarity as the outer magnet, and the fourth magnet unit has an end magnet having the same polarity as the outer magnet.

  In the magnetic circuit for magnetron sputtering of the present invention, it is further preferable that the connecting member has an adjustment hole in which a fastening member for fixing the magnet units is mounted so as to be movable along the connecting direction of the magnet units.

  According to the present invention, both end portions (second magnet bodies) are divided into straight portions (first magnet bodies) and corner portions (second magnet bodies) along the longitudinal direction of the magnetic circuit. Accordingly, the corner portion is further divided into a plurality of magnet units and a mechanism for adjusting the interval between the magnet units is provided, so that the material, polarity or shape of the magnet can be easily changed.

  As a result, the magnetic field strength (the horizontal direction component and the vertical direction component of the magnetic flux density) at a position away from the surface of the second magnet body by a predetermined distance (a position corresponding to the surface of the target) can be changed. Can be adjusted according to the material of the target, a stable film thickness distribution characteristic at the corner can be obtained, and a magnet sputtering apparatus capable of expanding the uniformity of the erosion region of the target can be realized. Therefore, the life of the target can be extended, and a thin film having a uniform film thickness can be formed on the substrate at a low cost.

  Moreover, since the magnetic circuit can be lengthened by increasing the number of magnet units constituting the second magnet body, a magnetic circuit corresponding to the substrate size can be easily produced.

  Details of the present invention will be described below with reference to the accompanying drawings. 1 is a plan view of a magnetic circuit for magnetron sputtering according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1, FIG. 3 is a sectional view taken along line BB in FIG. 5 is a cross-sectional view taken along the line CC of FIG. 1, FIG. 5 is an arrow view of FIG. 2 viewed from the direction D, FIG. 6 shows the second magnet unit, (a) is a plan view, and (b) is (a) in the E direction. 7 shows the third magnet unit, (a) is a plan view, (b) is an arrow view of (a) seen from the F direction, and FIG. 8 shows the fourth magnet unit ( a) is a plan view, and (b) is an arrow view of (a) seen from the G direction.

  A magnetic circuit 1 shown in FIGS. 1 and 2 is arranged at a predetermined interval on the back side of a target (not shown). In order to obtain a racetrack-shaped magnetic field distribution, the first magnetic body 2 and both sides thereof are provided. The connected 2nd magnet bodies 3 and 4 are provided. The right half of FIGS. 1 and 2 shows a state in which the second magnet body 3 is connected to the first magnet body 2, and the left half of FIGS. 1 and 2 has the connecting plate 5 fixed to the first magnet body 2. A state is shown and the state before the 2nd magnet body 4 shown with a dashed-dotted line is fixed is shown.

  The first magnet body 2 is installed so as to sandwich the center yoke 21 having a flat plate shape (for example, a rectangular shape), an inner magnet 22 installed in the center along the long side direction of the yoke, and the magnet as viewed from the plane. The outer magnet 23 is provided. The inner magnet 22 is formed, for example, by arranging a plurality of block magnets (permanent magnets having a rectangular parallelepiped shape) magnetized in the height direction in a line along the long side direction of the yoke, and the outer magnet 23 is opposite to the inner magnet 22. A plurality of block magnets magnetized in the direction are formed in a line in the same direction as the inner magnet 22. The magnetic circuit is configured so that each magnet has substantially the same height.

  The second magnet body 3 includes a first magnet unit 31, a second magnet unit 32, a third magnet unit 33, and a fourth magnet unit that are installed on a flat plate-like (for example, rectangular) connecting member (hereinafter referred to as a connecting plate) 5. 34 are arranged in this order.

  As shown in FIG. 2, the connecting plate 5 has a total length L that overlaps the center yoke (length L1), a portion that supports the first magnet unit 31 (length L2), and a second magnet unit (length). L5), a portion (length L3) that supports the third magnet unit (length L6) and the fourth magnet unit (length L7), and an extra length portion for adjusting the interval between each magnet unit This is the sum of (length L4). When the magnet units are in close contact with each other as shown in FIG. 2, the total length L of the connecting plate 5 is longer than the sum of L1, L2, and L3, and an extra length L4 is generated. Due to the presence of the extra length L4, the first magnet unit 32 to the fourth magnet unit 34 can be moved along the arrangement direction. Therefore, since the interval between adjacent magnet units (the positions of arrows S1, S2, S3, and S4) can be changed, the magnetic field strength can be adjusted.

  As shown in FIG. 5, the connecting plate 5 has a plurality (four in FIG. 5) of female screws 51 at a portion (length L <b> 1) fixed to the center yoke. In addition, in order to make the first magnet unit 32 to the fourth magnet unit 34 movable along the arrangement direction, two rows of long hole-shaped adjustment holes 52 and adjustment holes 53 are formed, and adjustment of each row is performed. The center of the hole is located on the same straight line when viewed from the plane. First, in a portion (length L2) where the first magnet unit 31 is set, two rows (four pieces) of elongated hole-shaped adjustment holes 52 are formed. The number of adjustment holes 52 may be selected according to the length of the first magnet unit 31, and may be two or six or more in the case of two rows. Furthermore, two (two rows) long hole-shaped adjustment holes 53 are formed in a portion (length L3) where the second magnet unit 32 to the fourth magnet unit 34 are set. The length of the adjustment hole 53 is not limited to this, and may be changed according to the number of magnet units other than the first magnet unit. For example, when the number of units is four or more, the length can be further increased. . These adjustment holes are countersunk to prevent the bolt heads from protruding from the connecting plate when a bolt (for example, a hexagon socket head cap screw) is screwed in.

  3 and 4, the first magnet unit 31 includes a flat plate-like first yoke 311 and an inner magnet 312 installed on the surface thereof. The inner magnet 312 is configured by arranging a plurality of block magnets magnetized in the same direction as the inner magnet 22 constituting the first magnet body 2 in two rows, and the outer magnet 313 is the outer magnet 22 constituting the first magnet body 2. A plurality of block magnets magnetized in the same direction are arranged in a line.

  The second magnet unit 32, the third magnet unit 33, and the fourth magnet unit 34 supported by the connecting plate 5 together with the first magnet unit will be described with reference to FIGS.

  As shown in FIG. 6, the second magnet unit 32 includes a rectangular second yoke 321, an inner magnet 332 erected on the surface thereof, and outer magnets 323 located on both sides thereof.

  As shown in FIG. 7, the third magnet unit 33 includes a rectangular third yoke 331, an inner magnet 332 erected on the surface thereof, and outer magnets 333 positioned on both sides thereof.

  As shown in FIG. 8, the fourth magnet unit 34 includes a rectangular fourth yoke 341 and a mountain-shaped end magnet 342 when viewed from a plane erected on the surface thereof.

  After these magnet units 31 to 34 are set (placed) on the connecting plate 5 (see FIGS. 2 and 5), the distance between the magnet units is adjusted and fixed at a position where a predetermined magnetic field strength can be obtained. Is done. That is, the first magnet unit 31 is fixed to the connecting plate 5 by screwing the four bolts 62 and then adjusting the distance from the first magnet body to completely tighten each bolt at a predetermined position. Next, the second magnet unit 31 is fixed to the connecting plate 5 by screwing the two bolts 63 and then adjusting the distance from the first magnet unit 31 to completely tighten each bolt at a predetermined position. Further, the third magnet unit 32 and the fourth magnet unit 33 are also fixed to the connecting plate 5 in the same procedure as the second magnet unit 32. Finally, a bolt (not shown) is screwed into the female thread 343 of the yoke 341 of the fourth magnet unit 34 (see FIG. 8), thereby assembling a magnetic circuit having a predetermined magnetic field strength.

  In the above description, an example in which one second magnet body is divided into four parts is shown. However, the present invention is not limited to this, and the magnetic field distribution can be adjusted by dividing into two or more parts. However, if the number of divisions is small, the adjustment range of the magnetic field is narrowed. If the number of divisions is large, the manufacturing cost and adjustment man-hours of the magnetic circuit increase. Therefore, the division number may be set in consideration of these factors.

  In the present invention, the members constituting the magnetic circuit can be formed of the following materials, for example. The magnet can be formed of a known permanent magnet material, but it is preferable to use a rare earth magnet in order to obtain a high magnetic flux density, and particularly R (R is at least one of rare earth elements such as Nd). ), T (T is Fe or Fe and Co.) and RTB-based sintered magnets (which have been subjected to various surface treatments from the viewpoint of corrosion resistance) using B and B as essential components. More preferred. In this R-T-B system anisotropic sintered magnet, the magnetic flux density on the target surface is improved, the erosion region of the target is expanded, the life of the target is extended, and a uniform thickness is formed on the substrate. In order to realize the film formation having a thickness, it is more preferable to have a magnetic characteristic having a maximum energy product of 40 MGOe or more.

  The yoke and the connecting plate are preferably formed of a ferromagnetic material such as a steel material (for example, SS material), and the surface thereof is preferably covered with, for example, a plating layer (for example, an electroless Ni plating layer) in order to impart corrosion resistance. The spacer may be formed of a nonmagnetic material (for example, an aluminum alloy).

It is a top view of the magnetic circuit for magnetron sputtering concerning embodiment of this invention. It is the sectional view on the AA line of FIG. It is the BB sectional view taken on the line of FIG. It is CC sectional view taken on the line of FIG. It is the arrow line view which looked at FIG. 2 from the D direction. (A) is a top view which shows a 1st corner part, (b) is the arrow line view which looked at (a) from E direction. (A) is a top view which shows a 2nd corner part, (b) is the arrow line view which looked at (a) from F direction. The 3rd corner part is shown, (a) is a top view, (b) is an arrow line view which looked at (a) from the G direction.

Explanation of symbols

1: Magnetic circuit,
2: first magnet body, 21: center yoke, 22: inner magnet, 23: outer magnet,
3: Second magnet body,
31: first magnet unit, 311: first yoke, 312: inner magnet, 313: outer magnet,
32: second magnet unit, 321: second yoke, 322: inner magnet, 323: outer magnet,
33: third magnet unit, 331: third yoke, 332: inner magnet, 333: outer magnet,
34: Fourth magnet unit, 341: Fourth yoke, 342: End magnet,
4: Second magnet body 5: connecting plate, 51, 54: female screw, 52, 53: adjustment hole,
62, 63: Bolt

Claims (3)

A first magnet body having a center yoke, an inner magnet installed in a central direction on the surface thereof and magnetized in a height direction, and outer magnets of opposite polarity to the inner magnets installed on both sides thereof; A second magnet body connected to both ends of the first magnet body, the second magnet body having a first yoke adjacent to the center yoke, an inner magnet and an outer magnet installed on the surface of the first yoke. Each magnet includes a first magnet unit, a second magnet unit having a second yoke adjacent to the first yoke, and a magnet disposed on the surface thereof, and one end side fixed to a back surface of the center yoke. A magnetic circuit for magnetron sputtering, wherein a unit is supported so as to be movable along the predetermined direction, and a racetrack-like magnetic field distribution can be adjusted. The second magnet body further includes a third magnet unit adjacent to the second magnet unit and a fourth magnet unit adjacent to the third magnet unit, wherein the second magnet unit and the third magnet unit are The magnetic circuit for magnetron sputtering according to claim 1, further comprising an outer magnet having the same polarity as the outer magnet, and the fourth magnet unit having an end magnet having the same polarity as the outer magnet. 3. The magnetic circuit for magnetron sputtering according to claim 2, wherein the coupling member has an adjustment hole in which a fastening member for fixing the magnet units is mounted so as to be movable along a coupling direction of the magnet units. .

Images