JP3919266B2 - Magnetron cathode electrode of sputtering equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetron cathode electrode of a type in which a magnet assembly disposed on the back side of a target of a sputtering apparatus is reciprocated with respect to the target.
[0002]
[Prior art]
Various electrode structures have been proposed for sputtering devices, and among them, magnetron type electrodes are most often used industrially. The reason is that the deposition rate is high and the productivity is high. There are various types of conventional magnetron type electrodes. At present, flat magnetron cathodes with flat targets are industrially useful. In recent years, there has been a demand for uniform film formation with a uniform film thickness distribution on a large-area substrate, particularly for manufacturing liquid crystal display devices. As a sputtering apparatus that satisfies this requirement, there is a system in which film formation is performed while the cathode electrode is stationary and the substrate is continuously moved. However, this apparatus needs to include a load lock chamber, a heating chamber, a transfer buffer space, a sputtering chamber, and the like, and the apparatus tends to be enlarged. In addition, since a non-sputtered region remains on the target surface, particles such as dust are generated, and the yield of the liquid crystal display device is reduced. In addition, non-economics due to non-uniform consumption of the target and non-uniform film quality of the sputtered film are also problems.
[0003]
Recently, in order to solve each of the above problems, a sputtering apparatus in which both the substrate and the cathode electrode are stationary to widen the target consumption region has been studied. Focusing particularly on the magnetron cathode, for example, in the apparatus disclosed in Japanese Patent Application Laid-Open No. 5-239640, the magnet assembly composed of a plurality of magnet units is reciprocated with respect to the target, and the erosion distribution in the target is uniform. Has improved. Further, even in the devices disclosed in Japanese Patent Laid-Open Nos. 4-329874 and 5-9724, similar examples in which a single magnet unit is reciprocated are disclosed.
[0004]
According to the above conventional apparatus, the erosion area on the surface of the target is expanded by reciprocating the magnet assembly, so that the utilization rate of the target is improved, and the ubiquity of erosion can be reduced. In addition, the uniformity of the thickness of the thin film formed on the substrate and the uniformity of the film quality are improved, and further, there is an advantage of suppressing particles generated due to the deposited film on the target surface.
[0005]
[Problems to be solved by the invention]
The first problem with such a film forming apparatus is the uniformity of the film thickness distribution. The size of a substrate for manufacturing a liquid crystal display device has been increasing year by year, and recently has reached about 550 mm × 650 mm. When the uniformity (±% value) of the film thickness distribution is defined by (maximum film thickness value−minimum film thickness value) ÷ (maximum film thickness value + minimum film thickness value) × 100%, it is used for manufacturing a liquid crystal display device. For this purpose, it is necessary to make the film thickness distribution uniformity in the substrate plane about ± 5%.
[0006]
Next, the problem of the film thickness distribution of the conventional sputtering apparatus will be described. FIG. 8 is a front sectional view of a conventional magnetron cathode electrode having five magnet units. A rectangular target 12 is disposed facing the substrate 10 facing downward. A back plate 14 is installed on the back side of the target 12 to form a part of the vacuum chamber. The back plate 14 is fixed to a part 18 of the vacuum wall with the insulating spacer 16 interposed therebetween. A shield 20 is provided around the target 12 to prevent the back plate 14 from being sputtered. Five magnet units 22 are installed on the rear side of the back plate 14, and these magnet units 22 form tunnel-like magnetic lines of force on the target surface. Each magnet unit 22 has a rectangular shape having a long side in a direction perpendicular to the paper surface of FIG. 8, and an inner magnet 24 in which the S pole appears on the upper surface and an outer magnet 26 in which the N pole appears on the upper surface. It consists of. A yoke 27 is fixed to the back side of these magnets. The five magnet units 22 are fixed on the magnet base 28. The magnet base 28 can reciprocate in the left-right direction in FIG. 8 (in the direction of the arrow 30), and accordingly, the plasma formed by the tunnel-like magnetic lines also reciprocates left and right. By such reciprocating motion, the entire surface of the target is consumed. Then, a thin film 32 is deposited on the lower surface of the substrate 10.
[0007]
FIG. 9 shows a film thickness distribution when a film is formed on a glass substrate having a size of 450 mm × 550 mm using such a magnetron cathode. FIG. 9 shows the film thickness distribution of the central 400 mm × 500 mm region of the surface of the substrate with contour lines. Contour line numbers in the figure are percentages when the maximum film thickness is 100%. The long side direction (left-right direction in the figure) of the substrate coincides with the reciprocating direction (direction of arrow 30) of the magnet assembly. The long side direction of the rectangular magnet unit coincides with the short side direction (vertical direction in the figure) of the substrate. The film thickness distribution in FIG. 9 is obtained by observing the film distribution from the top after the film is formed on the downward substrate 10 shown in FIG. As can be seen at a glance, thick portions appear at the upper right and lower left in FIG. It has been found that when the distance between the target and the substrate is shortened, such an uneven thickness distribution is emphasized.
[0008]
The reason why such a bias appears in the film thickness distribution is that the discharge intensity distribution is biased. That is, when the magnetron cathode of FIG. 8 is viewed from above, the discharge intensity is increased in the upper left and lower right regions of the rectangular target 12 (regions facing the thickened film thickness on the substrate). The intensity distribution reflects the film thickness distribution. The phenomenon of uneven discharge intensity is not due to the shape of the film formation chamber. Even if the shape of the film formation chamber is formed with good symmetry with respect to the target, a deviation in film thickness distribution as shown in FIG. 9 occurs. Then, when the polarity arrangement of the magnetic poles of the magnet unit is reversed (the inner magnet surface is N pole and the outer magnet surface is S pole), the discharge intensity bias condition changes, and the film thickness is opposite to FIG. Thick regions appear at the upper left and lower right of the substrate. Therefore, this bias phenomenon is presumed to be related to the drift motion of electrons in the magnetron discharge, but the detailed generation mechanism is unknown.
[0009]
In FIG. 9, the uniformity of the film thickness distribution is about ± 10%, and does not reach the uniformity of ± 5% required for manufacturing the liquid crystal display device. In particular, the decrease in film thickness at both the left and right ends in FIG. 9 is large, which is a major cause of reducing the uniformity of the film thickness distribution. The reason for the decrease in film thickness at the left and right ends is as follows. In the magnetron cathode electrode of FIG. 8, the magnet unit is moved to positions close to the left and right ends of the target in order to make the erosion region of the target as wide as possible. When the magnet unit approaches the left and right ends of the target, the plasma formed along the tunnel-like magnetic field lines is attenuated by the shield 20 existing near the end of the target. This causes a phenomenon that the film thickness decreases at both the left and right ends of the substrate. In order to prevent this, the magnet unit may be kept away from the shield 20, but in this case, the erosion area of the target is narrowed, and the uniformity of the film thickness distribution in the predetermined area of the substrate cannot be ensured. Further, when the erosion area of the target becomes narrow, an area where no erosion occurs is generated around the target, and film deposition occurs conversely in this area, which eventually peels off and causes particles. Further, if it is attempted to ensure the uniformity of the film thickness distribution by enlarging the target in order to cover the narrowing of the erosion region, the entire apparatus becomes large.
[0010]
The present invention has been made to solve such problems, and the object thereof has been to prevent the uniformity of the film thickness distribution in the cathode electrode of the magnetron sputtering apparatus for a large area substrate. An object of the present invention is to provide a magnetron cathode electrode capable of eliminating the two drawbacks, namely, the uneven distribution of the film thickness and the decrease in the film thickness generated at the edge of the substrate to ensure the uniformity of the film thickness distribution.
[0011]
[Means for Solving the Problems]
The magnetron cathode electrode of the present invention enables a reciprocating motion of a magnet assembly including a plurality of elongated magnet units with respect to a target, and a soft magnetic material is disposed between an inner magnet and an outer magnet of the magnet unit, This soft magnetic material is movable in a direction perpendicular to the target surface. The magnet unit has an elongated rectangular shape, and its long side is perpendicular to the reciprocating direction. The soft magnetic body can change the distance from the target surface according to the position along the long side direction of the magnet unit. More preferably, in conjunction with the reciprocating motion, the soft magnetic material periodically moves in a direction perpendicular to the target surface.
[0012]
According to the present invention, the magnetic field strength adjustment function by the soft magnetic material can make the magnetic field strength uniform on the target surface, correct the unevenness of the discharge strength, and improve the film thickness distribution on the substrate. Become.
[0013]
Next, a soft magnetic material that is one of the components of the present invention will be described. Ferromagnetic materials are roughly classified into hard magnetic materials and soft magnetic materials. Hard magnetic materials are not easily magnetized by an external magnetic field, but once magnetized, they are difficult to erase and can store magnetic energy. On the other hand, soft magnetic materials are easily magnetized when an external magnetic field is applied, and have a property suitable as a path for magnetic flux. However, when the external magnetic field is removed, the magnetism disappears and almost all magnetic energy is stored. I can't. In other words, the hard magnetic material has a large coercive force, and the soft magnetic material has a large magnetic permeability and a small hysteresis loss. As described above, since the soft magnetic material has a large magnetic permeability and is suitable as a path for magnetic flux, if the soft magnetic material is inserted in the magnetic field, the magnetic flux passes through the soft magnetic material, and the surroundings of the soft magnetic material. The magnetic field strength of the space decreases. Therefore, this soft magnetic material is suitable for performing the magnetic field strength adjusting function. As for the soft magnetic material used in the present invention, it is not always necessary to use a soft magnetic material having a high magnetic permeability (for example, trade name: Permalloy), and SUS430 / stainless steel is suitable in consideration of corrosion resistance. .
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a front sectional view of an embodiment of the magnetron cathode electrode of the present invention. A cathode body 38 is attached to a part of the wall 34 of the vacuum vessel via an insulating spacer 36. A back plate 40 is attached to the upper portion of the cathode body 38. The cathode body 38 and the back plate 40 constitute a part of the wall surface of the vacuum vessel, and the atmosphere and the vacuum chamber are separated from each other. A target 42 made of a predetermined material is bonded to the surface of the back plate 40 with a low melting point brazing material such as indium. A shield 43 is provided around the target 42 in order to prevent portions other than the target from being sputtered. A water cooling jacket 44 for cooling the back plate 40 and the target 42 is provided on the atmosphere side of the back plate 40. Inside the water cooling jacket 44, a water channel 46 is provided over the entire area in order to cool the entire back plate 40 uniformly. Cooling water is introduced from the water supply pipe 48 to the water channel 46, and the cooling water after target cooling is discharged from the drain pipe 50.
[0015]
A magnet assembly including five magnet units 52 is disposed behind the water cooling jacket 44. Each magnet unit 52 includes an inner magnet 54, an outer magnet 56, and a yoke 58. With respect to the arrangement of the magnetic poles, the surface on the target side of the inner magnet 54 is an S pole, and the surface on the target side of the outer magnet 56 is an N pole. Each magnet unit 52 is fixed on a common magnet base 60. The magnet base 60 is constrained by the guide rail 62 and has a structure capable of moving only in the left-right direction (the direction of the arrow 61) in FIG. That is, the magnet base 60 is connected to the rotating disk 70 via the support pin 64, the crank arm 66, and the pin 68. The rotating disk 70 is coupled to the output shaft of the motor 72. When the motor 72 rotates, the rotating disc 70 rotates, and the circular motion of the rotating disc 70 is converted into the reciprocating motion of the support pin 64 in the left-right direction by the crank motion of the arm 66. Thereby, the magnet base 60 reciprocates in the left-right direction. A plurality of holes for fixing the pins 68 are provided on the rotating disk 70 at different distances from the center of rotation. By changing the position of the pins 68, the amplitude of the reciprocating motion of the magnet base 60 can be changed. . The motor 72 is fixed to a cathode cover 74 that covers the entire cathode electrode. The cathode body 38, the back plate 40, the target 42, and the water cooling jacket 44 are electrically connected and insulated from other portions. Electric power is supplied to the cathode body 38 from an external power source 76.
[0016]
What is characteristic of this embodiment is that a shunt bar 78 made of a soft magnetic material is disposed between the inner magnet 54 and the outer magnet 56 of each magnet unit. The shunt bar 78 is coupled to the linear motion output shaft 82 of the servo motor 80. When the servo motor 80 rotates, the output shaft 82 moves in the vertical direction (the direction of the arrow 79) in FIG. 1 without rotating. The main body of the servo motor 80 is fixed to the magnet base 60. Further, the output shaft 82 has a structure that does not contact the magnet base 60 and the yoke 58. By controlling the rotation angle of the servo motor 80, the vertical position of the shunt bar 78 can be adjusted.
[0017]
FIG. 2 is an enlarged perspective view of the magnet unit 52 located on the rightmost side of FIG. FIG. 3 is a plan view thereof. In these drawings, between the inner magnet 54 and the outer magnet 56 surrounding it, there are two long side shunt bars 78a extending in the long side direction of the rectangular magnet unit, and two pieces extending in the short side direction. A total of four shunt bars of the short side shunt bar 78b are arranged. The output shafts of the two servo motors 80a are coupled to each of the two long side shunt bars 78a at intervals in the longitudinal direction. Each of the two short side shunt bars 78b is coupled to the output shaft of one servo motor 80b.
[0018]
4 is a cross-sectional view taken along line AA in FIG. It can be clearly seen that the output shaft 82 of the servo motor 80b is coupled to the short side shunt bar 78b. The short side shunt bar 78b is slidably disposed between two guides 84 made of fluororesin. These guides 84 are fixed to the yoke 58.
[0019]
FIG. 5A is a cross-sectional view taken along line BB in FIG. It can be clearly seen that the output shaft 82 of the servo motor 80a is coupled to each of two places spaced in the longitudinal direction of the long side shunt bar 78a. By independently adjusting the linear movement amount of the output shaft 82 of these two servo motors 80a, the long side shunt bar 78a can be arbitrarily inclined with respect to the target surface. In FIG. 5A, the upper side of the long side shunt bar 78a in the drawing is inclined so as to be farther from the target surface than the lower side. As shown in FIG. 3, the long side shunt bar 78a is also slidably disposed between the guides 84 made of fluororesin, like the short side shunt bar. In the perspective view of FIG. 2, the guide 84 is not shown in order to avoid complication of the drawing.
[0020]
FIG. 5B is an enlarged cross-sectional view showing a coupling portion between the long side shunt bar 78a and the output shaft 82 of the servo motor 80a. A counterbore 86 is formed in the long side shunt bar 78 a, and a through hole is formed in the bottom of the counterbore 86. A coil spring 88 is inserted into the spot facing 86, and a screw 90 is passed through the coil spring 88. Then, the tip of the screw 90 is fixed by being screwed into the female screw at the tip of the output shaft 82 of the servo motor after passing through the above-described through hole. The short side shunt bar 78b is also fixed to the output shaft of the servo motor using the same structure. FIG. 3 shows the positions of a total of six counterbore 86 formed on the long side shunt bar 78a and the short side shunt bar 78b, and the corresponding positions of the servo motors 80a and 80b. .
[0021]
In this embodiment, as shown in FIG. 3, two long side shunt bars 78a and two short side shunt bars 78b are arranged for one magnet unit. A total of 6 servo motors are installed. These servo motors can be controlled independently. Servo motors 80a and 80b for the shunt bars 78a and 78b and a motor 72 (see FIG. 1) for reciprocating the magnet base 60 are centrally controlled by a single computer.
[0022]
The shunt bars 78a and 78b have a function of adjusting the magnetic field intensity on the target. That is, when the shunt bar approaches the target, a large amount of tunnel-like magnetic flux generated from the magnetic poles on the upper surfaces of the inner magnet 54 and the outer magnet 56 is absorbed by the shunt bar, and the magnetic field strength on the target surface decreases. On the other hand, when the distance between the shunt bar and the target increases, the magnetic flux absorption effect by the shunt bar decreases, and the magnetic field strength on the target surface increases.
[0023]
Next, how to adjust the relative vertical relationship of the four shunt bars in each magnet unit will be described. As pointed out in the problems of the prior art, the uneven distribution of film thickness as shown in FIG. 9 is caused by the upper left and upper right regions (substrates) of the rectangular target 12 when the magnetron cathode of FIG. 8 is viewed from above. This is a reflection of the tendency of the discharge intensity to increase in the region facing the portion where the upper film thickness increases. In order to eliminate the unevenness of the discharge intensity, the magnetic field intensity at the place where the discharge is concentrated should be reduced. If the magnetic field strength is reduced, the drift velocity of electrons that make a circular motion while being constrained by the tunnel-like magnetic field lines is increased and the residence time of the electrons is shortened, so that the plasma density of the discharge is also reduced. In order to reduce the magnetic field strength in a desired region, the shunt bar may be brought closer to the target.
[0024]
In order to reduce the discharge intensity in the upper left and lower right areas of the target 42 when the magnetron cathode of FIG. 1 is viewed from above, the magnetic field intensity may be reduced in this area. . First, in the magnet unit located on the rightmost side, the two long side shunt bars 78a are inclined so that the lower side of the figure is closer to the target than the upper side, as shown in FIG. Further, the lower short side shunt bar on the lower side is brought closer to the target than the upper short side shunt bar on the upper side. On the contrary, in the magnet unit located on the leftmost side, the two long side shunt bars are inclined such that the upper side is closer to the target than the lower side. Further, the upper short side shunt bar on the upper side is brought closer to the target than the lower short side shunt bar on the lower side. By adjusting the vertical position of the shunt bar in this way, when the magnetron cathode of FIG. 1 is viewed from above, the magnetic field strength decreases in the upper left and lower right regions of the target 42, and the bias tendency of the discharge is canceled. Can do.
[0025]
Note that, in the three magnet units in the center portion in the left-right direction, the vertical position of each shunt bar is adjusted symmetrically in the left-right direction and the vertical direction in each magnet unit, unlike the case of the magnet units at the left and right ends. However, when a strong magnet capable of generating a strong magnetic field on the target is used as the inner magnet and the outer magnet, the tendency of the discharge to be biased toward the upper left and lower right on the target becomes stronger. In that case, the discharge uniformity can be improved by adjusting the vertical position of the shunt bar in the second two magnet units from the left and right ends as well as the magnet units at the left and right ends.
[0026]
Furthermore, in this embodiment, in order to solve the tendency of the film thickness to decrease near the left and right ends of the substrate, which was a problem of the prior art, the magnet units at the left and right ends are synchronized with the reciprocating motion of the magnet base 60. The vertical position of the shunt bar is changed periodically. This will be described with reference to FIG. FIG. 6A shows the vertical position of the shunt bar 78 at the moment when the reciprocating magnet base 60 comes to the rightmost side. The shunt bar 78 of the magnet unit located on the rightmost side is located on the lower side as compared with those of other magnet units. Therefore, the magnetic field intensity at the location corresponding to the rightmost magnet unit is greater than at other locations. In this case (periodic movement of the shunt bar linked to the reciprocating movement of the magnet base), the four shunt bars in the magnet unit on the rightmost side have a relative vertical positional relationship as described in FIG. The translation is done while keeping
[0027]
FIG. 6B shows the moment when the magnet base comes to the center of the target 42 in the left-right direction. The shunt bar 78 of the rightmost magnet unit that has moved downward in FIG. 6A moves slightly upward, and the shunt bar of the leftmost magnet unit moves slightly downward so that it is symmetrical as a whole. It is the arrangement of.
[0028]
FIG. 6 (C) shows the moment when the magnet base comes to the leftmost side. In this case, contrary to the case of FIG. 6A, the shunt bar in the magnet unit located on the leftmost side is at the lowest position. Further, the shunt bar 78 of the rightmost magnet unit is further raised as compared with FIG.
[0029]
In this way, by moving the vertical position of the shunt bar 78 in synchronization with the reciprocating motion of the magnet base, when the magnet approaches the shield 43 at the target end, the magnetic field strength at the target end on the approaching side increases. To do. This has the effect of increasing the plasma density at the target end. On the other hand, as described in the problem of the prior art, the plasma formed along the tunnel-like magnetic field lines tends to be attenuated by the shield 43 existing at the end of the target. Therefore, the factor of increasing the plasma density and the factor of decreasing are just balanced, and the plasma density can be made constant regardless of the position of the magnet base during the reciprocating motion. Thereby, the tendency for the film thickness to decrease at the edge of the substrate can be prevented, and a thin film having a uniform film thickness distribution can be formed on the substrate.
[0030]
In the present embodiment, among the five magnet units at the time of film formation, the shunt bars in the three magnet units in the central portion in the left-right direction are fixed and moved in synchronization with the reciprocating motion of the magnet base. I have not done it. In these central magnet units, the relative vertical positions of the shunt bars between the magnet units are appropriately adjusted and fixed in that state so that the film thickness distribution on the substrate is uniform. In the case of the present embodiment, among the three magnet units in the central portion, the shunt bars of the magnet units (second and fourth magnet units from the right side in FIG. 6) located on both sides are connected to the central magnet unit ( By making it relatively higher than the shunt bar of the third magnet unit from the right side, a good film thickness distribution is obtained. The optimum vertical relationship of the shunt bar between the plurality of magnet units in the central portion seems to change from device to device due to the influence of the structure of the sputtering chamber, etc., and needs to be confirmed by experiment for each device. When film formation is repeated over a long period of time, when the target is consumed, the distance between the target and each magnet unit also changes, and the magnetic field distribution on the target may also change. For this reason, when the uniformity of the film thickness distribution on the substrate deteriorates, the film thickness distribution is again adjusted by appropriately adjusting the vertical position of the shunt bar in the three magnet units in the central portion. Uniformity can be restored.
[0031]
FIG. 7 shows a film thickness distribution when a film is formed on a substrate of 450 mm × 550 mm size using the magnetron cathode electrode of this embodiment. FIG. 7 shows the film thickness distribution of the central 400 mm × 500 mm region of the surface of the substrate with contour lines. Contour line numbers in the figure are percentages when the maximum film thickness is 100%. As can be seen from this film thickness distribution, the disadvantages of the prior art, such as the uneven film thickness distribution and the decrease in film thickness at both the left and right sides of the substrate, are eliminated, and the uniformity of the film thickness distribution is about ± It is 5%.
[0032]
The present invention is not limited to the above-described embodiment, and the following modifications are possible.
(1) In the above-described embodiment, five magnet units are provided on the cathode electrode, but any number of magnet units other than five may be provided.
(2) As the shape of the soft magnetic material disposed between the inner magnet and the outer magnet, in addition to the rod-shaped shunt bar as described in the above embodiment, other shapes such as a plate shape are adopted. May be.
(3) In the above-described embodiment, four soft magnetic bodies are arranged in each magnet unit, but any number other than four can be used.
[0033]
【The invention's effect】
As described above, according to the present invention, the magnet assembly can be reciprocated with respect to the target, and the soft magnetic body between the inner magnet and the outer magnet of the magnet unit is oriented in a direction perpendicular to the target surface. Since it is movable, the magnetic field intensity on the target surface can be made uniform, the deviation of the discharge intensity (plasma density) can be corrected, and the film thickness distribution on the substrate is improved. Therefore, even in a sputtering apparatus for a large area substrate, uniform discharge can be generated, and the film thickness distribution on a large substrate can be made uniform.
[Brief description of the drawings]
FIG. 1 is a front sectional view of one embodiment of a magnetron cathode electrode of the present invention.
2 is a perspective view of a magnet unit located on the rightmost side of the cathode electrode in FIG. 1. FIG.
FIG. 3 is a plan view of the cathode electrode of FIG. 2;
4 is a cross-sectional view taken along line AA in FIG.
5 is a cross-sectional view taken along line BB in FIG. 3 and a partially enlarged view thereof.
FIG. 6 is a process diagram showing the interlocking relationship between the reciprocating motion of the magnet base and the vertical motion of the shunt bar.
FIG. 7 is a contour diagram showing the film thickness distribution of a thin film produced using the magnetron cathode electrode of FIG.
FIG. 8 is a front sectional view of a conventional magnetron cathode electrode for a large area substrate.
FIG. 9 is a contour diagram showing the film thickness distribution of a thin film produced using the conventional magnetron cathode electrode shown in FIG.
[Explanation of symbols]
40 Back plate
42 Target
43 Shield
52 Magnet unit
54 Inner magnet
56 outer magnet
58 York
60 magnet base
62 Guide rail
70 rotating disc
72 motor
78 Shunt Bar
80 Servo motor

Claims (4)

In the magnetron cathode electrode of the sputtering apparatus, comprising the magnet assembly disposed on the back side of the target and a moving mechanism for reciprocating the magnet assembly with respect to the target, the following characteristics (a) to ( g ) are provided. Magnetron cathode electrode provided.
(A) The magnet assembly includes a plurality of magnet units having an elongated rectangular shape.
(B) The plurality of magnet units are arranged in parallel to each other such that their long sides are adjacent to each other.
(C) Each magnet unit includes an elongated inner magnet having a magnetic pole on the surface side facing the target, and an outer magnet having a magnetic pole on the surface side facing the target and surrounding the inner magnet, The magnetic poles of the outer magnet and the magnetic poles of the outer magnets have opposite polarities.
(D) The magnet assembly can reciprocate in a direction perpendicular to the long side direction of the magnet unit.
(E) Among the plurality of magnet units, in at least two magnet units disposed on both ends in the reciprocating direction, a soft magnetic material for adjusting a magnetic field is provided between the inner magnet and the outer magnet. Is arranged.
(F) The soft magnetic material can move in a direction perpendicular to the target surface.
(G) The soft magnetic body has a moving structure in which the distance from the target surface can be changed according to the position along the long side direction of the magnet unit.   The soft magnetic body is composed of two long side soft magnetic bodies extending along the long side direction of the magnet unit and two short side soft magnetic bodies extending along the short side direction of the magnet unit. Two vertical movement mechanisms are coupled to the long-side soft magnetic body at an interval in the longitudinal direction, and one vertical movement mechanism is coupled to each short-side soft magnetic body to form one magnet. The magnetron cathode electrode according to claim 1, wherein a total of six of these vertical movement mechanisms for vertically moving the four soft magnetic bodies included in the unit can be driven independently of each other.   2. The magnetron cathode electrode according to claim 1, wherein the soft magnetic material periodically moves in a direction perpendicular to the target surface in conjunction with the reciprocating motion of the magnet assembly.   The magnetron cathode electrode according to claim 1, wherein the soft magnetic material is disposed in all the magnet units included in the magnet assembly.

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