JPH05179440A - Cathode for magnetron sputtering - Google Patents

Abstract

PURPOSE:To reduce unevenness in the erosion of a target, the max. depth of erosion and the cross-sectional area of an eroded part and to increase the rate of utilization of the entire target for deposition. CONSTITUTION:This cathode for magnetron sputtering has magnetism generating means 1, 2 installed at the central and peripheral parts of the rear side of a target 6 so that the gradient of a magnetic flux density component is made nearly zero between the center and periphery of the target 6. This cathode also has magnetic field adjusting means 60, 67 capable of transferring the zero point of a magnetic flux density component in a perpendicular direction on the front side of the target 6 from the center of the front side of the target 6 toward the periphery.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetron sputtering technique, and more particularly to a magnetron type sputter cathode having a high utilization efficiency of a target material which is a raw material of a thin film and which is made of a film forming material.

[0002]

2. Description of the Related Art The magnetron sputtering technique uses so-called magnetron discharge in which an electric field and a magnetic field are orthogonal to each other, so that low-temperature and high-speed sputtering is possible and has many advantages over the previous two-pole sputtering and the like. In particular, high-density plasma is concentrated near the zero point of the vertical magnetic flux density component near the target,
Since this portion is significantly eroded and takes a substantially V-shaped erosion form, its volume utilization rate is about 20%,
This has been a particular problem when a film is formed using an expensive target material.

In order to improve this point, in the magnetic flux density distribution in the range from the center near the upper surface of the target to the outer circumference, the gradient of the magnetic flux density component in the vertical direction is substantially zero between the center and the outer circumference. A so-called wide erosion cathode has been devised. This prior art cathode is shown in FIG.

[0004]

By improving the magnetron magnetic field (closed leakage magnetic field distribution) near the front and the upper surface of the target, the inclination of the magnetic flux density component in the vertical direction of the vertical and horizontal components is close to the direct upper surface of the target. In order to make it almost zero between the center and the outer circumference, usually the shape and configuration of the magnetic generation means
When the magnetic field generation direction is changed or the magnetic bypass means is arranged, the high density plasma is generated in the radial direction of the target or in a wide range from the center of the target to the outer peripheral direction.

However, among the above-mentioned high-density plasmas, the position at which the highest density is generated intersects with the zero point (0 [Gauss]) of the magnetic flux density component in the vertical direction, from positive to negative, or from negative to positive. Therefore, the rate of erosion at this position tends to increase compared to other parts of the target.

The above-mentioned zero points of the magnetic flux density component in the vertical direction are all the same radius in an arbitrary cross section including the center axis (or center plane) of the ring or race track forming the magnetron magnetic field. Since it is impossible to keep (or distance from the center) from the viewpoint of manufacturing technology, variations occur in the erosion shape, maximum erosion depth, erosion cross-section area, etc. of the target in the arbitrary section, especially the target life. The variation of the maximum erosion depth, which determines the maximum erosion depth, greatly affects the deposition utilization rate of the entire target.

In the rectangular cathode, when the magnetic field distribution of an arbitrary cross section including the center axis (or center plane) of the racetrack-shaped magnetron magnetic field is observed, the difference between the linear portion and the corner portion is large. There was a problem that it took a lot of time and effort to correct the variation.

As an example of the prior art, a magnetron type sputtering cathode for an 8 × 22 inch rectangular target is taken as an example, and the problem will be described below with reference to FIGS. 11 to 15. 11 to 15, 1 is a central magnetic pole, 2 is an outer magnetic pole, 5 is a magnetic bypass means, 6 is a target made of a film forming material, 7 is an intermediate magnetic pole made of a permanent magnet, 9 is a backing plate, 8 is a substrate, Reference numeral 11 is a schematic view of a magnetic field line (magnetron magnetic field) in a tunnel shape, 14 is a schematic cross-sectional view of an annular plasma, 15 is a schematic cross-sectional view showing an eroded portion, and 22 is a water pipe.

In FIG. 11, a magnetic bypass means 5 made of a high magnetic permeability material, which can be placed or embedded on the back surface of the backing plate 9, is provided between the central magnetic pole 1 and the outer magnetic pole 2.
A cross-sectional view in the short side direction of the conventional technology in which the gradient of the vertical magnetic flux density component of the magnetic flux density distribution in the range from the center near the upper surface of the target to the outer circumference is substantially zero between the center and the outer circumference. However, in a certain cross section, the erosion morphology of the target 6 becomes like 15.

However, when observing the erosion shape of the target 6 at the cross-sectional positions shown in FIGS.
As shown in FIG. 15, although variations in the erosion shape, maximum erosion depth, erosion cross-section, etc. immediately after the start of use of the target are small, these variations increase at the end of the life.

Of the maximum erosion depths of the cross sections shown in FIGS. 13 to 15, the one at the cross section position shown in FIG. 15 is the largest, and since the bottom of the target 6 is about to penetrate, another cross section shape is obtained. Even if there is a margin in the maximum erosion depth, it becomes impossible to use the target any more, and the volume utilization rate of the entire target is reduced.

<Object of the Invention> In a conventional cathode called a wide erosion type, an arbitrary cross section including a ring-shaped or racetrack-shaped central axis (or central surface) that forms a magnetron magnetic field near the target. The object of the present invention is to provide a magnetron-type sputter cathode in which variations in target erosion shape, maximum erosion depth, erosion cross-section, etc. are reduced and the deposition utilization rate of the entire target is further improved.

[0013]

The above-described object is to provide a magnetic field generating means disposed behind the target in the vicinity of the central portion and a magnetic field generating means arranged in an annular shape on the outer periphery of the target. A distribution (magnetron magnetic field) is obtained, and the gradient of the magnetic flux density component in the vertical direction of the magnetic flux density distribution in the range from the center near the upper surface of the target to the outer circumference is approximately zero between the center and the outer circumference. According to the above, by providing a magnetic field adjusting means capable of moving the zero point of the magnetic flux density component in the vertical direction in the vicinity of the target on the upper surface of the target in the radial direction or from the center of the target to the outer peripheral direction, Solved the problem.

[0014]

[Function] In a conventional cathode called a wide erosion type, a magnetic field is adjusted so that the zero point of the magnetic flux density component in the vertical direction near the top of the target can be moved in the radial direction on the top surface of the target or from the center of the target to the outer circumference. By adjusting the means, when the zero point is moved periodically from the center to the outer circumference, the generation position of the high-density plasma moves following it, so that the magnetron magnetic field is formed in the vicinity of the target, or It is possible to periodically move the maximum erosion position of the target in an arbitrary cross section including the racetrack-shaped central axis (or the central plane).

Therefore, the erosion shape in the arbitrary cross section
Variations such as the maximum erosion depth and erosion cross-sectional area are reduced, and the deposition utilization rate of the entire target can be further improved.

On the other hand, in the case of a cathode called a wide erosion type, since the gradient of the magnetic flux density component in the direction perpendicular to the target surface is substantially zero between the center and the outer periphery in the vicinity of the direct upper surface of the target, a high density plasma Since the magnetic field by the magnetic field adjusting means necessary for movement is small, the horizontal component of the magnetron magnetic field does not change much, the fluctuation of the plasma density on the target is small, and the influence on the discharge impedance and the film formation speed is negligible. At the same time, since the fluctuation of the magnetic field between the substrate and the target is small, the influence on the ion current density (charged particle density) in the vicinity of the substrate is almost negligible.

[0017]

EXAMPLE As an example of the present invention, a magnetron type sputtering cathode for a rectangular target of 8 × 22 inches will be described as an example with reference to FIGS. 1 to 1
In 0, 1 is a central magnetic pole composed of a permanent magnet which is a magnetic generating means arranged near the center of the back surface of the target, 2 is an outer magnetic pole which is a permanent magnet which is a magnetic generating means arranged annularly on the outer circumference of the back surface of the target, 4 Is a yoke made of a soft magnetic material or a high magnetic permeability material for magnetically coupling the central magnetic pole 1 and the outer magnetic pole 2, and 5 is made of a soft magnetic material or a high magnetic permeability material and is mainly for correcting the leakage magnetic field distribution near the upper surface of the target. Magnetic bypass means, 6 is a target made of a film-forming substance, 7 is an intermediate magnetic pole made of a permanent magnet, 9 is a backing plate provided on the back surface of the target 6, 8 is a substrate, 11 is the target 6
A schematic view of a tunnel-shaped magnetic field line (magnetron magnetic field) formed by each magnetic element on the back surface, 14 is a schematic cross-sectional view of an annular plasma confined by the tunnel-shaped magnetic field line 11, and 15 is for sputtering in the plasma 14. A schematic sectional view showing a portion where the target 6 is eroded by the collision of gas ions, 22 is a water pipe for cooling the inside of the target 6 and the cathode, 67 is a zero point of the magnetic flux density component in the vertical direction near the target, and the upper surface of the target. , An annular electromagnet (solenoid coil) which is a magnetic field adjusting means for moving the target from the center of the target in the outer peripheral direction (radial direction), and 60 is the electromagnet 6.
7 is an excitation power supply for supplying an excitation current to 7, and 63 is a schematic view showing an excitation direction of an electromagnet 67.

The first embodiment of the present invention shown in FIGS. 1 to 6 composed of the above-mentioned main components operates as follows.

Magnetic force lines 11 are formed in front of the target 6 by the respective magnetism generating means arranged on the back surface of the target 6. The magnetron-type sputter cathode is installed in the vacuum processing chamber so as to face the substrate 8 as in the conventional product, and is entrapped in the magnetic field lines 11 when the target 6 is supplied with power from the high voltage power source for glow discharge after the sputtering gas is introduced. The high-density plasma 14 for sputtering is generated.

In the range from the center of the magnetic flux density distribution of the magnetic force lines 11 to the outer circumference, the gradient of the magnetic flux density component in the vertical direction between the center and the outer circumference with respect to the target surface becomes substantially zero.
Each magnetic element is constructed and arranged like a so-called wide erosion type cathode.

At this time, the exciting current density supplied to the electromagnet 67, which is a magnetic field adjusting means arranged near the outer magnetic pole 2, is set to 0.
If [A / mm ² ] is set, the vertical and horizontal components of the leakage magnetic field distribution on the target 6 have a form as shown in FIG.
The center of the generation position of the high-density plasma 14 immediately above is 58 mm from the center in the short-side direction of the target.
The cross-sectional shape is as shown in FIG. This high-density plasma 1
The argon gas ions in 4 are accelerated by the cathode fall and the target 6 is 58
The area [mm] collides most (substantially proportional to the density distribution of the argon gas ions in the plasma 14) and knocks out the target atoms. Target atoms that have been knocked out are the substrate 8
At the same time as it is deposited on the surface and fulfills the sputtering film forming function, the vicinity of 58 [mm] from the center of the target 6 corrodes deepest.

Similarly, the exciting current density supplied to the electromagnet 67 is +5 [A / mm ² ] (exciting direction schematic diagram 6 shown in FIG. 3).
3), the vertical and horizontal components of the leakage magnetic field distribution are as shown in FIG. 4, so that the vicinity of 34 mm from the center of the target 6 is eroded.

Similarly, the excitation current density supplied to the electromagnet 67 is -5 [A / mm ² ] (excitation direction schematic diagram 6 shown in FIG. 5).
3), the vertical and horizontal components of the leakage magnetic field distribution are as shown in FIG. 6, so that the vicinity of 77 [mm] from the center of the target 6 is eroded.

Therefore, according to the first embodiment of the present invention,
The moving width of the center of the high-density plasma generation region is 43 [m
m] (34 [mm] to 7 from the center of the target in the short direction)
Therefore, the zero point of the magnetic flux density component in the vertical direction in the vicinity of the target is moved from the center of the target to the outer peripheral direction by the excitation of the electromagnet 67, which is the magnetic field adjusting means. By optimizing the adjustment of the staying time and repeatedly moving and controlling until the end of the target life, each cross section of the erosion state during the target life to which the conventional technique as shown in FIGS. 13 to 15 is applied is applied. Since variations in erosion shape, maximum erosion depth, erosion cross-section, etc. in the erosion are reduced, the volume utilization efficiency of the target material composed of the film-forming substance can be set to 40% or more.

FIG. 7 shows a second embodiment of the present invention, in which the central magnetic pole 1 and the outer magnetic pole 2 of the cathode shown in the first embodiment of the present invention are composed of obliquely magnetized permanent magnets. In comparison with the above, a plurality of general magnets are used, and the orientations thereof are combined vertically and horizontally to obtain a similar magnetic field distribution, and an electromagnet 67 is provided as a magnetic field adjusting means, and a magnetic flux density component in the vertical direction near the target is provided. Shows a cathode that can be moved from the center of the target to the outer peripheral direction.

FIG. 8 shows a third embodiment of the present invention, in which the central magnetic pole 1 and the outer magnetic pole 2 have their permanent magnets oriented at angles of +90 degrees and -90 degrees with respect to a plane parallel to the plane of the target 6, respectively. And the magnetic bypass means 5 made of a high magnetic permeability material and the intermediate magnetic pole 7 are provided, and the gradient of the magnetic flux density component in the vertical direction of the magnetic flux density distribution in the range from the center in the vicinity of the upper surface of the target to the outer periphery is the center. The magnetic field adjusting means is provided with an electromagnet 67 that is substantially zero between the outer circumference and the outer circumference, and the zero point of the vertical magnetic flux density component near the target is moved from the center of the target to the outer circumference. 1 shows a possible cathode.

FIG. 9 shows a fourth embodiment of the present invention, in which the central magnetic pole 1 and the outer magnetic pole 2 have their permanent magnets oriented at angles of +90 degrees and -90 degrees with respect to the plane parallel to the plane of the target 6, respectively. The magnetic bypass means 5 made of a high magnetic permeability material is provided between the central magnetic pole 1 and the outer magnetic pole 2, and the magnetic flux in the vertical direction of the magnetic flux density distribution in the range from the center near the upper surface of the target to the outer circumference is provided. The electromagnet 6 is used as the magnetic field adjusting means so that the gradient of the density component is substantially zero between the center and the outer circumference.
7 shows a cathode which is provided with 7 and is capable of moving the zero point of the magnetic flux density component in the vertical direction near the top of the target from the center of the target to the outer peripheral direction.

FIG. 10 shows a fifth embodiment of the present invention, in which the central magnetic pole 1 and the outer magnetic pole 2 have their permanent magnets oriented at angles of +90 degrees and -90 degrees with respect to the plane parallel to the plane of the target 6, respectively. Is arranged in an annular shape and is made of a high-permeability material, and is placed on the back surface of the backing plate 9 or can be embedded in the magnetic bypass means 5 between the central magnetic pole 1 and the outer magnetic pole 2 from the center near the upper surface of the target. The vertical magnetic flux density component of the magnetic flux density distribution in the range reaching the outer circumference is made to have a gradient of approximately zero between the center and the outer circumference, and an electromagnet 67 is provided as a magnetic field adjusting means, which is near the target. It shows a cathode capable of moving the zero point of the magnetic flux density component in the vertical direction from the center of the target to the outer peripheral direction.

In the embodiment of the present invention, the electromagnet 67 is used as a magnetic field adjusting means for moving the zero point of the magnetic flux density component in the vertical direction near the target in the radial direction on the upper surface of the target or from the center of the target to the outer peripheral direction. Outer magnetic pole 2
The magnetic field adjusting means may be provided inside the outer magnetic pole 2, or a plurality of magnetic field adjusting means may be provided near the central magnetic pole 1 and the outer magnetic pole 2 to obtain the same effect. 1, FIG. 3, FIG. 5, and FIG. 7 to FIG.
It is not limited to the first to fifth embodiments of the present invention shown in FIG.

Further, the above-mentioned magnetic field adjusting means, which is a feature of the present invention, has a magnetic field generating means arranged near the central portion behind the target and a magnetic field generating means annularly arranged on the outer periphery of the magnetic field adjusting means to close the leakage in front of the target. A magnetic field distribution (magnetron magnetic field) is obtained, and the gradient of the magnetic flux density component in the vertical direction of the magnetic flux density distribution in the range from the center near the upper surface of the target to the outer circumference is approximately zero between the center and the outer circumference. If the magnetic structure and arrangement of the so-called wide erosion type cathode as described above are applicable to all, it is possible to apply them to FIGS. 1, 3, 5, and 7 to 1.
It is not limited to the first to fifth embodiments of the present invention shown in FIG.

Therefore, FIG. 1, FIG. 3, FIG. 5, and FIG.
Even if the N-pole and S-pole polarities of the permanent magnets and the magnetizing directions of the electromagnets shown in the first to fifth embodiments of the present invention shown in FIG. 10 are completely reversed, the same effect can be obtained. , Each of the permanent magnets is a magnetized ring or elliptical integrally molded product,
It may be either a ring-shaped or ellipsoidally-assembled small piece magnet.

Further, in FIG. 10, the inclination of the magnetic flux density component in the vertical direction of the magnetic flux density distribution in the range from the center near the upper surface of the target to the outer circumference is set to be substantially zero between the center and the outer circumference. Therefore, the magnetic bypass means 5 made of a high magnetic permeability material is provided between the central magnetic pole 1 and the outer magnetic pole 2, and the cathode provided with the electromagnet 67 as the magnetic field adjusting means is shown. The same effect can be obtained by mounting or embedding on the back surface of the plate 9.

[0033]

According to the present invention, the leakage magnetic field distribution (magnetron magnetic field) closed in front of the target is obtained, and the magnetic flux density distribution in the range from the center near the upper surface of the target to the outer periphery in the vertical direction is obtained. In the so-called wide erosion type sputter cathode in which the gradient of the magnetic flux density component is set to be substantially zero between the center and the outer periphery,
The zero point of the magnetic flux density component in the vertical direction, in the radial direction of the target upper surface, or by providing a magnetic field adjusting means for moving from the center of the target to the outer peripheral direction, a ring forming a magnetron magnetic field near the target, Or
A magnetron that reduces variations in target erosion shape, maximum erosion depth, erosion cross-sectional area, etc. in any cross-section including the racetrack-shaped central axis (or center plane) and further improves the deposition utilization rate of the entire target. A type sputter cathode can be provided.

In the case of a cathode called a wide erosion type, since the gradient of the magnetic flux density component in the direction perpendicular to the target surface is substantially zero between the center and the outer periphery in the vicinity of the upper surface of the target, the density of a high density plasma is high. Since the magnetic field by the magnetic field adjusting means necessary for movement is small, the horizontal component of the magnetron magnetic field does not change much, the fluctuation of the plasma density on the target is small, and the influence on the discharge impedance and the film formation speed is negligible. At the same time, since the fluctuation of the magnetic field between the substrate and the target is small, the influence on the ion current density (charged particle density) in the vicinity of the substrate is almost negligible. For example, ITO (oxide of indium and tin alloy) is typical. Sensitive to the sputtered characteristics (It is not desirable if the various sputtering characteristics change during film formation. ) Film even when forming the can to provide a magnetron sputtering cathode which enables deposition of a desired film quality with a high target utilization.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a cross-sectional structure of a cathode part in a case where a high-density plasma is located in a substantially middle part of a moving range in a state where an electromagnet that is a magnetic field adjusting means is not excited in the first embodiment of the present invention, and FIG. 3 is a schematic cross-sectional view of the cathode showing the erosion state of the plasma and the target generated by the above.

FIG. 2 is a cross-sectional view of a target portion of a leakage magnetic field generated by a magnetic element of a cathode portion having a sectional structure shown in FIG. It is a diagram showing the magnetic flux density component in the horizontal direction and the magnetic flux density component in the vertical direction.

FIG. 3 is a schematic diagram of a cross-sectional structure of a cathode portion when plasma is located at the innermost circumference of a moving range by exciting an electromagnet that is a magnetic field adjusting means in the first embodiment of the present invention, and generated by it. FIG. 4 is a schematic cross-sectional view of the cathode showing the eroded state of the plasma and the target to be etched.

FIG. 4 shows a target surface in a range from the center of the direct upper surface of the target of the leakage magnetic field generated by all the magnetic elements of the cathode part having the cross-sectional structure shown in FIG. 3 in the first embodiment of the present invention to the outer periphery. FIG. 5 is a diagram showing a magnetic flux density component in a horizontal direction and a magnetic flux density component in a vertical direction.

FIG. 5 is a schematic diagram of a cross-sectional structure of a cathode part when plasma is positioned at the outermost periphery of a moving range by exciting an electromagnet which is a magnetic field adjusting means in the first embodiment of the present invention, and the generated cross-sectional structure thereof. FIG. 3 is a schematic cross-sectional view of a cathode showing an eroded state of a plasma and a target.

FIG. 6 is a diagram showing a leakage magnetic field generated by all the magnetic elements of the cathode portion having the cross-sectional structure shown in FIG. 5 in the first embodiment of the present invention on the target surface in the range from the center of the surface directly above the target to the outer periphery. FIG. 5 is a diagram showing a magnetic flux density component in a horizontal direction and a magnetic flux density component in a vertical direction.

FIG. 7 is a schematic sectional view of a cathode showing a second embodiment of the present invention.

FIG. 8 is a schematic sectional view of a cathode showing a third embodiment of the present invention.

FIG. 9 is a schematic sectional view of a cathode showing a fourth embodiment of the present invention.

FIG. 10 is a schematic sectional view of a cathode showing a fifth embodiment of the present invention.

FIG. 11 is a schematic cross-sectional view of a cathode showing an example of the prior art.

FIG. 12 is an overall perspective view of a target showing a position where a cross section of a target erosion pattern is observed when a conventional technique is applied.

13A and 13B are schematic cross-sectional views of the target erosion pattern shown in FIG. 12 at the cross-section observation position immediately after the target is used and at the end of its life.

FIG. 14 is a schematic cross-sectional view of the target erosion pattern shown in FIG. 12 immediately after the target is used and at the end of its life, at the cross-section observation position.

15 is a sectional observation position of the target erosion pattern shown in FIG. 12, immediately after the target is used, and
It is a cross-sectional schematic diagram at the time of life.

[Explanation of symbols]

 1 Central Magnetic Pole 2 Outer Magnetic Pole 4 Soft Magnetic Material Yoke 5 Magnetic Bypass Means for High Permeability Material 6 Target 7 Intermediate Magnetic Pole 8 Substrate 9 Backing Plate 11 Schematic Diagram of Magnetic Field Lines 14 Schematic Cross Section Diagram 15 Plasma Cross Section Schematic Diagram 22 Water piping 60 Excitation power supply 63 Schematic diagram showing the excitation direction of the electromagnet 67 Electromagnet ~ ▲ 11 ▼ Cross-section observation position of target erosion pattern

Claims (1)

[Claims] 1. A magnetism generating means arranged behind the target in the vicinity of the central portion and a magnetism generating means arranged in an annular shape on the outer periphery of the target so as to obtain a magnetron magnetic field having a leakage magnetic field distribution closed in front of the target, and , The gradient of the vertical magnetic flux density component of the magnetic flux density distribution in the range from the center near the top surface of the target to the outer circumference is set to be substantially zero between the center and the outer circumference. A magnetron-type sputtering cathode comprising magnetic field adjusting means capable of moving a zero point of a magnetic flux density component in the vertical direction in the vicinity of the target in a radial direction on the upper surface of the target or in the outer peripheral direction from the center of the target.