JP5903217B2 - Magnetron sputtering electrode and sputtering apparatus - Google Patents

Description

  The present invention relates to a magnetron sputtering electrode and a sputtering apparatus.

  2. Description of the Related Art Conventionally, a magnetron type sputtering (hereinafter referred to as “sputtering”) apparatus has a magnetron sputtering electrode. And a magnetron cathode unit having a magnet unit which is disposed below the target and forms a tunnel-like magnetic flux above the target.

  When sputtering a target by applying DC power or AC power having a negative potential to the target, the electrons above the target are captured by the above-mentioned magnetic flux and the secondary electrons generated by sputtering are captured. The plasma density is increased by increasing the density and increasing the collision probability between these electrons and rare gas gas molecules introduced into the vacuum chamber. According to this sputtering apparatus, for example, there is an advantage that the film forming speed can be improved without significantly increasing the temperature of the processing substrate. In recent years, a transparent conductive film is formed in a manufacturing process of a large area flat panel display. Widely used.

  Here, a case where a target having a substantially rectangular shape in plan view is used as an example will be described. As a magnet unit, a longitudinally-shaped support plate (yoke) arranged in parallel with the target is arranged in the longitudinal direction at the center of the upper surface of the support plate (yoke). For example, Patent Document 1 includes a configuration in which a central magnet is disposed linearly along the periphery, and peripheral magnets having different polarities on the target side are disposed over the entire periphery of the upper surface of the support plate so as to surround the periphery of the central magnet. Is known.

  When such a magnet unit is used, plasma is generated in a racetrack shape passing through a position where the vertical component of the leakage magnetic field is 0, but the magnetic flux density in the peripheral region of the sputtering surface of the target is locally increased. . That is, when looking at the magnetic field profile along the extension line of the central magnet, the vertical component of the magnetic field has one peak at a position closer to the inside from both ends of the central magnet in the X direction. For this reason, the sputtering rate in the peripheral region of the sputtering surface is increased, and a substantially uniform thin film is obtained over the entire surface of the substrate, but the target is eroded intensively in that region (that is, the target is preferentially sputtered). Area). In this case, there arises a problem that the utilization efficiency of the target is lowered. For this reason, it has been conventionally practiced to uniformly erode the target by changing the position of the tunnel-like magnetic flux (see, for example, Patent Document 2).

  That is, the longitudinal direction of the target is the X direction, the width direction of the target perpendicular to the X direction is the Y direction, the width of the support plate is made slightly smaller than the target, and the magnet unit is aligned along the Y direction of the target during sputtering. Reciprocate at the predetermined speed on the same plane between two points. At this time, it is also considered to reciprocate the magnet unit in the X direction of the target.

  As described above, it is known that a local erosion region is generated in the target even when the magnet unit is moved relative to the target during sputtering. This is presumably because a region where the stay time of the part having a high magnetic flux density is relatively long (so-called cross point) occurs during one reciprocation of the magnet unit. Therefore, for example, Patent Document 3 discloses that a magnetic shunt (magnetic body) having a rectangular outline is attached to a predetermined region of the backing plate and the magnetic field strength in this region is locally reduced. However, when a rectangular magnetic shunt is used, depending on the mounting orientation, local erosion along the side of the magnetic shunt occurs separately around the projection surface of the magnetic shunt on the target, improving target utilization efficiency. It has been found that the problem of restricting the effect of.

Japanese Patent Laid-Open No. 7-34244 JP 2005-290550 A JP 2005-68468 A

  This invention makes it the subject to provide the magnetron sputtering electrode and sputtering apparatus which can suppress generation | occurrence | production of the local erosion area | region to a target, and the utilization efficiency of the target improved further in view of the said point.

  In order to solve the above-mentioned problems, the magnetron sputtering electrode of the present invention is arranged on the lower side of the target with the target elongated in one direction arranged with the substrate to be processed in the sputtering chamber and the sputtering surface side of the target on the upper side. The magnet unit that forms a tunnel-like magnetic flux above the target, the longitudinal direction of the target in the X direction, the width direction of the target perpendicular to the X direction as the Y direction, and the magnet unit from a predetermined starting point Moving means that repeats the relative movement with respect to the target in at least one of the direction and the Y direction to return to the starting point, and the residence time of the portion having a high magnetic flux density in one cycle until returning to the starting point A magnetic shunt that locally lowers the magnetic field strength in the region where the magnetic field is long is fixed relative to the target. At least two sides extending along each of these sides, characterized in that inclined respectively toward and in the Y-direction target inward of and in the X-direction target center.

  According to the present invention, the magnetic shunt is provided at a position where the stay time of the portion having a high magnetic flux density is long, and the magnetic field strength is locally reduced. Here, if a magnetic shunt having a rectangular shape (rectangular shape) is used as in the conventional example, and each side of the magnetic shunt is attached so as to be substantially parallel to each side of the rectangular target, the magnetic shunt on the target Around the projection surface of the shunt, local erosion along the side occurs separately on the target. This is because part of the magnetic flux leaking from the magnet unit leaks to the target side along the surface of the magnetic shunt, so that the magnetic flux density around the projection surface increases locally (the magnetic field strength is locally increased). This is considered to be because the plasma easily stays around the projection plane even if the magnet unit is moved.

  On the other hand, in the present invention, the magnetic shunt has at least two sides extending along the X direction, and each of these sides is inclined in the center in the X direction and inward in the Y direction target. It was confirmed that local erosion can be prevented from occurring on the target. This is due to the original function of the magnetic shunt, in which the magnetic flux density is concentrated by the region where the magnetic flux density is concentrated continuously and gradually inward in the X direction due to the inclined side of the magnetic shunt. In addition, it can be considered that this is due to the function of locally changing the shape of plasma generated in a racetrack shape. Thereby, the life of the target can be extended by more evenly eroding the target. As a result, the relative utilization of the magnet unit and the target during sputtering can increase the target utilization efficiency in combination with the ability to expand the target erosion area.

  In this invention, it is preferable that the said magnetic shunt has the outline of the planar view triangle whose length of the said 2 sides is equivalent. According to this, the vertical component of the magnetic field has one peak at the position where the magnet unit is located inward from both ends of the central magnet in the X direction, and a predetermined value is applied from both ends of the target in the X direction for discharge stability and the like. In the case where the range is a non-erodible region, it is possible to realize a configuration in which the region provided with a magnetic shunt is eroded substantially evenly with a simple shape.

  In the present invention, the magnetic shunt is preferably formed by laminating a plurality of similar and different areas. According to this, the shape of the plasma can be appropriately changed according to the target erosion. For this reason, the structure which erodes a target more uniformly is realizable.

  Here, even if the same magnet unit is used, the position where the residence time of the part with a high magnetic flux density becomes long is the process condition (for example, the pressure in the vacuum chamber and the gas introduced into the vacuum chamber). The flow rate may vary. For this reason, when reducing the magnetic field intensity at the above-mentioned position, for example, it is conceivable to change the magnetic flux density locally by changing the configuration of the magnet unit, but this is extremely troublesome. Therefore, it is preferable that the magnetic shunt is attached to the lower surface of the backing plate joined to the target. Thereby, even after installing the magnetron sputtering electrode of the present invention in the sputtering apparatus, it may be possible to realize a configuration in which the magnetic field strength is locally reduced by a simple operation.

  In order to solve the above problems, a sputtering apparatus of the present invention includes a magnetron sputtering electrode according to any one of claims 1 to 5, a vacuum chamber capable of maintaining a vacuum state, and the vacuum A gas introduction means for introducing a predetermined gas into the chamber and a sputtering power source that enables power supply to the target are provided.

The figure which illustrates the sputtering device of this invention typically. (A) is a figure which illustrates typically the change of magnetic flux when moving a magnet unit relative to a target. FIG. 3B is a cross-sectional view taken along line bb in FIG. 2A, schematically illustrating target erosion when a magnetic shunt is not provided. FIG. 3C is a cross-sectional view taken along line cc of FIG. 2A, schematically illustrating target erosion when a rectangular magnetic shunt is provided. (A) is a figure explaining arrangement | positioning to the backing plate of the magnetic shunt of embodiment of this invention. (B) is the side view. (C) is sectional drawing which followed the CC line | wire of Fig.3 (a) explaining the erosion of a target typically.

  Hereinafter, with reference to the drawings, a magnetron sputtering according to the present invention will be described by taking as an example a case where a glass substrate used for manufacturing a flat panel display is used as a substrate S to be processed and a predetermined thin film such as Al is formed on the surface thereof. A sputtering apparatus SM having the electrode C will be described.

  As shown in FIG. 1, the sputtering apparatus SM is, for example, an in-line type, and includes a sputtering chamber 1 that can be maintained at a predetermined degree of vacuum via a vacuum exhaust means (not shown) such as a rotary pump or a turbo molecular pump. Prepare. In the following, as shown in FIG. 1, a target 41 and a substrate S, which will be described later, face each other in the sputtering chamber 1, the direction from the target 41 toward the substrate S is “up”, and the direction from the substrate S toward the target 41 is This will be described as “below”.

  A substrate transfer means 2 is provided in the upper space of the sputtering chamber 1. The substrate transport unit 2 has a known structure, for example, has a carrier 21 on which the substrate S is mounted, and can sequentially transport the substrate S to a position facing the target by intermittently driving the drive unit. Yes. The sputter chamber 1 is also provided with gas introduction means 3. The gas introduction means 3 communicates with a gas source 33 through a gas pipe 32 provided with a mass flow controller 31 so that a sputtering gas composed of a rare gas such as argon or a reactive gas used in reactive sputtering is constant in the sputtering chamber 1. It can be introduced at a flow rate of. The reaction gas is selected according to the composition of the thin film to be formed on the processing substrate S, and gas containing oxygen, nitrogen, carbon, hydrogen, ozone, water, hydrogen peroxide, or a mixed gas thereof is used. . A magnetron sputtering electrode C is disposed below the sputtering chamber 1.

  The magnetron sputtering electrode C includes a substantially rectangular parallelepiped (planar view rectangle) target 41 and a magnet unit 5 provided so as to face the sputtering chamber 1. In the following description, the longitudinal direction of the target will be described as the X direction, and the width direction of the target orthogonal to the X direction will be described as the Y direction. The target 41 is manufactured by a known method according to the composition of a thin film to be formed on the processing substrate S such as Al alloy, Mo, or ITO. The area of the sputtering surface 411 that is the upper surface of the target 41 is set larger than the outer dimension of the processing substrate S. Further, a backing plate 42 that cools the target 41 during sputtering is bonded to the lower surface of the target 41 via a bonding material such as indium or tin. Then, with the target 41 bonded to the backing plate 42, it is mounted on the frame 44 through the insulating plate 43.

  After the target 41 is disposed in the sputtering chamber 1, a shield 45 serving as an anode grounded to ground is mounted around the sputtering surface 411 of the target 41. In addition, an output terminal from a sputtering power source E having a known structure is connected to the target, and DC power or high-frequency power having a negative potential is input. Below, the magnet unit 5 is demonstrated with reference to FIG.1 and FIG.2.

  The magnet unit 5 includes a support plate (yoke) 51 that is provided in parallel with the sputtering surface 411 of the target 41 and is configured of a flat plate made of a magnetic material that amplifies the magnet's attractive force. On the support plate 51, a central magnet 52 disposed on the center line extending in the longitudinal direction of the support plate 51 and an annular shape along the outer periphery of the upper surface of the support plate 51 so as to surround the center magnet 52. The arranged peripheral magnet 53 is provided with the polarity on the target side changed. The volume when the volume of the central magnet 52 converted to the same magnetization is converted to the same magnetization of the peripheral magnet 53 surrounding the circumference (peripheral magnet: center magnet: peripheral magnet = 1: 2: 1 (see FIG. 1) )) Designed to be about. Thereby, tunnel-like magnetic fluxes M1 and M2 balanced above the target 41 are formed (see FIG. 1). The central magnet 52 and the peripheral magnet 53 are known ones such as neodymium magnets, and the central magnet 52 and the peripheral magnet 53 may be integrated, or may be configured by arranging a plurality of magnet pieces having a predetermined volume. Good.

  The support plate 51 is formed so that its outer dimension is slightly smaller than the target. Moving means 6 is attached to the support 51, and during sputtering, the magnet unit 5 is reciprocated at a predetermined speed and a constant stroke (X direction: D1) on the same plane in the X direction and the Y direction. In this case, the movement in the X direction and the Y direction may be performed separately, and the movement in the X direction and the Y direction may be synchronized (in this case, the magnet unit 5 is indicated by a solid line in FIG. 1). From the position shown, it moves so as to draw a predetermined elliptical arc, reaches the position shown by the alternate long and short dash line in FIG. 1, moves so as to draw the arc, and returns to the position shown by the solid line). The moving unit 6 repeatedly moves the magnet unit 5 relative to the target 41 from a predetermined starting point and returns it to the starting point. The stroke in the X direction is set so that a predetermined range from both ends of the target 41 in the X direction is a non-erosion region for discharge stability and the like.

  The moving means 6 includes a pair of left and right rail members 62R, 62L provided horizontally on the flat upper surface of the base plate 61 over the entire length in the longitudinal direction of the target 41 and wider than the width of the target 41, and a rail member 62R. , 62L, and a slider 63 provided with a drive motor (not shown), and a feed screw 64 having a drive motor M provided to be supported by the sliders 63, 63. A nut member 65 suspended from the center of the lower surface of the support plate 51 is screwed into the feed screw 64.

  According to the above sputtering apparatus SM, the substrate S is transported to a position facing the target 41 by the substrate transport means 2, a predetermined sputtering gas or reaction gas is introduced through the gas introduction means 3, and then the sputtering power source E is turned on. Then, direct current power or high frequency power having a negative potential is input to the target 41. As a result, an electric field perpendicular to the substrate S and the target 41 is formed, and high density plasma is generated above the target 41 in a racetrack shape passing through a position where the vertical component of the magnetic field becomes zero. Then, the target 41 is sputtered by argon ions in the plasma, and sputtered particles from the target 41 adhere to and deposit on the surface of the substrate S to form a predetermined thin film. During sputtering, the position of the magnetic fluxes M1 and M2 can be moved by moving the magnet unit 5 in the X direction and the Y direction by the moving means 6 as described above, and local erosion of the target 41 can be suppressed.

  Here, when the magnet unit 5 is moved by the moving means 6 during the sputtering, as shown in FIG. 2A, the residence time of the portion having a high magnetic flux density among the magnetic fluxes M1 and M2 formed by the magnet unit 5 is used. However, a region (so-called cross point CP) that is longer than other portions is generated. In such a case, as shown in FIG.2 (b), the amount of erosion of the target 41 increases locally in the area | region where residence time becomes long. For this reason, sputtering is performed while the target 41 and the magnet unit 5 are moved relative to each other, a local erosion region in the surface of the target 41 is specified, and in correspondence with the position, a virtual in FIG. As indicated by a line, it is conceivable to attach a magnetic shunt MP having a rectangular shape in plan view to the lower surface of the backing plate 42 (corresponding to a conventional example). In this case, as shown in FIG. 2C, local erosion corresponding to the length of the sides of MP1 and MP22 along the Y direction of the magnetic shunt MP around the target 41 is projected on the target. It occurs separately.

  In this embodiment, as shown in FIG. 3A, a magnetic shunt 7 having an isosceles triangular outline in plan view is used, and two magnetic shunts 7a and 7b having similar shapes and different areas are stacked concentrically. It was decided to configure. The magnetic shunts 7a and 7b are attached to the lower surface of the backing plate 42 so that at least two sides 71 and 72 extending in the X direction are inclined in the center in the X direction and inward in the Y direction target. The magnetic shunt 7 may be any material having a high maximum magnetic permeability and rigidity. For example, stainless steel having magnetism such as SUS430, metals such as pure iron and nickel that can enhance the magnetic field attenuation effect, permalloy, supermalloy An alloy having a high magnetic permeability such as can be used. The area and thickness of the magnetic shunt 7 are appropriately set in consideration of the material and the amount of erosion of the target 41 at the cross point. For example, the thickness of the magnetic shunt 7 is in the range of 1.0 to 5.0 mm. Is set. The number of magnetic shunts 7 to be stacked and the area difference are not particularly limited, and can be appropriately set according to the local erosion amount, and the materials of both magnetic shunts 7a and 7b may be changed.

  According to the magnetron sputter electrode C having the above-described configuration, the magnetic shunts 7a and 7b can be locally reduced by the magnetic shunts 7a and 7b, and the magnetic shunts 7a and 7b can be locally reduced. Thus, it is possible to suppress further local erosion from occurring on the target. This is because the region where the magnetic flux density is concentrated is continuously and gradually shifted inward in the X direction by the inclined sides 71 and 72 of the magnetic shunts 7a and 7b, thereby reducing the magnetic field strength. In addition to the original function of the magnetic shunt, it is considered that this is due to the function of locally changing the shape of plasma generated in a racetrack shape. In addition, a configuration in which the target 41 is more evenly eroded can be realized by stacking and configuring two simple-shaped magnetic shunts 7a and 7b. As a result, the target 41 can be eroded more evenly and the life can be extended, and the erosion area of the target 41 can be expanded by moving the magnet unit 5 and the target 41 relative to each other during sputtering. The utilization efficiency of 41 can be improved.

  Here, even if the same magnet unit 5 is used, the position where the residence time of the part with a high magnetic flux density is long is the process condition (pressure in the vacuum chamber, for example, the vacuum chamber is introduced into the vacuum chamber). Gas flow rate) and the like. For this reason, when reducing the magnetic field strength at the above position, for example, it is conceivable to change the magnetic flux density locally by changing the configuration of the magnet unit 5, but this makes the operation extremely troublesome. . In this embodiment, since the magnetic shunt 7 is affixed to the lower surface of the backing plate 42, it is possible to realize a configuration in which the magnetic field strength is locally reduced by a simple operation even after the magnetron sputtering electrode of the present invention is installed in the sputtering apparatus.

  In order to confirm the above effects, the following experiment was conducted. Al was used as the target 41 and formed into a substantially rectangular shape in plan view of 218 mm × 3400 mm × thickness 16 mm by a known method, and joined to the backing plate 42. Further, as the support plate 51 of the magnet assembly, one having an outer dimension of 100 mm × 3390 mm is used. On each support plate 51, a rod-shaped central magnet 52 along the longitudinal direction of the target 41, and the outer periphery of the support plate 51 A peripheral magnet 53 is provided along the line. At this time, the vertical component of the magnetic field has one peak P (about 210 G) at a position of about 51 mm from both ends in the longitudinal direction of the target 41.

  Then, a glass substrate having an external dimension of 3100 mm × 2900 mm is used as the substrate S, and the mass flow controller 31 is set such that the pressure in the sputter chamber 11 evacuated is maintained at 0.3 Pa as the sputtering condition. Was controlled to introduce argon as a sputtering gas into the sputtering chamber 1. The distance between the target 41 and the glass substrate was 210 mm, the input power (DC voltage) to the target 41 was 76 kW, and sputtering was performed until it reached 6300 kWh. The magnet unit 5 was reciprocated in the X direction at a speed of 15 mm / sec and a stroke of 70 mm.

  When an Al film is formed on the substrate surface under the above conditions, the amount of erosion of the target 41 at the center in the width direction of the target and at a position 120 mm from the end in the X direction of the target is about 170% as compared with the surrounding area. It was confirmed that it was deeply eroded. Therefore, as a comparative experiment, a magnetic shunt 7 made of SUS430 having a thickness of 120 × 50 mm and a thickness of 2 mm was attached to the center of the lower surface of the backing plate 42 at a position 80 mm from the longitudinal end of the target. According to this, when the amount of erosion of the target 41 at a position 120 mm from the X direction end of the target and 70 mm at both ends of the Y direction is confirmed, it is confirmed that the erosion is about 80% deeper than the surrounding area. It was done.

  Next, as an experiment of the invention product, an equilateral triangular magnetic shunt 7a made of SUS430 having a side of 120mm and a thickness of 0.5mm at the center of the lower surface of the backing plate 42, the center of which is 42mm from the longitudinal end of the target. Then, a regular triangular magnetic shunt 7b made of SUS430 having a side of 60 mm and a thickness of 0.5 mm was laminated. According to this, when sputtering was performed under the same conditions as described above, it was confirmed that local target erosion was prevented and the target could be eroded substantially uniformly over substantially the entire surface thereof.

  Although the sputtering apparatus SM including the magnetron sputtering electrode C according to the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. In the above embodiment, the magnetic shunt 7 has a substantially triangular shape. However, the present invention is not limited to this, and the magnetic shunt has at least two sides extending in the X direction. However, it may be inclined in the center in the X direction and inward in the Y direction target. For example, a pentagonal or hexagonal shape may be used. Moreover, in the said embodiment, in order to apply to what becomes the non-erosion area | region in the predetermined range from the X direction both ends of a magnet unit for discharge stability etc., the thing which made the magnetic shunt 7 into the substantially triangular shape was demonstrated. However, in the case where the magnet unit is configured to be an erosion region up to the vicinity of the target end, for example, a rhombus may be used. Further, when the magnetic shunts 7a and 7b having different areas are stacked, the stacking order is not limited.

  Moreover, although the said embodiment demonstrated to the example what provided the one magnet unit 5 under the target of 1 sheet, it is not limited to this, A plurality of targets are provided under the target of 1 sheet. The present invention can be applied even when the magnet unit 5 is provided, or when one magnet unit 5 is provided below a plurality of targets.

  Furthermore, in the above-described embodiment, the sputtering is performed while moving the magnet unit 5 relative to the target, the cross point is specified, and the magnetic shunt 7 attached to the backing plate 42 is described as an example. Yes. The magnetic shunt 7 may be provided other than the magnet unit 5 and may be interposed between the target 41 and the magnet unit 42 by a support member (not shown). On the other hand, the cross point can also be specified from a simulation of magnetic flux change when the magnet unit 5 is moved. In such a case, a concave portion for attaching the magnetic shunt 7 is formed in advance on the lower surface of the backing plate 42. In addition, it may be screwed.

  SM: sputtering apparatus, C: magnetron sputtering electrode, 1 ... sputtering chamber, 41 ... target, 42 ... backing plate, 5 ... magnet unit, 52 ... central magnet, 53 ... peripheral magnet, 6 ... moving means, 7 ... magnetic shunt, 3 ... Gas introduction means, E ... Sputtering power source, S ... Substrate, M1, M2 ... Magnetic flux

Claims (5)

A longitudinal target in one direction arranged with the substrate to be processed in the sputtering chamber;
A magnet unit that is arranged on the lower side of the target and forms a tunnel-like magnetic flux above the target, with the sputtering surface side of the target on the upper side,
Longitudinally in the X direction of the target, returning the width direction of the target orthogonal to the X direction and Y direction, the magnet unit from a predetermined starting point, the starting point are moved relative to the target in the Y direction even without least And moving means for repeating
A line passing through a position where the vertical component of the leakage magnetic field formed by the magnet unit is 0 is formed in a racetrack shape,
In one cycle until returning to the starting point, a magnetic shunt that locally lowers the magnetic field strength in the region where the stay time of the portion having a high magnetic flux density at the center of the target in the Y direction is long is fixed relative to the target. Provided
The magnetron sputter electrode, wherein the magnetic shunt has at least two sides extending in the X direction, and each of these sides is inclined toward the center of the X direction target and inward of the Y direction target.   The magnetron sputter electrode according to claim 1, wherein the magnetic shunt has a triangular outline in plan view having the same length of the two sides.   3. The magnetron sputter electrode according to claim 1, wherein the magnetic shunt is formed by laminating a plurality of similar magnetic shunts having different areas.   The magnetron sputter electrode according to any one of claims 1 to 3, wherein the magnetic shunt is attached to a lower surface of a backing plate joined to a target.   The magnetron sputtering electrode according to any one of claims 1 to 4, a vacuum chamber capable of maintaining a vacuum state, a gas introduction means for introducing a predetermined gas into the vacuum chamber, and a target A sputtering apparatus, comprising: a sputtering power source capable of supplying power.

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