WO2011024411A1

WO2011024411A1 - Magnetron sputtering electrode and sputtering device

Info

Publication number: WO2011024411A1
Application number: PCT/JP2010/005114
Authority: WO
Inventors: 遙平大野; 敬臣倉田; 真新井; 淳也清田; 暁石橋; 久三中村
Original assignee: 株式会社アルバック
Priority date: 2009-08-28
Filing date: 2010-08-19
Publication date: 2011-03-03
Also published as: JPWO2011024411A1; TW201127978A

Abstract

Disclosed is a magnetron sputtering electrode whereby a target can be used efficiently, with no localized erosion regions arising in the target even if a magnet unit and the target are moved relative to one another during sputtering. The disclosed magnetron sputtering electrode (C) is provided with: a target (41) disposed, inside a sputtering chamber (1), opposite a substrate (S) to be treated; a magnet unit (5) that is disposed below the target, where the side of the target facing the substrate is considered "up," and that forms a magnetic flux (M1, M2) in the shape of a tunnel above the target; and a movement means (6) that repeatedly moves the magnet unit relative to the target, from a prescribed starting point and then back to the starting point. A backing plate (42) is provided with a magnetic shunt (7) at a prescribed location. Said magnetic shunt locally reduces the magnetic field intensity at a location (CP) at which the magnetic flux density is high and in which the dwell time of the target is long over the course of one movement cycle, said movement cycle ending when the magnet unit returns to the aforementioned starting point.

Description

Magnetron sputtering electrode and sputtering apparatus

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 the magnetron sputtering electrode is disposed so as to face a substrate to be processed, and a side of the target facing the substrate. 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.

Then, when sputtering a target by applying a negative DC voltage or an AC voltage to the target, the electrons ionized in front of the target by the magnetic flux and secondary electrons generated by sputtering are captured to increase the electron density above the target. The plasma density is increased by increasing the probability of collision between these electrons and the gas molecules of the rare gas 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, in the case of using a substantially rectangular shape in plan view as the target, the magnet unit is linearly formed along the longitudinal direction at the center of the upper surface of the substantially rectangular support plate (yoke) arranged in parallel with the target. For example, Patent Literature 1 discloses a configuration in which a central magnet is disposed 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 central magnet. .

In the above magnet unit, the magnetic flux density in the peripheral region of the upper surface (the surface to be sputtered) 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 longitudinal ends of the central magnet. 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.

Therefore, in this type of sputtering apparatus, it has been conventionally performed to change the position of the tunnel-like magnetic flux to uniformly erode the target (see, for example, Patent Document 2). In other words, the outer dimension of the support plate is made slightly smaller than the target, and during sputtering, the magnet unit reciprocates on the same plane between two points along the width direction of the target (direction perpendicular to the longitudinal direction of the target) at a predetermined speed. Move. At this time, it is also considered that the magnet unit is reciprocated in the longitudinal direction of the target in addition to the width direction.

However, it has been found that when the magnet unit is reciprocated as described above during sputtering, a local erosion region occurs in the target. This is considered to be because a portion (so-called cross point) in which the staying time of the portion where the magnetic flux density is high becomes relatively long occurs during one reciprocation of the magnet unit. Thus, when a local erosion area | region arises in a target, the target lifetime will become remarkably short after all and the malfunction that the utilization efficiency of a target cannot be raised will arise.

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

In view of the above points, the present invention provides a magnetron sputtering electrode and a sputtering apparatus that do not cause a local erosion region in the target even when the magnet unit and the target are moved relative to each other at the time of sputtering, and have high target utilization efficiency. The task is to do.

In order to solve the above-mentioned problems, the magnetron sputtering electrode of the present invention is disposed below the target with the target disposed opposite to the substrate to be processed in the sputtering chamber and the side facing the substrate of the target as the upper side. A magnet unit that forms a tunnel-like magnetic flux above the target, and a moving unit that repeatedly moves the magnet unit relative to the target from a predetermined starting point and returns the starting point to the starting point, until returning to the starting point. A magnetic shunt for locally lowering the magnetic field strength at a position where the staying time of the part having a high magnetic flux density becomes long in one cycle is provided in addition to the magnet unit.

According to the present invention, the magnetic shunt has locally reduced the magnetic field strength at the position where the stay time of the portion having a high magnetic flux density is long, so that the occurrence of a local erosion region on the target is suppressed, and the target lifetime is reduced. Can be long. 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.

Here, even if the same magnet unit is used, the position where the residence time of the portion with a high magnetic flux density becomes long is the process condition (pressure in the vacuum chamber, for example, 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. On the other hand, the present invention employs a configuration in which the magnetic shunt is provided in addition to the magnet unit, so that it is not necessary to change the configuration of the magnet unit itself, which is advantageous.

In the present invention, if the magnetic shunt is affixed to the lower surface of the backing plate joined to the target, the magnetic field strength can be locally reduced by a simple operation even after the magnetron sputtering electrode of the present invention is installed in the sputtering apparatus. It is possible to realize a configuration that can be reduced. In such a case, sputtering may be performed while relatively moving the target and the magnet unit to identify a local erosion region in the target surface, and a magnetic shunt may be attached at that position.

In the present invention, for example, the target has a rectangular shape in plan view, and the magnet unit has a different polarity on the target side provided so as to surround the central magnet and the central magnet. The moving means reciprocates the magnet unit on the same plane in at least one of the width direction and the longitudinal direction of the target.

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 3, a vacuum chamber capable of maintaining a vacuum state, A gas introduction means for introducing a predetermined gas into the vacuum 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. The top view explaining a magnet unit. (A) is a figure which illustrates typically the change of magnetic flux when moving a magnet unit relative to a target. FIG. 6B is a cross-sectional view taken along line BB in FIG. FIG. 4C is a cross-sectional view taken along the line CC in FIG. 3A, schematically illustrating target erosion.

Hereinafter, referring 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. 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 intermittently drive the drive unit to sequentially transport the substrate S to a position facing a target to be described later. It has become.

A gas introducing means 3 is provided in the sputter chamber 1. 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 target 41 and a magnet unit 5 that are substantially rectangular parallelepiped (planar view rectangle) provided to face the sputtering chamber 1. In the following description, the direction from the target 41 toward the substrate S is “upper”, and the direction from the substrate S toward the target 41 is “lower”. Further, a description will be given assuming that the width direction of the target is the X direction and the longitudinal direction of the target 41 orthogonal to the width direction is the Y direction.

The target 41 is produced 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 attached 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 so that a negative DC voltage or a high-frequency voltage is applied.

As shown in FIG. 2, the magnet unit 5 includes a support plate (yoke) 51 that is provided in parallel to 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.

Then, 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 via the gas introduction means 3, and then a negative DC voltage or A high frequency voltage is applied to the target 41. Thereby, an electric field perpendicular to the substrate S and the target 41 is formed, plasma is generated above the target 41, and the target 41 is sputtered, whereby a predetermined thin film is formed on the surface of the substrate S. At this time, electrons ionized above the target by the magnetic fluxes M1 and M2 and secondary electrons generated by sputtering are captured to increase the electron density in front of the target, and these electrons and the sputtering gas introduced into the vacuum chamber 1 The plasma density above the target 41 is increased by increasing the probability of collision with the gas molecules.

By the way, in the magnet unit 5, although not particularly illustrated and described, when the magnetic field profile along the longitudinal direction of the central magnet 52 is viewed, the vertical component of the magnetic field is at a position closer to the inside from both longitudinal ends of the central magnet 52. It has one peak. When a thin film is formed by sputtering in this state, a substantially uniform thin film can be formed over the entire surface of the substrate S. On the other hand, when the sputtering rate in the peripheral region of the sputtering surface 411 is locally increased, the target 41 is eroded intensively in that region.

For this reason, the outer dimension of the support plate 51 is formed to be slightly smaller than the target, and a moving means 6 is attached to the support plate 51, and during sputtering, the magnet unit 5 is moved at a predetermined speed on the same plane in the X direction and the Y direction. It is reciprocated at a constant stroke (X direction: D1). 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 an arc, and returns to position A). 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 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 rail members 62R, A slider 63 slidably engaged with 62L and provided with a drive motor (not shown) and a feed screw 64 having a drive motor M provided to be supported by both

sliders

63 and 63 are provided. A nut member 65 suspended from the center of the lower surface of the support plate 51 is screwed into the feed screw 64.

By the way, when the magnet unit 5 is moved by the moving means 6 during the sputtering, as shown in FIG. 3, the staying time of the part having a high magnetic flux density among the magnetic fluxes M1 and M2 formed by the magnet unit 5 is A portion (so-called cross point CP: see FIG. 3A) that is longer than the portion is generated. In this case, the target 41 is substantially uniformly eroded in the longitudinal direction in the longitudinal direction (see FIG. 3B), but the erosion amount of the target 41 is locally increased at the portion where the stay time is long. This increases the life of the target 41 (see FIG. 3C).

Therefore, sputtering is performed while the target 41 and the magnet unit 5 are moved relative to each other, and a local erosion region in the surface of the target 41 is specified, and then a magnetic field having a predetermined area is formed on the lower surface of the backing plate 42 corresponding to the position. A shunt 7 was attached (see FIG. 2). The magnetic shunt 7 only needs to be a material having a high maximum magnetic permeability and rigidity. For example, stainless steel having magnetism such as SUS430, metal such as pure iron and nickel that can enhance the attenuation effect of the magnetic field, permalloy, supermalloy, etc. An alloy having a high magnetic permeability can be used. The thickness of the magnetic shunt is appropriately set in the range of 1.0 to 5.0 mm in consideration of the material and the amount of erosion of the target 41 at the cross point.

According to the magnetron sputter electrode C having the above-described configuration, the magnetic shunt 7 locally reduces the magnetic field strength at the position where the stay time of the portion having a high magnetic flux density is long. It is suppressed and the target life can be extended. As a result, the relative utilization of the magnet unit 5 and the target 41 during sputtering can increase the utilization efficiency of the target 41 in combination with the fact that the erosion area of the target 41 can be expanded.

Further, the position where the residence time of the portion with a high magnetic flux density becomes long varies depending on the process conditions (pressure in the vacuum chamber, for example, the flow rate of the gas introduced into the vacuum chamber), etc., even if the same magnet unit 5 is used. Although obtained, since the configuration in which the magnetic shunt 7 is provided in addition to the magnet unit 5 is adopted, there is no need to change the configuration of the magnet unit 5 itself, which is advantageous. In addition, even after the magnetron sputtering electrode C is installed in the sputtering chamber 1, it is possible to realize a configuration in which the magnetic field strength is locally reduced by a simple operation.

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.

A mass flow controller is used so that a glass substrate having an outer dimension of about 3100 mm × 2900 mm is used as the substrate S, and the sputtering chamber 1 is evacuated to a pressure of 0.3 Pa as a sputtering condition. 31 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 the 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 longitudinal end of the target is about 170% as compared with the surrounding area. It was confirmed that it was deeply eroded. Therefore, a magnetic shunt 7 made of SUS430 having a thickness of 120 × 50 mm and a thickness of 2 mm is 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. 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 almost uniformly over substantially the entire surface thereof.

Next, Al was used as the target 41 and formed into a substantially rectangular shape in a plan view of 180 mm × 950 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 × 880 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 136 G) at a position of about 61 mm from both ends in the longitudinal direction of the target 41.

As a sputtering condition, the mass flow controller 31 is controlled to introduce argon as a sputtering gas into the sputtering chamber 1 so that the pressure in the sputtering chamber 1 being evacuated is maintained at 0.5 Pa, and the target 41 The input power (DC voltage) to 13.6 kW was 13.6 kW and sputtered until it reached 2600 kWh. The transfer speed of the magnet unit 5 is set to 15 mm / sec, the stroke in the X direction is set to 60 mm, and the stroke in the Y direction is set to 50 mm. The magnet unit 5 is moved relative to the target 41 from a predetermined starting point and returns to the starting point. Were moved in the X and Y directions.

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 41 and at a position of 100 mm from the end in the longitudinal direction of the target is about 170 compared with the surrounding area. % Erosion was confirmed. Therefore, 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 55 mm from the longitudinal end of the target. And when sputter | spatter was carried out on the same conditions as the above, when the amount of erosion of the target 41 in the center of the width direction of the target 41 and the position of 100 mm from the longitudinal direction edge part of a target is seen, compared with the periphery, It was 110%, and even when moved in the X direction and the Y direction, it was confirmed that local target erosion was prevented and the target could be eroded almost uniformly over substantially the entire surface thereof.

As mentioned above, although the sputtering apparatus SM provided with the magnetron sputtering electrode C of the embodiment of the present invention has been described, the present invention is not limited to the above-described embodiment. In the above embodiment, the target is a rectangular in plan view, and the magnet unit 5 is driven in synchronization with the X direction and the Y direction. However, the present invention is not limited to this. For example, in the case where sputtering is performed while using a circular target and the magnet unit is rotationally driven with the position eccentric from the target as the rotation center, the relative movement from the predetermined starting point to the target and returning to the starting point should be repeated. If the position where the staying time of the part where the magnetic flux density is high becomes long when the magnet unit 5 is moved, the present invention can be applied to improve the utilization efficiency of the target.

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 5 by a support member (not shown). On the other hand, the cross point can also be specified from the simulation of the magnetic flux change when the magnet unit 5 is moved. In such a case, a recess for attaching the magnetic shunt 7 is formed in advance on the lower surface of the backing plate 42. Alternatively, 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

A target disposed opposite 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 side facing the substrate of the target as the upper side,
Moving means for repeatedly moving the magnet unit relative to the target from a predetermined starting point and returning it to the starting point; and
A magnetron sputter electrode comprising a magnetic shunt other than the magnet unit for locally reducing the magnetic field strength at a position where the staying time of the portion having a high magnetic flux density becomes long in one cycle until returning to the starting point .
The magnetron sputter electrode according to claim 1, wherein the magnetic shunt is attached to a lower surface of a backing plate joined to a target.
The target is rectangular in plan view, and the magnet unit is composed of a central magnet arranged in a line and peripheral magnets having different polarities on the target side so as to surround the periphery of the central magnet. The magnetron sputter electrode according to claim 1 or 2, wherein the means reciprocates the magnet unit on the same plane in at least one of the width direction and the longitudinal direction of the target.
The magnetron sputtering electrode according to any one of claims 1 to 3, 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 that enables power to be supplied.