JP2020169352A - Cathode unit for magnetron sputtering apparatus - Google Patents

Abstract

To provide a cathode unit for a magnetron sputtering apparatus having a structure capable of easily measuring a TM distance in a state where a storage chamber is set to a vacuum atmosphere and correcting a positional deviation of a magnet unit if the positional deviation of the magnet unit exists.SOLUTION: A cathode unit CU for a magnetron sputtering apparatus according to the invention includes a plurality of magnet units Mu in a side opposite to a sputtering surface 41 of a single target Tg, the magnet units working a stray magnetic field on each sputtering surface side of targets parallelly arranged along one direction. Each magnet unit is provided in a storage chamber 12 capable of forming a vacuum atmosphere. A transfer means 81 is provided for moving each magnet unit relative to a sputtering surface in an approaching and receding direction in the storage chamber. An optical displacement sensor 9 is provided on an inner wall surface of the storage chamber for measuring a distance between the sputtering surface and each magnet unit.SELECTED DRAWING: Figure 1

Description

The present invention is for a magnetron sputtering apparatus including a plurality of magnet units arranged side by side along one direction on the side facing the sputter surface of a single target and causing a leakage magnetic field to act on the sputter surface side of the target. Regarding the cathode unit of.

This type of cathode unit (so-called multi-magnet cathode) is known, for example, in Patent Document 1. In this case, each magnet unit is provided with a plate-shaped yoke, and on the main surface of the yoke on the target side, a linear central magnet and peripheral magnets surrounding the central magnet at predetermined intervals are polarities on the target side. It is provided by changing. Then, the two axes orthogonal to each other in the sputter plane are defined as the X-axis direction and the Y-axis direction, and the central magnet of each magnet unit is aligned with the Y-axis direction, and there is an interval in the X-axis direction as one direction. In addition, each magnet unit is set so that the distance (hereinafter, referred to as "TM distance") between the sputtered surface of the target and each magnet unit (specifically, the tip of the central magnet and the peripheral magnet of each magnet unit) becomes a predetermined value. Are lined up side by side.

In the above cathode unit, the magnetic field leaking from the target surface extends in the X-axis direction so that the line passing through the position where the vertical component of the magnetic field becomes zero by each magnet unit extends along the extending direction of the central magnet and closes like a race track. A plurality of racetrack-shaped plasmas are generated so as to be arranged at intervals in the X-axis direction in front of the sputter surface. Each magnet unit is also provided with a moving means such as a linear motor that moves the magnet unit so as to be close to and separated from the sputtered surface. Then, for example, the strength of the leakage magnetic field is adjusted for each magnet unit by changing the TM distance of each magnet unit according to the amount of erosion of the target, and the film thickness distribution of the thin film to be formed is uniform until the life end of the target. It is designed to maintain high sexuality.

Here, the target used for the cathode unit has a relatively large area. Therefore, when each magnet unit is arranged in the atmosphere, atmospheric pressure always acts on the back surface side of the target, and the target may be locally distorted due to the difference from the pressure in the vacuum chamber. When the target is distorted, the distance (distance between TSs) between the target and the substrate to be processed facing the target changes locally, and the uniformity of the film thickness distribution of the thin film is impaired. For this reason, it is common to provide a storage chamber capable of forming a vacuum atmosphere on the side opposite to the sputtering surface, and to arrange the magnet unit in the storage chamber.

By the way, at the time of performing maintenance such as opening the vacuum chamber to the atmosphere and exchanging the target, each magnet unit is also removed from the vacuum chamber together with the storage chamber, and the storage chamber is reattached to the vacuum chamber after the maintenance is completed. At this time, one of the magnet units may be misaligned for some reason. Such misalignment of the magnet unit affects the film thickness distribution of the thin film to be formed. From this, it has been desired to develop a cathode unit that can easily measure the TM distance even when the storage chamber is in a vacuum atmosphere and can easily correct the misalignment of the magnet unit.

Japanese Unexamined Patent Publication No. 2000-239841

In view of the above points, the present invention has a magnetron sputtering apparatus having a structure in which the TM distance can be easily measured in a state where the storage chamber is in a vacuum atmosphere, and if there is a misalignment of the magnet unit, it can be easily corrected. It is an object of the present invention to provide a cathode unit for this purpose.

In order to solve the above problems, a plurality of magnet units are provided on the side facing the sputter surface of a single target, which are arranged side by side in one direction and act on the sputter surface side of the target, respectively. In the cathode unit for the magnetron sputtering apparatus of the present invention, each magnet unit is provided in a storage chamber capable of forming a vacuum atmosphere, and each magnet unit is moved in the proximity and separation directions with respect to the sputtering surface in the storage chamber. The moving means is provided, and an optical displacement sensor for measuring the distance between the sputtering surface and each magnet unit is provided on the inner wall surface of the storage chamber.

According to the present invention, the sensor head of the displacement sensor provided on the inner wall surface of the storage chamber irradiates light (laser light of a predetermined wavelength) toward the magnet unit, and the reflected light is analyzed to form a magnet from the sensor head. The distance to the unit is calculated, and the TM distance can be measured from the calculated value and the design value of the device such as the thickness of the target and the height of the magnet unit. This makes it possible to measure the TM distance in a state where the storage chamber is in a vacuum atmosphere, and if there is a misalignment of the magnet unit, the magnet unit can be moved by a moving means to easily correct it. At this time, the displacement sensor is provided on the inner wall surface of the storage chamber separated from the magnet unit. There is no problem that the displacement sensor is affected by the (strong) magnetic field generated by the magnet unit.

By the way, since the storage chamber is removed from the vacuum chamber at the time of maintenance, it is preferable to reduce the thickness of the chamber wall to reduce its weight, while peeping to visually check the internal state thereof. A window may be provided. Therefore, when the storage chamber is evacuated, the chamber wall is locally distorted, and the TM distance may not be measured accurately. Therefore, in the present invention, the back surface of the target is used as a reference plane, the first distance from the displacement sensor to the reference plane is measured, and the second distance from the displacement sensor to the magnet unit is measured to obtain the first distance. It is preferable to adopt a configuration in which the distance between the sputter surface and each magnet unit is obtained from the difference from the second distance. This is advantageous because the TM distance can be measured accurately at all times.

The schematic diagram explaining the structure of the sputtering apparatus including the cathode unit for the magnetron sputtering apparatus of this embodiment. (A) and (b) are diagrams for explaining the method of specifying the TM distance.

Hereinafter, embodiments of the cathode unit for the magnetron sputtering apparatus of the present invention for forming a predetermined thin film on a substrate Sw such as a glass substrate will be described with reference to the drawings. In the following, the terms indicating the directions such as "upper", "lower", "left", and "right" are based on FIG. 1, which indicates the installation posture of the sputtering apparatus.

With reference to FIG. 1, Sm is a magnetron sputtering apparatus including the cathode unit CU of the present embodiment, and includes a vacuum chamber 1. An exhaust pipe 21 from a vacuum pump unit 2 composed of a turbo molecular pump or a rotary pump is connected to the vacuum chamber 1 so that the inside of the vacuum chamber 1 can be evacuated to a predetermined pressure. The vacuum chamber 1 is also connected to a gas introduction pipe 31 that introduces a rare gas such as argon or a reaction gas (sputter gas) such as oxygen if necessary. A mass flow controller 32 is interposed in the gas introduction pipe 31 so that the flow-controlled sputter gas can be introduced into the vacuum chamber 1. The cathode unit CU of the present embodiment is detachably mounted via a mounting opening 11 formed on one side surface of the vacuum chamber 1 so as to face the substrate Sw installed in the vacuum chamber 1 in an upright position. ..

The cathode unit CU is arranged on the target Tg having an area slightly larger than that of the substrate Sw, which has a contour corresponding to the substrate Sw, and on the right side of the target Tg (the side opposite to the sputtering surface 41 of the target Tg). A plurality of magnet units Mu for applying a leakage magnetic field are provided on the 41 side. The target Tg is selected according to the composition of the thin film to be formed on the surface of the substrate Sw such as Al, Al alloy, Mo and Ti. A backing plate 42 is joined to the back surface of the target Tg (the surface facing back to the sputtering surface 41), and the back surface of the backing plate 42 is composed of a plate material having a predetermined thickness and includes a vacuum chamber 1 and a storage chamber described later. A separator Sp is provided to isolate the above. Then, during sputtering of the target Tg, the target Tg can be cooled by flowing a refrigerant between the backing plate 42 and the separator Sp. The target Tg is provided so that its sputtering surface 41 faces the substrate Sw and faces the inside of the vacuum chamber 1 via an insulating member 43 that also serves as a vacuum seal provided at the inner peripheral edge of the mounting opening 11.

The output from the sputter power supply 5 such as a DC power supply or an AC power supply is connected to the target Tg so that DC power having a negative potential with respect to the target Tg or AC power having a predetermined frequency can be input depending on the target type. It has become. The vacuum chamber 1 is also provided with an annular shield plate 6 so as to surround the target Tg. The shield plate 6 is made of metal and is grounded so as to function as an anode during sputtering of the target Tg. Further, the storage chamber 12 is detachably attached to the vacuum chamber 1 via a vacuum seal (not shown) provided on the outer peripheral edge of the attachment opening 11. A branch pipe 22 branched from the exhaust pipe 21 is connected to the storage chamber 12 via an on-off valve (not shown) so that the inside of the storage chamber 12 can be evacuated to a predetermined pressure. Although not particularly illustrated and described, the vacuum chamber 1 and the storage chamber 12 are connected via a hinge, and the storage chamber 12 is attached to the vacuum chamber 1 shown in FIG. 1 with the inside of the storage chamber 12 being at atmospheric pressure. The posture can be changed from the film-forming position to the maintenance position that is swung 90 degrees downward with the hinge as the fulcrum. Then, each magnet unit Mu is assembled in the storage chamber 12.

Each magnet unit Mu has the same form and includes a plate-shaped yoke 71 installed in parallel with the sputtering surface 41. On the main surface (left side surface) of the yoke 71 located on the target Tg side, a linear central magnet 72 and a peripheral magnet 73 surrounding the central magnet 72 at predetermined intervals change the polarity on the target Tg side. It is provided. Specifically, the vertical direction of FIG. 1 is the Z-axis direction, the two axes orthogonal to each other in the plane orthogonal to the Z-axis are the X-axis direction and the Y-axis direction, and the central magnet 72 of each magnet unit Mu is in the Y-axis direction. There is an interval in the Z-axis direction in a posture that matches the above, and the distance between the sputter surface 41 and each magnet unit Mu (specifically, the tips of the central magnet 72 and the peripheral magnet 73 of each magnet unit Mu) ( Hereinafter, each magnet unit Mu is arranged side by side so that (hereinafter referred to as "TM distance") becomes a predetermined value. In this case, each magnet unit Mu is configured so that the volume when converted to the same magnetization of the central magnet 72 is equal to the sum of the volumes when converted to the same magnetization of the peripheral magnet 73, and each magnet unit Mu is used. The leakage magnetic field of the closed loop balanced in front of the spatter surface 41 of the target Tg acts so that the line passing through the position where the vertical component of the magnetic field becomes zero extends along the extending direction of the central magnet 72 and closes like a race track. I have to. As a result, when the sputtering gas is introduced into the vacuum chamber 1 in a vacuum atmosphere and a predetermined electric power is applied to the target Tg, a plurality of racetrack-shaped plasmas are arranged in front of the sputtering surface 41 at intervals in the Y-axis direction. Occurs in.

Drive shafts 81a from the linear motor 81 as a moving means are connected to the back surface of each yoke 71, respectively, and the magnet units Mu can be individually advanced and retreated in the X-axis direction, that is, in the proximity and separation directions with respect to the sputtering surface 41. I am trying to move each one. Further, a feed screw 82 extending in the Z-axis direction is provided in the storage chamber 12, and the feed screw 82 is provided with a plurality of sliders 83 screwed thereto. When the feed screw 82 is rotated by the motor 84 provided outside the storage chamber 12, each slider 83 advances and retreats (reciprocates) in synchronization with the Z-axis direction. A linear motor 81 that advances and retreats the magnet unit Mu individually in the X-axis direction is attached to each slider 83. As a result, if the feed screw 82 is appropriately rotated by the motor 84 during the film formation of the target Tg by sputtering, the region on which the leakage magnetic field acts from each magnet unit Mu can be changed to make substantially the entire surface of the target Tg an erosion region. Moreover, for example, if each magnet unit Mu is moved back and forth by each linear motor 81 to change the TM distance according to the amount of erosion of the target Tg, the thickness distribution of the thin film formed up to the life end of the target Tg High uniformity can be maintained.

At a predetermined position on the inner wall surface of the storage chamber 12 facing the yoke 71, optical displacement sensors 9 for measuring the TM distance are provided for each magnet unit Mu. Each displacement sensor 9 has the same form, and for example, a known spectroscopic interference type sensor can be used. That is, the displacement sensor 9 includes an optical unit 91 provided outside the storage chamber 12 and a sensor head 93 provided at the tip of an optical fiber 92 extending from the optical unit 91 through the side wall surface of the storage chamber 12, and is provided from the sensor head 93. It is possible to irradiate a laser beam of a predetermined wavelength. In this case, each sensor head 93 has a storage chamber 12 capable of irradiating the back surface of the yoke 71 and the back surface of the separator Sp with laser light when the magnet unit Mu moves forward and backward in the Z-axis direction. It is installed in the position.

The sputtering device Sm includes a control unit Cp including a display, a computer, a memory, a sequencer, etc., and the control unit Cp is, for example, a linear motor that advances and retreats a sputtering power supply 5, a mass flow controller 32, a vacuum pump unit 2, and a magnet unit Mu. In addition to controlling the operation of the 81 and the motor 84 in an integrated manner, the TM distance is measured by receiving the output from the displacement sensor 9 and displayed on the display, or the linear motor according to the measured TM distance. The position of each magnet unit Mu can be corrected by moving the 81 forward and backward. The position correction of each magnet unit Mu will be described below with reference to FIG.

First, at the film formation position of the storage chamber 12 shown in FIG. 1, the vacuum pump unit 2 is operated to evacuate the inside of the vacuum chamber 1 and the storage chamber 12. In this case, the feed screw 82 is appropriately rotated by the motor 84, and each magnet unit Mu is moved so that the back surface of the separator Sp can be irradiated with the laser beam. When the inside of the storage chamber 12 reaches a predetermined pressure, laser light is emitted from the sensor head 93 through the optical fiber 92 from a light source (not shown) provided in the optical unit 91 toward the back surface of the separator Sp (FIG. 2 (a)). ), The reference reflecting surface (not shown) provided in the sensor head 93 and the one reflected from the back surface of the separator Sp are returned to the optical unit 91 through the optical fiber 92. In this case, both reflected lights interfere with each other, and the interfering light is separated by a spectroscope (not shown) in the optical unit 91 and imaged on the CCD to obtain an intensity distribution according to the wavelength, and the separator Sp. The distance to the back surface of is calculated, and this is output to the control unit Cp. Data regarding the thickness of the target Tg, the backing plate 42, and the separator Sp are stored in advance in the control unit Cp, and the distance from the sensor head 93 to the sputtering surface 41 is measured from the calculated value and the stored value ( This is referred to as the "first distance"). In the present embodiment, the back surface of the separator Sp constitutes a reference surface on the back surface of the target Tg. When the target Tg is sputtered, the thickness of the target Tg becomes thin. Therefore, for example, it is preferable to obtain in advance the correlation between the integrated power to the target Tg and the thickness of the target Tg and correct it based on this.

Next, when the feed screw 82 is rotated by the motor 84 and each magnet unit Mu is moved so that the back surface of the yoke 71 can be irradiated with the laser beam from the sensor head 93 (see FIG. 2B), the above In the same manner as above, the distance to the back surface of the yoke 71 is calculated and output to the control unit Cp. Data regarding the plate thickness of the yoke 71 and the distance from the back surface of the yoke 71 to the tip surfaces of the central magnet 72 and the peripheral magnet 73 are stored in the control unit Cp, and the calculated value and the stored value are used from the sensor head 93. The distances to the tip surfaces of the central magnet 72 and the peripheral magnets 73 are measured (this is referred to as the "second distance"). Then, when the first distance and the second distance are measured, the control unit Cp specifies the TM distance from the difference between the first distance and the second distance, and the specified TM distance is set in advance. If they are different, each magnet unit Mu is moved forward and backward by each linear motion motor 81 to correct the position.

According to the above embodiment, it is possible to measure the TM distance in a state where the storage chamber 12 is in a vacuum atmosphere, and when any of the magnet units Mu has a misalignment, the linear motor 81 is moved forward and backward. The position of each magnet unit Mu can be easily corrected. At this time, the sensor head 93 of the displacement sensor 9 is provided on the inner wall surface of the storage chamber 12 separated from each magnet unit Mu. There is no problem that the displacement sensor 9 is affected by the (strong) magnetic field generated by the magnet unit Mu. Further, since the TM distance is obtained from the difference between the first distance and the second distance, the TM distance can be accurately measured at all times without the chamber wall when the storage chamber 12 is evacuated is affected by distortion or the like.

Although the embodiments of the present invention have been described above, various modifications can be made without departing from the scope of the technical idea of the present invention. In the above embodiment, as the optical displacement sensor 9, a spectroscopic interference type sensor 9 has been described as an example, but the present invention is not limited to this, and other types of displacement sensors 9 can also be used. Further, in the above embodiment, the case where the back surface of the separator Sp is used as a reference plane and the TM distance is specified from the difference between the first distance and the second distance has been described as an example, but the present invention is not limited to this. It is also possible to directly measure the TM distance from one distance and the design value of the device such as the thickness of the target Tg and the height of the magnet unit.

In the above embodiment, when measuring the first distance and the second distance, each magnet unit Mu is moved in the Z-axis direction in order to expand the erosion region of the target Tg, but the present invention is limited to this. For example, the sensor head 93 can be configured to be movable in the Z-axis direction.

CU ... Cathode unit, Mu ... Magnet unit, Sp ... Separator (constituting a reference surface on the back of the target), Tg ... Target, 12 ... Storage chamber, 41 ... Sputter surface, 81 ... Linear motor (moving means), 9 ... Displacement sensor.

Claims (2)

A cathode unit for a magnetron sputtering device equipped with a plurality of magnet units arranged side by side in one direction on the side facing the sputter surface of a single target and applying a leakage magnetic field to the sputter surface side of the target. There,
In the case where each magnet unit is provided in a storage chamber capable of forming a vacuum atmosphere, and a moving means for moving each magnet unit in the storage chamber in the proximity and separation directions with respect to the sputtering surface is provided.
A cathode unit for a magnetron sputtering apparatus, characterized in that an optical displacement sensor for measuring the distance between the sputtering surface and each magnet unit is provided on the inner wall surface of the storage chamber. With the back surface of the target as a reference plane, the first distance from the displacement sensor to the reference plane is measured, and the second distance from the displacement sensor to the magnet unit is measured, and the difference between the first distance and the second distance is used. The cathode unit for a magnetron sputtering apparatus according to claim 1, wherein a distance between a sputtered surface and each magnet unit is obtained.

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