JP2021001382A - Cathode unit for magnetron sputtering apparatus - Google Patents

Abstract

To provide a simply-structured cathode unit for a magnetron sputtering apparatus capable of suppressing an emission of an electron accompanied by an inertia movement of the electron as quickly as possible.SOLUTION: A magnet unit 5 is arranged in a backside of a sputtering surface 41 of a target 4 arranged in a vacuum chamber 1, and has a center magnet 52 and a peripheral magnet 53 of which polarities are different in a target side. A cathode unit Cu generates a stray magnetic field Mf such that a line passing a position in which a perpendicular component of a magnetic field in front of the sputtering surface is zero is closed in a race-track shape. When the cathode unit is installed in the vacuum chamber and a race-track shaped plasma is generated in front of the sputtering surface, a first corner part C1 is a position where an electron in the plasma moving along the plasm clockwise or counterclockwise changes a direction in an electromagnetic field, and a second corner part C2 is a position where the electron changes the direction at a second time, meander means 6 to meander the electron before reaching the first corner is further provided.SELECTED DRAWING: Figure 2

Description

The present invention relates to a cathode unit for a magnetron sputtering apparatus.

A cathode unit for this type of magnetron sputtering apparatus is known, for example, in Patent Document 1. It comprises a magnet unit located on the back side of the sputtered surface of the target installed in the vacuum chamber. The magnet unit includes, for example, a support plate (yoke) arranged in parallel with a target having a rectangular shape in a plan view, and a central magnet is linearly arranged in the center thereof so as to surround the central magnet with a gap. Peripheral magnets are arranged on the outer peripheral edge of the support plate with different polarities on the target side and the central magnet. The volume when converted to the same magnetization of the central magnet is set to be equivalent to the sum of the volumes when converted to the same magnetization of the peripheral magnets, and the target extends along the longitudinal direction of the central magnet and closes like a race track. The leakage magnetic field acts in front of the sputtered surface.

When the cathode unit is attached to the vacuum chamber of the sputtering apparatus, sputter gas such as argon gas is introduced into the vacuum chamber in the vacuum atmosphere where the substrate is installed, and a predetermined power is applied to the target, the magnet unit moves forward of the sputter surface. A racetrack-like vacuum is generated in. The electrons in the plasma are moving clockwise or counterclockwise along the race track, depending on the polarity of the central magnet and the peripheral magnet on the target side. At this time, the electrons are bent by the electromagnetic field on both ends in the longitudinal direction of the target and change their directions twice. However, when the second change of direction, the inertia of the electrons due to the acceleration of the electrons when the direction is changed the first time. It is generally known that an electron is ejected to the tip side in the lateral direction of the target while the motion remains. The ejection of electrons due to such inertial motion causes problems such as unstable discharge, and it is necessary to suppress this as much as possible.

In the above conventional example, the magnet unit is divided into a central portion in the longitudinal direction and divided portions on both sides thereof, and the positions of both divided portions are changed with respect to the fixed central portion, so that electrons are ejected due to inertial motion. Is being prevented. However, if such a configuration is adopted, there arises a problem that the structure of the magnet unit itself becomes complicated and the manufacturing cost increases.

JP-A-2007-154291

In view of the above points, it is an object of the present invention to provide a cathode unit for a magnetron sputtering apparatus having a simple structure capable of suppressing the ejection of electrons due to the inertial movement of electrons as much as possible. To do.

In order to solve the above problem, a magnet unit is provided on the side facing the sputter surface of the target installed in the vacuum chamber and applying a leakage magnetic field on the sputter surface side of the target, and the magnet unit is a wire. A central magnet in the shape of a shape and a peripheral magnet that surrounds the central magnet at intervals are provided with different polarities on the target side, and pass through a position in front of the sputtering surface where the vertical component of the magnetic field becomes zero. In the cathode unit for the magnetron sputtering apparatus of the present invention in which a leakage magnetic field is applied so that a wire extends along the longitudinal direction of the central magnet and closes in a racetrack shape, the cathode unit is attached to the vacuum chamber of the sputtering apparatus to create a vacuum atmosphere. When a sputter gas containing a rare gas is introduced into the vacuum chamber of the above and a predetermined power is applied to the target to generate a racetrack-like plasma in front of the sputter surface, clockwise or counterclockwise along this. The position where the electrons in the plasma moving in the direction change in the electromagnetic field is the first corner part, the position where the electrons change direction next is the second corner part, and the electrons meander before reaching the first corner part. It is characterized by further providing means. In this case, the meandering means is provided at a predetermined position on the upper surface of the central magnet located on the target side, at a predetermined position on the upper surface of the peripheral magnet located on the target side, and a first magnet piece arranged with the same polarity on the target side. A configuration may be adopted in which a second magnet piece arranged so that the polarities on the target side are matched is provided, and the first magnet piece and the second magnet piece are offset from each other in the longitudinal direction.

According to the present invention, the first magnet piece and the second magnet piece as meandering means are arranged offset from each other in the longitudinal direction on the central magnet and the peripheral magnet, in other words, the central magnet and the peripheral magnet parallel thereto are arranged. The first magnet piece and the second magnet piece are provided in a staggered manner in the longitudinal direction, respectively, and a portion having a strong magnetic field strength on the central magnet side and a portion having a strong magnetic field strength on the peripheral magnet side in the longitudinal direction are provided. By making them alternately, the electrons moving in the section where the first magnet piece and the second magnet piece exist so as to move while meandering so as to alternately repel the central magnet side and the peripheral magnet side. Become. As a result, the acceleration of the electrons when the direction is changed at the first corner portion is suppressed, and the ejection of electrons from the target end due to the inertial movement of the electrons is suppressed as much as possible. In this case, it is not necessary to divide the magnet unit into the central portion in the longitudinal direction and the divided portions on both sides as in the conventional example, but it is an extremely simple configuration in which the magnet piece is installed in the existing magnet unit. Therefore, the ejection of electrons from the target end can be suppressed as much as possible.

By the way, if the first magnet piece and the second magnet piece are locally arranged on the central magnet and the peripheral magnet, the electron density in the plasma becomes locally high, and the film thickness distribution in the substrate surface may be deteriorated. is there. Therefore, in the present invention, the first magnet pieces are arranged at predetermined intervals over the entire length of the central magnet, and at predetermined intervals over the entire length of the peripheral magnets that match the length of the central magnet. It is preferable that the second magnet piece is arranged. According to this, since the electron density in the plasma can be made uniform, it is possible to form a film with a good film thickness distribution in the substrate surface, which is advantageous.

The schematic diagram which shows the sputtering apparatus which incorporated the cathode unit for the magnetron sputtering apparatus of embodiment of this invention. The schematic plan view which shows the meandering means 6 shown in FIG. The schematic plan view which shows the meandering means 60A which concerns on the modification. The schematic plan view which shows the meandering means 60B which concerns on a modification. The schematic plan view which shows the meandering means 70A which concerns on the modification. The schematic plan view which shows the meandering means 70B which concerns on a modification.

Hereinafter, a sputtering apparatus including a cathode unit for the magnetron sputtering apparatus according to the embodiment of the present invention will be described with reference to the drawings.

With reference to FIGS. 1 and 2, the SM is a sputtering apparatus, and the sputtering apparatus SM includes a vacuum chamber 1 defining a film forming chamber 10. In the following, the terms indicating the directions such as up and down are based on FIG. 1, which is the installation posture of the sputtering apparatus SM.

Although not particularly illustrated, a vacuum pump is connected to the vacuum chamber 1 via an exhaust pipe so that the film forming chamber 10 can be evacuated to a predetermined pressure (for example, 1 × ^10-5 Pa). .. A substrate transfer device 2 is provided above the vacuum chamber 1. The substrate transfer device 2 has a carrier 21 that holds the substrate Sw in a state where the lower surface as a film forming surface is open, and conveys the carrier 21 and thus the substrate Sw to a position facing the target 4, which will be described later, by a drive device (not shown). You can do it. Since a known substrate transfer device 2 can be used, further description thereof will be omitted.

The vacuum chamber 1 is provided with gas introduction means 3. The gas introducing means 3 communicates with the gas source 33 through the gas pipe 32 provided with the mass flow controller 31, so that the sputter gas can be introduced into the film forming chamber 10 at a predetermined flow rate. The sputtering gas includes not only a rare gas such as argon gas for forming a plasma atmosphere, but also a reactive gas such as oxygen gas and nitrogen gas used in reactive sputtering.

A cathode unit Cu for the magnetron sputtering apparatus of the present invention is provided in the lower part of the vacuum chamber 1. The cathode unit Cu has a substantially rectangular parallelepiped (rectangular contour) target 4 provided so as to face the film forming chamber 10 and a magnet unit 5 provided below the target 4 (opposite the sputtering surface 41). The target 4 is manufactured according to the composition of a thin film to be formed on the film-forming surface (lower surface) of the substrate Sw, such as Al alloy, copper, Mo or ITO, and the area of the sputtered surface 41 of the target 4 is the substrate Sw. It is set larger than the external dimensions. The target 4 is also bonded to the backing plate 42 that cools the target 4 via a bonding material such as indium or tin during sputtering, and the sputter surface 41 faces the substrate Sw through an insulator 43. It is mounted on the lower wall of the vacuum chamber 1. The output from the sputter power source E is connected to the target 4, so that DC power or AC power (high frequency power) having a negative potential can be input to the target 4.

The magnet unit 5 has a support plate (yoke) 51 made of a flat plate made of a magnetic material arranged in parallel with the target 4, and a wire provided at the center of the support plate 51 so that the polarity on the target side is S, for example. On the outer peripheral edge of the support plate 51, the polarity on the target side is changed (so that the polarity on the target side is N) so as to surround the central magnet 52 and the center magnet 52 with a gap. It is provided with an annular peripheral magnet 53 provided along the line. In this case, the volume when converted to the same magnetization of the central magnet 52 is equivalent to the sum of the volumes when converted to the same magnetization of the peripheral magnet 53 (peripheral magnet: central magnet: peripheral magnet = 1: 2: 1). It is set so that a closed-loop leakage magnetic field Mf in which a line passing through a position where the vertical component of the leakage magnetic field Mf becomes zero acts like a racetrack above the target 4 (spatter surface 41 side). Then, when a film is formed on the surface of the substrate Sw by the sputtering apparatus SM, the substrate Sw is conveyed to a position facing the target 4 (deposition position), and the sputtering gas is introduced into the film forming chamber 10 by the gas introducing means 3. It is introduced at a predetermined flow rate, and a predetermined power is applied to the target 4. Then, a racetrack-shaped plasma is generated above the sputtered surface 41 of the target 4 by the magnet unit 5, the target 4 is sputtered by the ions of the rare gas in the plasma, and the sputtered particles scattered from the target 4 adhere to the surface of the substrate Sw. By depositing, a thin film is formed on the surface of the substrate Sw.

Here, when the plasma is generated as described above, the electrons in the plasma move counterclockwise along the race track as shown by the alternate long and short dash line in FIG. Then, on both ends in the longitudinal direction of the target 4, the electrons are bent by the electromagnetic field at the first corner portion C1 and the second corner portion C2 to change the direction twice. At this time, the second corner portion C2 faces the second time. When changing the direction, the inertial motion of the electrons due to the acceleration of the electrons when the direction is changed for the first time at the first corner portion C1 remains, and the electrons jump out to the tip side in the width direction of the target 4.

In the present embodiment, a single first magnet piece 61 arranged on the upper surface of the central magnet 52 so as to match the polarity on the target side, and a peripheral magnet 53 located on the first corner C1 side and extending along the central magnet 52. It was decided to provide the meandering means 6 composed of two second magnet pieces 62a arranged so as to match the polarities on the target side on the upper surface of the straight portion 531 of the above. In this case, one second magnet piece 62a is arranged at the longitudinal end of the straight line portion 531 and is offset from the first second magnet piece 62a in the longitudinal direction with the first magnet piece 61. The other second magnet piece 62a is arranged in a staggered pattern. As a result, a portion having a strong magnetic field strength on the central magnet 52 side and a portion having a strong magnetic field strength on the peripheral magnet 53 side are alternately formed in the longitudinal direction, so that the section where the first magnet piece 61 and the second magnet piece 62a exist. (That is, the electrons before reaching the first corner portion C1) meander so as to alternately repel the central magnet 52 side and the peripheral magnet 53 side as shown by the alternate long and short dash line in FIG. As a result, the acceleration of the electrons when the direction is changed for the first time at the first corner portion C1 is suppressed.

As the first magnet piece 61 and the second magnet piece 62a, permanent magnets having a predetermined magnetic force can be used, but if the acceleration of electrons at the first change of direction can be suppressed, the first magnet piece 61 The magnetic force of the magnet piece 61 and the second magnet piece 62a, the installation position and the number of installations on the central magnet 52 and the peripheral magnets 53 are not limited to those described above. Further, as shown by the dotted line in FIG. 2, the polarity of the target side is made to match the upper surface of the straight line portion 531 of the peripheral magnet 53 located on the second corner portion C2 side, and the polarity of the target side is directly opposed to one of the second magnet pieces 62a. The third magnet piece 62b may be provided so that the electrons when the direction is changed for the second time at the second corner portion C2 repels the central magnet 52 side.

According to the above embodiment, with a simple configuration in which the first magnet piece 61 and the second magnet piece 62a are arranged in the existing magnet unit 5, the acceleration of electrons when the direction is changed at the first corner portion C1 can be accelerated. By suppressing it, the ejection of electrons from the target end due to the inertial movement of the electrons is suppressed as much as possible.

Although the embodiments of the present invention have been described above, the present invention is not limited to those of the above embodiments, and various modifications can be made as long as the gist of the present invention is not deviated. In the above embodiment, the meandering means 6 in which the first magnet piece 61 is arranged on the central magnet 52 and the second magnet piece 62a is arranged on the peripheral magnet 53 has been described as an example, but before reaching the first corner portion C1. As long as the electrons can be meandered and the acceleration of the electrons when the direction is changed at the first corner portion C1 can be suppressed, the present invention is not limited to this, and the space between the target 4 and the magnet unit 5 is limited. Permanent magnets and electromagnets can be arranged as appropriate to meander the electrons.

By the way, when the first magnet piece 61 and the second magnet piece 62a are locally arranged on the central magnet 52 and the peripheral magnet 53 as in the above embodiment, the electron density in the plasma is locally increased, and the film in the substrate surface is formed. The thickness distribution may worsen on the contrary. Therefore, as in the meandering means 60A shown in FIG. 3, the first magnet pieces 61 are arranged on the central magnet 52 at predetermined intervals over the entire length thereof, and the first corner portion C1 side that matches the length of the central magnet 52 is arranged. It is preferable that the second magnet pieces 62a are arranged at predetermined intervals over the entire length of the straight portion 531 of the peripheral magnet 53 located at. According to this, since the electron density in the plasma can be made uniform, it is possible to form a film with a good film thickness distribution in the substrate surface, which is advantageous. In this case as well, the third magnet pieces 62b can be provided at predetermined intervals over the entire length of the straight portion 531 of the peripheral magnet 53 located on the second corner portion C2 side.

Here, in the portion indicated by the circle of the virtual line in FIG. 3, the width of the race track, that is, the distance of the electrons moving in the opposite direction is shortened, so that the plasma discharge may become unstable due to the collision of the electrons. Therefore, like the meandering means 60B shown in FIG. 4, the first magnet piece 61a arranged on one side (right side in FIG. 4) of the central magnet 52 orthogonal to the longitudinal direction and the other side in the width direction (FIG. 4). The first magnet pieces 61a and 61b arranged on the upper surface of the central magnet 52 may be arranged in a staggered manner so that the first magnet pieces 61b arranged on the left side of 4) are offset in the longitudinal direction. In this case as well, the electrons moving in the section where the first magnet pieces 61a and 61b and the second magnet pieces 62a exist move while meandering, so that the acceleration of the electrons when the direction is changed at the first corner portion C1 is suppressed. Therefore, the ejection of electrons from the target end due to the inertial motion of the electrons is suppressed as much as possible.

Further, in the above embodiment and the modified example, the case where the meandering means is formed by the magnet pieces has been described as an example, but as shown in FIG. 5, the central magnet 52 and the peripheral magnets 53 are offset in the longitudinal direction. The meandering means 70A can also be configured by the first magnetic shunt piece 71 and the second magnetic shunt piece 72 provided in this way (that is, in a staggered pattern). Also in this case, as shown by the alternate long and short dash line in FIG. 5, the electrons move while meandering so as to be alternately attracted to the central magnet 52 side and the peripheral magnet 53 side. Therefore, the acceleration of the electrons when the direction is changed at the first corner portion C1 is suppressed, and the ejection of electrons from the target end due to the inertial movement of the electrons is suppressed as much as possible. The effect of morphology is obtained. Further, like the meandering means 60B shown in FIG. 4, the first magnetic shunt piece arranged on the side surface of the central magnet 52 on one side in the width direction (left side in FIG. 6) like the meandering means 70B shown in FIG. The first magnetism arranged on both side surfaces of the central magnet 52 so that the 71 and the first magnetic shunt piece 71 arranged on the side surface on the other side (right side in FIG. 6) in the width direction are offset in the longitudinal direction. The shunt pieces 71 may be arranged in a staggered pattern. According to this, it is possible to prevent the plasma discharge from becoming unstable due to collision of electrons moving in the opposite direction, which is advantageous. Since known magnetic shunt pieces 71 and 72 can be used, detailed description thereof will be omitted here.

Further, in the above embodiment, the case where one target 4 is installed in the vacuum chamber 1 has been described as an example, but there is also a case where a plurality of targets 4 are arranged side by side with an interval in the width direction. The present invention is applicable. In this case, a magnet unit 5 is provided below the sputter surface 41 of each target 4, and the first magnet piece 61 and the second magnet piece 62a (and the third magnet piece 62b) are attached to the central magnet 52 and the peripheral magnet 53 in the same manner as described above. If each of the above is arranged, it is possible to cope with the case of forming a film on a large substrate Sw, which is advantageous.

Cu ... Cathode unit, C1 ... 1st corner, C2 ... 2nd corner, Mf ... Leakage magnetic field, SM ... Sputtering device, 1 ... Vacuum chamber, 4 ... Target, 5 ... Magnet unit, 52 ... Central magnet, 53 ... Peripheral magnets, 6,60A, 60B, 70A, 70B ... Serpentine means, 61 ... 1st magnet piece, 62a ... 2nd magnet piece.

Claims (3)

A magnet unit is provided on the side facing the sputter surface of the target installed in the vacuum chamber and applying a leakage magnetic field to the sputter surface side of the target.
The magnet unit has a linear central magnet and a peripheral magnet that surrounds the central magnet at intervals with different polarities on the target side, and the vertical component of the magnetic field is zero in front of the sputtering surface. In a cathode unit for a magnetron sputtering apparatus, a leakage magnetic field is applied so that a line passing through a position thereof extends along the longitudinal direction of a central magnet and closes in a racetrack shape.
The cathode unit is attached to the vacuum chamber of the sputtering apparatus, sputter gas containing a rare gas is introduced into the vacuum chamber in a vacuum atmosphere, and a predetermined power is applied to the target to generate a racetrack-shaped plasma in front of the sputtering surface. In this case, the position where the electrons in the plasma moving clockwise or counterclockwise along this turn in the electromagnetic field is the first corner, and the position where the electron turns next is the second corner. A cathode unit for a magnetron sputtering apparatus, further comprising a meandering means for causing electrons to meander before reaching the first corner portion. The meandering means has a first magnet piece arranged at a predetermined position on the upper surface of the central magnet located on the target side with the same polarity on the target side, and a predetermined position on the upper surface of the peripheral magnet located on the target side on the target side. The cathode for a magnetron sputtering apparatus according to claim 1, further comprising a second magnet piece arranged so as to have the same polarity, and the first magnet piece and the second magnet piece are offset from each other in the longitudinal direction. unit. The first magnet pieces are arranged at predetermined intervals over the entire length of the central magnet, and the second magnet pieces are arranged at predetermined intervals over the entire length of the peripheral magnets that match the length of the central magnet. 2. The cathode unit for a magnetron sputtering apparatus according to claim 2.

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