JP6265534B2 - Sputtering cathode - Google Patents

Description

  The present invention relates to a sputtering cathode used in a magnetron type sputtering apparatus. More specifically, the present invention relates to a sputtering cathode surface of a target, and the side facing away from the sputtering surface is provided above the target and locally below the sputtering surface of the target. The present invention relates to a magnetic field generating unit that generates a magnetic field and a scanning unit that scans a region where the magnetic field is generated along a sputtering surface of a target.

  This type of sputtering cathode is known from Patent Document 1, for example. In this device, an epicyclic scanning actuator as a scanning means is provided above the target assembly. The scanning means has an inner rotating shaft and an outer rotating shaft arranged concentrically, and is driven to rotate by the first and second motors, respectively. Further, the inner rotating shaft and the outer rotating shaft are coupled to an epicyclic mechanism, and a magnetron as a magnetic field generating means is held by the epicyclic mechanism via a mounting base. In this case, the gear box and the counterweight are fixed to the lower end portion of the outer rotating shaft, and the sun gear is fixed to the lower end portion of the inner rotating shaft in the gear box.

  A driven gear is supported in the gear box and coupled to the sun gear via an idler gear. The shaft of the driven gear is fixed to the magnet arm, and the magnet arm is rotated by the driven gear. The magnetron and its counterweight are fixed at both ends of the magnet arm, the gearbox acts as the inner arm, the magnet arm acts as the outer arm, and the magnet arm acts as a planetary gear mechanism with the sun gear and the driven gear. The magnetron can be scanned in an almost arbitrary pattern by a rotating shaft controlled separately by each motor. However, since the conventional example uses two motors, the number of parts is large, and the control of the motor for scanning the magnetic field generating means in a predetermined pattern over the entire target surface is complicated. There is a problem.

JP 2011-50596 A

  In view of the above points, an object of the present invention is to provide a low-cost sputtering cathode capable of scanning a magnetic field generating unit over the entire target surface with a simple configuration.

In order to solve the above-mentioned problems, a magnetic field generating means for generating a magnetic field locally on the side facing away from the sputtering surface of the target and generating a magnetic field locally above the target and below the sputtering surface of the target is generated. The sputtering cathode of the present invention comprising scanning means for scanning the region along the sputtering surface of the target, the scanning means comprises a single motor, a first rotating body connected to the output shaft of the motor, and a first A second rotating body that rotates in conjunction with the rotation of the first rotating body around the rotating shaft parallel to the output shaft below the rotating body, and one side rotates to a position eccentric from the rotating center of the second rotating body is rotatably connected, and the shaft body magnetic field generating means are provided other side, interlocked with the rotation of the second rotary member, and a guide means for guiding the reciprocation of the magnetic field generating means in the same line, the guide means The second In conjunction with the rotation of the rotary member and performing a rotational movement relative to the output shaft of the motor.

  According to the above, when the first rotating body is rotationally driven, the magnetic field generating means is based on the combination of the rotational motion around the output shaft and the reciprocating motion on the same line in the direction approaching and separating from the second rotating body (spiral). A predetermined area of the sputter surface is reliably scanned while drawing the trajectory. In this case, since the configuration in which the magnetic field generating means scans a predetermined area of the sputtering surface with a single motor can be realized, the apparatus configuration is simple and low in cost, and the complicated control as in the above conventional example is also possible. do not need.

  In the present invention, there is a reduction gear train provided between the first rotator and the second rotator, and the gear on the output side of the gear train meshes with another gear provided on the rotating shaft. Is preferred. According to this, if the speed reduction gear train is appropriately set, the period of reciprocation of the magnetic field generating means is changed, and if the (rotational) speed ratio of the second rotating body to the first rotating body is changed, the magnetic field is generated. The trajectory drawn by the means can be arbitrarily changed. Thereby, the magnetic field generating means can be efficiently scanned over the entire sputtering surface of the target. In addition, it is preferable that the rotation speed (angular velocity) ratio of the 2nd rotary body with respect to a 1st rotary body shall be 0.1-0.3. Within this range, the magnetic field generating means can be reliably scanned over the entire sputtering surface of the target.

The figure which shows typically the structure of the sputtering device provided with the sputtering cathode of embodiment of this invention. The figure explaining the structure of a scanning mechanism. Sectional drawing along the III-III line of FIG. Sectional drawing along the IV-IV line of FIG. Sectional drawing along the VV line | wire of FIG. The figure which shows the locus | trajectory which the magnetic center of a magnetic field generation means draws. The figure which shows the locus | trajectory which the magnetic center of a magnetic field generation means draws. (A)-(d) is a figure which shows the locus | trajectory which the magnetic center of a magnetic field generation means draws.

  Referring to the drawings, an embodiment of a sputtering apparatus equipped with a sputtering cathode according to the present invention will be described in the case where a substrate to be processed is a wafer W, a target T is made of Cu, and a Cu film is formed on the surface of the wafer W. A form is demonstrated. In the following, with reference to FIG. 1, the direction from the wafer W toward the sputtering surface T1 of the target T is “up” and the opposite is “down”, and terminology indicating the direction is used.

Referring to FIG. 1, the sputtering apparatus SM is of a magnetron type and includes a vacuum chamber 1 that defines a sealed processing chamber 11. Connected to the side wall of the vacuum chamber 1 is a gas introduction pipe 2 for introducing a sputtering gas containing an inert gas such as argon (it can also contain a reaction gas such as oxygen). The gas introduction pipe 2 is connected to a mass flow controller. A sputtering gas whose flow rate is controlled by communicating with a gas source (not shown) via 21 can be introduced into the vacuum chamber 1. Further, an exhaust pipe 3 leading to a vacuum pump P such as a turbo molecular pump or a rotary pump is connected to the bottom wall of the vacuum chamber 1 so that the processing chamber 11 can be evacuated to a predetermined pressure (for example, 10 ⁻⁵ Pa).

  A stage 2 is disposed on the bottom surface of the vacuum chamber 1. Although not shown and described above, a so-called electrostatic chuck is provided on the upper portion of the stage 2 to hold the wafer W by suction. Note that an output from a high-frequency power source having a known structure may be connected to the stage 2 so that a bias potential is applied to the stage 2 during film formation by sputtering. Thereby, the sputtered particles ionized in the processing chamber 11 can be actively drawn into the wafer W.

  A conductive anode shield 4 is disposed in the vacuum chamber 1. The anode shield 4 is formed of a cylindrical member that covers the periphery of the target T and extends downward to above the stage 2. A DC power source E1 is connected to the anode shield 4 so that a positive DC potential is applied during film formation by sputtering. As a result, the sputtered particles ionized by the anode shield 4 are reflected and assisted to be emitted to the wafer W with strong straightness. A sputtering cathode SC including a target T disposed in a vacuum seal so as to face the processing chamber 11 facing the wafer W is provided with the sputtering surface T1 facing downward. Yes.

  2 to 5, the sputtering cathode SC includes a magnetic field generating means 5 for generating a magnetic field locally below the sputtering surface T1 of the target T, and a region Mf where the magnetic field is generated within a predetermined range of the sputtering surface T1. And scanning means 6 for scanning. The target T is not limited to Cu, and can be appropriately selected according to the composition of the thin film to be formed on the wafer W to be processed (for example, made of Ti or Ta). Formed. The target T is attached to the vacuum chamber 1 through the insulator I also serving as a vacuum seal in a state where the target T is mounted on the backing plate Tb. The magnetic field generating means 5 and the scanning means 6 provided above the target T are housed in a box 7. The target T is connected to a sputtering power source (DC power source) E2 for applying a predetermined power having a negative potential. The sputtering power source E2 is not limited to the DC power source, and a high frequency power source or the like can be used according to the target type.

  The magnetic field generating means 5 includes a plurality of annular permanent magnets 52 having different diameters on the lower surface of a circular support plate (yoke) 51 made of a magnetic material provided in parallel to the back surface of the backing plate Tb. It is configured by changing the concentricity. Then, a closed-loop balanced magnetic field is generated in the space below the sputtering surface T1 of the target T, and electrons and the like ionized below the sputtering surface T1 during the sputtering are captured in this magnetic field generation region Mf and scattered from the target T. Ions are efficiently ionized. In this case, when the target T is a cylinder, the diameter of the support plate 51 with respect to the diameter of the target T is 0.25 to 0.33 times in order to cause the magnetic field generating means 5 to scan over the entire sputtering surface T1. It is preferable to set the range. Note that the magnetic field generating means 5 is not limited to the above, and well-known ones having various forms such as those including electromagnets instead of permanent magnets can be used, and detailed description thereof is omitted here.

  The scanning unit 6 includes a single motor 61 provided on the upper surface of the box 7, and a first rotating body 62 is connected to an output shaft 61 a of the motor 61 protruding into the box 7. In this case, a known DC motor or the like can be used as the motor 61, and the output shaft 61 a is disposed on a center line CL passing through the center of the stage 2. The first rotating body 62 includes an upper rotating plate 62a and a lower rotating plate 62b arranged with a predetermined interval in the vertical direction. Four support shafts 62c are erected on the lower surface of the upper rotating plate 62a at intervals of 90 ° in the circumferential direction, and planetary gears 63 are provided on the respective support shafts 62c. The planetary gear 63 is suspended from the upper gear 64b of the sun gear 64 having an upper gear 64b and a lower gear 64c fixed to the same rotation shaft 64a with a predetermined interval in the vertical direction, and from the upper inner surface of the box 7. The outer ring gear 65 provided is meshed. The planetary gear 63, the sun gear 64, and the outer ring gear 65 constitute a reduction gear example of the present embodiment.

  Below the first rotator 62, a second rotator 66 is provided that rotates in conjunction with the rotation of the first rotator 62 about another rotation shaft 66a parallel to the output shaft 61a. The second rotating body 66 includes a crank gear 66b and a crank disk 66c that are smaller in diameter than the lower rotating plate 62b and are fixed to the rotating shaft 66a with a predetermined interval in the vertical direction. The diameters of the crank gear 66b and the crank disk 66c are set smaller than the radius of the lower rotating plate 62b. The crank gear 66b meshes with the lower gear 64c corresponding to the gear on the output side of the gear train.

  A support pin 67 is erected at a position eccentric from the rotation center of the crank disk 66c, and a crank shaft 68 as a shaft body is rotatably connected to the support pin 67. A slide block 69a is provided on the other side of the crankshaft 68, and the magnetic field generating means 5 is fixed to the lower portion of the slide block 69a. In this case, the length of the crankshaft 68 may be formed approximately equal to the radius of the sputtering surface, and the magnetic field generation region Mf may be reciprocated over the entire radius of the sputtering surface. Further, the upper portion of the slide block 69a is supported by a slide guide 69b as guide means provided by being supported by support columns 62d and 62d erected on the lower surface of the lower rotary plate 62b so as to extend in the radial direction of the crank disk 66c. It is slidably engaged.

  According to the above, when the first rotating body 62 is rotationally driven by the rotation of the motor 61, each planetary gear 63 rotates while rotating around the output shaft 61a, and thus around the center line CL, and the sun gear 64 is accordingly rotated. Rotate in the same direction as the upper rotating plate 62a. The rotational speed in this case is determined by the speed transmission ratio of the outer ring gear 65, the planetary gear 63, and the sun gear 64. Then, while the second rotating body 66 revolves around the center line CL by the crank gear 66b meshing with the lower gear 64c of the sun gear 64, the crank disk 66c rotates and the slide block 69a moves along the slide guide 69b. Reciprocates. Thereby, the magnetic field generating means 5 is based on the combination of the rotational motion around the center line CL and the reciprocating motion on the same line in the direction of approaching and separating from the second rotating body 66 in the radial direction of the crank disk 66c (spiral). ) A predetermined area of the sputter surface T1 is scanned while drawing a trajectory. In this case, since the configuration in which the magnetic field generating means 5 scans a predetermined area of the sputtering surface T1 with a single motor 61 can be realized, the apparatus configuration is simple, low cost, and complicated as in the conventional example. It does not require any control. In addition, if the speed reduction gear train is appropriately set, the reciprocating cycle of the magnetic field generating means 5 is changed, and if the (rotational) speed ratio of the second rotating body 66 to the first rotating body 62 is changed, the magnetic field is generated. The trajectory drawn by the means 5 can be arbitrarily changed. Thereby, the sputtering surface T1 of the target T can be efficiently scanned over the entire surface. Note that the angular velocity ratio of the crank disk 66c to the first rotating body 62 is preferably 0.1 to 0.3. Within this range, the sputtering surface T1 of the target T can be reliably scanned over the entire surface.

  Next, the locus drawn by the center (magnetic center) of the support plate 51 of the magnetic field generating means 5 was simulated using the sputtering cathode SC shown in FIG. In this case, the reduction gear train was designed so that the ratio of the angular speed of the crank gear 66b to the lower rotating plate 62b was 0.3. According to this, when the lower rotating plate 62b is rotated twice, it is confirmed that the magnetic center moves spirally as shown in FIG. 6, and when the lower rotating plate 62b is rotated ten times, as shown in FIG. 7 was drawn, and from this, it was confirmed that the magnetic field generating means 5 can be scanned over the entire sputtering surface T1 of the target T (that is, discharge can be performed over the entire sputtering surface T1).

  Further, the reduction gear train is designed so that the ratio of the angular velocity of the crank gear 66b to the lower rotating plate 62b is 0.1, 0.2, 0.4, 0.5, and the lower rotating plate 62b is rotated 10 times. It was confirmed that the center draws the trajectories shown in FIGS. 8A to 8D, respectively. According to this, when the ratio of the angular velocity of the crank gear 66b to the lower rotating plate 62b is 0.4 or more, the magnetic field generating means cannot be scanned over the entire sputtering surface T1 of the target T at a rotational speed of about 10 revolutions. Was confirmed.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this. In the above-described embodiment, an example in which a reduction gear train is provided has been described, but this may be omitted.

  SC ... Sputtering cathode, T ... Target, T1 ... Sputtering surface, 5 ... Magnetic field generating means, 6 ... Scanning means, 61 ... Motor, 61a ... Output shaft, 62 ... First rotating body, 66 ... Second rotating body, 66a ... Rotating shaft 68... Crank shaft (shaft body) 69 b. Slide guide (guide means).

Claims (2)

A magnetic field generating means for generating a magnetic field locally above the target with the side facing away from the sputtering surface of the target being above the target, and the region where the magnetic field was generated is used as the target sputtering surface. A sputtering cathode comprising scanning means for scanning along,
The scanning means interlocks with the rotation of the first rotating body around the rotation axis parallel to the output shaft below the first rotating body, the first rotating body connected to the output shaft of the motor, and the first rotating body. The second rotating body rotating, a shaft body having one side pivotably connected to a position eccentric from the center of rotation of the second rotating body, and a magnetic field generating means on the other side, and rotation of the second rotating body And a guide means for guiding the reciprocating motion of the magnetic field generating means on the same line ,
A sputtering cathode characterized in that the guide means performs a rotational movement with respect to the output shaft of the motor in conjunction with the rotation of the first rotating body . It has a reduction gear train provided between the first rotary body and the second rotary body, and the gear on the output side of the gear train meshes with another gear provided on the rotary shaft. Item 2. The sputtering cathode according to Item 1.

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