JP4086792B2 - Sputtering equipment - Google Patents

Description

  The present invention relates to a sputtering apparatus in which high-energy particles collide with a target in a vacuum chamber, thereby firing material molecules constituting the target from the target, and the structure including cooling means is a molecular collision surface of the target. The present invention relates to a sputtering apparatus in which the target is cooled at the time of sputtering.

  When a multilayer thin film is formed on a substrate such as a semiconductor wafer by sputtering, it is necessary to form a plurality of materials on the substrate by sputtering a target made of different materials in a vacuum chamber. Even when a single material layer is formed, if a large amount of target is required, it is necessary to change the target to be sputtered from the target consumed by sputtering to a new target.

  Conventionally, when forming a film by sputtering a plurality of targets as described above, it is necessary to previously install the necessary types and number of targets in the vacuum chamber. These targets are installed in a vacuum chamber as a unit including a cooling mechanism such as electrodes such as a cathode or a magnetron electrode and a cooling pipe for cooling the electrodes. Then, a substrate on which a film is formed by sputtering is introduced and placed at a position facing each target through a load lock cell by a transfer mechanism such as a rotation mechanism, and sputtering is performed.

  However, when a plurality of targets are installed in a vacuum chamber as a unit having electrodes and cooling mechanisms attached thereto as described above, the number of targets, cooling mechanisms, and the like are required for the number of targets. become. On the substrate side, a cooling mechanism such as a heating / cooling mechanism must be provided at the position of the substrate facing the target. Therefore, the apparatus is complicated as a whole, and its operation is also complicated.

  In view of this, the present inventor provided a turntable that rotates below the position where the target is sputtered in the vacuum chamber, and arranged a plurality of targets on a circumference at a certain distance from the center of rotation of the turntable. By rotating and stopping the positioning, a plurality of targets were sequentially conveyed directly under the sputtering position, and the target was pushed up to the sputtering position by the actuator head and sputtered. The target electrode is provided on the upper end side of the actuator head, and the target is cooled by a cooling piping system that is circulated so as to cool the actuator head.

  In this sputtering apparatus, since the substrate is in a fixed position, the cooling mechanism is only one unit. On the target side, by providing electrodes and a cooling mechanism on the actuator head side that sequentially raises and lowers the target, a plurality of targets can be handled with a single electrode and cooling mechanism.

However, in the conventional sputtering apparatus that cools the target through the actuator head in this way, heat transfer from the actuator head to the target is poor, and the heat of the target cannot be absorbed smoothly into the cooling piping system of the actuator head. There is a problem that it cannot be cooled sufficiently. For this reason, sufficient discharge energy cannot be applied to the charged particles that collide with the target in the vacuum chamber, which causes a problem of reduction in film formation efficiency.
JP 2002-256425 A

  In view of the problem in the conventional sputtering apparatus that cools the target via the actuator head, the present invention can smoothly absorb the heat generated in the target at the time of sputtering from the contact surface of the actuator head. The purpose is to increase the efficiency. As a result, even if sufficient energy is given to the charged particles and they collide with the target, the temperature of the target is not increased, and efficient film formation can be performed.

  As a result of investigations to achieve the above-mentioned object, the present inventor has provided a mesh 4 on the contact surface of the actuator head 11 serving as a cooling source with the target 9, and is generated at the target 9 via the mesh 4. It has been found that efficient cooling can be achieved by absorbing the heat to the actuator head 11 side.

That is, in the sputtering apparatus according to the present invention, the actuator head 11 is moved up and down in the vacuum chamber 12, and the actuator head 11 is brought into contact with and separated from the back of the molecular collision surface of the target 9 by this movement. A cooling piping system 22 for cooling the target 9 is provided in the actuator head 11 by the head 11 ascending and contacting the back of the molecular collision surface of the target 9. The mesh plate 4 is stretched on the contact surface of the actuator head 11 that comes into contact, and the actuator head 11 is contacted behind the target 9 via the mesh plate 4.
The actuator head 11 has acceleration means for accelerating and colliding the collision molecules for sputtering with the target 9 .

  In the sputtering apparatus that cools the target 9 via the actuator head 11 as described above, the surfaces of the actuator head 11 and the target 9 that are in contact with each other are finished to be smooth surfaces. However, in reality, the surfaces of the actuator head 11 and the target 9 that are in contact with each other have fine irregularities and curvatures, and the portions that come into contact are limited.

  In contrast, in the sputtering apparatus according to the present invention, the mesh plate 4 is stretched on the surface of the actuator head 11 that contacts the target 9, and the actuator head 11 contacts the target 9 via the mesh plate 4. Are dispersed through the mesh of the mesh plate 4 and absorbed by the actuator head 11. Thereby, the cooling efficiency of the target 9 at the time of sputtering improves, and the temperature rise is suppressed.

  In this way, in the sputtering apparatus according to the present invention, the cooling efficiency of the target 9 can be increased, so that the temperature rise of the target 9 during sputtering can be suppressed. Thereby, sputtering with a large discharge energy can be performed. Therefore, since sufficient energy can be given to the charged particles to bombard the target, film formation can be stabilized and efficiency can be improved.

In the present invention, the mesh 4 is provided on the contact surface of the actuator head 11 that serves as a cooling source with the target 9, and the target 9 is cooled from the actuator head 11 via the mesh 4, thereby enabling efficient cooling. did.
Hereinafter, examples of the present invention will be described in detail with specific examples with reference to the drawings.

1 to 4 are views showing an outline of a sputtering multi-target apparatus according to an embodiment of the present invention, and the vacuum chamber 12 is not shown in FIG.
As shown in these drawings, a disk-shaped target support plate 2 is horizontally installed in the vacuum chamber 12, and the target support plate 2 is provided with a target holding portion 10 having a circular hole. It has been. The target holding unit 10 is provided at a position facing a substrate holder on which a substrate 24 on which a thin film is to be formed by sputtering is installed. A shutter 25 is provided between the target holding unit 10 and the substrate 24. In the illustrated example, target holding portions 10 are provided at two locations on the target support plate 2, but since one target holding portion 10 is not used, the hole is closed with a lid 19.

  A disc-shaped turntable 1 is disposed directly below the target support plate 2 in parallel with the target support plate 2. Circular actuator head passage holes 14 are formed at equal intervals on one circumference at a certain distance from the center of the turntable 1. The target 9 is disposed in the actuator head passage hole 14 in a state where the peripheral portion of the disk-shaped target 9 is supported. In the illustrated example, four actuator head passage holes 14 are opened at 90 ° intervals. However, when the number of targets 9 to be used is large, more actuator head passage holes 14 may be provided.

  A plunger receiver 7 is provided on the imaginary straight line connecting the center of the turntable 1 and the center of the actuator head passage hole 14 and on the outer peripheral edge of the turntable 1. The plunger receiver 7 is provided with a plunger insertion hole 8 in the radial direction of the turntable 1, and the plunger insertion hole 8 is provided with a taper that has a smaller diameter on the back side than the front side.

  The center of the turntable 1 is connected to a vertical shaft 14, and rotation is introduced into the shaft 14 via a rotation introducing machine 3 and a flange 13 from a rotation driving source (not shown) provided outside the vacuum chamber 12. The turntable 1 rotates intermittently. In the case of the illustrated example, the turntable 1 rotates intermittently at 90 ° intervals, and the position where the turntable 1 stops is that each actuator head passage hole 14 is located directly below the target holding portion 10 of the target support plate 2. It is a place to do.

An actuator head 11 is provided just below the position where the actuator head passage hole 14 of the turntable 1 stops just below the target holding portion 10 of the target support plate 2. The actuator head 11 has a cylindrical shape whose outer diameter is smaller than that of the actuator head passage hole 14, and a metal mesh plate 4 is provided on the upper surface thereof. The mesh plate 4 has a good heat conductivity made of oxygen-free copper or the like having a wire diameter of φ0.65 and # 8.
As shown in FIG. 3, the actuator head 11 is moved up and down in the vertical direction by an actuator 15 as a lifting mechanism attached to a port 17 provided in the lower portion of the vacuum chamber 12 via a flange.

As shown in FIGS. 3 and 4, a sputter electrode 21 is provided in the actuator head 11 for applying energy to charged particles such as ions generated in the vacuum chamber to collide with the target 9. Yes. For example, in the DC bipolar sputtering method, a cathode is provided as the sputtering electrode 21, and in the magnetron sputtering method, a magnetron electrode is provided as the sputtering electrode 21.
Further, a cooling piping system 22 for circulating cooling water is provided inside the actuator head 11 so that the upper surface can be cooled from the inside of the actuator head 11.

  An air cylinder is provided on the side of the vacuum chamber 12 as the actuator 5 that constitutes the positioning mechanism of the turntable 1. The actuator 5 is attached to a port 18 provided on the side of the vacuum chamber 12 via a flange. The actuator 5 is arranged on an imaginary straight line connecting the center of the turntable 1 and the center of the actuator head passage hole 14 of the turntable 1 that stops just below the target holding portion 10 of the target support plate 2. The plunger 6 strokes in an extension line direction of the virtual straight line.

  FIG. 4 is an enlarged view showing a state in which the tip of the plunger 6 of the actuator 5 is fitted in the plunger insertion hole 8 of the plunger receiver 7. As shown in this figure, the tip of the plunger 6 is provided with a taper having the same gradient as that formed in the plunger insertion hole 8 of the plunger receiver 7.

Next, the operation of the sputtering multi-target apparatus will be described below.
First, in the vacuum chamber 12, the periphery of the target 9 is placed on the actuator head passage hole 14 of the turntable 1. In this state, the inside of the vacuum chamber 12 is depressurized to a required degree of vacuum.

  When the first target 9 is sputtered after depressurizing the inside of the vacuum chamber 12, first, the turntable 1 is rotated to move the first target 9 directly below the target holding part 10 of the target support plate 2. Stop there. When the turntable 1 rotates, the plunger 6 of the actuator 5 is retracted. However, when the turntable 1 stops at the above position, the actuator 5 is activated, the plunger 6 is extended, and the tip is tapered. Along with this, the plunger is inserted into the plunger insertion hole 8 of the plunger receiver 7. Thereby, the turntable 1 is accurately positioned and held such that the first target 9 is positioned directly below the target holding portion 10 of the target support plate 2.

  When the turntable 1 rotates, the actuator head 11 is at the lowest position, and the upper surface of the actuator head is below the turntable 1. As described above, when the first target 9 on the turntable 1 is accurately positioned and stopped so as to be positioned directly below the target holding portion 10 of the target support plate 2, the actuator head 11 is raised and its upper surface is The target 9 is placed on the mesh 4, and further raised through the actuator head holding hole 14, and the target 9 is arranged on the target holding portion 10 of the target support plate 2. This state is shown in FIG.

  In this state, the inside of the vacuum chamber 12 is made a rare gas atmosphere such as argon, and a glow discharge or the like is generated in the vacuum chamber 12 to ionize argon and generate ions. At this time, the sputter electrode 21 is operated, and the generated ions are given energy by the electric field or magnetic field generated by the sputter electrode 21, collide with the target 9, and the target 9 is sputtered. As a result, the molecules of the material constituting the target 9 are released from the target 9, and these molecules adhere to the substrate and form a film. During this time, the upper surface of the actuator head 11 is cooled by the cooling piping system 22, and heat generated in the target 9 by the impact of ions is absorbed by the cooling piping system 22 from the upper surface of the actuator head 11 via the mesh 4.

  When the sputtering of the first target 9 is completed in this way, the actuator head 11 is lowered to return the sputtered target 9 to the original position on the turntable 1. Thereafter, the turntable 1 is rotated to move the next second target 9 directly below the sputtering position. Therefore, the turntable 1 is positioned and held in the same manner as the first target 9. Similarly, after the second target 9 is raised to the sputtering position by the actuator head 11 and sputtered, the turntable 11 is returned to the original position. Thereafter, the third and fourth targets 9 move in the same manner and perform sputtering.

Table 1 below shows the target temperature when sputtering is performed on a 5 mm-thick aluminum by using a DC bipolar sputtering method with a degree of vacuum: 7.0 ⁻¹ Pa, discharge gas: argon, and discharge energy: DC 200 W. Is shown. As an embodiment of the present invention, the actuator head 11 provided with the mesh 4 on the upper surface is compared with the one not provided.

  As is clear from Table 1, there were significant differences in the temperature rise suppression and cooling time of the target depending on the presence or absence of the mesh. Further, when sputtering was carried out in the same manner by applying a high frequency voltage of 200 W to the magnetron electrode by the magnetron sputtering method, the temperature of the target was less than 300 ° C. even after discharging for 15 minutes.

It is the perspective view which abbreviate | omitted elements, such as a vacuum chamber which shows the multi-target apparatus for sputtering by one Embodiment of this invention, and showed only the main elements. It is a top view which shows the multi-target apparatus for sputtering by the same embodiment. It is the sectional view on the AA line of FIG. FIG. 4 is an enlarged cross-sectional view of a main part showing the vicinity of the upper surface of the actuator head of FIG. 3.

Explanation of symbols

4 Mesh plate 9 Target 11 Actuator head 12 Vacuum chamber 15 Actuator 22 Cooling piping system

Claims (2)

In the sputtering apparatus in which the actuator head (11) is moved up and down in the vacuum chamber (12) and the actuator head (11) contacts and separates behind the molecular collision surface of the target (9) by this movement, the actuator is used during sputtering. The actuator head (11) is provided with a cooling piping system (22) for cooling the target (9) by raising the head (11) and contacting the back of the molecular collision surface of the target (9). A mesh plate (4) is stretched on the contact surface of the actuator head (11) that contacts the back of the target (9) when ascending by (15) , and behind the target (9) through the mesh plate (4). A sputtering apparatus characterized by contacting an actuator head (11). 2. The sputtering apparatus according to claim 1, wherein the actuator head has acceleration means for accelerating and colliding the collision molecules for sputtering with the target.

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