KR20070121838A - Sputtering system - Google Patents

Abstract

A multi-chamber processing system is described for depositing materials on multiple workpieces (wafers, display panels, or any other workpieces) at a time in a vacuum chamber. The system includes a sputtering chamber and a separate pre-clean chamber, where wafers can be transferred between the two chambers by a robotic arm without breaking a vacuum. The wafers are mounted one-by-one onto a rotating pallet in the pre-cleaning chamber and sputtering chamber. The pallet is firmly fixed to a rotatable table in the sputtering chamber. Multiple targets, of the same or different materials, may concurrently deposit material on the wafers as the pallet is rotating. Multiple magnets (one for each target) in the magnetron assembly in the sputtering chamber oscillate over their respective targets.

Description

Sputtering System {SPUTTERING SYSTEM}

The present invention relates to deposition systems for semiconductor wafers and other workpieces, and more particularly to sputtering systems.

Sputtering systems are widely used in the semiconductor manufacturing industry to deposit materials on semiconductor wafers. Sputtering is sometimes referred to as physical deposition, or PVD. In sputtering operations, thin films comprising materials such as Al, Au, Cu, Ta, etc. are vacuum deposited onto a silicon wafer or other substrate. To produce thin film stacks of different materials, one common practice is to use a plurality of single-wafer process chambers, in which each chamber deposits only one material on one substrate at a time. For a three layer structure comprising Ti / Cu / Au, three separate single-wafer process chambers are needed to continuously deposit Ti, Cu and Au on the substrate. Providing each process chamber for a particular material deposition increases equipment and process costs. Restriction of single-wafer movement between chambers reduces system throughput.

There are many other problems with conventional sputtering systems. These problems relate to inefficient magnetron operation, uneven coverage, poor temperature control on the wafer, contamination of the wafer and other components, and uneven target corrosion among others.

A multi-chamber batch processing system for depositing materials on a plurality of workpieces in one vacuum chamber is described.

The system includes a sputtering chamber and a separate pre-clean chamber, in which wafers can be moved between the two chambers by the robot arm without breaking the vacuum. In one embodiment, 4-6 wafers are processed at one time in each chamber.

Individual pre-clean chambers, such as inductively coupled plasma (ICP) chambers, increase throughput and provide faster etch rates, resulting in reduced contamination of the sputtering chamber and damage to electronic circuits on the wafer. Will be reduced. In addition, since there is no need for a shutter to isolate the sputtering target during the pre-clean process, there is no additional contamination from the shutter during the sputtering process.

The wafers are mounted one by one from the load holding device to the rotating pallet in the ICP chamber. In one embodiment, the pallet is aluminum. Aluminum is anodized to form an insulating film on its surface (or another insulator is formed). This prevents the pallet from being etched in the ICP chamber and prevents particles from the pallet from contaminating the wafer. do.

The robot arm moves the wafer one by one from the IPC chamber to the sputtering chamber without exposing the wafer to the atmosphere, thereby avoiding unwanted chemical reactions, such as oxides, on the wafer surface.

The wafer is mounted on a direct-drive rotary pallet in the sputtering chamber. The pallet is fixed to the rotatable table in the sputtering chamber, providing good thermal and electrical conductivity between the pallet and the table. The copper tubing in the table couples RF energy to the wafer, and the coolant flowing through the copper tubing controls the temperature of the wafer.

Multiple targets of the same or different materials may simultaneously deposit material on the wafer as the pallet rotates. This allows for higher throughput, creates uniform deposition, and can be used to deposit films of various compositions on the workpiece.

The plurality of magnets (one for each target) of the magnetron assembly in the sputtering chamber oscillate (per 0.5-10 second period) over the associated target for uniform target corrosion and uniform deposition on the wafer. Each magnet is made up of many small magnets, and their arrangement and relative sizes are selected to optimize target corrosion and increase throughput.

The target back substrate between each of the magnets and the target has a coolant channel flowing through it. The distance between the magnets and the targets is very small by a thin aluminum substrate fixed to the bottom of the target back substrate by a deep brazing process. This small distance increases magnetic coupling and thus increases the density of the plasma and improves the deposition rate and target utilization.

In order to prevent cross-sectional contamination from the target, and to prevent sputtered target material from entering the gap in the chamber and shorting the insulators, various shields are described.

Other novel configurations of the system are described.

The system can also be used to deposit materials on LCD panels (eg, conductors for thin film arrays) and other workpieces.

1 is a perspective view of a multi-chamber sputtering and cleaning system with the cover removed to illustrate some internal components;

2 is a top plan view of a multi-chamber system exposing the robot arm and rotating pallets in the conveying module;

3 is a cross-sectional view of the sputtering chamber;

4A is a sectional view of a rotating shaft, a table, and a pallet in the sputtering chamber;

4B is a bottom view of a table showing copper pipe and coolant flow for RF coupling;

5A shows the distribution of certain magnetic flux lines in a permanent magnet used in a magnetron;

5B is a cross-sectional view of the magnet of FIG. 5A;

6A is a perspective view of a magnetron assembly, forming an upper end of a sputtering chamber, having a magnet vibrating in an intermediate position;

6B is a perspective view of the magnetron assembly having one vibrating magnet in its leftmost position;

7 is a cross-sectional perspective view of a portion of a top substrate and a target back substrate (to support the target and magnet) of the sputtering chamber;

8 is a top plan view of a thin coverless target back substrate showing a coolant channel;

9 is an exploded cross-sectional view illustrating a deep brazing process for forming a target back substrate between a magnet and a target;

10 is a cross-sectional view of a top substrate and a target back substrate having a mounted target;

11 is a perspective view from below the top substrate showing the targets and the cross-contamination shield.

In the various drawings, the same reference numerals refer to the same components.

1 illustrates a multi-chamber sputtering and pre-clean system 10 for a workpiece such as a semiconductor wafer, LCD panel, and other workpieces requiring thin film deposition. Examples of thin films include Al, Cu, Ta, Au, Ti, Ag, Sn, NiV, Cr, TaNx, Hf, Zr, W, TiW, TiNx, AlNx, AlOx, HfOx, ZrOx, TiOx, and among these elements It contains at least two alloys. The top covers of the sputtering chamber 12, the clean-clean chamber 14, and the wafer transfer module 16 were removed. The robot arm at the wafer transfer module 16 is not shown in FIG. 1 to see the access ports 18, 19 from the load locks 20, 21.

Typical wafer sizes are 6, 8, and 12 inches and the system is suitably set up for a particular workpiece for process processing.

2 is a top plan view of the system 10, where the wafer support pallets are shown in chambers 12 and 14. Robotic arm 24 is shown within conveying module 16.

In order to load the wafer into the system 10 for thin film deposition, a wafer stack supported on a cassette is placed in the load lock 20. The cassette supports each wafer by its edges. At that time, a vacuum is formed in the load lock 20 and the transfer module 16 by the vacuum pump. The vacuum pump used in the system 10 may form a pressure of 0.001 millitorr (133.322 * 10 ⁻⁶ dyne / cm ² ) or less.

The robot arm 24 rotates to align itself with the load lock 20, and the arm 24 is inserted into the load lock 20 by the rotation of the arm 26. The cassette is arranged by the elevator so that the bottom wafer is slightly above the arm 24. The elevator then lowers the cassette such that the wafer is entirely supported by the arm 24. The arm 24 is then retracted into the transfer module 16, and the arm 24 is aligned with the port 28 of the pre-clean chamber 14. The pre-clean chamber 14 is isolated from the conveyance module 16 by a slit valve (not shown). The pressure in the pre-clean chamber 14 is pulled down to the same pressure (bottom pressure) as the conveying module 16 by the vacuum pump 29 (FIG. 1), and the slit valve is opened. Arm 24 extends the wafer over rotatable pallet 30 in chamber 14. The pallet 30 rotates to align the wafer support region 32 under the wafer. Wafer support area 32 is an indented area within pallet 30 sized to accommodate a particular wafer to be processed. In another embodiment, an electrostatic chuck (ESC) is used to support the wafer. ESCs provide increased flexibility in applying force to the wafer, and each ESC can be controlled individually. ESC may provide better thermal conductivity between the wafer and pallet 30 due to the strong clamping action on the wafer. Four pins under the pallet 30 are raised to extend through the four holes 34 in the wafer support area 32 to lift the wafer from the arm 24. The arm 24 is recovered, the pins are lowered so that the wafer is seated in the indentation and the entire backside of the wafer is in contact with the pallet 30. This is important for temperature control and biasing, which will be described later.

The robot arm 24 then rotates to obtain another wafer from the cassette, and the pallet 30 rotates to align the next wafer support region 32 with the port 28. This transfer process is repeated until five wafers are placed on the pallet 30. In a preferred embodiment, the pallet 30 has four to six wafer support regions 32, but may be more or less as desired.

During the process of loading the pre-clean chamber 16, the arm 24 may remove the purified wafers from the pallet 30 and place them on a similar pallet 36 in the sputtering chamber 12. The sputtering chamber 12 has a port 37 and a slit valve similar to the pre-clean chamber 14. The loading process onto the pallet 36 is the same as the loading process described above.

The preclean process of the wafer is important for removing impurities, for example oxides from the wafer surface, so that the metal films deposited in the sputtering chamber 12 are not electrically insulated from the wafer. By performing a pre-cleaning process in chamber 14, which is part of a multi-chamber vacuum environment to which sputtering chamber 12 is connected, wafers are waiting (or otherwise contaminated) from the cleaning chamber 14 to the sputtering chamber 12. It can be transferred without being exposed to, so that no impurities are formed on the workpiece during the transfer time. In addition, the vacuum pump-down cycle is reduced because the vacuum is maintained in the multi-chamber system while transferring the purified wafer into the sputtering chamber. Only when the cassette is full in the load lock 21 or when the cassette is empty in the load lock 20, the system needs to stop the vacuum to remove the wafer from the system or to introduce it into the system.

In some sputtering systems, the pre-clean process is performed in the same chamber as the sputtering (in situ process). This results in equipment design damage and causes etched particles to accumulate on the chamber wall and other parts. Such particles contaminate the wafer during the sputtering process and shorten the period between maintenance cycles. In addition, since there is no need for a shutter to isolate the sputtering target during the pre-clean process, there is no additional contamination from the shutter during the sputtering process.

In a preferred embodiment, the pre-clean chamber 14 uses inductively coupled plasma (ICP) to etch the wafer. To create an excitation field in chamber 14, top coil 38 (FIG. 1) of chamber 14 is activated with an external RF source (e.g., 13.56 MHz). Argon gas flows through the chamber 14 from an external gas source. Argon atoms in the chamber 14 are ionized by RF energy and thus charged. The wafer is biased by a DC bias source coupled to the aluminum pallet 30 so that its ions are attracted to the wafer to etch the wafer. Different gases may be used depending on the desired etch rate and the material to be etched. The etching is a cleaning process rather than a process of etching the components in the wafer material and so the energy level will be low. This prevents damaging circuit elements and components already formed on the wafer. ICP etching is a well known process, so no additional details are needed to describe the chamber 14 and its operation.

The aluminum pallet 30 in the pre-clean chamber 14 is anodized to form an electrical insulating film on its surface. This reduces the etch rate of the pallet 30 when the wafer is purged in the ICP chamber and prevents particulates from the pallet that contaminate the wafer. The anodized surface can be obtained by heating the palette 30 in an oxygen atmosphere, depositing an aluminum oxide layer, or plasma spraying the aluminum oxide layer. The insulating surface of the pallet 30 can also be obtained by depositing a ceramic coating or other insulating films. Thicker insulating films reduce the effective bias at the pallet surface and thus reduce the etch rate of the pallet. In one embodiment, the insulating film is greater than 2 mils (0.05 mm).

In another embodiment, the material desired to be deposited on the wafer during the pre-clean process may be deposited on the pallet 30. The plasma clean process will then remove the material from the pallet 30 and coat the material on the wafer. After the pre-clean process, where unwanted natural oxides are etched from the wafer surface, the robot arm 24 moves five wafers one by one into the sputtering chamber 12. 3 is a cross-sectional view of the sputtering chamber 12 with its cover removed. The following description of the pallet 36 and the table 40 in the sputtering chamber 12 will also apply to the pallet 30 and the table in the pre-clean chamber.

3 describes a pallet 36 mounted on a rotatable table 40. The pallet 36 and the table 40 may be formed of aluminum. The pallet 36 may be continuously rotated or temporarily stopped at any speed to control the deposition of sputtered material from the target 43 overlying the wafer. Wafer 41 is shown in one of five wafer support regions 32.

In order to move the wafer to or from the robot arm 24, a pin bellows 39 is shown in FIG. 3 to push four pins (not shown), described above, into the wafer support region 32. The pin bellows 39 may be controlled by air pressure or directly driven by a motor.

The chamber shield 35 prevents contaminants from accumulating on the chamber walls.

4A is a cross-sectional view of pallet 36 and table 40. Pallet 36 is about 1/4 to 1/2 inch (6.3-12.7 mm) thick and table 40 is about 1 inch (25.4 mm) thick. The pallet 36 is a single piece fixed to the table 40 by conical screws 42 at the indentations in each wafer support area 32, so that the wafer prevents the sputtered material from depositing on the screws 42. You can do it. The pallet 36 can be removed for cleaning by turning the screw 42.

Thus, the entire backside of each wafer is in electrical and thermal contact with the pallet 36, which in turn is in electrical and thermal contact with the table 40.

In order to obtain a neat and reliable thin film, it is important to control the temperature of the wafers during the sputtering process. The temperature of the wafer is controlled by flowing the coolant 44 (FIG. 4A) through the copper pipe 46 in direct contact with the table 40. In one embodiment, the copper tube 46 is soldered to the table 40. The copper pipe 46 extends in the groove 48 around the table 40, as shown in FIG. 4B, which is a bottom view of the table 40.

The copper pipe 46 extends through the axis of rotation 49 attached to the table 40.

The external cooling source 50 cools the coolant (eg, water) and recycles the coolant to the table 40. The flexible tubing 51 from the cooling source 50 is rotated to provide a hermetic coupling between the rotating copper pipe 46 (input and output) and the stationary piping 51 from / to the cooling source 50. Is attached to the possible coupler 52.

In another embodiment, a cooling source may be replaced or added to the heating source to increase the workpiece temperature regardless of the ICP or sputtering process.

RF and bias source 54 are electrically coupled to copper tube 46 with rotatable coupling 52 to run table 40 and thus to drive pallet 36 and the wafer for sputtering process. In another embodiment, the table 40 is grounded, suspended, or biased with only a DC voltage source.

Chamber 12 is evacuated and backfilled with a certain amount of Ar gas at a constant pressure (eg, 20 millitorr (2.67 dyn / cm ² )) and the gas is operated from a DC source, an RF source or a combination of the two sources. If so, an electromagnetic field is coupled inside the chamber 12 to generate a uniform high density plasma near the target surface. The plasma (described later) confined near the target surface contains positive ions and free electrons (such as Ar +). In the plasma ions strike the target material and sputter the material from the target. The wafer receives the sputtered material to form a deposition layer on the wafer surface. In one example, up to 20 kilowatts of DC power may be formed in each target. In such a case, each target may simultaneously deposit about 1 micron (10 ⁻⁶ m) of copper per minute on the plurality of workpieces.

The chamber 12 wall is typically electrically grounded in process operation.

The bias voltage on the wafer can drive flux of the kind (Ar + and / or atomic vapor sputtered from the target) charged on the wafer. The flux can modify the properties (eg, density) of the material sputtered on the wafer. Generating plasma for sputtering and various biasing designs are well known and known techniques can be implemented with the described sputtering system.

In a preferred embodiment, the chamber gas is provided by the distribution channel at the bottom of the chamber 12, rather than the top of the chamber 12, which makes it possible to reduce particle contamination and optimize the magnetron assembly during the sputtering process. Described).

3 describes a motor 58 for rotating the shaft 49. The shaft 49 is coupled directly to the motor 58 such that the pallet 36 is driven directly by the motor 58. This greatly increases the positioning accuracy of the pallet 36 on the belt drive or gear drive top. In the embodiment of FIG. 3, the motor 58 has a central rotating sleeve that surrounds the shaft 49 and is fixed to the shaft 49. Motor 58 may be a servo or a stepper motor. In one embodiment, the motor is a servo motor that uses an independent encoder attached to the shaft 49 to determine the angular position of the shaft 49. In an independent encoder, a disc with fine optical symbols can uniquely identify each position without the need to count pulses or determine home positions. For example, the disk may be glass covered with an opaque film having a plurality of etched concentric rings in the form of permeable dashes of different lengths. The set of bright openings in each radial position across the ring can create a unique digital code. Using an LED and a phototransistor, the motor controller senses the optical indication at each radial position and uses that information to position the axis 49 for wafer loading and unloading and the deposition process (typically 5 -30 RPM) to control the RPM of the pallet 36.

In order to maintain the low pressure in the chamber 12, the seal 57 forms a seal around the shaft 49.

The sputtering chamber 12 uses a magnetron assembly outside the vacuum to further control the impact of the target by the plasma. In a typical system, a fixed permanent magnet is placed behind the target (acting as a deposition source), allowing the plasma to be confined to the target area. The resulting magnetic field forms a closed-loop annular path that acts as an electron trap, reshaping the trajectory of secondary electrons exiting the cycloid path from the target, and greatly increases the ionization potential of the sputtering gas in the confined region. Inert gases, especially argon, are commonly used as sputtering gases because they tend not to react with the target material or combine with any process gas and because they form high sputtering and deposition rates due to their high molecular weight. . Positively charged argon ions from the plasma are accelerated towards the negatively biased target and impinge on the target, resulting in material sputtering from the target surface.

FIG. 5A describes one of three magnets 60 formed over the target back substrate 59 (FIG. 3), supported by the top substrate 62 (FIG. 3) grounded in the sputtering system. The magnet 60 has a triangular or delta shape with rounded corners. In one embodiment, the thickness of the magnet 60 is between 0.5-1 1/4 inches (12-31 mm). In the example of FIG. 5A, there are three rings (appropriately nested forms) where neighboring rings have opposite poles so that the magnetic field spans one ring across the ring. Several magnetic field lines 64 are shown. Since there are three magnet rings, there is a field line of two race tracks. These magnetic fields pass through the target back substrate 59 and cross the target 43 attached to the lower side of the target back substrate 59 in FIG. 3. The plasma density (and thus the erosion rate) at the target is the largest at the highest magnetic field strength. The size, shape, and distribution of each magnet 63 are selected to produce a uniform erosion of the target, as described below.

5B is a cross-sectional view of one embodiment of a magnet 60. The magnet 63 is mounted to a magnetic back substrate 65, which is known as a shunt substrate, formed of an iron material. The shape and magnetic properties of the shunt substrate 65 can be modified to optimize the performance of the magnet 60.

Magnet 60 may also be an electromagnet.

6A describes the magnetron portion of the sputtering chamber 12, where one magnet 60 is shown above the target (not shown). Two different identical magnets will be placed on top of two different targets in a 120 degree interval. A servo motor 66 using an independent encoder, similar to the motor 120 for the axis 49 that rotates the table 40, has three tunes on its associated target top in a vibration period between 0.5-10 seconds. It is controlled by the motor controller to vibrate the magnet 60 back and forth. The magnet 60 vibrates so that the magnetic field is not always in the same position with respect to the target. By uniformly distributing the magnetic field over the target, target erosion becomes uniform.

If the vibration is too slow, there will be time for particles of one material to accumulate on portions of the target of different materials in areas that are not affected by the magnetic field for a delayed period of time. As a result, when the magnet scans over that portion of the target, the sputtered material will undesirably constitute the mixed materials (changing the stoichiometry of the sputtered material). For stoichiometrically sensitive reaction films sputtered on the workpiece, a 0.5-10 second cycle is suitable. The oscillation period may be slower to obtain a non-stoichiometric photoresist film sputtered onto the workpiece.

The insulating bracket 67 fixes each magnet 60 to the motor 66 so that the gap between the vibrating magnet 60 and the target back substrate 59 is minimized.

Since there is no magnetic field in the middle portion of the magnet 60, the magnet 60 has at least half (and preferably almost all of its width) such that the center portion of the target exhibits the same magnetic field as the other portions of the target. Should be scanned.

The individual magnets 63 along the edge of the magnet 60 are smaller than the internal magnets so that the magnetic field can extend near the magnet edge. The range of the magnetic field can be approximated by the distance between the centers of the two opposite poles. Therefore, the diameter of the outer magnet 63 is made small (for example, 0.5-1 cm). The inner rings of the magnet 63 may be larger. In an embodiment, the inner magnets 63 are rectangular to shorten the distance between the inner magnets and the outer magnets.

The size of the magnet 60 depends on the size of the wafer, which determines the size of the target. In one embodiment, the magnet 60 is about 10.7 inches (27 cm) long and about 3 inches (7.6 cm) wide at its widest portion. Eight inch wafers may use targets that are 10-13 inches in radial length. 12 inch wafers can use targets with a radial length of 13-18 inches. These target and magnet length dimensions are very small compared to the prior art. These small dimensions mean more effective in terms of chamber volume, thus making computer space smaller; It also makes targets smaller and more effective, resulting in lower target and system costs. In general, the target and magnet length perpendicular to the scanning direction is a value between 1.1 and 1.5 times the minimum dimension of the workpiece surface facing the target.

6A shows the magnet 60 in its intermediate position during vibration, while FIG. 6B shows the magnet 60 in its leftmost position during vibration.

In order to maximize the magnetic field around the target, the distance between the magnet 60 and the target should be minimized. In addition, the target back substrate 59 having the magnet 60 on one side and the target on the other side needs to be cooled due to the high temperature plasma in the chamber 12.

FIG. 7 is a cross-sectional perspective view of the upper substrate 62 and the target back substrate 59, all formed of aluminum. The thickness of the upper substrate 62 is about 1 3/8 inch (35 mm). The magnet 60 vibrates in the concave region 70 of the target back substrate 59. The target 72 is in the shape of an approximately concave region 70 and is secured to the target back substrate 59 by soldering, brazing, conductive epoxy, copper diffusion or other known techniques.

The target back substrate 59 (including the recessed area 70 and the raised area 74 around the recessed area 70) and the target 72 are negative to concentrate the plasma in the area of the target 72. Is electrically connected to a bias voltage source. A wire (not shown) that carries a negative bias voltage is screwed into the raised region 74 using one of the screw holes 75. The target 72 is also referred to as the cathode because it is negatively biased. The upper substrate 62 supporting the target rear substrate 59 is electrically grounded. An insulator ring 76 (eg, a synthetic rubber ring, or other elastic material) insulates the target back substrate 59 from the ground. The ring 76 also mechanically supports the target back substrate 59. In order to prevent short circuits between the target back substrate 59 and the grounded portion, it is important to prevent conductive sputtered particles from contacting the ring 76.

The thickness of the concave region 7 (distance between the magnet 60 and the target 72) must be thin to maximize magnetic coupling with respect to the target 72. In one embodiment, the thickness is between 0.5-0.75 inches (12.7-19 mm). The upper end of the concave region 70 is a thin aluminum substrate 78 (for example, 0.7-3 mm) that is deep brazed to the bottom portion 80 of the concave region 70. Between the substrate 78 and the bottom portion 80 is a coolant (eg water) channel 82 shown in FIG. 8. The heated liquid may also flow through the channel 82.

8 shows a simplified channel 82 formed in the bottom portion 80 between the coolant input port 84 (see FIG. 7) and the coolant output port 86. Flexible tubing (not shown) connects each port 84/86 for each magnet to an external coolant source such that each recessed area 70 can be independently cooled by coolant flow through the channel 82. As shown in FIG. 8, the channel 82 is serpentine and is shaped to vary based on the amount of cooling required to maintain the same temperature over the entire concave region 70. In one embodiment, the thickness of coolant channel 82 is 1-3 mm. The coolant flows in a large portion of the target back substrate 59 which is usually the highest in temperature.

The substrate 78 forming the top surface of the recessed area is deep brazed to the bottom portion 80 as follows. As shown in FIG. 9, a thin aluminum alloy foil 88 (material of eutectic) that takes the general shape of the bottom portion 80 is inserted between the bottom portion 80 and the thin substrate 78. The eutectic foil 88 has a melting point lower than the melting temperature of aluminum used to form the bottom portion 80 and the thin substrate 78. Various eutectic aluminum alloys can be used. The clamp presses the thin substrate 78 and bottom 80 together and the structure is placed in a cast salt bath at a temperature sufficient to melt the eutectic foil 88 or not high enough to melt pure aluminum. do. Melting of the eutectic sheet 88 brazes the thin substrate 78 to the bottom portion 80.

In one embodiment, the aluminum used for the bottom 80 and thin substrate 78 is referred to in the art as 6061 aluminum and has a melting temperature of 1110 degrees F (598 degrees C). The material used for the eutectic foil 88 is referred to in the art as 4047 aluminum and has a melting temperature of 1065 degrees F (574 degrees C). The composition of 4047 aluminum is: Si 11.0-13.0%; Cu 0.3%; Mg 0.1%; Fe 0.8%; Zn 0.2%; Mn 0.15%; The rest is Al.

10 shows a portion of the grounded top substrate 62, the insulator ring 76, the target back substrate 59 (including the thin substrate 78 deep brazed to the bottom portion 80) and the target 72. Is a cross-sectional view. Grooves 87 for gas tight gaskets are formed in the upper substrate 62. Magnet 60 and coolant channel 82 are not shown.

After being in negative bias, the target 72 should not contact the grounded top substrate 62. As such, there must be a gap between the target 72 and the top substrate 62. If this gap is small enough, it forms a dark space without enough space to produce a plasma. Sputtered particles entering the dark space from the target 72 will accumulate on the insulator 76 and consequently shorten the target back substrate 59 to the top substrate 62. If manufacturing errors are formed in the size of the top substrate 62 and the target 72 as well as the mounting of the target 72, it is very difficult to ensure that the gap between the target 72 and the top substrate 62 is minimized. . To remove the dark space and prevent contamination of the insulator 76, a thin top shield 90 is secured to the top substrate 62 by conical screws. 10 shows the resulting narrow gap 91.

FIG. 11 is a perspective view of the lower side of the upper substrate 62 and the target 72 showing the upper shield 90. If the top shield is thin aluminum or stainless steel and easily manufactured with precise error, it would be easy to set the gap between the target 72 and the top substrate 62 to a minimum value (eg, 1-2 mm). The thickness of the top shield 90 will be in the range of 3 / 16-1 / 4 inch (4.7-6.3 mm). The diameter of the upper substrate 62 is about 28 inches (71 cm). In conventional systems, a separate anode ring was installed for the dark space, and the gap between the target and the top substrate was first determined and then aligned.

  The top shield 90 lies on all other exposed portions of the top substrate 62 to prevent accumulation of sputtered material on the top substrate 62 (top substrate 62 in FIG. 11). When the exposed edges of the chamber are located at the top of the chamber wall (shown in FIG. 3) and thus are not exposed in the chamber. (By screw 94) is easily removed and cleaned or processed. Typically, the top shield 90 will be cleaned up to ten times and then discarded. This can avoid more complicated operations, such as removing the top substrate 62 for cleaning. Thus, only one, cheap top shield is used to create a dark space and to protect the top substrate 62.

11 is a cross section between each target 72 position to prevent deposition of sputtered material from one target on a wafer that is not directly below the target when the pallet 36 (FIG. 3) rotates. -Show the contamination shield 96. 3 shows a portion of the after-pollution shield 96. The vertical walls of the cross-section shield 96 should be 10 mm or less, preferably 3 mm or less, from the top of the wafer (or other workpieces). The height of the cross-contamination shield 96 depends on the height of the top substrate 62 on top of the wafer, but will typically be about 1-6 inches (2.5-15 cm).

The sputtering system described makes it possible to sputter the same or different materials simultaneously on a wafer during a batch process for all three targets. This increases throughput and makes it possible to sputter alloys or layers on a wafer without breaking the vacuum. To select an alloy composition, one target may be one material and the other two targets may be a second or third material. In order to deposit stacks of different materials, only one material may be deposited at a time (eg, one target may be run at a time or multiple targets of the same material may be run at a time). In order to deposit mixed layers (eg, alloys of different materials), if the targets are made of different materials, all targets can be run simultaneously.

More targets and wafers may be provided in the system than shown in the embodiment. For example, there can be eight targets. The number of such targets is limited only by the ability to make narrower magnets, which deliver a suitable magnetic flux on the target surface.

The table / pallet on which the wafer is placed may have a heater to heat the wafer if desired. Heating may be generated by a resistive heater mounted to a table or by flowing heated fluid through copper piping 46 (FIG. 4A). Such heaters are well known. Resistive heaters are described in US Pat. No. 6,630,201 and incorporated into documentation.

The system sputters about 240 kW (240 * 10 ^-10 m) of Al for an input energy of 1 kW-minute. In contrast, conventional conventional systems deposit about 90 kW (90 * 10 ^-10 m) of Al for an input energy of 1 kW-min when all other conditions are the same.

Conventional aspects of such systems, not described in detail, are well known to those skilled in the art by US Pat. No. 6,630,201 and for certain conventional aspects relating primarily to plasma generation and gas supply to the process chamber. 0160125 A1 is hereby incorporated by reference.

Although the system has been described in connection with forming a metal film on a semiconductor wafer, the system may deposit any material, including dielectrics, and process any workpiece, such as LCD panels and other flat panel displays. In one embodiment, the system is used to deposit material onto a plurality of thin film transistor arrays for LCD panels.

Although the invention has been described in detail, those skilled in the art will recognize that modifications may be made to the invention without departing from the spirit and concept of the invention described herein from this specification. As such, the scope of the invention should not be limited to the particular embodiments shown and described above.

Claims (98)

In the sputtering apparatus, A chamber having at least one workpiece support area for receiving a workpiece, the chamber having a wall, the chamber being sealable to create a low pressure environment within the chamber while sputtering material on the workpiece; A target located within the chamber, the target with the front of the target facing into the chamber for sputtering material from the target onto the workpiece; A magnet opposing the rear surface of the target; And An actuator coupled to the magnet to scan the magnet back and forth on the target during a sputtering operation; Sputtering device. The method of claim 1, The magnet is generally triangular in shape and the actuator scans the magnet back and forth in arc form on the target during the sputtering operation. Sputtering device. The method of claim 1, The magnet has a width in the direction of movement of the magnet, and the motor scans the magnet for a distance greater than half the magnet width for each scan of the magnet. Sputtering device. The method of claim 1, The magnet has a width in the direction of movement of the magnet and the motor scans the magnet for a distance less than the full width of the magnet for each scan of the magnet. Sputtering device. The method of claim 1, The actuator is an independent encoder motor, and each position of the magnet is known by detecting the encoder code. Sputtering device. The method of claim 1, The apparatus further comprises an insulating bracket connecting the actuator to the magnet. Sputtering device. The method of claim 1, The magnet is a permanent magnet Sputtering device. The method of claim 1, The magnet includes a plurality of magnets arranged in a plurality of nested patterns Sputtering device. The method of claim 8, The plurality of nested patterns includes at least an inner ring and an outer ring, wherein magnets in the outer ring are smaller than magnets in the inner ring. Sputtering device. The method of claim 1, The workpiece is a semiconductor wafer Sputtering device. The method of claim 1, The workpiece is part of a flat panel display Sputtering device. The method of claim 1, The first wall of the chamber supports the target such that the rear surface of the target faces one side of the first wall, and the magnet is located outside of the chamber behind the second side of the first wall and The back of the target is opposed to the first wall between the magnet and the target Sputtering device. The method of claim 12, The magnet is a first magnet, The device, At least two additional magnets spaced about the same distance, wherein the at least two additional magnets are behind the second side of the first wall, the back of each target being at least two additional magnets and each target The at least two additional magnets facing the first wall in between; And And an actuator coupled to the magnet for injecting the at least two additional magnets back and forth on each target top during a sputtering operation. Sputtering device. The method of claim 13, The actuator is disposed in the center region between the magnets Sputtering device. The method of claim 1, The actuator vibrates back and forth in a cycle of 0.5-10 seconds Sputtering device. The method of claim 1, The target and magnet length perpendicular to the scanning direction are 1.1 to 1.5 times the smallest size of the workpiece surface facing the target. Sputtering device. The method of claim 1, The actuator is a motor Sputtering device. A method for sputtering material on a workpiece disposed in a chamber, the chamber having a wall and comprising a target, the front side of the target being directed into the chamber for sputtering material from the target onto the workpiece. In the method, Injecting a magnet back and forth on the target top during a sputtering operation, opposite the back side of the target; Sputtering method. The method of claim 18, Injecting the magnet includes scanning the magnet in a front-rear arc shape on the target top during a sputtering operation. Sputtering method. The method of claim 18, The magnet has a width in the direction of movement of the magnet, wherein scanning the magnet comprises scanning the magnet over a distance less than the full width of the magnet for each scan of the magnet. Sputtering method. The method of claim 18, The magnet is a first magnet, the method further comprising scanning back and forth at least two additional magnets on top of each target during the sputtering operation. Sputtering method. In the process processing system, The system, At least one load lock for receiving a plurality of workpieces for processing and for storing the processed workpieces, said at least one load lock being sealable to a pressure significantly lower than ambient pressure; A transfer module connected to said at least one load lock and sealable to be at said low pressure; A robot arm in a transfer module for transferring the workpiece from and to the load lock at the low pressure; A cleaning chamber coupled to the transfer module, the cleaning chamber being hermetically sealable to be at the low pressure, the cleaning chamber including a first workpiece support region for supporting a plurality of workpieces at once for a batch purification process of a workpiece using plasma; Cleaning chamber; At least one sputtering chamber coupled to said transfer module, said sputtering chamber being sealable to be at said low pressure, said sputtering chamber being a second workpiece support region for supporting a plurality of workpieces at once for batch sputtering on said workpiece; Wherein the sputtering chamber comprises at least one such sputtering chamber comprising a plurality of targets for sputtering target material onto the workpiece using plasma; And The workpiece is transported from the at least one load lock to the cleaning chamber, from the cleaning chamber to the sputtering chamber and from the sputtering chamber to the at least one load lock without the plurality of workpieces being exposed to ambient pressure. The robot arm and system so configured to be; Containing Process processing system. The method of claim 22, The base pressure of the cleaning chamber is lower than the pressure in the transfer module during the cleaning operation. Process processing system. The method of claim 22, The base pressure of the sputtering chamber is lower than the pressure in the transfer module during the sputtering operation. Process processing system. The method of claim 22, The sputtering chamber is: Low pressure chamber; A first rotatable pallet within said chamber, said rotatable first pallet having a plurality of workpiece support regions for simultaneously supporting a plurality of workpieces on said first pallet; A plurality of targets having a sputtering surface facing the first pallet; A first port for receiving workpieces one at a time for loading one at a time onto the workpiece support area; And A first motor that rotates the first pallet such that workpieces face different target sputtering surfaces at different times during the sputtering operation; Containing Process processing system. The method of claim 25, The cleaning chamber is: Low pressure cleaning chamber; A second rotatable pallet within the cleaning chamber, the second rotatable pallet having a plurality of workpiece support regions for simultaneously supporting a plurality of workpieces on the second pallet for a batch cleaning process of the workpiece using plasma; ; A second port for receiving workpieces one at a time to load one at a time onto the workpiece support area; And A second motor for rotating the second pallet; Including; The robot arm allows the workpiece to be transported one at a time from the second pallet to the first pallet within the sputtering system without exposing the workpiece to ambient pressure. Process processing system. The method of claim 22, The cleaning chamber is an inductively coupled plasma chamber having a plasma generator. Process processing system. In the process processing system, The system includes a sputtering system, The sputtering system is: Low pressure chamber; A first rotatable pallet within said chamber, said rotatable first pallet having a plurality of workpiece support regions for simultaneously supporting a plurality of workpieces on said first pallet; A plurality of targets having sputtering surfaces facing the first pallet; A first port for receiving workpieces one at a time for loading one at a time onto the workpiece support area; And A first motor that rotates the first pallet such that workpieces face different target sputtering surfaces at different times during the sputtering operation; Containing Process processing system. The method of claim 28, The plurality of targets includes at least one first target of a first material and a second target of a second material different from the first material, wherein the first target and the second target are surfaces of a plurality of workpieces. Sputtering material into the phase simultaneously Process processing system. The method of claim 28, The plurality of targets includes at least one first target and a second target, wherein the first target and the second target are formed of the same material, and the first target and the second target are on the surface of the plurality of workpieces. Sputtering material at the same time Process processing system. The method of claim 28, The system, A receiving area for receiving a plurality of workpieces for processing; A transport module connected to said receiving area, said transport module being sealable to a low pressure significantly lower than ambient pressure; A robot arm in the transfer module for transferring the workpiece from the receiving area to a cleaning chamber; A cleaning chamber coupled to the transfer module, the cleaning chamber being sealable to be at the low pressure, The cleaning chamber is: Low pressure cleaning chamber; A second rotatable pallet in the cleaning chamber, the second rotatable pallet having a plurality of workpiece support regions for simultaneously supporting a plurality of workpieces on the second pallet for a batch cleaning process of the workpiece using plasma; A second port for receiving workpieces one at a time to load one at a time onto the workpiece support area; And A second motor for rotating the second pallet; The robot arm for transporting the purified workpieces one at a time from a second pallet to a first pallet within the sputtering system without exposing the workpiece to ambient pressure; Containing additional Process processing system. The method of claim 28, The first pallet is directly driven by the first motor, the motor shaft is fixedly connected to the first pallet Process processing system. The method of claim 1, The first motor is an independent encoder servo motor Process processing system. The method of claim 28, The workpiece support area includes an electrostatic chuck Process processing system. The method of claim 28, The first motor rotates the pallet while sputtering is performed. Process processing system. The method of claim 28, The first motor causes the pallet to stop rotating while sputtering is performed. Process processing system. The method of claim 28, A plurality of movable pins having a first position under the pallet, each support region for lifting the workpiece away from the support region during loading of the workpiece onto the pallet and during unloading of the workpiece from the pallet; And the plurality of movable pins controlled to raise and extend through holes in the pallet at When the pins are moved to their first position, the workpiece is lowered onto the support area such that the entire backside of the wafer contacts the pallet. Process processing system. The method of claim 37, wherein With at least 4 pins per support area Process processing system. In the method of sputtering onto a workpiece, Placing a plurality of workpieces, one at a time, on a rotatable first pallet having a plurality of workpiece support regions in the sputtering chamber; Generating a plasma in the sputtering chamber to sputter material from the plurality of targets into the workpiece; Rotating a first pallet to face different targets at different times during the sputtering operation; And Rotating the first pallet between sputtering operations to align each workpiece support area with at least one port of the sputtering chamber to add and remove the workpiece from and to the first pallet; Containing Sputtering onto a workpiece. The method of claim 39, The plurality of targets includes at least one first target of a first material and a second target of a second material different from the first material, the method further comprising: from the first target and the second target; Further comprising sputtering the material simultaneously onto the surfaces of the plurality of workpieces, Sputtering onto a workpiece. The method of claim 39, The plurality of targets includes at least one first target and a second target, wherein the first target and the second target are formed of the same material, and the method includes the plurality of targets from the first target and the second target. And sputtering the material simultaneously onto the surfaces of the workpieces. Sputtering onto a workpiece. The method of claim 39, Receiving a plurality of workpieces in the receiving area for processing; Generating a low pressure in a transfer module connected to the receiving area; Transferring the workpiece from the receiving area to a cleaning chamber, using a robot arm in the transfer module; Generating a low pressure in the cleaning chamber; Rotating the second pallet in the cleaning chamber, wherein the second rotatable pallet supports a plurality of workpieces to simultaneously support a plurality of workpieces on the second pallet for a batch cleaning process of the workpieces using plasma; The rotatable second palette having an area; Rotating the second pallet between batch cleaning operations to align each workpiece support area with at least one port of the cleaning chamber to add and remove the workpiece from and to the second pallet; And Transferring the purified workpieces one at a time by the robot arm from a second pallet to a first pallet in the sputtering system without exposing the workpieces to ambient pressure; Containing additional Sputtering onto a workpiece. The method of claim 39, The first pallet is directly driven by the first motor, and the first motor is directly connected to an axis fixed to the first pallet. Sputtering onto a workpiece. The method of claim 42, The first motor is an independent encoder servo motor Sputtering onto a workpiece. The method of claim 39, The pallet is rotated during sputtering, Sputtering onto a workpiece. The method of claim 39, The pallet is stopped while sputtering is performed, Sputtering onto a workpiece. The method of claim 39, The method further includes selectively operating less than all targets in the sputtering chamber such that only sputtering from the activated target occurs. Sputtering onto a workpiece. The method of claim 39, The method, A first position under the pallet, and during loading of the workpiece onto the pallet and during unloading of the workpiece from the pallet, extending through holes in the pallet in each support area to lift the workpiece from the support area Moving a plurality of movable pins to a second position, wherein Wherein the pins further comprise such a step as to lower the workpiece onto the support area such that when moved to their first position, the entire backside of the wafer contacts the pallet. Sputtering onto a workpiece. 49. The method of claim 48 wherein With at least 4 pins per support area Sputtering onto a workpiece. In the sputtering system, Low pressure chamber; A pallet in the chamber, the pallet having a plurality of workpiece support regions for simultaneously supporting a plurality of workpieces on the pallet; A target support surface for supporting a plurality of targets having a sputtering surface facing the pallet; A rotary table for supporting the pallet, the pallet having a bottom surface in thermal and electrical contact with the table; A conduit in thermal contact with a table for controlling the temperature of the workpiece supported on the pallet, the conduit controlling a temperature of a liquid flowing therethrough; And A motor that rotates the pallet such that workpieces face different target sputtering surfaces at different times during the sputtering operation; Containing Sputtering system. 51. The method of claim 50, The conduit comprises a thermally conductive tube in contact with the table, the tube rotating with the table Sputtering system. The method of claim 51 wherein The tube is electrically conductive and in electrical contact with the table. Sputtering system. The method of claim 51 wherein And further comprising a voltage source coupling the voltage to the tube for coupling the voltage to the pallet. Sputtering system. The method of claim 53 wherein The voltage is DC Sputtering system. The method of claim 53 wherein The voltage is at the radio frequency Sputtering system. 51. The method of claim 50, The pallet is screwed to the table Sputtering system. 51. The method of claim 50, The pallet is screwed to the table and threaded holes are disposed within the workpiece support area such that no sputtered material is deposited on the screw. Sputtering system. 51. The method of claim 50, The workpiece support area includes an electrostatic chuck Sputtering system. 51. The method of claim 50, The system further comprises a heated liquid flowing through the conduit Sputtering system. 51. The method of claim 50, The system further comprises cooled liquid flowing through the conduit Sputtering system. 51. The method of claim 50, The motor rotates the pallet during sputtering Sputtering system. 51. The method of claim 50, The motor stops pallet rotation during sputtering. Sputtering system. In the process processing system, The system includes a cleaning system for cleaning workpieces, the cleaning system comprising: Low pressure cleaning chamber; A pallet rotatable in the cleaning chamber, the rotatable pallet having a plurality of workpiece support areas for simultaneously supporting a plurality of workpieces on the pallet for a batch cleaning process of the workpiece using plasma, the pallet being The rotatable pallet formed of a conductive material and wherein the surface of the workpiece is in electrical contact with the pallet; A motor for rotating the pallet; A bias source for biasing the workpiece at a bias voltage, the bias source being electrically connected to the pallet to electrically couple the bias voltage to the workpieces, in turn, during the batch cleaning process; And Insulating material on the pallet in a region different from the workpiece support region to reduce the etch rate of the pallet but not reduce the etch rate of the workpiece; Including, Process processing system. The method of claim 63, wherein The insulating material is an anodized layer of the pallet Process processing system. The method of claim 63, wherein The pallet is aluminum and the insulating material is an anodized layer of the pallet Process processing system. The method of claim 63, wherein The insulating material is a ceramic coating Process processing system. The method of claim 63, wherein The pallet is aluminum and the insulating material comprises aluminum oxide. Process processing system. The method of claim 63, wherein A bias voltage is applied to the pallet, Process processing system. The method of claim 63, wherein The bias voltage is DC Process processing system. The method of claim 63, wherein The bias voltage is AC, Process processing system. The method of claim 63, wherein The insulation material is greater than about 2 mils (0.05 mm) Process processing system. In the sputtering system, the system, Low pressure chamber; A pallet in the chamber, the pallet having a plurality of workpiece support regions for simultaneously supporting a plurality of workpieces on the pallet; A plurality of electrically conductive target support surfaces for supporting a plurality of targets having a sputtering surface facing the pallet; An electrically conductive first substrate supporting the target support surface and electrically insulated from the target support surface by an insulator, wherein the first substrate and the target support surface are formed of the wall for the chamber to maintain low pressure within the chamber. The electrically conductive first substrate forming at least a portion; Each target support surface comprises: each target support surface separated from the first substrate by a first gap to form an electrical insulation between each target support surface and the first substrate; And A shield substrate fixed to the first substrate, the shield substrate having an opening for a target, the shield substrate shielding the first substrate during a sputtering process, and the shield substrate between each target supporting region and the first substrate The shield substrate so formed on a portion of the first gap such that the resulting second gap in is smaller than the first gap; Containing Sputtering system. The method of claim 72, The shield substrate is screwed to the first substrate Sputtering system. The method of claim 72, The first substrate and the shield substrate is aluminum Sputtering system. The method of claim 72, The shield substrate is generally circular with an opening for the target Sputtering system. The method of claim 72, The second gap is 2 mm or less Sputtering system. In the sputtering system, Low pressure chamber; A pallet in the chamber, the pallet having a plurality of workpiece support regions for simultaneously supporting a plurality of workpieces on the pallet; A generally circular first substrate on said pallet, said first substrate supporting a plurality of targets having a sputtering surface facing said pallet; The first substrate forming at least a portion of the chamber wall to maintain low pressure in the chamber; A plurality of cross-contamination shields secured to the first substrate and extending toward the pallet, wherein one cross-contamination shield is positioned between adjacent targets, the cross-contamination shields being sputtered from a particular target; A plurality of such cross-contamination shields that at least partially shield workpieces not directly underneath the particular target; Containing Sputtering system. 78. The method of claim 77 wherein The system further includes a shield substrate secured to the first substrate, the shield substrate having an opening for a target, the shield substrate shielding the first substrate during the sputtering process, and the cross-contamination shield the shield Fixed to the board Sputtering system. 78. The method of claim 77 wherein There are at least three targets arranged around the generally circular first substrate Sputtering system. 78. The method of claim 77 wherein The cross-contamination shield terminates less than 10 mm from the workpiece supported by the pallet. Sputtering system. 78. The method of claim 77 wherein The cross-contamination shield terminates less than 3 mm from the workpiece supported by the pallet. Sputtering system. In the sputtering system, Low pressure chamber; A workpiece support area for supporting the workpiece; A target back substrate, comprising: the target back substrate supporting a target on a first side of the target back substrate having a sputtering surface; The target back substrate comprises: the target back substrate forming at least a portion of the chamber wall to maintain low pressure in the chamber; And A magnet facing the second side of the target back substrate for opposing the target through the target back substrate; Including; The target back substrate, A first metal portion having a depression forming a coolant channel; The metal substrate forming a wall of the coolant channel as the metal substrate fixed to the first portion; And A brazing metal between the first portion and the substrate, wherein the brazing metal is melted and solidified to fix the substrate to the first portion, and the brazing metal is a melting temperature below the melting temperature of the first portion and the substrate. Said brazing metal having; Containing Sputtering system. 83. The method of claim 82, The first portion and the substrate comprises aluminum Sputtering system. 83. The method of claim 82, The first portion and the substrate is 6061 aluminum Sputtering system. 83. The method of claim 82, The brazing metal comprises aluminum Sputtering system. 83. The method of claim 82, The brazing metal is 4047 aluminum Sputtering system. 83. The method of claim 82, The target back substrate is less than 0.75 inches (19.05 mm) thick. Sputtering system. 83. The method of claim 82, The thickness of the substrate is less than 2mm Sputtering system. A method of forming a target backing substrate in a sputtering chamber, wherein the target backing substrate forms at least a portion of the chamber wall, and the target backing substrate is between a target and a magnet in a method of forming a target backing substrate in such a sputtering chamber. In Providing a metal first portion having a depression forming a liquid channel for temperature control; Providing the metal substrate forming a wall of the channel as a metal substrate fixed to the first portion; Providing a metal foil between the first portion and the substrate, the metal foil having a melting temperature below the melting temperature of the first portion and the substrate; Clamping the first portion against the substrate; Immersing the target backing substrate in a high temperature bath having a temperature sufficient to melt the metal foil or a temperature not high enough to melt the first portion or substrate; And Recovering the target back substrate from the hot bath to solidify the metal forming the metal foil; Containing A method for forming a target back substrate in a sputtering chamber. 92. The method of claim 89, The hot bath is a cast salt bath A method for forming a target back substrate in a sputtering chamber. In the sputtering system, Low pressure chamber; A workpiece support area for supporting the workpiece; A target back substrate, comprising: the target back substrate supporting a target on a first side of the target back substrate having a sputtering surface; The target back substrate comprises: the target back substrate forming at least a portion of the chamber wall to maintain low pressure in the chamber; And A magnet facing the second side of the target back substrate for opposing the target through the target back substrate; Including; The target back substrate, A coolant channel formed between opposing walls of a target back substrate, the coolant channel having portions between the magnet and the target for cooling the target back substrate and the target, the coolant channel being the magnet Comprising such coolant channels having coolant inlet and outlet ports in the peripheral region of the target backing substrate not covered by Sputtering system. 92. The method of claim 91 wherein The magnet scans back and forth within an indentation formed in the target back substrate, wherein the raised wall of the target back substrate substantially surrounds the indent and the cooling inlet and outlet ports are located on the raised wall. Sputtering system. 92. The method of claim 91 wherein The coolant channel is in the serpentine path Sputtering system. 92. The method of claim 91 wherein The coolant channel has an area of varying cross section in the target back substrate, and the coolant channel has a larger cross-sectional area near the middle of the target back substrate than near the edge of the target back substrate. Sputtering system. 95. The method of claim 94, The magnet scans back and forth on the target back substrate so that the intermediate portion of the target back substrate requires more cooling than the periphery of the target back substrate. Sputtering system. 92. The method of claim 91 wherein The coolant channel has an area of varying cross section in the target back substrate, the cross sectional area depending on the amount of cooling required to maintain a substantially constant temperature over the entire target back substrate between the magnet and the target. Sputtering system. 97. The method of claim 96, The magnet scans back and forth on the target back substrate so that the intermediate portion of the target back substrate requires more cooling than the periphery of the target back substrate. Sputtering system. 92. The method of claim 91 wherein The target back substrate is less than 0.75 inches (19.05 mm) thick. Sputtering system.

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