Multi-station sputtering and cleaning system
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. Copper tubing in the table couples RF energy to the wafers, and a liquid running through the copper tubing controls the temperature of the wafers. 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 for uniform target erosion and uniform deposition on the wafers. An electrically insulated target backing plate between each magnet and a target has a liquid channel running through it for controlling temperature. The distance between the magnets and the targets is made very small by a thin aluminum plate fixed to the bottom segment of the target backing plate by a dip brazing process. Various shields are described to prevent cross-contamination from the targets and prevent the sputtered target material from entering gaps in the chamber and shorting out insulators.
1. A method performed by a processing system comprising:
receiving a plurality of workpieces in at least one load lock;
creating a low pressure in the at least one load lock significantly below ambient pressure;
rotating a first pallet in a cleaning chamber to successively align individual workpiece support areas on the first pallet with a first entrance into the cleaning chamber, each workpiece support area only supporting a single workpiece;
controlling a robotic arm in a transport module to move workpieces, one at a time, from the at least one load lock to associated workpiece support areas on the first pallet through the first entrance into the cleaning chamber while the first pallet rotates to successively align the workpiece support areas with the first entrance into the cleaning chamber and while the at least one load lock, the transport module, and the cleaning chamber are at the low pressure, the robotic arm only placing one workpiece over an associated workpiece support area;
controlling the cleaning chamber to etch all workpieces on the first pallet, while the workpieces are supported on the first pallet, for batch cleaning of the workpieces using a plasma,
wherein no additional workpieces are introduced into the cleaning chamber, and no workpieces are removed from the cleaning chamber, until batch cleaning of all the workpieces on the first pallet has been completed;
after the batch cleaning of all the workpieces in the cleaning chamber is completed, rotating the first pallet in the cleaning chamber to successively align each workpiece support area with the first entrance to the cleaning chamber while the robotic arm transports the workpieces, one at a time, from the first pallet to a rotating second pallet in a sputtering chamber through a second entrance into the sputtering chamber while the second pallet rotates to successively align workpiece support areas on the second pallet with the second entrance for receiving associated workpieces from the robotic arm and while the cleaning chamber, the transport module, and the sputtering chamber are at the low pressure, each workpiece support area on the second pallet only supporting a single workpiece, the robotic arm only placing one workpiece over an associated workpiece support area on the second pallet,
the sputtering chamber comprising a plurality of targets for sputtering target material onto the workpieces using a plasma;
batch sputtering target material on the workpieces while the workpieces are supported on the second pallet,
wherein no additional workpieces are introduced into the sputtering chamber, and no workpieces are removed from the sputtering chamber, until batch sputtering on all the workpieces on the second pallet has been completed; and
after the batch sputtering, rotating the second pallet in the sputtering chamber to successively align each workpiece support area on the second pallet with the second entrance to the sputtering chamber while the robotic arm transports the workpieces, one at a time, from the second pallet to the at least one load lock while the sputtering chamber, the transport module, and the at least one load lock are at the low pressure.
2. The method of claim 1 wherein a base pressure in the cleaning chamber is lower than a pressure in the transport module during a cleaning operation.
3. The method of claim 1 wherein a base pressure in the sputtering chamber is lower than a pressure in the transport module during a sputtering operation.
4. The method of claim 1 wherein the workpieces are wafers.
5. The method of claim 1 wherein the workpieces are semiconductor substrates.
6. The method of claim 1 wherein there are the same number of workpiece support areas on the first pallet and second pallet.
7. The method of claim 1 wherein there are at least four workpiece support areas on the first pallet and second pallet.
8. The method of claim 1 further comprising:
extending a plurality of pins from each of the workpiece support areas of the first pallet and the second pallet as each workpiece support area is aligned with the first entrance and the second entrance to temporarily support a workpiece delivered by the robotic arm through the first entrance and the second entrance; and
withdrawing the pins into the workpiece support areas after the robotic arm has positioned a workpiece on the pins to cause the workpiece to rest on an associated workpiece support area of the first pallet and second pallet.
9. The method of claim 1 wherein controlling the cleaning chamber to etch all workpieces on the pallet for batch cleaning of the workpieces using a plasma comprises creating an inductively coupled plasma in the cleaning chamber.