Insulated pallet in cleaning chamber
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 processing system comprising:
a cleaning system for cleaning workpieces comprising:
a low pressure cleaning chamber;
a rotatable pallet in the cleaning chamber, the rotatable pallet having a plurality of workpiece support areas for concurrently supporting a plurality of workpieces on the pallet for batch cleaning of the workpieces using a plasma, the pallet being formed of a conductive material, a surface of the workpieces being in electrical contact with the pallet,
a motor for rotating the pallet;
a biasing source for biasing the workpieces at a bias voltage, the biasing source being electrically connected to the pallet which, in turn, electrically couples the bias voltage to the workpieces during the batch cleaning; and
an insulating material on the pallet in areas other than the workpiece support areas to reduce an etching rate of the pallet but not reduce an etching rate of the workpieces.
2 . The system of claim 1 wherein the insulating material is an anodized layer of the pallet.
3 . The system of claim 1 wherein the pallet is aluminum, and the insulating material is an anodized layer of the pallet.
4 . The system of claim 1 wherein the insulating film material is a ceramic coating.
5 . The system of claim 1 wherein the pallet is aluminum, and the insulating material comprises an aluminum oxide.
6 . The system of claim 1 wherein a biasing voltage is applied to the pallet.
7 . The system of claim 1 wherein the biasing voltage is DC.
8 . The system of claim 1 wherein the biasing voltage is AC, at a radio frequency.
9 . The system of claim 1 wherein the insulating material is greater than about 2 mils.