Platen assembly

A clamp system for supporting a substrate comprising:

• a platen assembly comprising a base and a clamping layer fixed to the base, where a portion of the base that faces the clamping layer and a portion of the clamping layer that faces the base defines a gap between the base and the clamping layer;
• a thermal unit configured to provide a fluid to the gap during a first operating mode and to remove the fluid from the gap before operation in a second operating mode;
• and
• a vacuum system configured to generate a pressure in the gap during the second operating mode to cause a thermal conduction between the base and the clamping layer to be less in the second operating mode than in the first operating mode.

A method of operating a platen assembly over a wide temperature range, comprising:

• providing a gap in the platen assembly having a base fixed to a clamping layer, the gap defined by a portion of the base that faces the clamping layer and a portion of the clamping layer that faces the base;
• circulating a fluid in the gap during a first operating mode;
• removing the fluid from the gap after completion of the first operating mode;
• heating the clamping layer for operation during a second operating mode;
• and
• generating a pressure in the gap for operation during the second operating mode to cause a thermal conduction between the base and the clamping layer to be less in the second operating mode than in the first operating mode.