Plasma reactor electrostatic chuck with cooled process ring and heated workpiece support surface

A method of performing a plasma-enhanced etch process on a workpiece in a chamber of a plasma reactor, said plasma reactor comprising:

• an insulating puck in said chamber and an ESC electrode in said insulating puck;
• a metal base layer beneath and contacting said insulating puck and having a diameter exceeding a diameter of said insulating puck, said metal base layer being coupled to a common potential;
• an RF plasma bias power generator having a power terminal coupled to said ESC electrode and a return terminal coupled to said common potential;
• said method comprising:
• providing a semiconductive process ring overlying a peripheral portion of said insulating puck and a gap between said process ring and said insulating puck preventing direct thermal contact between said process ring and said insulating puck;
• providing a thermal ring between and in contact with said base layer and said semiconductive process ring, said thermal ring being a thermal conductor and an electrical insulator, wherein said thermal ring has a thermal conductivity in excess of about 100 Watts/m-° K;
• holding a workpiece on a surface of said insulating puck, introducing a process gas into said chamber and coupling plasma source power into the interior of said chamber;
• cooling said process ring below a first temperature by flowing coolant through coolant flow passages in said base layer;
• and
• heating said workpiece above a second temperature by applying electric power to a heating element inside said insulating puck.