Abstract: An electrostatic chuck comprises an electrode cap with a dielectric layer for attracting and holding the back side of a semiconductor wafer positioned on the top surface of the dielectric layer, and a lower electrode. The electrostatic chuck is heated by resistive heating elements attached to or embedded within the chuck. The electrostatic chuck is cooled by circulating liquid coolant through the body of the chuck. Coolant gas is provided at the back side of the semiconductor wafer to improve thermal transfer. A feedback control mechanism maintains the chuck, and consequently the wafer, at a predetermined temperature by actively controlling both the heating and the cooling functions.