Abstract: A temperature control system 145 is used to control the temperature of a process chamber 25 during processing of a semiconductor substrate 70. The temperature control system 145 comprises a heat exchanger plate 155 for removing heat from the chamber 25, and a heat transfer member 158 for conducting heat to the heat exchanger plate 155. The heat transfer member 158 comprises a lower heat conduction surface 205 bonded to an external surface of the chamber 25, and an upper heat transmitting surface 210 thermally coupled to the heat exchanger plate 155. Preferably, the temperature control assembly comprises a heater 150 for heating the chamber 25, and a computer control system 165 for regulating the heat removed by the heat exchanger plate 155 as well as the heat supplied by the heater 150, to maintain the chamber 25 at substantially uniform temperatures.