Using both chemical phase change and wireless thermistor temperature measurement techniques, wafer temperatures were measured during plasma processing in a MERIE dielectric etch tool. An inorganic low-k dielectric etch process was studied first, and many parameters were varied to determine their effect on wafer temperature. Wafer temperature rose rapidly when the plasma was turned on, approaching a stable temperature after about 30 s. When the lower electrode temperature setpoint or the rf power setting was increased, wafer temperature increased linearly. Wafer temperature decreased as backside He cooling pressure was increased. A dual-zone electrostatic chuck allowed separate control of center and edge He pressure, and these pressures were varied individually or together. Temperature measurements indicated that the zones give reasonably independent control of center and edge wafer temperature. Wafer temperature throughout a complete organic low-k dielectric stack etch process was also measured.