Abstract: A semiconductor-wafer chuck for heating and cooling a device-under-test includes a heat-spreader plate with a clamping surface for a semiconductor wafer. A heater is disposed within the heat-spreader plate. A chiller heat-exchanger provides for heat removal. A motion control system is used to move the chiller heat-exchanger in relation to the heat-spreader plate, and thus provide for an adjustment of the thermal resistance and thermal coupling between the two. The heater comprises electric heating elements with a variable power input, and the chiller heat-exchanger is moved sufficiently far away to prevent boiling and evaporation of a coolant disposed inside. A device-under-test temperature controller controls the device-under-test temperature by adjusting the heater power, chiller fluid temperature and/or by moving the chiller heat-exchanger in relation to the heat spreader plate.