Temperature control module using gas pressure to control thermal conductance between liquid coolant and component body

A method of controlling a temperature of a plasma processing component having multiple regions, comprising:

• supporting a semiconductor substrate in a plasma processing chamber containing a temperature control module, wherein the multiple regions of the plasma processing component are in thermal contact with heating/cooling zones of the temperature control module, the temperature control module including a thermally conductive component body, channels in the component body, each channel having an interior surface, a tube in each channel, the tube having an exterior surface, a space between the exterior surface of each tube and the interior surface of the channel, the space adapted to contain a volume of pressurized heat transfer gas, a liquid source connected to each tube and operable to flow heat transfer liquid through the tube, a controller, a gas source and a vacuum pump connected to the spaces, the gas source operable to selectively increase a static gas pressure in each space in response to the controller and the vacuum pump operable to selectively evacuate each space in response to the controller, a plurality of heating elements in thermal contact with the component body, wherein each heating/cooling zone contains one or more channels and one or more heating elements, and a power supply adapted to selectively supply power to the heating elements in response to the controller;
• flowing liquid through the tubes of the temperature control module;
• measuring a temperature of one or more of the multiple regions of the plasma processing component;
• increasing a pressure of a heat transfer gas to an elevated pressure in at least one of the spaces when the temperature of the one or more regions is above a target temperature and decreasing the pressure of the heat transfer gas when the temperature of the one or more regions is below the target temperature;
• and
• maintaining or decreasing the pressure of the heat transfer gas to a reduced pressure in one or more of the spaces and applying power to one or more of the heating elements when the temperature of the one or more regions is below the target temperature and terminating power to the one or more heating elements when the temperature of the one or more regions rises above the target temperature;
• wherein a temperature difference across the multiple regions is less than 50° C.