Substrate support assembly and plasma processing apparatus

A substrate support assembly includes: a base including a flow path for a temperature control medium; a substrate support including an electrode plate installed on the base and an electrostatic chuck installed on the electrode plate, and configured to support a substrate; a heater configured to heat the substrate; an elastic member installed between the base and the electrode plate, configured to separate the substrate support from the base, and configured to define a heat transfer space between the base and the electrode plate, a heat transfer gas being supplied into the heat transfer space; a tightening member configured to fasten the base and the electrode plate to each other, with the elastic member sandwiched and supported between the base and the electrode plate; and a heat insulator configured to prevent heat transfer between the base and the electrode plate via the elastic member.