A thermal plate for a substrate support assembly in a semiconductor plasma processing apparatus, comprises multiple independently controllable planar thermal zones arranged in a scalable multiplexing layout, and electronics to independently control and power the planar heater zones. Each planar thermal zone uses at least one Peltier device as a thermoelectric element. A substrate support assembly in which the thermal plate is incorporated includes an electrostatic clamping electrode layer and a temperature controlled base plate. Methods for manufacturing the thermal plate include bonding together ceramic or polymer sheets having planar thermal zones, positive, negative and common lines and vias.