System and method for monitoring temperatures of and controlling multiplexed heater array

A system operable to measure temperatures of and control a multi-zone heating plate in a substrate support assembly used to support a semiconductor substrate in a semiconductor processing apparatus, the heating plate comprising a plurality of planar heater zones, a plurality of diodes, a plurality of power supply lines and a plurality of power return lines, wherein each planar heater zone has at least one heater element, is connected to one of the power supply lines and one of the power return lines, and no two planar heater zones share the same pair of power supply line and power return line, and a diode is serially connected between each planar heater zone and the power supply line connected thereto or between each planar heater zone and the power return line connected thereto such that the diode does not allow electrical current flow in a direction from the power return line through the planar heater zone to the power supply line;

• the system comprising:
• a first switching arrangement configured to connect each of the power return lines selectively to an electrical ground, a voltage supply or a first electrically isolated terminal, independent of the other power return lines;
• a second switching arrangement configured to connect each of the power supply lines selectively to the electrical ground, a power supply, a current measurement device or a second electrically isolated terminal, independent of the other power supply lines, wherein the current measurement device is connected between the electrical ground and the second switching arrangement;
• and
• a calibration device connected between the current measurement device and the voltage supply, wherein the calibration device is connected to the current measurement device via an on-off switch.