Patent ID: 8895889

Claim:
An apparatus for processing a substrate, comprising: a process chamber; an RF source to provide RF energy to form a plasma in the process chamber; a component disposed in the process chamber so as to be heated by the plasma when formed; a heater configured to heat the component; a heat exchanger configured to remove heat from the component; a chiller coupled to the heat exchanger via a first flow conduit having an on/off flow control valve disposed therein and a bypass loop to bypass the flow control valve, wherein the bypass loop has a flow ratio valve disposed therein; a controller for opening or closing the flow control valve; a temperature measuring device situated to indicate a temperature of the component; and input(s) into the controller indicating the power going to the plasma forming electrodes or groups of such electrodes; wherein the controller substantially operates according to the following control parameters: if Σω i P i > P UL and T > T sp − dT LL open flow control valve if Σω i P i < P LL and T < T sp + dT UL close flow control valve where T sp is a target temperature, dT UL is a predetermined upwards temperature differential from the target temperature, dT LL is a predetermined downwards temperature differential from the target temperature, P i is the power consumption of one of i=1 to n plasma-forming electrodes and/or groups thereof, where co, is a weighting factor for one of i=1 to n sources of RF power being delivered to the process chamber, P UL is a predetermined upper limit for summed power consumption, and P LL is a predetermined lower limit for summed power consumption.