Patent ID: 6353210
Filing Date: 2002-03-05
Classification: C30B,H01L

Abstract:
A method of maintaining the temperature of a production wafer during processing in a production plasma reactor near a desired temperature, said method comprising:installing onto a test wafer support in a test reactor a test wafer having an optically reactive dye on a backside thereof; optically observing through said test wafer support the optical behavior of said dye on said test wafer backside during plasma processing of said test wafer and deducing from said optical behavior the temperature of said test wafer as said test wafer is heated by interaction with plasma in said test reactor; measuring the temperature of said test wafer support during plasma processing of said test wafer, and storing information in a memory correlating temperature of said test wafer with temperature of said test wafer support; installing onto a production wafer support in said production reactor a production wafer; measuring the temperature of said production wafer support during plasma processing of said production wafer; inferring temperature drift of said production wafer from said production wafer support temperature using said information in said memory correlating said test wafer temperature and said test wafer support temperature; and changing the pressure of a coolant applied to said production wafer support so as to minimize said temperature drift of said production wafer.