Patent ID: 7802917

Claim:
A method for controlling wafer temperature during a wafer fabrication process, comprising: generating a thermal calibration curve for a chuck by, (a) holding a test wafer on the chuck in exposure to a heat source, (b) applying a gas at a substantially constant pressure at an interface between the test wafer and the chuck, (c) removing the heat source, (d) measuring a temperature of the test wafer as a function of time following removal of the heat source while maintaining the applied gas pressure, (e) determining a value of a thermal characterization parameter of the chuck representing a behavior of the measured temperature of the test wafer as a function of time following removal of the heat source, wherein the value of the thermal characterization parameter of the chuck is associated with the applied gas pressure, and wherein the thermal characterization parameter of the chuck defines a thermal performance of the chuck, (f) repeating operations (a) through (e) for a number of different applied gas pressures, and (g) establishing a correlation between the determined values of the thermal characterization parameter of the chuck and associated gas pressures to generate the thermal calibration curve for the chuck; determining a target value for the thermal characterization parameter of the chuck to be used to hold a wafer during a wafer fabrication process; examining the generated thermal calibration curve for the chuck to determine a backside gas pressure value corresponding to the target value of the thermal characterization parameter of the chuck, wherein the backside gas pressure corresponds to a pressure of a gas applied at an interface between the wafer and the chuck; setting the backside gas pressure to the value corresponding to the target value of the thermal characterization parameter of the chuck; and maintaining the backside gas pressure substantially constant during an entirety of the wafer fabrication process so as to control a temperature of the wafer during the wafer fabrication process.