Patent US 6,033,922

A method for monitoring the temperature of a product wafer during thermal processing of the product wafer in an emissivity independent thermal processing system includes processing a test wafer in the emissivity independent thermal processing system that thermally processes the product wafer. The test wafer is pretreated before being thus placed in the thermal processing system. The test wafer is thermally processed following a substantially same thermal processing recipe as that used for thermal processing of the product wafers. After the thermal processing of the test wafer, a sheet resistance of the test wafer is measured. This sheet resistance is correlated to a wafer temperature at the test wafer that was achieved during the thermal processing of the test wafer. Because the product wafer and the test wafer are thermally processed within an emissivity independent thermal processing system, the test wafer temperature is correlated to a product wafer temperature at the product wafer that was achieved during the thermal processing of the product wafer. With such monitoring of the product wafer temperature during actual thermal processing of the product wafer, thermal processing may be more tightly controlled to ensure that a thermal processing recipe is accurately followed.