Monitoring wafer temperature during thermal processing of wafers by measuring sheet resistance of a test wafer

A method for monitoring temperature during processing of a product wafer within a thermal processing system that is emissivity independent, the method including the steps of:

• A. pretreating a test wafer to include a pretreatment material, step A further including the steps of:
• starting with a test wafer that is a p-type lightly doped silicon wafer having a sheet resistance of 10 .OMEGA./square to 40 .OMEGA./square;
• precleaning the test wafer with a RCA etch and lastly with hydrofluoric acid;
• and
• depositing a layer of titanium having a thickness of 1000 .ANG., as the pretreatment material, on the test wafer, wherein an initial sheet resistance measured on the test wafer after depositing the 1000 .ANG. thick layer of titanium is 6.3.+-.0.2 .OMEGA./square, and wherein a measurement of the initial sheet resistance at a plurality of locations on the test wafer results in a standard deviation that is less than 1% of a mean of the measurement of the initial sheet resistance at the plurality of locations;
• B. placing the test wafer with the product wafer into the thermal processing system to process the product wafer and the test wafer with a substantially same thermal processing recipe within the thermal processing system;
• C. measuring sheet resistance of the test wafer, wherein the sheet resistance of the test wafer is correlated to a test wafer temperature achieved during step B for lower processing temperatures including 400.degree. Celsius to 700.degree. Celsius;
• and
• E. correlating the test wafer temperature to a product wafer temperature achieving during step B, and
• wherein the titanium is annealed with the test wafer during step B, and wherein the sheet resistance of the test wafer measured in step C varies with extent of the titanium annealing with the test wafer.