Patent attributes
A method of determining the degree of calibration of an RTP chamber (1) includes providing a test wafer having a deposited sichrome layer (22) of sheet resistance Rsi on an oxide layer (21) formed on a silicon substrate (20). The test wafer is annealed in the RTP chamber for a selected duration at a selected anneal temperature which is measured by the a permanent thermocouple or pyrometer (8). The sheet resistance of the annealed sichrome is measured, and a sheet resistance change ΔRs=Rsi−Rsf is computed. The “actual” value of the anneal temperature is determined from predetermined characterizing information relating ΔRs to a range of values of anneal temperature. The RTP chamber is re-calibrated if in accordance with the value of ΔRs if the difference between the “actual” value of the anneal temperature and the value measured by the permanent thermocouple or pyrometer exceeds an acceptable error. The basic technique can be utilized to determine an anneal time and anneal duration for annealing sichrome resistors to precisely adjust the sheet resistance or TCR thereof.
