ITS-90 calibration of radiation thermometers for RTP using wire/thin-film thermocouples on a wafer

Light-pipe radiation thermometers (LPRTs) are the sensor system of choice in RTP tools. They can be calibrated against blackbodies with an uncertainty $(k=1)$ less than 0.3 °C. In an RTP tool, however, account must be made for wafer emissivity and wafer-chamber interreflections, or else temperature measurement uncertainties will be orders of magnitude higher. We have used two complementary approaches for accomplishing this: 1) in situ calibration using high-accuracy wire/thin-film thermocouples calibrated on the International Temperature Scale of 1990 (ITS-90) and 2) developing optical models to estimate the effective emissivity of the wafer $εeff$ when used in the radiation environment of the RTP tool. The temperature measurement uncertainty of LPRTs using either technique is 2.1 °C or less.