Effects of wafer emissivity on lightpipe radiometry in RTP tools

We investigated the effect of different silicon wafer emissivities and the effect of low emissivity films on rapid thermal processing (RTP) wafer temperature measurements using lightpipe radiation thermometers (LPRTs). These tests were performed in the NIST RTP test bed. We used a NIST thin-film. thermocouple (TFTC) calibration wafer to calibrate the LPRTs in situ. The measurement; of LPRTs viewing Au and Pt thin-film spots in the center of the wafer were compared to LPRT radiance temperature readings that viewed bare Si/SiO/sub 2/. We found differences of up to 36/spl deg/C at 900/spl deg/C in the LPRT measurements due to the low emissivity films. A model of the wafer temperature measurement is presented to provide an insight into the effects of wafer emissivity on LPRT measurements in RTP tools.