At the National Institute of Standards and Technology (NIST), we have been developing methods to improve the temperature measurement accuracy of semiconductor materials undergoing high-temperature thermal processing. Our goal is for accuracies of 2℃ in the range from 700℃ to 1000℃. We have demonstrated new methods for calibrating lightpipe radiation thermometers (LPRTs) against blackbodies with an uncertainty of 0.2℃ (k=1). A more challenging issue is how to achieve accurate traceable temperature measurements in process environments. We have studied two approaches: in-situ calibration of the LPRT against a thin-film thermocouple test wafer; and making model-based corrections to spectral radiance temperatures using an LPRT calibrated against a blackbody. We have achieved uncertainties of 2.3℃ and 3.5℃ for the two methods, respectively. While the work specifically addresses a semiconductor application, the approaches have general applicability for achieving reliable, traceable temperature measurements using LPRTs in other material processing and manufacturing environments.
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