Calibration of Thin-Film Thermocouples on Silicon Wafers

摘要

Thin-film thermocouples (TFTCs) can be fabricated from a much broader range of electrical conductors than wire thermocouples, but even with the same composition as the wire thermocouple, the TFTCs may have different thermoelectric coefficients. Also, the TFTCs are used to measure temperature differentials across short distances on the substrate and cannot be calibrated by standard procedures. Therefore, we at NIST have a continuing project to improve the calibration methods for TFTCs. We have developed a calibration test for TFTCs on 10 mm x 50 mm silicon wafer substrates using the comparison method up to 950 AC with NIST-calibrated, highly accurate, platinum/palladium wire thermocouples as the reference thermometers. The expanded uncertainty (k = 2) for our method for calibration of the thin-film thermocouples was less than 0.2 % of the emf at 800 degrees C.