The use of thermocouples made from platinum group metals and their alloys for the measurement of high temperatures is long established and widespread, and is based upon their reproducible thermoelectric properties, their accuracy over a wide temperature range and their resistance to corrosion. Now it is possible to fabricate thin-film thermocouples using integrated circuit technology and a recent paper from the IBM Thomas J. Watson Research Center describes a process for producing thin-film platinum-iridium thermocouples with the same thermoelectric behaviour as bulk couples (H. M. Tong, G. Arjavalingam, R. D. Haynes, G. N. Hyer and J. J. Ritsko, Rev. Sci. Instrum., 1987, 58, (5), 875–877).

The thicknesses of the platinum and iridium films were 0.51 and 0.29 μ m, respectively, which ensured continuity on the alumina substrate. The thermocouple has been calibrated up to 790°C. With a fast response time and low thermal capacity the thermocouple is very suitable for monitoring instantaneous temperatures during device processing.