Fabrication and calibration of integrated Cu-Cr thermocouple gauge

We report here the design, fabrication, and testing of an integrated thermocouple gauge. The gauge uses a thin-film Cr heater and a thin-film Cu-Cr differential thermocouple on a 5- × 3-mm glass substrate. The thermocouple measures the difference between the heater and the substrate temperature. Calibration of the thin-film Cu-Cr thermocouple gauge was done by using a standard K-type thermocouple as reference. At a constant difference temperature the measured power input to the heater is a function of the surrounding vapor pressure. The thermocouple gauge was calibrated using a McLeod gauge with He, Ar, N₂, H₂O, and CO₂ gases. Our measurements show that the range of the gauge can possibly be extended to the μTorr range. This gauge uses a standard thin-film processing technique for fabrication resulting in a lower cost of production. Also, small size makes this gauge versatile and unique in comparison to many commercial gauges.