Stability of Cernox™ Resistance Temperature Sensors

Abstract

Cryogenic temperature sensing devices fabricated from sputtered zirconium oxynitride thin films have been commercially available from Lake Shore Cryotronics, Inc. under the tradename Cernox™ Resistance Thermometers (CXRTs) since 1992. These sensors possess many qualities desired in a cryogenic thermometer and are presently widely used. To date, no long term stability data has been available in the literature. Over the past six years, thirty-nine temperature sensors from six of the initial wafer production lots have been calibrated periodically and monitored for long term calibration stability and aging effects. These devices were stored at room temperature between calibration. Stability comparisons are given in terms of elapsed time, package type, wafer lot, and sensitivity level. Analysis of calibration data over the six year period show that these devices have repeated their initial calibration to within an average of ±0.08% of temperature over the 1.4 K to 325 K temperature range. Small qualitative and quantitative differences in stability were measured with respect to wafer lot, sensor sensitivity and package.