Verification of wafer-level calibration accuracy at cryogenic temperatures

This article presents the results of accuracy verification of wafer level calibration at cryogenic temperatures based on coplanar calibration standards. For the first time, the electrical characteristics of commercially available coplanar calibration lines were extracted at the temperature of liquid helium. It was demonstrated that the temperature dependent variation of the characteristic impedance of the tested lines is within ±1% tolerance of the nominal value of 50 Ω for a temperature range from room temperature down to 4 K Finally, the accuracy of the LRM+ calibration method at cryogenic temperatures was verified by definition of the worst case error bounds for the measurement of passive devices and compared to the reference NIST multiline TRL.