On-Wafer Vector-Network-Analyzer Measurements at mK Temperatures

Abstract

We describe a system for performing on-wafer vector-network-analyzer measurements from 100 MHz to 15 GHz at mK temperatures (i.e., less than 20 mK). We first demonstrate a camera-less probe positioning system and calibrate this system at 4.4 K. We then use this positioning system to perform both on-wafer scattering-parameter calibrations and on-wafer large-signal-network-analysis calibrations at 4.4 K and mK temperatures. The scattering-parameter calibrations were based on cooled printed transmission lines while the power and electrical phase calibrations required for on-wafer large-signal network analysis calibrations were performed by transferring room temperature coaxial power and electrical phase calibrations through long attenuated coaxial lines to our cryogenic on-wafer reference plane. Finally, we perform scattering-parameter measurements of common interconnect structures and measurements of modulated-signals typical of those used to control superconducting transmon qubits commonly used in quantum-computing applications. We also demonstrate our ability to predistort the modulated signals we created, and we assess the drift and stability of our system, which we found to be on the order of a few tenths of a dB and a few degrees.INDEX TERMS Cryogenic measurement, large-signal network analysis, on-wafer measurement, vector network analysis.

RF and microwave metrology for quantum computing – recent developments at the UK’s National Physical Laboratory

“…These reference planes can be shifted through proper de-embedding. On-wafer S-parameter measurement at cryogenic temperatures has been reported in prior work, including those at 4 K [14,15] and less than 20 mK [10] temperatures.…”

“…Recent research in this area has focused on developing measurement systems to characterize microwave and quantum devices at temperatures down to tens of mK. These include the S-parameter measurement system to characterize coaxial connectorized devices [2][3][4][5][6], on-chip devices [7][8][9], on-wafer devices [10], and substrate materials [11]. These devices under test (DUTs) are typically operated inside a cold, isolated environment such as a dilution refrigerator and interfaced with room temperature test equipment such as a Vector Network Analyzer (VNA) using microwave cabling and components.…”

“…Characterizing on-wafer devices and materials using a cryogenic probe station has the potential to achieve better accuracy due to direct probing, eliminating the effects of interconnects used to interface DUTs to fixture such as bond wires. Currently, the cryostat-based approach can be used to perform device characterization down to temperatures of tens of mK, whereas characterization using probe station is typically limited to 2 K. Recently, an automated probing system inside the mK stage of a dilution refrigerator was implemented at NIST for characterization of on-wafer devices, which enabled on-wafer measurements at mK temperatures using a hybrid approach [10].…”