Accurate, Robust, and Convenient On-Wafer Measurements of GaAs Devices From 1 to 220 GHz by Single-Tier Calibration

Abstract

We present a calibration substrate fabricated on 50-μm-thick semi-insulating GaAs for on-wafer ultra-wideband calibration from 1 to 220 GHz. Currently, due to substrate mismatch between a conventional alumina-based calibration substrate and the device under test, two-tier calibration is required for on-wafer measurement of GaAs devices and circuits. By contrast, our calibration substrate enables single-tier calibration using a matched substrate material, which is more convenient yet agrees with conventional two-tier calibration within 5%. To further reduce statistical uncertainty, our calibration substrate includes multiline through-reflect-line standards, resulting in robust calibration under different wafer chucks, probe configurations, and pad groundings. The calibration substrate includes not only microstrip and coplanar standards, but also standards in substrate-integrated waveguides for which no commercial calibration standards are available. Although demonstrated on GaAs, the same single-tier calibration based on a matched substrate can be extended to other semiconductor substrates such as Si, SiC, and InP.