A Non-Contact Waveguide Probe for On-Wafer $S$-Parameter Measurements for Submillimeter-Wave to Terahertz Band

This paper presents a non-contact on-wafer S- parameter measurement method for submillimeter-wave and terahertz frequency range. The proposed method is based on using open-ended waveguide probes along with on-wafer waveguide transitions to measure the S-parameters of waveguide based components and devices. To enable non-contact measurements, an RF choke is designed and machined on the metallic cross section of the probes using electric discharge machining. Additionally, to enhance the accuracy and repeatability of the measurements, a probe aligner is micromachined over the on-wafer transition. In order to validate the measurement concept, a full-band transition operating at J-band (220-325 GHz) is designed and tested. To achieve high accuracy, the fabrication of the on-wafer waveguide and the transition is performed using silicon micromachining. It is shown that the designed back-to-back transition has a return loss of better than 15 dB and an insertion loss of less than 0.2 dB over the entire frequency band. The measurement results of the fabricated transition also show a good agreement with the simulated results.