Terahertz WR-2.2 Waveguide to Transmission-Line Transition on Silicon Substrate Fabricated Using MEMS Technology

The frequency band from 356 to 450 GHz with 94-GHz bandwidth is available for wireless communication. It makes ultrahigh-speed wireless communication possible. In this study, we conducted research aimed at realizing a waveguide transition (WGT) in the 325-500-GHz band (WR-2.2 standard) as a terahertz wave interface on a Si substrate. Our work shows the possibility of the realization of the WR-2.2 wideband chip-to-WGT with an on-chip back-short (BS) structure by using MEMS technology and Au wire as a probe. The structure of the WGT on a Si substrate was optimized by an electromagnetic (EM) simulator (EMPro 2019, KEYSIGHT). We constructed the WGT structure directly on the Si substrate using MEMS technology. A Cu film was deposited on the prepared WGT by physical vapor deposition, and an Au wire as a transmission line was bonded with a UV curable bond to complete the WR-2.2 WGT. The maximum difference between the measured and the simulated reflection coefficients of the three prototypes was 2.1 dB. The maximum loss of the WGT of the three samples is estimated to be 4.5 dB at 400 GHz by comparing the measured and simulated results.