Terahertz low-loss bent waveguide with multi-step transition utilizing silicon-based DRIE process

This paper reports a waveguide for terahertz electromagnetic wave transmission, featuring a complex multilayer stepped bend waveguide. The waveguide was fabricated on a silicon wafer using deep reactive ion etching, which had better mechanical performance compared to Silicon-On-Insulator based etching. After etching, the wafer underwent gold plating, low-temperature bonding, and dicing to produce the silicon waveguide, overcoming the integration challenges and slow processing of metal based waveguides. The experimental work focuses on investigating the key fabrication parameters that influence the waveguide’s transmission performance, as well as optimizing the Bosch process for etching the multi-layer stepped structure. Finally, an analysis was conducted on the differences between the measurement and simulation results. Results showed that the insertion loss of the waveguide was about 0.5 dB within the 300-530 GHz, achieving low-loss terahertz electromagnetic wave transmission.