Research on the process technology of silicon-based low-loss slow-wave structure of terahertz traveling wave tube based on DRIE

Abstract

The manufacturing of the slow-wave structure of a traveling wave tube usually adopts computer digital controlled precision machining technology. With the increase of the operating frequency, the requirements for the characteristic dimensional accuracy of the slow-wave structure have reached the micro-nano level, which leads to great difficulty in processing, long cycle and high cost, which limits the rapid development of the technology to a certain extent. The silicon-based MEMS processing technology has excellent three-dimensional morphology controllability, high dimensional control accuracy and good batch consistency. In this paper, a three-dimensional integrated process manufacturing technology based on silicon substrate materials was developed to meet the design requirements of the terahertz traveling wave tube power source for the double-slot deep folded waveguide slow-wave structure. The photoresist masking combined with the dielectric masking process method was used to focus on optimizing the etching passivation balance parameters in deep reactive ion etching (DRIE), and the complete process flow of electroplating gold and gold-gold bonding was developed. The 150 mm wafer-level process preparation of high-performance silicon-based terahertz slow-wave structures with an operating frequency of 0.65 THz and a unit length insertion loss as low as 1.6 dB/mm was achieved, which laid a technical foundation for the technological breakthrough and application development of terahertz traveling wave tubes.