UV-LIGA Microfabrication of 0.3 THz Double Corrugated Waveguide

Abstract— Two advanced microfabrication processes based on ultraviolet photolithography (UV LIGA) to enable both fabrication and rapid, low cost prototyping of relatively high aspect ratio Slow Wave Structures (SWS) for sub-THz vacuum electron devices (VEDs) have been developed. One process is based on the use of a multi-layer SU-8 photoresist. The multi-layer approach ensures the planarity and the surface quality required to electroform the ground plane or for assembly surfaces. This also ensures low ohmic losses of the SWS. The second process is developed as metal-coated SU-8 process which can serve as a fast and low cost prototyping technique prior final robust realization of the structure in a full metal shape. The main steps of the two processes are here reported for the fabrication of the double corrugated waveguide at 0.3 THz. The combined approach of fast prototyping and microfabrication techniques proposed will enable fast, affordable and accurate fabrication of 3D SWSs for sub-THz VEDs.