Research on UV-LIGA Process of a Folded Waveguide for 850GHz TWTs

Folded waveguide is the most mature slow-wave structure for submillimeter-wave and terahertz travelling-wave tubes (TWTs). The UV-LIGA process of the folded waveguide for 850GHz TWTs is introduced. In which a new RD-2050 photoresist is employed instead of commonly used SU-8. Good RD-2050 patterns are achieved repeatedly under optimized processing conditions. The critical dimensional (narrow side of
$\mathbf{25\mu m}$
) accuracy of the structure is better than
$\mathbf{1.2\mu{m}}$
with a nearly vertical profile.