Fabrication of 340-GHz Folded Waveguides Using KMPR Photoresist

This letter presents the fabrication of 340-GHz copper folded waveguides (FWGs) using the UV-LIGA method. During the process, KMPR photoresist was employed instead of SU-8 due to its easy removability after electroforming. KMPR patterns with a sidewall height of 300 μm and a trench width of 100 μm were achieved repeatedly under one single-spin deposition and optimized processing conditions, such as UV exposure dose and KMPR bake temperature and time. The dimensional accuracies of the wide side (500 μm ) and narrow side (100 μm) of the copper FWGs were found to be ≤ 6 and ≤ 2 μm, respectively, and the sidewall surface roughness was about 44 nm, with a profile of about 90°.