Fabrication of solid copper two-level waveguide circuits for a THz radar system by UV lithography

The availability of reliable, compact source operating at 0.67 THz will have a significant impact on a variety of defense applications such as high data-rate communication, high resolution imaging in inclement conditions, and radar. As frequency increases, waveguide feature structure dimensions and tolerances decrease. Submicron precision and surface finish are needed in order to achieve the required power performance of the circuits. Thermal management of high radiation power is needed for stabile continuous operation, which can only be achieved with an all-copper structure for the waveguide. We report the fabrication of solid copper two-level folded waveguide circuits. The fabrication method is based on UV-lithography using copper plate as a substrate for SU-8 resist, followed by copper electroforming.