Development of low loss organic-micromachined interconnects on silicon at microwave frequencies

We present the design and development of an ultra-violet (UV) LIGA (a German acronym for electroplating, lithography and molding) micromachining process on Silicon substrates at microwave/millimeter wave frequencies. The process employs an ultra-thick negative photoresist SU-8 that can be spin-coated and processed using conventional lithography techniques. Using this process, we've developed micromachined coplanar waveguide (CPW) interconnects on Si substrates. The conductor-backed micromachined CPW on Si (7.2 Omega-cm) achieves a measured attenuation of 0.18 dB/cm at 20 GHz.