Fabrication of 3-dimensional coaxial cable for RF-MEMS application

This paper presents the fabrication of a 3-dimensional coaxial cable with a thick oxidized porous silicon (OPS) for RF-MEMS application. The structure was fabricated by hydrofluoric acid, nitric acid, acetic acid (HNA) etching, followed by OPS processing, electroplating and photoresist (PR) reflow. The fabricated devices are expected to improve the characteristics of insertion loss and transmission line dispersion. The return loss of Cu coaxial cable on OPS layer is -35.73 dB at 13 GHz and the insertion loss of Cu coaxial cable on OPS layer is -0.17 dB at 5.5 GHz. Therefore, the fabricated devices are expected to improve the characteristics of insertion loss and transmission-line dispersion. Furthermore, the cable can possibly be used as a micro-size coaxial cable.