Towards Fabrication of High-Tuning-Range Liquid Crystals High-Aspect-Ratio Coplanar Waveguide Phase Shifter by LIGA, DRIE and Laser Ablation

The increasing demand for high-performance (tunability) millimeter-wave reconfigurable devices has led to a growing interest in the development of high-resolution fabrication techniques for addressing the challenge and need of manufacturing high-aspect-ratio planar transmission line structures, e.g., a tall-copper-profile coplanar waveguide (CPW) featuring an enhanced tunability possibility for a liquid crystals (LCs)-enabled 0-360° continuously variable phase shifter targeted 60–90 GHz applications. For the first time, this study evaluates the potential approaches towards the fabrication of LCs-based top-electrode-free fully-symmetric CPW structures by leveraging the insights from LIGA (Lithographie, Galvanik und Abformung, i.e., German acronym for lithography, electroplating, and molding), deep reactive ion etching (DRIE), and laser ablation. Specifically, our prototype of a 70 μm-thick CPW demo fabricated by laser ablation is presented.