Enhancement of Silicon-Based Inductor Q-Factor Using Polymer Cavity

A simple low-cost post-complementary metal-oxide-semiconductor-compatible process to enhance the performance of the planar spiral inductor in standard silicon (Si) substrate is demonstrated. In this process, the high loss and high permittivity of Si which reduces the inductor´s performance is replaced by a lower loss and lower permittivity thick polymer material. In this way, a measured high Q-factor of more than 37 and a high self-resonance frequency of 25 GHz are achieved for a 1.7-nH inductor. Using this newly developed process, the performance of the inductor can be further improved by optimizing the design.