Design, Fabrication and Characterization of a Novel TSV Interposer Integrated Inductor for RF Applications

As Through Silicon Vias (TSV) based System In a Package (SIP) technology is booming, high quality integrated inductor is desired for Radio Frequency (RF) application. Due to the substrate loss, traditional TSV interposer integrated inductor confronts low quality factor (Q) issues. In this study, we present a TSV interposer integrated suspended spiral inductor to address the substrate loss issues. To testify this concept, a process is designed, which is featuring in a releasing process by a combination of Si Deep Reactive Ion Etching (DRIE) and Reactive Ion Etching (RIE) process to achieve TSV interposer integrated suspended inductor. Based on the process, two inductors which are used as test vehicles are designed fabricated and tested. A releasing gap of 40mm is achieved for the samples. One inductor has an inductance of 2nH and a quality factor of 20 at 20GHz, another has an inductance of 5nH and a quality factor of 9 at 5GHz, which are about one times improvement in quality factor and about two times improvement in working bandwidth compared with the referring inductor designs of similar structure but without substrate releasing.