Preparation of wafer level glass-embedded high-aspect-ratio passives using a glass reflow process

This paper presents an innovative, uncomplicated and inexpensive method based on a glass reflow process to fabricate glass-embedded passives for RF MEMS packaging. Experimental results show that various glass-embedded passives, including annular cylindrical and coaxial cylindrical conductive through-holes, plate and coaxial torus trench capacitors, square spiral, circular spiral and meander trench inductors, and filters, can be manufactured void-free with vertical and smooth sidewall and large signal pathways. This glass-embedded design implements passives with large thickness and provides much surface space for 3D MEMS integration. The HFSS simulation results show that a minor thickness increase contributes to a large increase in Q and a relatively small decrease in L. The best Q (38.9-83.9) and L (19.9-15 nH) were achieved by using square spiral inductors.