High-performance electroplated solenoid-type integrated inductor (SI/sup 2/) for RF applications using simple 3D surface micromachining technology

Abstract

Electroplated solenoid-type integrated inductors (SI/sup 2/s) have been demonstrated to have high performance and small area occupation for GHz applications, using a new, simple, and highly adaptable 3D surface micromachining technology. The method utilizes simply modified conventional photolithography and well-established electroplating at a low process temperature (<120/spl deg/C), so that the post-IC process and batch fabrication are possible. We have fabricated a 20-turn SI/sup 2/ with an inductance of 2.5nH, a peak Q-factor of 19 at 5.5 GHz, and the surface area occupation of 800 /spl mu/m by 90 /spl mu/m excluding pads (50 nH/mm/sup 2/), from the entirely unoptimized initial fabrication on a glass substrate. Also, a 10 nH and a peak Q of 12.5 at 2.3 GHz have been obtained from an 80-turn SI/sup 2/ (27 nH/mm/sup 2/).