Micromachined semi-encapsulated spiral inductors for microelectromechanical systems (MEMS) applications

Abstract

Semi-encapsulated spiral inductors for microelectromechanical systems (MEMS) applications have been designed, fabricated, and characterized using micromachining and electroplating techniques. The inductors are fabricated on a Pyrex glass wafer using a simple three mask process and have an area of 4 mm by 4 mm. Devices consist of electroplated copper conductor lines with width 50 mu m, thickness 25 mu m, and spacing 30 mu m; they are semi-encapsulated with an electroplated Ni-Fe (81%/19%) magnetic core. At the low frequency of 10kHz, the inductance of the devices was measured as 1.5 mu H, while they exhibited a low resistance of only 3 ohms. Their low resistance and reasonably high inductance makes them ideal in MEMS applications as either sensors or actuators.