A generic micromachined silicon platform for high-performance RF passive components

Abstract

This paper describes the development of a micromachined silicon platform fabricated using the dissolved wafer process that supports: (1) high self-resonance frequency and quality factor inductors suspended on a dielectric membrane, (2) low-loss thin-film capacitors, and (3) polysilicon resistors. The process uses deep boron diffusion to create silicon anchors, which support a stress compensated dielectric membrane. A thick resist mold is used to gold electroplate the inductor, top capacitor plate, and bonding pads. This platform can be used to build miniature high-performance transceivers or other RF subsystems using either hybrid-attached surface-mount components or flip-chip bonded RF circuits. Using this technique, a Colpitts transmitter with a five-turn dielectric suspended inductor was designed and fabricated. The transmitter oscillates in the frequency band of 275-375 MHz, consumes 200 µA when operated continuously and 100 µA when amplitude modulated (on-off keying) at a rate of 1 Mbps (50% duty cycle).