Spiral capacitor based on copper electroplating

A novel MEMS spiral capacitor on glass substrate has been designed, simulated and fabricated. The square spiral capacitors with different width, space, thickness and turn number have been studied by HFSS. The fabrication process has been developed based on copper electroplating, and it is compatible with the copper inductor fabrication process, which can be integrated into LC filter. Finally, spiral capacitors with different dimensions and LC filters have been fabricated successfully

I. Introduction

Nowadays, RF MEMS has been widely used in communication and power delivery because of its small size, low energy and high performance. Integrated RF systems are based on MEMS capacitor, inductor and switch, such as filter, transceiver, and resonator [1]. One common MEMS capacitor with comb structure is fabricated by DRIE (deep reaction ion etching) process [2]. Another uses parallel plates and sacrificial layer fabrication process [3]. Both of these capacitors have one common insufficiency that the fabrication process is much complicated and they can hardly be integrated with other RF MEMS components, which limits their application considering the yield and cost. Compared with them, the spiral capacitor is easy to fabricate, thus has the potential to integrate.