A Multimetal Surface Micromachining Process for Tunable RF MEMS Passives

• Published in: Journal of microelectromechanical systems Vol. 21; no. 4; pp. 867 - 874
• Main Authors: Shim, Yonghyun, Wu, Zhengzheng, Rais-Zadeh, Mina
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-08-2012; Institute of Electrical and Electronics Engineers
• Subjects: Capacitance; Capacitors; Exact sciences and technology; Gold; High quality factor; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Mechanical instruments, equipment and techniques; Micromechanical devices and systems; Physics; Radio frequency; RF MEMS; Stress; surface micromachining; tunable passives; Tuning; ultra high frequency; Passive component; High performance; Capacitors; Precision engineering; Switches; High quality factor; System on a chip; Radiofrequency; Sandwich structures; Tuning; RF MEMS; Complementary MOS technology; ultra high frequency; Capacitance; Surface micromachining; tunable passives; Microelectromechanical device; Sacrificial layer; Production process
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2012.2192911

This paper reports on a microfabrication technology for implementing high-performance passive components suitable for advanced RF front-ends. This technology offers three metal layers with different thicknesses, one dielectric, and two sacrificial layers, enabling the fabrication of continuously tuned capacitors, capacitive and ohmic switches, as well as high- inductors all on a single chip. To demonstrate the versatility of this technology, several passive components are fabricated on a Borosilicate glass substrate . A high- tunable capacitor is fabricated exhibiting an electrostatic tuning range of more than 6 : 1. The temperature variation of capacitance from 223 to 333 K is less than 9%, and the tuning speed is better than 80 . To achieve a higher zero-bias capacitance, a tunable capacitor bank is also implemented, which can be tuned from 2.2 pF to 6.1 pF. In addition, a coupled inductor pair with self-inductances of 15 and 21 nH is implemented showing s exceeding 40 at 800 MHz. Measurements are compared with high frequency structure simulator (HFSS) electromagnetic simulations, showing good agreement. The technology reported is post-CMOS compatible and low cost.