Investigation of the Electrical Contact Behaviors on RF MEMS Switches Using Nano-Indenter

Abstract

Radio-Frequency (RF) Microelectromechanical system (MEMS) switches have become the promising devices due to their advantages such as higher off-impedance, lower insertion loss, and low power consumption. However, RF-MEMS switches have not been in commercialization to date due to the reliability problems such as increasing in electrical contact resistance and stiction of the switch electrode and etc. In order to improve their reliability, it is necessary to understand the micro-contact behaviors in electrical switching. In this work, a nano-indenter was modified to simulate DC switching of RF MEMS switches and to investigate the micro contact reliability. The contact reliability of thin Au film contacts was characterized; electric contact between both Au coated ball tip and Si wafer was permanently shorted out after certain switching cyc1es. The surface of contact area was deformed by melting and mass transfer and it causes contact area decreasing and breaking electrical contacts. There was some f1uctuation on penetration depth change curve just before the electrical failure and this result implies the change in depth curve seems to be an indicator of failure broken.