Validation of bending tests by nanoindentation for micro-contact analysis of MEMS switches**This article was originally submitted for the special section ‘Selected papers from the 20th Micromechanics Europe Workshop (MME 09) (Toulouse, France, 20–22 September 2009)’, Journal of Micromechanics and Microengineering, volume 20, issue 6.

Abstract

Research on contact characterization for microelectromechanical system (MEMS) switches has been driven by the necessity to reach a high-reliability level for micro-switch applications. One of the main failures observed during cycling of the devices is the increase of the electrical contact resistance. The key issue is the electromechanical behaviour of the materials used at the contact interface where the current flows through. Metal contact switches have a large and complex set of failure mechanisms according to the current level. This paper demonstrates the validity of a new methodology using a commercial nanoindenter coupled with electrical measurements on test vehicles specially designed to investigate the micro-scale contact physics. Dedicated validation tests and modelling are performed to assess the introduced methodology by analyzing the gold contact interface with 5 µm2 square bumps at various current levels. Contact temperature rise is measured, which affects the mechanical properties of the contact materials and modifies the contact topology. In addition, the data provide a better understanding of micro-contact behaviour related to the impact of current at low- to medium-power levels.