Study on Ti/Au Two-Layered Cantilevers with Different Aspect Ratio for MEMS Devices

Abstract

We report the structure stability of Ti/Au two-layered micro-cantilevers with the various ratios of length and width for the first time. The cantilevers were fabricated by gold electroplating, a key technology for post-CMOS process for CMOS-MEMS devices. Ti is conventionally used for adhesion layers of gold electroplating, while the mechanical properties of Ti/Au structures have not been investigated. To evaluate the structure stability, the lengths of Ti/Au cantilevers were varied from 100 μm to 1000 μm. The experimental results showed that the cantilever of less than 500 μm in length and 5 μm in width made the structure more stable. Moreover, the cantilever of 1000 μm-length and 15-μm width showed high flatness. These results reveal the potential of Ti/Au layers to be applied to MEMS structures.

Effective Young’s Modulus of Complex Three Dimensional Multilayered Ti/Au Micro-Cantilevers Fabricated by Electrodeposition and the Temperature Dependency

“…The increases were small, but all three types of the micro-cantilever showed the same trend. The increase is suggested to be caused by the formation of Ti-Au intermetallic compounds at the Ti/Au interface [26,27]. At an elevated temperature, diffusions of titanium and gold elements would be enhanced to promote the formation of the intermetallic compounds, and eventually cause an increase in the Young's modulus.…”