Cu-alloying effect on structure stability of electrodeposited gold-based micro-cantilever evaluated by long-term vibration test

This paper reports Cu-alloying effects on the structure stability of gold-based micro-cantilevers evaluated by long-term vibration test for applications as movable micro-components in MEMS devices. AuCu alloy micro-cantilevers are fabricated by lithography and AuCu alloy electrodeposition. The composition is affected by the applied current density, and the thickness is controlled by the deposition time. Length of the micro-cantilever is ranged from 50 to 1000 μm, and the width is from 5 to 20 μm. After removal of the sacrificial layer, long-term vibration test is carried out to reveal the structure stability. Cycle numbers of the vibration are ranged from 103 to 107. The structure stability is quantified by evaluating height profiles of top surface of the micro-cantilevers by a 3D optical microscope after a number of the vibration cycle. The height at tip of the AuCu alloy micro-cantilever composed of 0.83 wt% Cu with the length at 1000 μm does not show significant change after 107 cycles of the vibration, which demonstrates the high structure stability by alloying with Cu. [Display omitted] •High long-term structure stability was observed in AuCu alloy micro-cantilever•The structure stability is quantified by the tip defection after vibration test•Tip deflection is almost zero for 1000 μm long cantilever after 107 cycles of test•Solid-solution strengthening is the main cause for the enhanced structure stability•The structure stability is improved with an increase in width of the cantilever