Effect of fabrication process on fracture strength and fatigue life of micromirrors made from single-crystal silicon

Abstract

We evaluated the effects of the source wafers [bare silicon (Si) and silicon-on-insulator (SOI)] and fabrication process on the fracture strength and fatigue life of micromirrors. The fracture strength of the Si-made micromirrors was 10–30% lower than that of the SOI-made ones. The decrease in strength was caused by the sidewall roughness. The low fracture strength shortened the fatigue life of the Si-made mirrors, but there is no significant difference in fatigue exponents between the Si- and SOI-made samples. By improving the fabrication process, we will be able to realize highly reliable Si-made micromirrors at a low cost.