Modification on surface roughness by combining dry and wet etching

Abstract

The materials owning the rough surface have been adopted in many applications, such as MEMS devices, solar cell, DRAM, and so on. However, the modified targets on the previous methods were almost limited to silicon-type materials, and some had the limitations in the material properties. Recently, a process combining spin-on photoresist and one-step RIE was proposed to modify various materials, which can be etched by RIE. Here, a modification process, which combines spin-on photoresist, two-step RIE, and wet etching, is proposed to extend the feasible materials to be modified, because more materials can be etched by chemical solutions. Also, it is a low temperature process, and no extra mask is needed. From the experimental results, the modified surface can be used to alleviate stiction of microstructures, and a detachment length is found to be about 2.2 times longer than the cantilevers without the modified surface. Moreover, the related parameters for the anti-stiction are also developed, and the effects are compared with the previously developed one-step RIE method.