Reducing MEMS stiction by increasing surface roughness

摘要

A mechanism for reducing stiction in a MEMS device by decreasing surface area between two surfaces, such as a travel stop and travel stop region, that can come into close contact is provided. Reduction in contact surface area is achieved by increasing surface roughness of the travel stop region. This is achieved by depositing a polysilicon layer over a dielectric layer using gaseous hydrochloric acid as one of the reactants. A subsequent etch back is performed to further increase the roughness. The deposition of polysilicon and subsequent etch back may be repeated one or more times in order to obtain the desired roughness. A final polysilicon layer may then be deposited to achieve a desired thickness. This final polysilicon layer is patterned to form the travel stop regions. The rougher surface decreases the surface area available for contact and, in turn, decreases the area through which stiction can be imparted.