TRIBOLOGY OF ION-BOMBARDED SILICON FOR MICROMECHANICAL APPLICATIONS

Silicon is used in the fabrication of microelectromechanical systems (MEMS). The friction and wear characteristics are of major design concern for any mechanical device requiring relative motion. In the present investigations we have studied the influence of ion bombardment on the microstructure, crystallinity, composition, microhardness, friction, and wear behavior. The ion bombardment modifies the elastic/plastic deformation characteristics and crack nucleation that occurs during the indentation. C+ bombarded monocrystalline and polycrystalline Si exhibit very low coefficient of friction (0.025-0.05) and wear factors (10(-7) mm3/N m) while slid against 52100 steel and alumina in dry and moist air and dry nitrogen atmospheres. Ion bombardment resulted in the formation of an amorphized layer that consists of SiC, C, and Si. We have shown that the improvements in friction and wear are because of the formation of SiC and not because of amorphization alone.