The Fracture Toughness of Polysilicon Microdevices: A First Report

Polysilicon microfracture specimens were fabricated using surface micromachining techniques identical to those used to fabricate microelectromechanical systems (MEMS) devices. The nominal critical J-integral (the critical energy release rate) for crack initiation, J_c, was determined in specimens whose characteristic dimensions were of the same order of magnitude as the grain size of the polysilicon. J_c values ranged from 16 to 62 N/m, approximately a factor of four larger than J_c values reported for single crystal silicon.