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.