Fracture toughness and crack growth phenomena of plasma-etched single crystal silicon

We have measured the fracture toughness, K-Ic, of the < 110 > crystal plane in micro-machined silicon structures fabricated using a common deep reactive ion plasma etch process. Crack initiation occurred at surface features left by the etch process. Wide scatter in the notch toughness (0.96-1.65 MPa m(1/2)), presumably due to a distribution of surface flaws, was measured in 11 samples. The data fit a Weibull distribution with m = 4.84. Crack propagation in the sample occurred as a series of discrete fracture events interspersed with periods of no growth. (C) 2000 Elsevier Science S.A. All rights reserved.