Fracture of single crystal silicon caused by nonlinear evolution of surface acoustic waves

ZW Liu and B Lin and XH Liang and AY Du and XK Ma, ENGINEERING FRACTURE MECHANICS, 269, 108505 (2022).

DOI: 10.1016/j.engfracmech.2022.108505

High-amplitude surface acoustic waves (SAWs) undergo nonlinear sharpening during propagation due to the elastic nonlinearity of the material, which leads to material fracture. The degree of nonlinear evolution and material strength are usually characterized by two parameters: the second-order nonlinearity parameter and the critical fracture stress. To study the influence of processing defects, residual stress and temperature on these two parameters, we carry out mo-lecular dynamics modeling of nonlinear propagation of SAWs on non-ideal surfaces. The Stillinger and Weber (SW) and the Lee-modified second nearest-neighbor modified embedded-atom-method (2NN MEAM) potentials are used to study the SAW nonlinear evolution and surface crack nucleation in silicon (111)112 geometry, respectively. The results show that processing defects have the greatest influence on the SAW evolution and material strength. For a defined level of defects, the size of initial SAW wavelength directly affects the degree of attenuation of harmonic waves and stress concentration, and then determines the measured nonlinear parameter and critical stress. Temperature can affect the magnitude of the two characterization parameters through thermal dissipation and thermal fluctuations. In the presence of residual stresses only, the relative degree of variation of these two parameters is weak. This study may provide a valuable reference for the establishment of nonlinear SAW atomic-level theory and material character-ization experiments.

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