H-induced subcritical crack propagation and interaction phenomena in (001) Si using He-cracks templates

H and He ion implantations allow the formation of nanocracks within controlled subsurface depths in semiconducting materials. Upon annealing, crack propagation and coalescence provides a way of cutting monocrystalline thin films. Here, the mechanisms of coalescence by crack-tip interactions are depicted in 001 Si wafers. Starting from overpressurized He-cracks, subcritical propagation was activated by diffusional H. Nanocrack interaction can occur by elastic forces, causing tip folding, or by plastic deformation forming extended defects. These observations are discussed and modeled using elasticity and fracture mechanics. The model suggests that kinetic effects in the cutting process depend on the crack interplanar separations.