The fundamental phenomenon of crack deflection in single-crystal silicon when a dynamically propagating crack collides with stationary, intrinsic, and inclined screw dislocations, leading to high and long surface perturbations, was investigated. High resolution electron microscopy (HRSEM) and atomic force microscopy (AFM) were used to study the fracture surface. It was observed that an perturbation of height about 8 nm was form, when the crack collided with a single dislocation. while the crack collided with a group of adjacent dislocations, the perturbation extended up to 80 nm in height and 250 μm in length. It was also predicted that no interaction takes place, when a dislocation's line is perpendicular to the crack surface.