The effect of film-edge and corner-stress fields upon the behavior of dislocations was investigated. The stresses which arose from a nitride-film pad on a Si substrate were calculated by using a finite-element method, and the resultant spatially-varying stress-tensor components were used in numerical simulations of the dislocation behavior. The dislocation-dynamics code involved a full 3-dimensional implementation of the Peach-Koehler force formalism. By studying the motion of dislocations on various slip systems, in various locations relative to the nitride pad, it was possible to determine the stationary dislocation configurations which could be achieved in this geometry. Zero resolved-stress contours near to the surface were shown to be a useful tool for understanding both the nature of the dislocation propagation, as well as the final dislocation configurations. The nucleation of dislocations was considered from the critical-radius point of view, and so-called hot-spots for nucleation were identified near to the nitride-film edge. Thicker nitride films were found to furnish a greater number of possible nucleation sites, and a greater variety of possible stable configurations; as was observed experimentally. The simulations were extended in order to study the effect of changing the pad-edge orientation relative to the Si lattice. The method was also applied to the types of behavior that resulted from cross-slip, to reconnection between dislocations that were nucleated on intersecting glide planes, to Frank-Read spiral sources and to moving dislocations that interacted with nitride edges.

Dislocation dynamics near film edges and corners in silicon K.W.Schwarz, D.Chidambarrao: Journal of Applied Physics, 1999, 85[10], 7198-208