Effects of surface films and film edges on dislocation movement in silicon

Abstract

We report the observation of two effects of surface films on the movement of dislocations in silicon substrates. One is the retarded movement of dislocations near the film−covered surface. The second effect is associated with the discontinuities in the surface films on continuous substrates and is either a blocking or an enhancement of the movement of dislocation loops in the vicinity of the discontinuities—depending on the direction of the movement. We conceive a model to explain that the second effect is the result of differential contraction between the film−substrate composite, giving rise to a nonvanishing shear stress component τ_zx, which peaks in the vicinity of the film discontinuity. These two effects are demonstrated by the observation of the consequent response of the shape and the size of indentation dislocation rosettes and the distribution of dislocation loops in the rosettes.