Origins of defect structures in dendritic web silicon

Abstract

Defects introduced into dendritic web silicon during growth have deleterious effects on electrical properties, and in extreme cases can lead to growth termination. This study used transmission X-ray topography and etch pitting techniques to elucidate the formation of several defect structures in dendritic web silicon. Results indicate that the formation of third dendrites is caused by liquid droplet entrapment within the web. Inverted U-shaped surface features have no correlation with internal dislocation structure, but are probably caused by a decrease in web thickness near the growth initiation. Stringers are formed by the reaction of two dislocations of different Burger's vectors, and the stringer density does not increase with ribbon length. Finally, web curvature is caused by plastic deformation due to a build up of glissile dislocations pinned by surface steps. An understanding of the causes of the formation of these defects can lead to improved processing for more efficient web growth.