Interaction of mechanical stress with residual defects in implanted Si

Abstract

After drive-in of arsenic-implanted emitter structures dislocations are found at the edge of the masking window and in the unimplanted surrounding regions while the implanted areas are defect-free. These dislocations originate from a defect structure which exists temporarily in the emitters during drive-in heat treatment. The dislocations are attracted to the window edge and are pushed into the surrounding region by mechanical stresses which have their origin in the intrinsic stress of the masking layer. No penetration of dislocations outside the implanted area is observed when the implantation is done through a thin oxide film. A mechanical stress analysis of film edge induced stresses can account for the observed defect patterns.