IS THERE AN EFFECT OF THE PROXIMITY OF A FREE-SURFACE ON THE FORMATION OF END-OF-RANGE DEFECTS

We have studied the effect of the proximity of the wafer surface on th e formation of End-Of-Range defects. These experiments are aimed at el ucidating the behavior, upon annealing, of the Si self-interstitial su persaturation responsible for transient enhanced diffusion of boron in pre-amorphized silicon wafers. By implanting with Ge at constant ener gy while carefully etching away increasing thicknesses of the amorphou s layer the nucleation and growth of End-Of-Range defects have been st udied by transmission electron microscopy. Clearly, no influence in th e loop population can be shown even when using state-of-the-art ''quan titative'' electron microscopy. These results are explained by conside ring that the c/a interface is a diffusion barrier for the Si self-int erstitial atoms during the nucleation stage, i.e., when the supersatur ation is high. Only after the solid phase epitaxial regrowth, i.e., du ring the coalescence of the loops when the supersaturation is already low, the surface can interact with the loops. However, this interactio n is not measurable through the observation of extended defects and th is leads to simplifying assumptions for the simulation of Transient En hanced or Retarded Diffusion in pre-amorphized Si wafers.