Cross‐Sectional TEM Observation of Process‐Induced Defects in Heavily Arsenic‐Diffused Silicon Layers

Abstract

Heavily arsenic‐diffused silicon layers formed using doped polysilicon diffusion source and arsenic ion implantation are investigated by cross‐sectional TEM observation. By comparing depth distribution of process‐induced defects observed by cross‐sectional TEM with arsenic depth profiles measured by neutron activation analysis, it is found that dislocation loops are generated in the arsenic concentration region above by low‐temperature heat‐treatment, and that density of the dislocation loops changes reversibly with change of heat‐treatment temperature, irrespective of the diffusion source. These results and data on electrically inactive arsenic atoms indicate that dislocation loop generation occurs together with electrically inactive arsenic atom formation. This suggests that dislocation loop generation is caused by the decrease in solid solubility of arsenic in silicon.