Control of RIE-induced Surface Damage and Junction Leakage Current in Field Isolation Process

Surface damage induced by reactive ion etching (RIE) of SiN/SiO/sub 2/ stack used in the field isolation process was investigated in terms of its depth distribution and its correlation with junction leakage current. High leakage current is observed when oxidation induced stacking faults (OSF) are generated near bird's beaks in active regions from the Carbon-rich surface damage induced by so called stop-on-Si RIE prior to the field oxidation process. Control of both OSF and the junction leakage current at lower levels is made possible if the C-rich surface damage is eliminated either by chemical dry etching (CDE) treatment of the surface or by use of RIE conditions with lower ion energies.