REEVALUATION OF THE BENEFITS OF POSTOXIDATION ANNEALING ON SUB-100 ANGSTROM GATE BRIDE QUALITY

The effects of postoxidation annealing (POA) on thin gate oxide qualit y are evaluated in two different MOS integration schemes. One scheme i nvolves a high temperature backend step consisting of a 20-s 1065 degr ees C rapid thermal anneal after gate polysilicon deposition, The seco nd involves a much lower temperature backend step consisting of a 20-s 800-850 degrees C rapid thermal anneal, It is demonstrated that, alth ough the POA significantly improves dielectric properties such as char ge-to-breakdown and interface hardness at very low backend temperature s, it does little to improve such properties at high backend temperatu res. Given that typical semiconductor processes often include thermal steps that exceed gale oxidation temperatures, it, may be possible to eliminate POA with no adverse effects. Eliminating POA can in turn red uce processing time and further reduce total thermal budget.