EFFECT OF POSTOXIDATION ANNEALING ON THE RELIABILITY OF RAPID THERMALTHIN GATE OXIDES

The reliability of thin gate oxides grown by rapid thermal oxidation i n O-2 followed by one and two step postoxidation annealing (POA) in N- 2 was studied, The one step POA was carried out by switching O-2 into N-2 immediately after oxidation without changing temperature, while th e two step POA was cooled down first and subsequently heated to the sa me temperature as oxidation in N-2. It was experimentally observed tha t the oxide thickness increases significantly with the POA time in one step POA, while the oxide thickness shows very little change during t wo step POA, The interfacial properties and the oxide breakdown endura nce can be improved by the two step POA, Also, the radiation hardness of oxide is less degraded by the two step POA than by one step POA, Th e effect of oxide thickness variation due to POA is chiefly responsibl e for the observation and is important to thin gate oxides.