Rapid thermal postoxidation anneal engineering in thin gate oxides with Al gates

Abstract

The effects of rapid thermal postoxidation annealing (POA) on the characteristics of thin gate oxides, /spl sim/10 nm, were systematically studied with respect to POA time, temperature and pressure. Two kinds of rapid thermal POA techniques were examined. One (POA1) was carried out by switching oxygen into nitrogen immediately after oxidation, while the other (POA2) was done by cooling down first and subsequently heating again in pure nitrogen. It was experimentally observed that the samples annealed by POA2 have larger charge-to-breakdown, Q/sub BD/, and lower interface trap density, D/sub itm/, than those annealed by POA1. But, the samples annealed by POA2 will result in poor immunity to radiation damage. In addition, it is also found that the samples with high POA temperature and low POA pressure treatments have large improvement in Q/sub BD/, but have serious degradation in the radiation hardness. A reoxidation technique after POA was used to improve the radiation hardness degraded by POA.