Method and structure for oxide/silicon nitride interface substructure improvements

Abstract

A transistor gate dielectric structure includes an oxide layer formed on a substrate, a superjacent nitride layer and a transition layer interposed therebetween. The presence of the transition layer alleviates stress between the nitride and oxide layers and minimizes any charge trapping sites between the nitride and oxide layers. The transition layer includes both nitrogen and oxygen as components. The method for forming the structure includes forming the transition layer using a remote nitridation reactor at a sufficiently low temperature such that virtually no nitrogen reaches the interface formed between the oxide layer and the substrate. The oxide layer/substrate interface is relatively pristine and defect-free. In an exemplary embodiment, the oxide layer may be a graded structure formed using two distinct processing operations, a first operation at a relatively low temperature and a final operation at a temperature above the viscoelastic temperature of the oxide film.