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.

What is claimed is:  
     
         1 . A semiconductor product comprising a transistor formed on a semiconductor surface, and having a gate structure including an oxide layer formed on said semiconductor surface, a transition layer including nitrogen and oxygen directly on said oxide layer, a nitride layer directly on said transition layer and a gate electrode layer over said nitride layer.  
     
     
         2 . The semiconductor product as in  claim 1 , wherein said semiconductor product is characterized by essentially no nitrogen being present at the interface formed between said semiconductor surface and said oxide layer.  
     
     
         3 . The semiconductor product as in  claim 1 , wherein nitrogen concentration at an interface formed between said semiconductor surface and said oxide layer does not exceed 0.5%.  
     
     
         4 . The semiconductor product as in  claim 1 , wherein a combined thickness of said oxide layer, said transition layer, and said nitride layer is no greater than 20 angstroms.  
     
     
         5 . The semiconductor product as in  claim 1 , wherein said oxide layer comprises a graded oxide layer including a lower portion formed at a relatively high temperature and an upper portion formed at a relatively low temperature.  
     
     
         6 . The semiconductor product as in  claim 1 , wherein said transition layer comprises silicon oxynitride (SiO x N y ).  
     
     
         7 . The semiconductor product as in  claim 1 , wherein said transition layer comprises nitrogen-doped silicon dioxide.  
     
     
         8 . The semiconductor product as in  claim 1 , wherein said transition layer comprises oxygen of an upper surface of said oxide layer in combination with nitrogen.  
     
     
         9 . The semiconductor product as in  claim 1 , wherein said transition layer includes a thickness of less than 5 angstroms.