The effects of thermal nitridation and reoxidation on the interfacial stress and structure of silicon dioxide gate dielectrics

Electron spin resonance spectroscopy is used to study the effects of thermal NH₃ nitridation and subsequent reoxidation on the structure of the dielectric/silicon interface. This is accomplished by study of the P _b center, an interfacial point defect. The values of g _⊥ in P_b spectra observed in the nitrided oxide and reoxidized nitrided oxide systems differ from Si/SiO₂ systems, suggesting that the average value of the tensile stress in the silicon substrate increases upon nitridation while reoxidation acts to return the interfacial stress to prenitridation levels. The implications of these structural changes upon device performance are discussed.