Electron spin resonance spectroscopy is used to study the effects of thermal NH3nitridation and subsequent reoxidation on the structure of the dielectric/silicon interface. This is accomplished by study of thePbcenter, an interfacial point defect. The values ofg⊥inPbspectra observed in the nitrided oxide and reoxidized nitrided oxide systems differ from Si/SiO2systems, 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. ©1995 American Institute of Physics.