TRAPS IN REOXIDIZED NITRIDED OXIDES OF VARYING THICKNESSES

A study was conducted on the reliability aspects of thin reoxidized ni trided oxides (ROXNOX), as an alternative gate dielectric to thermal s ilicon dioxide in submicron metal oxide semiconductor (MOS) devices. M OS capacitors, with ROXNOX gate oxides of thicknesses ranging from 7 t o 10 nm, were subjected to constant voltage stressing. The density and distribution of the traps inside of the insulator were determined bef ore and after high field stressing. The ROXNOX exhibited a high initia l trap density in contrast to the normally low initial trap density in oxides. The trap generation rate, after stressing, was considerably l ower than that measured in thermal oxides. The low-level leakage curre nts were higher in the ROXNOX than in thermal oxides, and their voltag e and fluence dependences after stressing were different. Leakage curr ents under low fields in unstressed ROXNOX were composed of a transien t component and an ohmic de component. The de resistivity of the ROXNO X increased as the thickness increased. A model was proposed to explai n the mechanism of low field conduction in the ROXNOX.