The effects of interfacial sub-oxide transition regions and monolayer level nitridation on tunneling currents in silicon devices

Direct tunneling (D-T) in Si metal-oxide-semicon ductor (MOS) devices having 1.8 to 3 nm thick gate oxides is reduced approximately tenfold by monolayer Si-dielectric interface nitridation with respect to devices with nonnitrided interfaces. The reduction is independent of gate oxide-equivalent thickness, and gate or substrate injection, and extends into the Fowler-Nordheim tunneling (F-N-T) regime for thicker oxides as well. A barrier layer model, including sub-oxide transition regions, has been developed for the interface electronic structure for tunneling calculations using X-ray photoelectron spectroscopy data. These calculations provide a quantitative explanation for the observed tunneling current reductions.