Photoemission studies of pulsed-RF plasma nitrided ultra-thin SiON dielectric layers

Results are presented of a photoemission study of the electronic structure of SiON layers formed by a pulsed-RF decoupled plasma nitration (DPN) of ultra-thin SiO2 grown base layers approximately 1.0 nm thick. The optical thickness of these device grade nitrided dielectric layers was in the range 1.4–1.6 nm. X-ray photoelectron spectroscopy (XPS) studies indicate that the nitrogen is incorporated in a single chemical environment at concentration levels in the range 15–17%. Angle resolved XPS measurements show that the nitrogen is distributed through the layer, with the binding energy of the N 1s peak at 398.3 eV which is indicative of a Si3N4-like chemical species in an oxide environment. High resolution core level photoemission studies of the spin orbit stripped Si 2p4+ peak revealed full width half maximum values in the range 1.4–1.55 eV, which are significantly larger than the 1.15 eV value reported for SiO2 layers. Synchrotron radiation photoemission studies of the valence band spectra enable the valence band off-set at the Si/SON interface to be evaluated as 2.3 eV and to infer a conduction band off-set of 2.1 eV.