HIGH-RESOLUTION DEPTH PROFILING IN SILICON OXYNITRIDE FILMS USING NARROW NUCLEAR-REACTION RESONANCES

We report here on the determination of depth profiles of oxygen and ni trogen with nanometer resolution in silicon oxynitride films with thic knesses below 3 nm, We have studied oxynitride films grown by rapid th ermal processing of Si (0 0 1) wafers in various Nitric Oxide (NO) atm ospheres. Angle Resolved X-Ray Photoelectron Spectroscopy (ARXPS) anal yses were carried out to determine the chemical composition of the fil ms as well as the spatial distribution of the chemical bonds. The nucl ear depth profiling: method uses narrow, isolated resonances found in the cross section of the nuclear reactions O-18(p,alpha)N-15 at 152 ke V and N-15(p,alpha gamma)C-12 at 429 keV. The excitation curves of the nuclear reactions in the neighbourhood of the resonance energies can be used to determine the concentration versus depth profiles by means of SPACES, a personal computer implementation of the stochastic theory of energy loss. We discuss aspects of the simulation of excitation cu rves and the effect of NO pressure on the structure of the oxynitride film. (C) 1998 Elsevier Science B.V.