HIGH-RESOLUTION SIMS PROFILING OF NITROGEN IN ULTRA-THIN SIO2-FILMS NITRIDED BY RTP IN NH3 AND N2O

Nitrogen profiles in ultra-thin SiO2 films nitrided in NH3 or N2O by rapid thermal processing (RTP) were measured by high-resolution SIMS. By tracking the N-14+ species, rather than the (SiN+)-Si-42 one, as usually done, much improved results are obtained. In particular, a spurious N background in the substrate is strongly reduced. For comparable nitridation conditions, the nitrogen content at the SiO2/Si interface increases more rapidly in NH3- than in N2O-nitrided films. No simple relationship between N profiles and electrical characteristics were found.