Improved MOS device performance through the enhanced oxidation of heavily doped n+silicon

The thermal oxidation of heavily doped silicon is well known to produce faster oxidation kinetics than lightly doped silicon. The physical mechanism responsible for this is reviewed, and quantitative data are presented which demonstrate that the effect is most pronounced over n⁺regions on substrates, oxidized at low temperatures in an H2O ambient. Understanding of this phenomenon allows it to be applied to a wide variety of technologies and device structures in which improved device performance is achieved simply through optimization of oxidation conditions. Specific examples of this improvement are described for NMOS and DMOS structures. Utilization of phenomena such as the one described here becomes increasingly important as devices and technology are pushed toward ultimate physical limits.