ANNEALING BEHAVIOR OF PHOSPHORUS IN NATIVE-OXIDE FILMS ON HEAVILY PHOSPHORUS-DOPED SILICON

Phosphorus redistribution and its chemical structure in the native oxi de/Si as well as thermal oxides (similar to 30 nm)/Si were investigate d using X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). The Si substrates were both heavily P-doped Si(10 0) and poly-Si, together with nondoped poly-Si. The in-depth profiles of P obtained by both XPS and SIMS showed that the dopant-P redistribu ted in the thin native oxide film (NOF) even at room temperature, and the amount of P increased drastically upon annealing. The amount of re distributed P was much larger for Si(100) than for poly-Si. The domina nt chemical structure of P was not P2O5 but elemental-P and/or Si-P. C lear pileup of P at the NOF/Si interface could not be observed, since the thickness of NOF is very thin and probably P diffused into through out the NOF. In the case of thermal oxides, both SIMS and XPS profiles exhibited a big pileup-P at the oxide/Si interface. The amount of pil eup-P was about two times larger for the Si(100) than for the poly-Si, and it increased with annealing temperature. In the oxide films, the P-31 in SIMS as well as P-0 and P2O5 features in XPS were also detecte d, although the intensities were very weak compared to those at the in terface.