Optical properties of N+ ion-implanted and rapid thermally annealed Si(100) wafers studied by spectroscopic ellipsometry

The optical properties of N+ ion-implanted Si(100) wafers have been studied using the spectroscopic ellipsometry (SE). The N+ ions are implanted at 150 keV with fluences in the range between 1x1016 and 7.5x1016 cm-2 at room temperature. A Bruggeman effective-medium-approximation and a linear-regression analysis require a four-phase model (substrate/first and second damaged layers/ambient) to explain the experimental data of the as-implanted samples. These analyses suggest that the buried fully amorphous layer can be formed at around ∼5x1016 cm-2 dose. The rapid thermal annealing is performed at 750 deg. C in a dry N2 atmosphere on N+ ion-implanted samples. The SE data reveal that the recrystallization starts to occur very quickly. The time constant for the defect annealing in the deeper damaged layer is determined to be 36 s. The dielectric-function spectra ε(E) of microcrystalline silicon deduced here differ appreciably from that of the single-crystalline silicon, especially in the vicinity of the critical points