Redistribution of P atoms in oxidized P-implanted silicon during annealing

Abstract

Phosphorus ions were implanted into silicon at energies of 20∼200 keV and then a region ranging from the surface to about 0.26 nm was oxidized in wet-oxygen atmosphere at 1000 °C for 90 min. Two groups, samples (capped samples) for which the SiO₂ was not removed, and samples (removed samples) for which the SiO₂ was removed, were prepared from the oxidized samples. Subsequently, the samples were annealed in inert gas at 1000 °C for 30∼180 min. The annealed capped samples prepared from the 20 keV ion-implanted silicon had approximately the same P atom distribution profiles as the as-oxidized sample regardless of annealing time: the implanted P atoms had not diffused into silicon during the annealing. The annealed removed samples had P atom distribution profiles approximated by a solution of the diffusion equation with constant-total-dopant. When the samples prepared from the 200 keV ion-implanted silicon were annealed, the distribution profiles of carriers were approximated the same regardless of whether or not the SiO₂ film was removed from the sample.