Thermal activation of As implanted in bulk Si and separation by implanted oxygen

Abstract

We have studied arsenic (As) diffusion and its electrical activation in two different types of silicon substrates: bulk Si and separation by implanted oxygen (SIMOX) wafers. Both substrates were implanted with a dose of 531014 cm-² As+ at 20 keV. The samples were annealed and physical characterization was performed with secondary ion mass spectrometry (SIMS), Rutherford backscattering spectrometry, and medium energy ion scattering. The electrical properties of the film were extracted by Hall measurements. The SIMS results showed a lower dopant outdiffusion loss to the atmosphere during annealing in the SIMOX samples. The electrical results for the SIMOX samples were also superior to those of bulk Si due to the higher dopant retention, likely the result of a higher concentration of vacancies, which in turn increases the relative fraction of As which is activated (in substitutional sites). The net effect was a higher sheet carrier concentration and lower sheet resistance in the SIMOX samples. The implantation damage removal was superior in SIMOX samples compared to bulk Si ones.