Thermal stability of electrically active dopants in laser annealed silicon films

Abstract

Single crystal Si wafers and polycrystalline Si films on Si3N4 have been implanted with large doses (1×1015/cm2–4×1016/cm2) of P or As and laser annealed with either a cw or pulsed laser. The samples were then subjected to thermal anneals between 450 and 900 °C to determine the thermally stable dopant concentration for each sample. Sheet resistance and Hall measurements have been used to measure the electrical properties in each case. SIMS, RBS, and TEM have been used to measure atomic profiles, As substitutionality and residual defects after laser and thermal annealing. In each case the maximum electrically active dopant concentration achieved by laser annealing decreased after a 700–800 °C thermal anneal.