Characteristics of the thermal oxidation of heavily boron-doped polycrystalline silicon thin films

Abstract

Dry oxidation kinetics were compared for 2 × 10 20 cm −3 boron-implanted and in-situ doped films deposited at temperatures ranging between 520 and 620 °C. The characteristics of the thermal oxidation of these films have been studied over the oxidation temperature range of 750 to 1 050 °C and for durations of 10 min to 26 h. High values of both the surface oxidation rate k s and the oxide diffusion coefficient D are evidenced as typical of the in-situ doped films. In addition to the well-known effect that heavy doping increases the rate of oxidation similar to what is observed in single-crystal silicon, it is also shown specially, for the in-situ boron-doped films compared with 2 × 10 20 cm −3 in-situ phosphorus-doped ones, that the greatest oxidation rate is observed at high oxidation temperatures ( T ox > 1 000 °C). This enhancement is related to some specific factors of these materials, such as grain boundary structures, defects, texture and electrical properties related to the segregation and supersaturation phenomenon which occur at these levels of doping.