CHARACTERISTICS OF THE THERMAL-OXIDATION OF HEAVILY BORON-DOPED POLYCRYSTALLINE SILICON THIN-FILMS

Dry oxidation kinetics were compared for 2 x 10(20) cm(-3) boron-impla nted and in-situ doped films deposited at temperatures ranging between 520 and 620 degrees C. The characteristics of the thermal oxidation o f these films have been studied over the oxidation temperature range o f 750 to 1050 degrees C and for durations of 10 min to 26 h. High valu es of both the surface oxidation rate k(s) and the oxide diffusion coe fficient D are evidenced as typical of the in-situ doped films. In add ition to the well-known effect that heavy doping increases the rate of oxidation similar to what is observed in single-crystal silicon, it i s also shown specially, for the in-situ boron-doped films compared wit h 2 x 10(20) cm(-3) in-situ phosphorus-doped ones, that the greatest o xidation rate is observed at high oxidation temperatures (T-ox > 1000 degrees C). This enhancement is related to some specific factors of th ese 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.