Ion beams as analytical tools in the thermal growth of ultrathin silicon oxide films

Proton and deuteron beams were used to induce nuclear reactions (O-18(p, al pha)N-15 and O-16(d, p(0))O-17) in order to determine the areal densities o f O-18 and O-16 in ultrathin films of SiO2 thermally grown on Si in O-18(2) at low temperatures (700 degreesC and 800 degreesC) and pressures (0.7, 7. 0 and 70.0 mbar). It was observed that film thickness increases with time, temperature and O-2 pressure. Moreover, O-2 partial pressure was seen to be determinant in a process that leads to a reversal in the growth kinetics b ehavior of SiO2 films for the two Si crystalline orientations tested: (0 0 1) and (1 1 1), In the sequence, experimental kinetics were fitted using a diffusion-reaction model (de Almeida et al,, Phys, Rev. B 61 (2000) 12992). In some cases good agreement was observed, allowing the determination of d iffusivities of the oxidizing species through the oxide films. (C) 2001 Els evier Science B.V. All rights reserved.