Simulation of wet oxidation of silicon based on the interfacial silicon emission model and comparison with dry oxidation

Abstract

Silicon oxidation in wet ambients is simulated based on the interfacial silicon emission model and is compared with dry oxidation in terms of the silicon-atom emission. The silicon emission model enables the simulation of wet oxidation to be done using the oxidant self-diffusivity in the oxide with a single activation energy. The amount of silicon emission from the interface during wet oxidation is smaller than that during dry oxidation. The small emission rate for wet oxidation is responsible for the insignificant initial oxidation enhancement and the linear pressure dependence of the oxidation rate observed in wet oxidation. Using a unified set of parameters, the whole range of oxide thickness is fitted for both (100) and (111) substrates in a wide range of oxidation temperatures (800 °C–1200 °C) and pressures (1–20 atm).

Oxidation of silicon: Further tests for the interfacial silicon emission model

“…7 Apart from these features ͑initial oxidation enhancement in O 2 but not in H 2 O, sublinear dependence on P O 2 , dependence on substrate orientation͒ already highlighted by Uematsu et al, we have identified additional experimental results that can be qualitatively explained by the interfacial emission model. These are the experiments showing an enhancement of the oxidation after annealing of thin oxides in inert atmosphere.…”

“…Uematsu et al have succeeded in fitting several series of X͑t͒ curves with very good accuracy: Series 1, dry oxidation of Si͑100͒ at 1 atm measured by several authors in the 800− 1200°C temperature range, 6,7 notably the experimental points by Massoud et al 8 in the thin oxide regime; Series 2, the oxygen pressure dependence in the 1-20 atm range and thickness above 100 Å ͑Refs. 7 and 9͒ measured by Lie et al; 10 Series 3, dependence on Si substrate orientations ͑100͒ and ͑111͒ at several temperatures and oxygen pressures 11 measured by Massoud et al 8 and Lie et al; 10 and Series 4, a similar series for wet oxidation.…”

“…7 and 9͒ measured by Lie et al; 10 Series 3, dependence on Si substrate orientations ͑100͒ and ͑111͒ at several temperatures and oxygen pressures 11 measured by Massoud et al 8 and Lie et al; 10 and Series 4, a similar series for wet oxidation. 7 The enhanced initial oxidation and the sublinear dependence on the oxygen partial pressure of the linear rate constant ͑revealed in Series 1 and 2͒ are accounted for by the interfacial emission model in an elegant and unified way. Let us explain first the initial enhanced oxidation with the help of Fig.…”

“…III. We have solved the equations of the model with the parameters already published by Uematsu et al 7 Some technical details of our calculations are given in the Appendix, and the results corresponding to the particular experiments are given in Secs. II and III.…”

“…The equations of the interfacial emission model have been solved with the same parameters used for fitting the Si͑100͒ oxidation curves at 1 atm, 7 except for C O * , which is proportional to P O 2 . The predicted dX / dt versus X curves are plotted as solid lines in Fig.…”