Fabrication of ultrathin silicon dioxide layers in ultra high vacuum

Silicon dioxide layers of thickness 1-10 nm have been manufactured by the plasma oxidation of silicon in ultra high vacuum (UHV). UHV chamber is a very clean environment, temperature and molecular fluxes are easily controllable and in situ device processing is possible. In the temperature range 700-850 degrees C the oxidation is very slow in the beginning. After an uniform layer is developed on the surface, the growth rate increases. Increasing temperature also clearly increases the growth rate, as the temperature dependence of the initial growth phase is probably less. Our measurements predict, that to get a good quality layer, the processing temperature should be at least 700 degrees C.