THE STRUCTURE OF THERMALLY GROWN NONCRYSTALLINE SIO2-FILMS ON SILICON

Oxygen transport during thermal growth of noncrystalline (nc) SiO//2 films on silicon reveals a subtle difference in their structure as compared with silica glass. The kinetics of oxide growth demonstrate that the oxygen transport parameter increases with increasing oxide thickness and may even exceed that calculated from O//2 permeation in SiO//2 glass. This effect is suggested to be due to the formation of structural channels in the oxide film during its growth. Concomitant with this change the activation energy decreases from approximately 2. 2 to approximately 0. 9 ev. These values indicate that transport in thin ( less than approximately 70 nm) films is associated with interactions between O//2 molecules and network O atoms ( greater than approximately 1. 2 ev), whereas an essentially non-interactive transport of O//2 molecules dominates in thicker ( greater than approximately 100 nm) films ( less than equivalent to approximately 1. 2 ev).