QUANTITATIVE MODELING OF SI/SIO2 INTERFACE FIXED CHARGE .2. PHYSICAL MODELING

The fixed-oxide charge density of N//f at the Si/SiO//2 interface has been studied as a function of process variables. The process parameters used were temperature, time, ambient, and oxidation cycle. To explain the experimental data, it is postulated that oxide charges are located at specific interface sites, perhaps, the kinks and steps thought to be associated with the oxidation process. It is also postulated that silicon interstitials generated at the Si/SiO//2 interface recombine with kinks and steps via a monatomic surface regrowth process. Using these concepts, the process dependence of oxide charges is modeled quantitatively in oxidizing and nonoxidizing ambients. The model, which is physically based, can be used to predict N//f in the temperature range of 700 degree -1100 degree C, and in the oxidant partial-pressure range of 0-100% O//2 in Ar.