Oxygen migration, agglomeration, and trapping:: Key factors for the morphology of the Si-SiO2 interface

The measured activation energies for oxide growth rates at the initial and late stages of oxidation of Si are 2 and 1.2 eV, respectively. These values imply that oxidation can proceed at temperatures much smaller than the 800 degrees C normally used to obtain devices with exceptionally smooth Si-SiO2 interfaces. Here, we use first-principles calculations to identify the atomic-scale mechanisms of the 2 eV process and of additional processes with higher barriers that control the interface morphology and ultimately provide for smooth layer-by-layer oxide growth, as observed at high temperatures.