Atomic scale investigation of local strain effect on the primary stages of silicon oxidation process using a coupling between Activation Relaxation Technique and first principles calculations

International audienceThe SiO2/Si interface is still a crucial issue in silicon-based nanotechnology, since the electronic properties of achieved devices are directly dependent of the quality of this interface. In the context of extreme miniaturization, the control of nanoscale structure and defects formation during the elaboration process are thus major challenges for the microelectronics industry.Despite lot of experimental and theoretical studies dedicated to the Si oxidation, the growth process and interfacial layer formation remains elusive because of the complex oxide growth as a characteristic crystalline/amorphous transition occurs. In recent studies, the interfacial strain appears as being at the origin of the Si atom emission, creating defect and reactive site, that could enhance the oxidation process. In this paper, we focus on how the strain evolution drives the nanoscale mechanisms of the first steps of the oxidation process thanks to an atomic scale approach coupling Density Functional Theory Calculations and Activation Relaxation Technique-nouveau. The adsorption of oxygen molecules on a fully oxidized surface and resulting interfacial strain is described. Further activation barriers of interfacial atomic diffusion are also discussed, as primary clues of amorphisation and defects formation