OXIDATION SIMULATION OF SILICON NANOSTRUCTURES ON SILICON-ON-INSULATOR SUBSTRATES

摘要

We present a two-dimensional simulation of pattern-dependent oxidation (PA-DOX) of silicon nanostructures fabricated on silicon-on-insulator (SOI) substrates. The characteristic features of PADOX are mainly determined by the oxidation-induced strain and by the oxidation from below, which pushes the silicon on the oxide upward. In order to reproduce these features in the simulation, the volume expansion due to silicon oxidation is treated as a dilational strain, and the strain is applied to a transition region in which silicon is converted to oxide. In addition, the silicon oxide and transition layer are treated as viscoelastic solids, and the stress dependencies of the oxidation reaction, oxygen self-difrusion in the oxide, and oxide viscosity are taken into account. The simulated silicon and oxide shapes after oxidation satisfactorily reproduce the experimental results. The simulation results suggest that the rounded silicon shapes that appear after oxidation are mainly caused by the stress-induced reduction of oxide viscosity.