Impact of H2, O2, and N2 anneals on atomic-scale surface flattening for 3-D Ge channel architecture

We evaluated atomic-scale surface morphology changes of Ge wafers after thermal flattening in H₂, O₂, and N₂ gas ambient. Analysis of atomic force microscopy results revealed that the atomic steps and terraces of Ge were evident after annealing at over 500°C for 160 s. The atomistic surface morphologies varied with the different annealing atmospheres. Nearly uniform step-terrace structure due to the suppression of terrace etching was obtained on N₂-annealed Ge surfaces.