The effect of Cl coverage on Si(100) surface reactivity: implications for Cl etching of Si

Abstract

We have carried out first-principles calculations of the potential energy as a function of the distance from the Cl to the surface normal for various surface sites. A comparison between the potential energies of the clean and Cl-covered (1 ML) surfaces indicates a significant change in Si surface reactivity. Our results suggest that it is critical to consider the effect of Cl coverage when simulating Cl plasma etching of Si. With regard to the mechanism responsible for Cl etching of Si(100), we have ruled out the pathway where Cl penetrates into the Si substrate via adsorption on top of the exposed second-layer Si atoms. Both of the pathways via the exposed third- and fourth-layer Si atoms are found to be energetically possible. Finally, we have found, in contrast to the findings of previous theoretical studies, that the bridge-bonded Cl structure is stable with the Si-Si dimer bond remaining intact, in agreement with the experimentally suggested structure.