Reaction Dynamics and the Mechanism of Surface Chemical Etching:

Chemical etching involves the removal and patterning of materials, and is a critical step in device fabrication. Our goal is to understand the factors that control the final surface morphology and limit the precision of chemical etching. The present view is that the morphology is the result of continuous etching of an essentially static surface. We are interested in possible effects caused by the diffusion and coalescence of small etch-induced defects. Indeed, the actual mechanism of chemical etching remains elusive and a detailed atomic-scale mechanism is another goal of this project. We are particularly interested in determining whether etching is simply a rearrangement of species on the surface or whether impinging gas phase molecules actually play a role.

Our approach involves the use of variable temperature STM to directly measure the surface dynamical process as they occur in real-time. This system allows images to be acquired over a wide temperature range (25K to 1000K) and during which the halogen gas is delivered to the surface during imaging process. In this manner we hope to identify the mechanism and key surface dynamical processes that are involved.

Morphology of Etched Silicon (100) Surface