Plasma-assisted etching mechanisms: The implications of reaction probability and halogen coverage

Abstract

Evidence is presented which indicates that the way in which energetic ion bombardment accelerates the etching of Si in a fluorine environment is by a direct acceleration of the product formation step and not by damage‐enhanced chemistry. The use of fluorine coverage to characterize the etching process is discussed in detail and the assumption that the etch rate of Si can be decoupled into a spontaneous and an ion‐assisted contribution is questioned. Finally, examples of the influence of ion bombardment on Al(100)–Cl₂, Cu(100)–Cl₂ at 310 °C, and Nb–XeF₂ are used to emphasize that some of the conclusions reached for the Si–XeF₂ system are not generally applicable to all gas–solid combinations.