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.