Plasma interactions with high aspect ratio patterned surfaces: ion transport, scattering, and the role of charging

Etching of a patterned semiconductor surface in a plasma depends strongly o n the transport of ion and neutral species between the features. Factors al tering ion scattering at the sidewalls of high aspect ratio features, such as ion temperature, mask erosion, and charging, influence significantly the final profile shape. Models to describe the inelastic and reactive scatter ing at various surfaces, coupled to ion trajectory calculations in the shea th and between features, are used to illustrate the contribution of these f actors to microtrenching and sidewall bowing. A transition in the profile s hape from exhibiting microtrenching to having a rounded bottom is predicted as a result of plasma-induced charging in very high aspect ratio insulatin g masks. (C) 2000 Elsevier Science S.A. All rights reserved.