Anisotropy control in CF4 microwave plasma etching

Abstract
A parametric study of the etching of silicon with CF4 has been performed in a multipolar microwave plasma with independent rf biasing. According to the plasma conditions, up to three transitions from anisotropic to nonanisotropic etching can be found. The mechanisms involved are discussed in terms of the coadsorption of reactive fluorine atoms and CFx radicals which are responsible for the wall passivation by polymer formation.