Kinetic etch front instability responsible for roughness formation in plasma etching

Abstract

A universal, kinetic etch front instability responsible for plasma etching induced roughness is proposed. The kinetic process of plasma rough etching is modeled based on Kinetic Monte Carlo method. The basic idea is that adatoms of etching inhibitor preferentially bond with each other rather than the substrate due to the mismatch of binding energies. This ultimately leads to the three-dimensional island growth of etching inhibitor, which, after micro-masking, induces roughness. Numerical simulations give results consistent with experimental findings on morphological characteristics as well as roughness dependencies on various etching conditions. The proposed mechanism provides a new viewpoint for understanding the roughness development in dry etching, meanwhile could be a useful tool for developing the processing recipes for both smooth etching and nano-texturing.