Molecular Dynamic Simulation of the Effects of Glancing-Angle Scatterings on the Formation of High Aspect Ratio Features

Abstract

A common objective in plasma etching is to form high aspect ratio (HAR) features into a patterned substrate. Modelling ions travelling through HAR features helps in quantifying etching effects as a function of ions energy and direction to optimize etching processes. Since those ions generated from plasma sheath are both energetic and directional, the collisions between ions and side walls are glancing-angle scatterings when ions travelling through HAR features, most with angles of incidence greater than 80 degrees. These glancing-angle events depend on both incident energies and angles, generating a range of exit energies and angles after the scattering event, modifying the effective distribution as a process moves deeper into HAR features. This work will focus on glancing-angle scattering as a function of incident ions energy and direction, material types, and material surface roughness. The motivation is to provide this data to improve etch process as well as feature-level simulation efforts to elucidate the effects on the profile of HAR features.