Etching, sidewall passivation and microtrenching in contact holes and edge regions

Summary form only given. Our analytical/numerical models for etching in semiconductor fabrication of integrated circuits are extended to include sidewall passivation and microtrenching for contact holes (vias) and edge regions. The models fit oxide etch profiles in SEMS that were etched by a CF4/CHF3/Ar plasma in a MERIE reactor. Mild microtrenching is due to the anisotropic ion flux and isotropic deposition neutral flux. The model for contact holes includes an approximate analytic expression for the ion energy flux, Langmuir kinetics for the ions and etching neutrals and the flux for deposition neutrals. The deposition neutrals are modeled by an interpolation between shadowed and isotropic neutrals. The edge region (half trench) model may include enhanced microtrenching by scattered ions. The basic shape of the etch profile of the half trench is determined by the ion energy flux and the deposition flux. Much of the sidewall of the via and edge region is a characteristic of the evolution partial differential equation. Comparison of the etch model for the edge region and via for the same process conditions is presented.