Plasma-etching profile model for SiO2 contact holes

A theoretical plasma-etching model for contact holes (vias) is presented. The significant feature of this model is that the etch and deposition rates are given by analytical equations. The etch-profile simulations for the contact holes are computed from the trajectory equations of the surface-evolution equation by using a computer package of MATLAB. The ion and neutral etch rates are proportional to the energy and particle fluxes, respectively. A new approximate analytic expression for the ion-energy flux is reported for contact holes; the neutral flux expressions were found previously. The scanning-electron microscopy micrographs of SiO₂ contact holes etched in a gas mixture of CF₄/CHF₃/Ar in a magnetically enhanced reactive ion etching reactor are fitted well using the developed model.