Coupling of Monte Carlo sputter simulation and feature-scale profile simulation and application to the simulation of back etching of an intermetal dielectric

We demonstrate the coupling of Monte Carlo sputter simulation with feature-scale simulation of profile evolution during sputter etching. With the Monte Carlo sputter simulation, the dependence of the sputter yield on the angle of incidence and on the energy of ions impinging onto the surface is determined. The yield curves obtained thereby are fed into a feature-scale etching profile simulator which predicts the local etch rates based on these sputter yield curves and on ion fluxes which are calculated for a substrate placed in a sputter reactor. For validating the simulations, a process sequence consisting of deposition and back etching (in an argon plasma) of silicon oxide between metal lines has been studied. Assuming an ion energy of 250 eV allows us to consistently reproduce profiles observed experimentally.