Level set approach to simulation of feature profile evolution in a high-density plasma-etching system

The simulation of feature profile evolution in high-density plasma-etching processes has been carried out using a level-set technique. The main feature of this work is the inclusion of sheath dynamics, angular distribution of ions and reemission of neutrals in the trench, etch kinetics, and a level set equation for tracking a moving front of the feature profile. Sheath dynamics showed that the damped potential was somewhat shifted to the right and smaller than the applied potential. Etch profile simulations were performed for etching of silicon in inductively coupled plasmas of Cl₂ and CF₄ under various conditions. In dry etching of Si with CF₄ discharges, polymer deposition was dominant at p_CFx≫10 mTorr, while surface fluorination (or ion-enhanced etching) was a main mechanism at p_CFx≪10 mTorr. The predicted etch profiles showed a slight bowing on the sidewalls and substantial tapering near the bottom, depending on the plasma parameters. © 2001 American Vacuum Society.