| AVS 56th International Symposium & Exhibition | |
| Plasma Science and Technology | Wednesday Sessions |
| Session PS1-WeA |
| Session: | Plasma Modeling |
| Presenter: | P.J. Stout, Applied Materials |
| Authors: | P.J. Stout, Applied Materials J.A. Kenney, Applied Materials S. Rauf, Applied Materials |
| Correspondent: | Click to Email |
Discussed will be results of three dimensional feature scale modeling of high aspect ratio (HAR) dielectric etching. The feature model is coupled to a reactor model which supplies specie flux values and angle and energy distribution functions to the feature model. The feature model has been used to study the mechanisms which contribute to the HAR etched profile. The mechanisms in the model include etchant transport to the surface, specular and diffusive reflection within the feature, adsorption, surface diffusion, energy loss, deposition, and etching. Typical requirements for HAR dielectric etch include reduction of profile bow, no off-axis profiles (i.e twisting, tilting), large bottom cd's, and no bottom profile distortion or rotation. Mechanisms contributing to off-axis etch profiles and bottom distortion will be discussed including mask shape, polymer deposition, etch by products, off-axis ion incidence, and yield curves. The effect of source power, bias power, and frequency mixing on the etched profile will also be explored. The shape of the mask at the opening controls the amount and direction of etchants entering the feature. Thus, the shape and evolution of the feature mask opening plays a large role in the evolution of the etched profile. For instance, a more angled mask increases the bow of the etched profile for a fixed process. Mask shape influences how polymer builds up at the opening and how the hard mask facets at the opening. Polymer buildup at the feature lip alters the path of striking ion incident near the feature opening. Facets forming at the feature opening also steer a portion of incoming ion flux from their largely wafer normal trajectory inside the feature. So the evolution of the mask shape over the course of the etch influences the ion trajectories and neutral shadowing to the etch front changing the character of the etched dielectric profile as the etch process proceeds.