AVS 55th International Symposium & Exhibition
    Plasma Science and Technology Monday Sessions
       Session PS-MoA

Paper PS-MoA9
Can Plasma Modeling Be a Predictive Tool in Process Development?: Etching of Very High Aspect Ratio Features and Gate Stacks*

Monday, October 20, 2008, 4:40 pm, Room 304

Session: Invited Highlights on Plasma-Surface Interactions - Honoring the Distinguished Career of Herbert H. Sawin
Presenter: M.J. Kushner, Iowa State University
Authors: M. Wang, Iowa State University
Y. Yang, Iowa State University
J. Shoeb, Iowa State University
M.J. Kushner, Iowa State University
Correspondent: Click to Email

The use of modeling in the development of plasma tools has achieved a significant degree of success. Optimizing the uniformity and energies of reactant fluxes with results of modeling prior to prototyping by varying, for example, the aspect ratio of the reactor or frequency of excitation is now accepted practice. The assist of modeling to develop plasma processes has provided a less clear return on investment. This is due, in part, to the complexity of the reaction mechanism and the lack of fundamental data. The rate of technology development will likely outstrip our ability to generate the required fundamental data, at least in the near term. As such, what are the realistic expectations for modeling to provide high value to the development of plasma processes? In this talk, the general status and the potential success of plasma modeling in the development of processes will be discussed with results from two case studies using reactor and feature scale modeling platforms. In the first, sporadically occurring twisting of via-like features in extremely high aspect ratio etching has been attributed to the stochastic nature of fluxes entering the feature as the size of the opening shrinks. This is an effect exacerbated by charging. Here the reaction mechanism, fluorocarbon plasma etching of Si and SiO2, is relatively well known. So modeling has assisted in developing a dc-augmented strategy for the capacitively coupled tools that addresses the contribution of charging to twisting. In the second, high-k dielectric HfO2 gate stack etching, the reaction mechanism is at best poorly known. Here, the contribution of modeling has been to refine that reaction mechanism based on the existing but fragmentary database and so narrow the now broad range of operating conditions that might be considered in process development.

*Work supported by the Semiconductor Research Corp., Micron Inc., Applied Materials Inc. and Tokyo Electron Ltd.