AVS 46th International Symposium
    Manufacturing Science and Technology Group Wednesday Sessions
       Session MS-WeP

Paper MS-WeP2
A Two-Dimensional Modeling Study of Pattern Dependent Etching@footnote 1@

Wednesday, October 27, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: B. Lay, University of Illinois, Urbana
Authors: B. Lay, University of Illinois, Urbana
M.J. Kushner, University of Illinois, Urbana
Correspondent: Click to Email
Pattern dependent etching has become an increasingly important problem as feature sizes have decreased. It has been observed that a large exposed region on a die in close proximity to fine features tend to decrease the etch rates of the small features. In order to have process-independent uniform etching, the cause of this phenomenon must be determined. Previous studies have shown that gas phase processes alone, particularly at low pressures (< 10-20 mTorr), are unable to explain these observations. In this paper, the results of a numerical study of pattern dependent etching will be presented. A 2-dimensional computer model has been developed which addresses current flow through both the solid wafer material and the plasma. The Plasma-Solid-Simulator (PSS) solves Poisson's equation coupled with the continuity equations for electrons and ions in the plasma, and current density in the bulk, on a triangular mesh. The equations are linearized and implicitly integrated using Newton's method. The PSS calculates the conduction and displacement currents flowing through a partially exposed wafer during the etching process and relates them to etching characteristics. Parametric results from the PSS will be discussed as a function of plasma power and pattern layout. The observed increase in electric fields surrounding the unmasked portions of the wafer may lead to additional electron heating. @FootnoteText@ @footnote 1@This work was supported by SRC, AFOSR/DARPA, Applied Materials and LAM Research