Modeling Superconformal Electrodeposition Using the Level Set Method

Published

May 1, 2003

Author(s)

Daniel Wheeler, Daniel Josell, Thomas P. Moffat

Abstract

Superconformal filling (superfill) occurs when a high aspect ratio feature on a silicon wafer fills due to preferential metal deposition on the bottom surface that permits it to escape before deposition on the side walls causes them to close off. This process only occurs when additives accumulate at the metal/electrolyte interface. The two crucial mechanisms by which the additive enables superfill to occur are (a) interface coverage change with increasing/decreasing arc length and (b) accelerator behavior increasing the copper deposition rate as a function of coverage. A model for superconformal electrodeposition that induces these effects is implemented using the zero level set of a continuous scalar variable to track the interface. The level set method lends itself well to tracking the interface position and for accurately determining the interface curvature required to update the value of the additive coverage at the interface. The modeling of the additive accumulation in conjunction with the level set method presents areas for novel numerical approaches. Several test cases are examined to validate the surface coverage model as well as comparison with experimental results for feature superfilling simulations.

Citation

Journal of the Electrochemical Society

Volume

150

Issue

No. 5

Pub Type

Journals

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Keywords

Copper, Damascene, Electrodeposition, Level Set, Numerical Method, Superconformal

Citation

Wheeler, D. , Josell, D. and Moffat, T. (2003), Modeling Superconformal Electrodeposition Using the Level Set Method, Journal of the Electrochemical Society, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=853094 (Accessed April 19, 2024)