AVS 49th International Symposium
    Plasma Science Wednesday Sessions
       Session PS+MM-WeA

Paper PS+MM-WeA10
3-Dimensional Feature Profile Evolution Using Level Set Methods

Wednesday, November 6, 2002, 5:00 pm, Room C-105

Session: Feature Profile Evolution /Plasma Processing for MEMS
Presenter: H. Hwang, NASA Ames Research Center
Authors: H. Hwang, NASA Ames Research Center
T.R. Govindan, NASA Ames Research Center
M. Meyyappan, NASA Ames Research Center
Correspondent: Click to Email
Modeling feature profile evolution due to etching of semiconductor materials is typically done in two dimensions. However, these 2-D simulations make assumptions about geometries, such as semi-infinite trenches, that are unrealistic. Since a semi-infinite trench will "collect" higher amounts of fluxes than a finite one, the calculated ion and neutral fluxes to the surfaces in 2-D will not account for the shadowing of the opening due to the finite size. These larger fluxes will then lead to a larger overall etch rate, compared with calculations done in 3-D. Furthermore, any asymmetries (due to ion angular distribution functions, for example) can only be captured in 2-D. Inherently 3-D situations, such as striation patterns of the trenches, cannot be studied without the third spatial dimension. We will present results using an etching 3-D simulation which uses level set methods to advance the moving front. This code is an extension of SPELS, the Simulation of Profile Evolution using Level Sets, to calculate etch rates of silicon in chlorine discharges. We will show animations of the evolving trench for different geometries as well as for different process conditions. We will make comparisons of cross sections of the 3-D profiles to calculations from 2-D simulations and demonstrate the effects of a finite trench versus a semi-infinite trench on etch rates.