AVS 45th International Symposium
    Plasma Science and Technology Division Monday Sessions
       Session PS-MoM

Paper PS-MoM8
Modeling of Finite 3-Dimensional Features in High Density Plasma Etching@footnote 1@

Monday, November 2, 1998, 10:40 am, Room 318/319/320

Session: Feature Evolution
Presenter: R.J. Hoekstra, University of Illinois, Urbana-Champaign
Authors: R.J. Hoekstra, University of Illinois, Urbana-Champaign
M.J. Kushner, University of Illinois, Urbana-Champaign
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The development of 2-dimensional profile simulators for fabrication of microelectronics devices has significantly progressed in recent years enabling modeling of etch profile evolution under many different processing conditions. Submicron device development and increasing device density leads to more complex and innately 3-dimensional features which require improved dimensionality in profile simulators. Two issues of concern are: 1) To what degree can 2-d simulators can be applied to modeling 3-d structures? and 2) What systemmatic perturbations to 2-d profiles are cause by 3-d structures (such as finite length trenches)? In this paper, results for the Monte Carlo Feature Profile Model (MCFPM) will be used to investigate the these issues. There are 2-d and 3-d versions of the MCFPM which are identical with the exception of increased dimensionality. Comparisons are made of profiles predicted by the 2-d and 3-d MCFPM for finite length trenches and square vias for etching of poly-Si in an ICP reactor using Cl@sub 2@. The aspect ratio of the trench and the angular spread of the ion flux were varied. In the center of "long" trenches (e.g., 1 µm x 4 µm) profiles from the 2-d model are similar to those from the 3-d model except that the etch rate is lower due to increased shadowing of reactants. As the ends of the trenches are approached (that is, one is near "3-plane" corners) increased sidewall sloping and curvature is predicted from the 3-d models compared to the 2-d model. This necessitates a greater amount of over-etching to fully clear these features than predicted by 2-d models. The effects of angular spread and asymmetry of the ion flux, and redeposition of etch products were examined to determine their role in 3-d profile evolution. With redeposition, we found that narrow ion angular distributions were more sensitive to being near 3-plane corners, resulting in more variation in transverse etch profiles along the trench. @FootnoteText@ @footnote 1@Work supported by SRC and NSF.