Hwang, Gyeong S. and Giapis, Konstantinos P. (1997) On the origin of the notching effect during etching in uniform high density plasmas. Journal of Vacuum Science and Technology B, 15 (1). pp. 70-87. ISSN 1071-1023 http://resolver.caltech.edu/CaltechAUTHORS:HWAjvstb97c
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We present a two-dimensional Monte Carlo simulation of profile evolution during the overetching step of polysilicon-on-insulator structures, which considers explicitly (a) electric field effects during the charging transient, (b) etching reactions of energetic ions impinging on the poly-Si, and (c) forward inelastic scattering effects. Realistic energy and angular distributions for ions and electrons are used in trajectory calculations through local electric fields near and in the microstructure. Transient charging of exposed insulator surfaces is found to profoundly affect local sidewall etching (notching). Ion scattering contributions are small but important in matching experimental notch profiles. The model is validated by capturing quantitatively the notch characteristics and also the effects of the line connectivity and open area width on the notch depth, which have been observed experimentally by Nozawa et al. [Jpn. J. Appl. Phys. 34, 2107 (1995)]. Elucidation of the mechanisms responsible for the effect facilitates the prediction of ways to minimize or eliminate notching.
|Additional Information:||©1997 American Vacuum Society. (Received 14 June 1996; accepted 15 November 1996) The authors are grateful to J. W. Coburn and V. M. Donnelly for insightful suggestions and a critical review of the manuscript. They would also like to thank V. Vahedi for sharing his knowledge of plasma sheaths and proposing the decaying dipole field explanation. This work was partially supported by Caltech start-up funds and by a NSF Career Award to K. P. G. (CTS-9623450).|
|Subject Keywords:||PLASMA; ETCHING; SILICON; ION COLLISIONS; COMPUTERIZED SIMULATION; MONTE CARLO METHOD; INELASTIC SCATTERING; DISTRIBUTION FUNCTIONS; MICROSTRUCTURE; silicon-on-insulator; sputter etching; Monte Carlo methods; semiconductor process modelling|
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|Deposited On:||21 Feb 2006|
|Last Modified:||26 Dec 2012 08:46|
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