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Proceedings Paper

Modelling and optimization of film thickness variation for plasma enhanced chemical vapour deposition processes
Author(s): Ewan Waddell; Des Gibson; Li Lin; Xiuhua Fu
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Paper Abstract

This paper describes a method for modelling film thickness variation across the deposition area within plasma enhanced chemical vapour deposition (PECVD) processes. The model enables identification and optimization of film thickness uniformity sensitivities to electrode configuration, temperature, deposition system design and gas flow distribution. PECVD deposition utilizes a co-planar 300mm diameter electrodes with separate RF power matching to each electrode. The system has capability to adjust electrode separation and electrode temperature as parameters to optimize uniformity. Vacuum is achieved using dry pumping with real time control of butterfly valve position for active pressure control. Comparison between theory and experiment is provided for PECVD of diamond-like-carbon (DLC) deposition onto flat and curved substrate geometries. The process utilizes butane reactive feedstock with an argon carrier gas. Radiofrequency plasma is used. Deposited film thickness sensitivities to electrode geometry, plasma power density, pressure and gas flow distribution are demonstrated. Use of modelling to optimise film thickness uniformity is demonstrated. Results show DLC uniformity of 0.30% over a 200 mm flat zone diameter within overall electrode diameter of 300mm. Thickness uniformity of 0.75% is demonstrated over a 200mm diameter for a non-conformal substrate geometry. Use of the modelling method for PECVD using metal-organic chemical vapour deposition (MOCVD) feedstock is demonstrated, specifically for deposition of silica films using metal-organic tetraethoxy-silane. Excellent agreement between experimental and theory is demonstrated for conformal and non-conformal geometries. The model is used to explore scalability of PECVD processes and trade-off against film thickness uniformity. Application to MEMS, optical coatings and thin film photovoltaics is discussed.

Paper Details

Date Published: 3 October 2011
PDF: 11 pages
Proc. SPIE 8168, Advances in Optical Thin Films IV, 81681I (3 October 2011); doi: 10.1117/12.896696
Show Author Affiliations
Ewan Waddell, Thin Film Solutions Ltd. (United Kingdom)
Des Gibson, Thin Film Solutions Ltd. (United Kingdom)
Li Lin, Changchun Univ. of Science and Technology (China)
Xiuhua Fu, Changchun Univ. of Science and Technology (China)

Published in SPIE Proceedings Vol. 8168:
Advances in Optical Thin Films IV
Michel Lequime; H. Angus Macleod; Detlev Ristau, Editor(s)

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