Plasma Jet-Substrate Interaction in Low Pressure Plasma Spray-CVD Processes
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JTTEE5 21:202–210 DOI: 10.1007/s11666-011-9702-5 1059-9630/$19.00 ASM International
Plasma Jet-Substrate Interaction in Low Pressure Plasma Spray-CVD Processes Ph. Guittienne, D. Grange, Ch. Hollenstein, and M. Gindrat (Submitted April 7, 2011; in revised form October 17, 2011) Conventional equipment for plasma spraying can be adapted for operation at low pressure so that PECVD-like processing can be performed. The plasma jet generated by the torch is characterized by a high convective velocity and a high gas temperature. The influence of these properties on a deposition process are investigated in the framework of simple theoretical considerations and illustrated by various experimental results obtained with SiOx deposition. A conclusion of this study is that the deposition process is dominated by diffusion effects on the substrate surface: the deposition profiles and the deposition rates are determined by the precursor density and by the gas temperature on the substrate surface. The high velocity of the jet does not play a direct role in the deposition mechanism. On the other hand it strongly increases the precursor density available for the deposition since it efficiently transports the precursor up to the substrate.
Keywords
coating, heat transfer, low pressure, PECVD, plasma torch, thin film
1. Introduction Plasma based processes are well known to be very widely used in many industrial applications, and for the production of very various types of products. Quite popular examples of plasmas applications are silicon etching, typically for integrated circuits (IC) manufacturing, and silicon or transparent conductive oxides (TCO) thin film deposition for solar cell production. But plasmas are also encountered in food packaging industry, space propulsion thrusters, compact discs manufacturing, flat screen televisions, waste treatment technology, and many others. As a consequence of these competitive markets interest there is a constant demand for the concerned industries in processes performance improvement. Within the specific needs inherent to each application two general trends can be distinguished: faster and larger. Especially large area processing is of great interest as it could allow a larger amount of work pieces to be treated at the same time, but also new kinds of products to be developed as larger work pieces could be processed. A large part of plasma based processes concerns thin film deposition (typ. 100 nm) which is currently obtained by plasma-enhanced chemical vapour deposition (PEC-
Ph. Guittienne, D. Grange, and Ch. Hollenstein, Centre for Research in Plasma Physics (CRPP), Ecole Polytechnique Fe´de´rale de Lausanne (EPFL), Lausanne, Switzerland; and M. Gindrat, Sulzer Metco Switzerland AG, Wohlen, Switzerland. Contact e-mails: [email protected] and david.grange@ epfl.ch.
202—Volume 21(2) March 2012
VD) typically performed under low pressure conditions (1-100 Pa) (Ref 1). A major part of the PECVD reactors relies on radio frequency (RF) capacitive or inductive sources, but d
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