Parallel Plate Plasma Etching for MEMS Processing-Reactor Modelling

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The model presented analyses the uniformity of dry etching polyslicon films which are used in resonator cavity for MEMS fabrication/1,2/. The increase of the uniformity is very important for nanotechnology and very strong required of MEMS because the dimensional configuration precision of mechanical structures has a direct influence on the mechanical properties. It was found that the uniformity can be improved by decreasing the power and pressure or by increasing the flow rate. 2. Model formulation The model was developed for a radial symmetric single-wafer parallel plate plasma reactor shown schematically in fig.1. Feed gas enters uniformly through the porous upper electrode. Etching products and unreacted feed gas are pumped radially outwards. The wafer is in good thermal and electrical contact with the lower grounded electrode and the etching surface temperature is assumed to be constant. Gas temperature variations are neglected. Due to the consumption on the wafer surface large concentration gradients may develop at the boundary between the wafer and the surrounding electrode. Because the etching rate is usually a function of the local etch agent concentration, the etching is nonunifom. Assuming constant gas physical properties and negligible volume change during reaction, the momentum equation can be decoupled from the mass and heat transfer equations. Considering the continuum approximation which is valid for pressure above about 0.2 torr, we used the Navier-Stokes equations and the continuity equations. The differential equation can be solved only by numerical techniques /3/. When we consider the wall Reynolds number Rw

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Journal: TechConnect Briefs
Volume: 1, Technical Proceedings of the 2003 Nanotechnology Conference and Trade Show, Volume 1
Published: February 23, 2003
Pages: 526 - 529
Industry sector: Sensors, MEMS, Electronics
Topicss: Advanced Manufacturing, Nanoelectronics
ISBN: 0-9728422-0-9