OFF-LINE SHEET GLASS COATING SYSTEM

High deposition efficiency (> 20%), low bulk resistivity (less than or equal to 6.0 x 10(-4) Omega cm), tin oxide coatings have been prepare d on an off-line coating system. The system developed includes a coate r nozzle, vapor feed system, oven, organotin-based deposition chemistr y and a complete emissions control system. The coater nozzle design wa s modelled using PHOENICS dagger, a finite volume computational fluid dynamics program. The design criteria used was to minimize the velocit y variation across the feed slot. The actual design employed consists of distribution holes, with size and spacing determined from macroscop ic calculations and positioning determined from flow modelling. The sl ot design used to deliver the feed vapor resulted in < 5% variation in film sheet resistance across the substrate (perpendicular to coating direction). The feed system incorporates a unique method to vaporize a high boiling point (T-b > 200 degrees C) organotin that provides for uniform, steady state vaporization of precursor mixtures, especially t hose having different vapor pressures, while minimizing thermal abuse and degradation. Coatings have been produced for photovoltaics, low ep silon, and resistive heating. For example, at a conveyor speed of 2.1 cm/s, 280 nm of conductive tin oxide was deposited on soda-lime-silica glass with deposition efficiency of 28% and sheet resistance of 23 oh m/square. The deposition chemistry is currently in use in the industry and is composed of monobutyl tin trichloride (MBTC) and an organofluo rine. Coatings with bulk resistivities as small as 5.5 x 10(-4) Omega cm with an accompanying deposition efficiency of 31% have been demonst rated. (C) 1997 Elsevier Science B.V.