On-line coating of glass with tin oxide by atmospheric pressure chemical vapor deposition.

Abstract

Atmospheric pressure chemical vapor deposition (APCVD) of tin oxide is a very important manufacturing technique used in the production of low-emissivity glass. It is also the primary method used to provide wear-resistant coatings on glass containers. The complexity of these systems, which involve chemical reactions in both the gas phase and on the deposition surface, as well as complex fluid dynamics, makes process optimization and design of new coating reactors a very difficult task.In 2001 the U.S. Dept. of Energy Industrial Technologies Program Glass Industry of the Future Team funded a project to address the need for more accurate data concerning the tin oxide APCVD process. This report presents a case study of on-line APCVD using organometallic precursors, which are the primary reactants used in industrial coating processes. Research staff at Sandia National Laboratories in Livermore, CA, and the PPG Industries Glass Technology Center in Pittsburgh, PA collaborated to produce this work.In this report, we describe a detailed investigation of the factors controlling the growth of tin oxide films. The report begins with a discussion of the basic elements of the deposition chemistry, including gas-phase thermochemistry of tin species and mechanisms of chemical reactions involved in the decomposition of tin precursors. These results provide the basis for experimental investigations in which tin oxide growth rates were measured as a function of all major process variables. The experiments focused on growth from monobutyltintrichloride (MBTC) since this is one of the two primary precursors used industrially. There are almost no reliable growth-rate data available for this precursor. Robust models describing the growth rate as a function of these variables are derived from modeling of these data. Finally, the results are used to conduct computational fluid dynamic simulations of both pilot-and full-scale coating reactors. As a result, general conclusions are reached concerning the factors affecting the growth rate in on-line APCVD reactors. In addition, a substantial body of data was generated that can be used to model many different industrial tin oxide coating processes. These data include the most extensive compilation of thermochemistry for gas-phase tin-containing species as well as kinetic expressions describing tin oxide growth rates over a wide range of temperatures, pressures, and reactant concentrations.3

Influencing FTO thin film growth with thin seeding layers: a route to microstructural modification

“…9,10 Future performance advances for conventional TCO will require more sophisticated methods for effecting property improvements, such as more precise tailoring of film properties to specific applications, in addition to the exploration of less conventional TCO frameworks, e.g. [27][28][29] APCVD involves the use of discrete chemical precursors, the concentration of which is controlled by gas flows prior to mixing and the subsequent deposition for film formation, to control functional properties. [11][12][13][14][15][16][17][18] The former includes the control of secondary properties through, for example, film preferred orientation to minimise charge carrier obstacles and tune morphology so as to best suit the optical scattering needs of an application.…”

“…[24][25][26] The production of fluorine-doped SnO 2 (FTO) -one of the worlds most widely used and produced TCO -and other conventional TCO is frequently carried out by atmospheric-pressure chemical vapour deposition (APCVD), most notably by Pilkington-NSG for their TEC glass range. [27][28][29] APCVD involves the use of discrete chemical precursors, the concentration of which is controlled by gas flows prior to mixing and the subsequent deposition for film formation, to control functional properties. 30 However, whilst optimised electrical conductivity and optical transmittance TCO values can be achieved using this high-throughput deposition method, control of microstructure, particularly the various morphologies afforded by techniques such as aerosol-assisted CVD (AACVD), cannot be reproduced due to the lack of growth control on the amorphous glass substrate.…”