SUBLIBOX: A Proprietary Solvent Free Method for Intense Vaporization of Solid Compounds

Abstract

Chemical vapour deposition and atomic layer deposition using precursors that are solids at ambient temperature and pressure present challenges due to the often low saturating vapour pressure of these compounds. Additional concerns arise from the difficulty to maintain a reproducible and stable precursor flow rate to the deposition chamber and from the possible particle contamination if suitable safeguards are not built into the precursor delivery line. In the present contribution, SUBLIBOX, a pilot industrial scale sublimator is presented. SUBLIBOX is based on a new sublimation process involving gas-solid fluidization technology. Aluminum acetyl–acetonate [Al(acac)3], a promising precursor for the processing of alumina films despite its low saturated vapour pressure, is used as a model, though technologically interesting system. Mass balance measurements, involving trapping of the sublimed precursor at the exit of the sublimation chamber, reveal that SUBLIBOX ensures (a) stable, (b) efficient, (c) reproducible and (d) long term precursor vapour flow rates. The process is particularly well adapted for delivering vapours to CVD reactors for coatings on glass and stainless steel or for producing optical fibbers preforms by various techniques.