RESUMO
Tris(dimethylsilyl)amine (TDMSA) is used in the presence of O2 and NH3 for the atmospheric pressure chemical vapor deposition (CVD) of conformal, corrosion barrier silicon oxynitride (SiOxNy) films at moderate temperature. Plausible decomposition pathways taking place during the process, as well as resulting gas-phase by-products, are investigated by an innovative methodology, coupling solid-state films characteristics with gas phase analysis. Liquid NMR, gas chromatography coupled with mass spectrometry (GC-MS) and electron spin resonance (ESR) allow probing stable compounds and radical intermediate species in the gas phase. At least fifteen by-products are identified, including silanols, siloxanes, disilazanes, silanamines, and mixed siloxane-silanamine molecules, in addition to more usual compounds such as water. The radical dimethylsilane, Me2HSiË, is noted across all experiments, hinting at the decomposition of the TDMSA precursor. Deposition of SiOxNy films occurs even in the absence of NH3, demonstrating the judicious choice of the silanamine TDMSA as a dual source of nitrogen and silicon. Additionally, the presence of Si-H bonds in the precursor structure allows formation of SiOxNy films at temperatures lower than those required by other conventional silazane/silanamine precursors. Addition of NH3 in the inlet gas supply results in lower carbon impurities in the films. The identified by-products and formulated decomposition and gas-phase reactions provide stimulating insight and understanding of the deposition mechanism of SiOxNy films by CVD, offering possibilities for the investigation of representative chemical models and process simulation.
RESUMO
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.
RESUMO
Metallic thin films of the single-component, neutral, molecular solid Ni(tmdt)2 have been prepared by electrocrystallization on passivated silicon substrates. Metallicity is achieved down to 6 K despite the polycrystalline morphology.
