On the kinetics of boron nitride CVD from BF3-NH3-Ar : 2 - Influence of the precursor composition and chemical mechanisms

Stéphane Prouhet (1) , Gerard L. Vignoles (1) , Francis Langlais (1) , Alain Guette (1) , Roger Naslain (1)

1 LCTS - Laboratoire des Composites Thermostructuraux

An experimental study was carried out to assess the kinetics of boron nitride CVD from BF3-NH3-Ar mixtures and the influence of the initial gas phase composition on the transition from mass transfer to chemical reaction rate-controlled processes. The extension of chemical reaction trate-controlled domain in the coordinates P_{BF3}-P_{NH3} is determined for three temperatures (1250, 1350 and 1450 K) and a given total flow rate (Q_{tot} = 119 sccm). In the surface reaction controlled regime, the kinetic laws are established ; apparent partial reaction orders with respect to Ar and NH3 are nil and those with respect to BF3 and HF are depending on temperature and total pressure. Finally, reactional mechanisms, following the kinetic laws and chemical analyses performed on deposits obtained in the domains corresponding to these laws, are proposed to explain the chemical processes of BN deposition. One mechanism assumes the occurence of the BF3:NH3 adduct in the gas phase at low temperatures ; the other, at higher temperatures, is based on the hypothesis that NH3 is preferentially adsorbed on the substrate and reacts with the BF3 present in the gas phase.

Mots clés: Boron nitride; CVD

Domaines: Matériaux

Stéphane Prouhet, Gerard L. Vignoles, Francis Langlais, Alain Guette, Roger Naslain. On the kinetics of boron nitride CVD from BF3-NH3-Ar : 2 - Influence of the precursor composition and chemical mechanisms. European Journal of Solid State and Inorganic Chemistry, 1993, 30, pp.971-989. ⟨hal-00327304⟩