Mass spectrometry as an ancillary tool in metallo-organic chemical vapour deposition studies. The case of zirconium-cyclopentadienyl derivatives

Abstract

Mass spectrometry has been employed as a diagnostic tool to investigate the decomposition of some zirconium cyclopentadienyl derivatives, namely dimethyl zirconium bis(cyclopentadiene) [(C5H5)2Zr(CH3)2] (1), dimethyl zirconium bis(methylcyclopentadiene) [(CH3C5H4)2Zr(CH3)2] (2) and bis(methylcyclopentadienyl) zirconium ditetrahydroborane [(CH3C5H4)2Zr(BH4)2] (3), used as precursors in the metallo-organic chemical vapour deposition (MOCVD) technique for ZrO2 thin films, as an alternative to the β-diketonates and alkoxides which represent the usually employed precursors. The measurements, performed both under electron ionization and electrospray ionization conditions, indicate that the most favoured decomposition channel involves the loss of the methyl or the tetrahydroborane ligands. For compounds 2 and 3 a more complicated decomposition mechanism, involving molecular rearrangements with formation of species containing intramolecular bonds by CH2 bridges, is observed. Copyright © 1998 John Wiley & Sons, Ltd.