New precursors for organometallic chemical vapor deposition of rhodium

The η-cyclopentadienyl (Cp) and η-allyl (C3H5) complexes [RhCp(CO)2], [RhCp(cod)] where cod = 1,5-cyclooctadiene, [Rh(η-C3H5)(CO)2], and [Rh(η-C3H5)3] have been shown to be useful precursors for the chemical vapour deposition (CVD) of rhodium films. The rhodium films contain carbon impurities but these can be greatly reduced if CVD is carried out in the presence of hydrogen. The films adhere well to a silicon substrate. The pyrolysis of [RhCp(CO)2] gives CO and [Rh2Cp2(CO)2(μ-CO)] and [Rh3Cp3(μ-CO)3] at intermediate stages. Pyrolysis of [Rh(η-C3H5)3] or [Rh(η-C3H5)(CO)2] gives 1,5-hexadiene as the only organic product, but similar pyrolysis in the presence of hydrogen gives much propene as well as 1,5-hexadiene. Key words: rhodium, deposition, allyl, cyclopentadienyl.