LOW-TEMPERATURE VAPOR-DEPOSITION OF HIGH-PURITY IRIDIUM COATINGS FROM CYCLOOCTADIENE COMPLEXES OF IRIDIUM - SYNTHESIS OF A NOVEL LIQUID IRIDIUM CHEMICAL VAPOR-DEPOSITION PRECURSOR

High-purity, crystalline iridium coatings have been prepared by low-temperature chemical vapour deposition (CVD) from three volatile cyclooctadiene (COD) iridium precursors. One of these, (MeCp)Ir(COD) (MeCp = methylcyclopentadieny), is a novel complex which melts at low temperature (40-degrees-C) and therefore can be used as a liquid iridium source for CVD. When hydrogen is used as a carrier gas, iridium coatings containing < 1 atm.% carbon are generated at ca. 120-degrees-C using (MeCp)Ir(COD) and Cplr(COD) (Cp = cyclopentadienyl). Likewise, deposition under low oxygen pressure in partial vacuum also generates coatings free of carbon and oxygen. However, when the deposition is carried out in vacuo (no carrier gas), ca. 80% carbon is incorporated into the films. When [(COD)Ir(mu-OAc)]2 (OAc = acetate) is used as the metal-organic CVD (MOCVD) precursor, films containing < 1% carbon and oxygen are obtained at ca. 250-degrees-C in vacuo without the need for a carrier gas.