COPPER(I) PRECURSORS FOR CHEMICAL VAPOR-DEPOSITION OF COPPER METAL

Several copper(I) complexes are compared as precursors for deposition of Cu metal from the vapor phase in H-2 carrier gas. The best of these, (hfac)Cu(I)(COD) (hfacH = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione; COD = 1,5-cyclooctadiene), yields films of low resistivity (3-4-mu-OMEGA-cm) and high purity (96%, by Auger electron spectroscopy); these are similar to films produced by H-2 reduction of the more familiar copper(II) complex Cu(hfac)2. (Hfac)Cu(I)(1,3-butadiene) and [(hfac)Cu(I)]2(mu-1,3,5,7-cyclooctatetraene) produce films of only slightly higher resistivity (4-6-mu-OMEGA-cm), but films from CpCu(I)(PR3) (R = CH2CH3, OCH3, OCH2CH3) are noticeably inferior (rho > 10-mu-OMEGA-cm). (hfac)Cu(I)(COD) has also been studied by X-ray crystallography. (Hfac)Cu(I)(COD), monoclinic, space group P2(1)/c; a = 10.042 (2), b = 9.878 (2), c = 15.756 (3) angstrom; beta = 108.64 (2)-degrees; Z = 4; R = 0.044 (R(w) = 0.051) for 1790 reflections (I > 3-sigma(I)) and 233 parameters. The structure contains a 2-fold disorder in the Cu atom position, corresponding to eta-2 and eta-4 bonding modes of the COD ligand.