Lewis-base copper(I) formates: Synthesis, reaction chemistry, structural characterization and their use as spin-coating precursors for copper deposition

• Published in: Inorganica Chimica Acta 2011-01, Vol.365 (1), p.10-19
• Main Authors: Tuchscherer, André, Shen, Yingzhong, Jakob, Alexander, Mothes, Robert, Al-Anber, Mohammed, Walfort, Bernhard, Rüffer, Tobias, Frühauf, Swantje, Ecke, Ramona, Schulz, Stephan E., Gessner, Thomas, Lang, Heinrich
• Format: Article
• Language: English
• Subjects: Carboxylic acid; Copper; Formate; Hydrogen-bonding; Spin coating
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2010.05.048

The synthesis of a series of copper(I) formates of type [L m CuO 2CH·HO 2CR] and [{[Ti]( μ- σ, π-C CSiMe 3) 2}CuO 2CH·HO 2CR] is discussed (L = n Bu 3P, c C 6H 11, (CF 3CH 2O) 3P, (CH 3CH 2O) 3P; m = 1, 2, 3; R = H, CH 3, CF 3, C 6H 5; [Ti] = ( η 5-C 5H 4SiMe 3) 2Ti). The use of [( n Bu 3P) 2CuO 2CH·HO 2CH] for the deposition of pure copper films by the spin-coating process is described. The molecular structures of two samples in solid state are reported. Consecutive synthesis methodologies for the preparation of a series of copper(I) formates [L m CuO 2CH] (L = n Bu 3P: 4a, m = 1; 4b, m = 2; 5, L = [Ti](C CSiMe 3) 2, m = 1, [Ti] = ( η 5-C 5H 4SiMe 3) 2Ti) and [L m CuO 2CH·HO 2CR] (L = n Bu 3P: 7a, m = 1, R = H; 7b, m = 2, R = H; 7c, m = 2, R = Me; 7d, m = 2, R = CF 3; 7e, m = 2, R = Ph. L = ( c C 6H 11) 3P, R = H: 8a, m = 2; 8b, m = 3. L = (CF 3CH 2O) 3P, R = H: 9a, m = 2; 9b, m = 3. L = (CH 3CH 2O) 3P, R = H: 10a, m = 2; 10b, m = 3. L = [Ti](C CSiMe 3) 2; m = 1: 11a, R = H; 11b, R = Ph) is reported using [CuO 2CH] ( 1) and L ( 2a, L = n Bu 3P; 2b, L ( c C 6H 11) 3P; 2c, L = (CF 3CH 2O) 3P; 2d, L = (CH 3CH 2O) 3P; 3, L = [Ti](C CSiMe 3) 2) as key starting materials. Addition of formic acid ( 6a) or carboxylic acid HO 2CR ( 6b, R = Me; 6c, R = CF 3; 6d, R = Ph) to the afore itemized copper(I) formates 4 and 5 gave metal–organic or organometallic 7– 11. The molecular structures of 8a and 11a in the solid state are reported showing a threefold coordinated copper(I) ion, setup by either two coordinatively-bonded phosphorus atoms and one formate oxygen atom ( 8a) or two π-bonded alkyne ligands and one oxygen atom ( 11a). A formic acid molecule is additionally hydrogen-bonded to the CuO 2CH moiety. The use of 7b as suitable precursor for the deposition of copper onto TiN-coated oxidized silicon wafers by the spin-coating process below 300 °C is described. Complex 7b offers an appropriate transformation behavior into metal phase by an elimination–decarboxylation mechanism. The morphology of the copper films strongly depends on the annealing conditions. A closed grain network densified by a post-treatment is obtained (8 °C min −1, N 2/H 2 carrier gas). Hydrogen post-anneal to 420 °C after film deposition gave a copper film showing resistivities from 2.5 to 3.7 μΩ cm. This precursor was also used for gap-filling processes.