title: Study of bismuth alkoxides as possible precursors for ALD.
abstract: While searching for bismuth precursors for thin film preparation by atomic layer deposition (ALD) three bismuth alkoxides Bi(O(t)Bu)(3) (1), Bi(OCMe(2)(i)Pr)(3) (2), Bi(OC(i)Pr(3))(3) (3), bismuth beta-diketonate, Bi(thd)(3) (4), and bismuth carboxylate, Bi(O(2)C(t)Bu)(3) (5), were synthesized and evaluated. The compounds were characterized by CHN, NMR, MS, and TGA/SDTA. Earlier unknown crystal structures of compounds 1 and 3 were solved. Compound 1 forms dimeric and loose polymeric structures in the solid state while 3 is strictly monomeric. For compound 2 crystals suitable for complete structure solution could not be grown. Crystallization trials of 2 from hexane and toluene resulted in oxygen bridged tetramer [Bi(2)O(OCMe(2)(i)Pr)(4)](2) (6). Compound 4 has dimeric structure and compound 5 forms loose tetramers as reported earlier. The structure of toluene solvated crystal [Bi(O(2)C(t)Bu)(3)](4).2MeC(6)H(5) (7) was solved. All compounds studied showed relatively good volatility and thermal stability. They were all tested in ALD deposition experiments, in which compound 2 was found to be the most suitable for ALD growth of Bi(2)O(3). It exhibited a clear improvement over Bi precursors studied earlier.
authors.affiliation: Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, 00014 University of Helsinki, Finland. Timo.Hatanpaa@helsinki.fi
authors.forename: Timo
authors.initials: T
authors.lastname: Hatanpää
authors.forename: Marko
authors.initials: M
authors.lastname: Vehkamäki
authors.forename: Mikko
authors.initials: M
authors.lastname: Ritala
authors.forename: Markku
authors.initials: M
authors.lastname: Leskelä