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Published on: July 3, 2015
Photoassisted Chemical Vapor Deposition Using (η4-Diene)Ru(CO)3 Precursors
Christopher R Brewer1, Bishwaprava Das2, Rashmi Singh2
1Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas 75080, United States.
Abstract:
Six (η4-diene)Ru(CO)3 (diene = cyclooctatetraene, cyclohexadiene, cyclobutadiene, 1,3-butadiene, isoprene, and 2,3-dimethyl-1,3-butadiene) complexes that undergo photolytic loss of diene and/or CO ligands at room temperature have been synthesized and prescreened for their utility in Ru photoassisted chemical vapor deposition (PACVD). PACVD onto functionalized alkanethiolate self-assembled monolayers (SAMs) with -COOH, -OH, or -CH3 terminal groups has identified four of these precursors as suitable candidates for area-selective deposition of Ru. After exposure to 150,000 L of (η4-2,3-dimethyl-1,3-butadiene)Ru(CO)3 under UV irradiation, selective deposition of Ru is observed on -COOH-terminated SAMs. However, after exposure to 500,000 L, deposition selectivity is lost and deposition is observed on all three functionalized SAMs studied. Deposition from (η4-1,3-butadiene)Ru(CO)3 was nonselective, with Ru deposition observed on all three functionalized SAMs. Further, the deposition was less efficient; Ru deposition was observed to begin after 303,000 L, which is approximately twice the dose required for (η4-2,3-dimethyl-1,3-butadiene)Ru(CO)3. After exposure to 76,000 L of (η4-isoprene)Ru(CO)3 under UV light, selective deposition of Ru is also observed on -COOH-terminated SAMs. Using (η4-COT)Ru(CO)3 selective deposition onto -COOH-functionalized SAMs was achieved at 25× lower precursor dose than using (η4-2,3-dimethyl-1,3-butadiene)Ru(CO)3. The deposition results are discussed in the context of precursor design for area-selective deposition by PACVD.
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