backCopyright 1992 by the American Chemical Society and reprinted by permission of the copyright owner.
Organometallic Chemical Vapor Deposition of Platinum. Reaction Kinetics and Vapor Pressures of Precursors'
Ziling Xue, Hareesh Thridandam, Herbert D. Kaesz,
and Robert F. Hicks,
Department of Chemical Engineering and Chemistry and Biochemistry,
University of California at Los Angeles, Los Angeles, California 90024-1592
Received August 14, 1991. Revised Manuscript Received September 26, 1991
The kinetics of chemical vapor deposition of platinum from cyclopentadienyltrimethylplatinum (CpPtMe3) and (methylcyclopentadienyl)trimethylplatinum (MeCpPtMe3) under hydrogen atmosphere have been studied. For deposition on substrates heated to between 90 and 180'C, the platinum films are essentially pure, containing less than 1.0 atom % carbon and oxygen and no other impurities. The ligands on the organometalhc complexes are quantitatively converted into their hydrocarbon analogues: 1 mol of CpPtMe3 produces 3 mol of methane and 1 mol of cyclopentane, and 1 mol of MeCpPtMe3 produces 3 mol of methane and 1 mol of methylcyclopentane. The decomposition reaction is initially very slow and then rapidly accelerates due to autocatalysis by the fresh platinum deposit. The rate of the initial slow decomposition depends on the substrate composition, indicating that this reaction is also heterogeneous. Use CpPtMe3, the activation energy for initiation of deposition (i.e., for the induction period) is 115 +/- 10 kJ/mol on glass and 60 +/- 15 kJ/mol on Teflon. The heats of sublimation of CpPtMe3 and MeCpPt.Me3 are 71.2 +/- 2.1 and 71.5 +/- 2.1 kJ/mol, respectively. The heat of vaporization of MeCpPtMe3 is 43.6 +/- 1.3 kJ/mol. The vapor pressures of CpPtMe3 and MeCpPtMe3 at 23'C are 0.045 and 0.053 Torr.