Transition Metal Complex Chemistry

Precursor Design for the Chemical Vapor Deposition of Metals

The semiconductor industry knows the advantages of copper diketonates for chemical vapor deposition to produce uniform thin films of copper on substrates such as TiN, TaN, TiSiN or SiO₂. To increase their volatility currently all widely used precursors contain fluorine, which has been shown to have a potential to contaminate the resulting copper films. But not only fluorine is known to increase the volatility, but also silicon containing functional groups. We developed a wide range of silicon containing metal diketonates and also developed a corresponding chemical vapor deposition process.

The ligands were synthesized via coupling of a dithiane with a bromoketone or by Claisen type condensation. The ligands were characterized by NMR, UV/VIS, IR, MS and elemental analysis. The complexes were characterized by crystallography, DSC, TGA, UV/VIS and MS. Thin films of copper were deposited using a standalone CVD stainless steel CVD reactor equipped with mass flow controllers, a resistive heater and vacuum gauges. Usual deposition parameters included a hydrogen flow of 20 sccm and a deposition temperature of a 300 °C. The copper films were characterized by four point probe, AES, XRD, RBS, SEM, FIB, TEM and XPS.
This work was collaborative with the NYS Center for Advanced Thin Film Technology.

References

• R. U. Claessen, A. M. Kornilov, K. K. Banger, S. C. Ngo, S. Higashiya, C. C. Wells, E. V. Dikarev, P. J. Toscano, J. T. Welch, "Investigations into the Preparation of Sila-β-diketones via 2-Trimethylsilyl-1,3-dithianes: Structural Characterization of a Second Polymorph of Bis(2,2,6,6-tetramethyl-2-sila-3,5-heptanedionato)copper(II)." J. Organomet. Chem. 2004, 689, 71-81.
• K. S. Bousman, P. J. Toscano,* and J. T. Welch, "The Effect of Sulfur on CVD Performance of Pd(II) Beta-diketonate Precursors and the Completion of a Structural trans-Influence Series: Synthesis and Structural Characterization of Pd(S,S-tmhd)2 Inorg. Chim. Acta, 2004, 357(13), 3871-3876.
• Mark J. DelaRosa, Kulbinder K. Banger, Seiichiro Higashiya, Silvana C. Ngo, Daniel H. Hunt, Kenneth S. Bousman, Paul J. Toscano*, John T. Welch* "Structural investigations of copper(II) complexes containing fluorine-substituted β-diketonate ligands." J. Fluorine Chem. 2003, 123, 109-117.
• M. J. DelaRosa, K. S. Bousman, J. T. Welch*, and P. J. Toscano, "Structural Investigations of Copper(II) Complexes Containing Unsymmetrical β-diketonate and Monothio-β-diketonate Ligands," J. Coord. Chem. 2003, 56, 1339-1349.
• Synthesis of fluorinated α-sila-β-diketones and their Cu (II) complexes
  S. Higashiya, K. K. Banger, S. C. Ngo, P. N. Lim, P. J. Toscano, and J. T. Welch, Inorg. Chim. Acta, 2003, 351, 291-304.
• MOCVD precursor engineering: The preparation and physical and structural characterization of novel non-fluorinated α-sila-β-diketonate copper(II) complexes, Cu[R'C(O)CHC(O)SiR₃]₂, via the facile synthesis of the α-sila-β-diketones, R'C(O)CH₂C(O)SiR₃
  K. K. Banger, S. C. Ngo, S. Higashiya, R. U. Claessen, C. Birringer, K. S. Bousman, P. Lim, P. J. Toscano and J. T. Welch, J. Organomet. Chem., 2005, 678, 15-32.
• Thermal and structural characterization of a series of homoleptic Cu(II) dialkyldithiocarbamate complexes: bigger is only marginally better for potential MOCVD performance
  S. C. Ngo, K. K. Banger, M. J. DelaRosa, P. J. Toscano and J. T. Welch, Polyhedron, 2005, 22, 1575-1583.
• Physical and structural characterization of Ce(IV) β-diketonate complexes: Evidence for geometrical isomers in the solid state
  M. J. DelaRosa, K. S. Bousman, J. T. Welch, and P. J. Toscano, J. Coord. Chem. 2002, 55, 781-793. abstract
• Synthesis and physical and structural characterization of Ag(I) complexes supported by non-fluorinated β-diketonate and related ancillary ligands
  S. C. Ngo, K. K. Banger, P. J. Toscano and J. T. Welch, Polyhedron, 2002, 21, 1289-1297. abstract
• MOCVD Precursors Based on Organomettalloid Ligands
  U.S. Patent 6,340,768. 22 January 2002. PCT Int. Appl. WO 0246200. J. T. Welch, S. Higashiya, K. K. Banger, S. C. Ngo. Research Foundation of the State University of New York.
• MOCVD Precursors Based on Organomettalloid Ligands
  U.S. Patent 6,184,403. 6 February 2001. PCT Int. Appl. WO 0069863. J. T. Welch, P. J. Toscano, A. M. Kornilov, R. U. Claessen, K. K. Banger, Research Foundation of the State University of New York.
• MOCVD Processes Using Organomettalloid Ligands
  U.S. Patent 6,099,903, 8 August 2000. PCT Int. Appl. WO 070119. J. T. Welch, P. J. Toscano, A. M. Kornilov, R. U. Claessen, K. K. Banger and A. E. Kaloyeros. Research Foundation of the State University of New York.
• The 2,2,6,6-tetramethyl-2-sila-3,5-heptanedione route to the chemical vapor deposition of copper for gigascale interconnect applications
  R. U. Claessen, J. T. Welch, P. J. Toscano, K. K. Banger, A. M. Kornilov, E. T. Eisenbraun, and A. E. Kaloyeros, Mater. Res. Soc., Symp. Proc. (Materials, Technology and Reliability for Advanced Interconnects and Low-k Dielectrics), 2000, 612, D6.8.1 - D6.8.6.
• K.K. Banger, A. Kornilov, R. U. Claessen, E.T. Eisenbraun, A. Kaloyeros, P.J. Toscano, and J. T. Welch. "Facile Preparation and Isolation of the Sila-β-diketone, 2,2,6,6-Tetramethyl-2-sila-3,5-heptanedione: The Influence of Silicon Substitution on the Volatility and Chemical Vapor Deposition Properties of the Cu (II) Complex." Inorg. Chem. Commun. 2001, 4, 496-500.
• K.K. Banger, P. Lim, P.J. Toscano, and J.T. Welch, "A Facile Synthesis of 2,2,6,6-Tetramethyl-2-germa-3,5-heptandione: The Preparation and Characterization of the First Germa-β-diketonate Copper(II) Complex. Organometallics, 2001, 20, 4745-4748.

Catalyst Systems for the Syndiotactic Polymerization of Styrene

The syntheses, characterization and applications of cyclopentadienyltitanium triflate and bistriflimide complexes have been investigated. To pursue these aims the preparation of and structural investigations on a series of titanium triflate derivatives as well as the corresponding bistriflimide complexes of titanium has been explored. Our search for an alternative to the triflate ligand led us to the bistriflimide anion (N(SO₂CF₃)₂ or NTf₂). This anion appears to satisfy the criteria for a good, weakly-coordinating anion; i.e., it has a low overall charge of -1, a high degree of charge delocalization, good solubility and kinetic stability. This anion also has the potential for diversity with the use of its homologues or unsymmetrical imides such as the perfluoromethylsulfonyl perfluorobutylsulfonylimide reported by DesMarteau. The application of these complexes as catalysts lead to the efficient syndiotactic polymerization of styrene.

References

• Preparation and characterization of half-sandwich (pentamethylcyclopentadienyl)(triflato)titanium(IV) complexes: Solid-state structural motifs and catalysis studies
  S. C. Ngo, P. J. Toscano, and J. T. Welch, Helv. Chim. Acta, 2002, 85, 3366-82. abstract
• Triflimide Containing Catalysts for Polymerization
  U.S. Patent 5,986,120, 16 November 1999. PCT Int. Appl. WO 9940124. European Patent EP 1053259. J. T. Welch, R. U. Claessen, and S. C. Ngo, Research Foundation of the State University of New York.
• Bistriflate Titanium Complexes for the Polymerization of Styrene
  S. C. Ngo, J. T. Welch, J. Okuda, and P. J. Toscano, Polymer Preprints, 1996, 37, 330-331.