A tale of two studies: Syntheses of silicon nitride chemical vapor deposition precursors and divalent lanthanide N,N-dimethylaminodiboranate complexes
Silicon nitride thin films have key industrial applications in the manufacturing of semiconductors, but these applications impose strict requirements on the film growth process. Specifically, the SiN films must be deposited at temperatures below 400 °C to avoid device degradation, and they must be deposited conformally to meet the demand of smaller feature sizes. In chapter 1, the synthesis and deposition of a new precursor for silicon nitride thin films, 1,1-diazido-1-silacyclopent-3-ene (1) is described. Precursor 1, a known compound, was synthesized by treating 1,1-dichloro-1-silacyclopent-3-ene with two equivalents of NaN3 in acetonitrile, and was purified by distillation under reduced pressures. Deposition experiments were performed in a hot-wall chemical vapor deposition (CVD) reactor show that 1 deposits films at temperatures as low as 400 °C and with excellent conformality in trenches with aspect ratios up to 3.5:1. Elemental characterization of these films, performed by Auger spectroscopy, show that these films contain Si (~10 %) and N (~10 %) in a 1:1 ratio but have high C (~40 %) and O (~40 %) contents, which is likely attributed to the presence of residual moisture and oxygen in the reaction chamber and the slow removal of volatile organic byproducts. In chapter 2, we describe the syntheses and molecular structures of new SmII and TmII N,N-dimethylaminodiboranate (DMADB) complexes. Treatment of solutions of SmI2(thf)2 in thf with Na(H3BNMe2BH3) results in the formation of Sm(H3BNMe2BH3)2(thf)3 which can be readily converted to the dimethyoxyethane (dme) adduct, Sm(H3BNMe2BH3)2(dme)2 by treatment with dme. We also show that Sm(H3BNMe2BH3)2(thf)3 can be prepared by the reduction of the SmIII compound, Sm(H3BNMe2BH3)3(thf), with KC8,and that addition of 18-crown-6 to this reaction mixture results in the formation of Sm(H3BNMe2BH3)2(18-crown-6). The new TmII complexes were synthesized analogously to 1; treatment of TmI2 solutions in thf with Na(H3BNMe2BH3) resulted in the formation of 1:1 mixtures of Tm(H3BNMe2BH3)2(thf)3 and Tm(H3BNMe2BH3)2(thf)2. IR and 1H NMR data are reported for all these compounds along with their crystal structures.
Chemical Vapor Deposition, f-block elements, lanthanides, silicon nitride, divalent samarium, divalent thulium
University of Illinois - Urbana-Champaign
Networked Digital Library of Theses and Dissertations
University of Illinois at Urbana-Champaign