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    National Tsing Hua University Institutional Repository > 理學院 > 化學系 > 期刊論文 >  Thermal Decomposition Mechanisms of Tungsten Nitride CVD Precursors on Cu(111)

    Please use this identifier to cite or link to this item: http://nthur.lib.nthu.edu.tw/dspace/handle/987654321/57329

    Title: Thermal Decomposition Mechanisms of Tungsten Nitride CVD Precursors on Cu(111)
    Authors: YANG Yaw-Wen;WU Jin-Bao;JELIN WANG;LIN Yi-Feng;CHIU Hsin-Tien
    教師: 楊耀文
    Date: 2006
    Publisher: Elsevier
    Relation: SURFACE SCIENCE, Elsevier, Volume 600, Issue 3, FEB 1 2006, Pages 743-754
    Keywords: Transition elements
    Chemical reactions
    Surface reactions
    Abstract: Chemisorption and thermal decomposition of metallorganic chemical vapor deposition precursors, (t-BuN)2W(NHBu-t)2, bis(tert-butylimido)bis(tert-butylamido)tungsten (BTBTT) and (t-BuN)2W(NEt2)2, bis(tert-butylimido)bis(diethylamido)tungsten (BTBDT), on Cu( 111) have been investigated by means of thermal desorption spectroscopy (TDS) and synchrotron-based X-ray photoelectron spectroscopy (SR-XPS) under ultrahigh vacuum conditions. The precursors remain intact upon chemisorption on Cu(111) at 100 K, and at 300 K both precursors decompose readily via the characteristic hydride abstraction/elimination pathways to produce two stable surface intermediates for each precursor. For BTBTT, one species is W(=NBu-t)3 and the other is proposed to be a bridged amido complex, [(t-BuN)2W(μ-NBu-t)]2. In comparison, a W-imine complex and a W-N-C metallacycle are two intermediates produced from BTBDT. Annealing toward 800 K further decomposes the intermediates and the detectable desorption species are completely derived from the ligands. The desorption products from BTBTT include t-butylamine generated from α-H abstraction, isobutylene from γ-H elimination, acetonitrile from β-methyl elimination, and molecular hydrogen. In addition to these desorption species, BTBDT produces hydrogen cyanide and imine (EtN = CHMe) via β-H elimination, not possible with BTBTT due to the absence of β-H in the ligands. Eventually, tungsten nitrides incorporating oxygen atoms and a small amount of graphitic carbons are formed and the stoichiometry is approximated as WN1.5O0.1. Oxygen incorporation, driven by a large oxide formation enthalpy, is sensitively dependent on the moisture exposure in UHV environment.
    URI: http://www.elsevier.com/
    Appears in Collections:[化學系] 期刊論文

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