Browsing by Author "Wu, JB"

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Adsorption and decomposition studies of t-butylamine, diethylamine, and methylethylamine on Si(100)-(2 x 1)
(2004-02-05)
Wu, JB
;
Yang, YW
;
Lin, YF
;
Chiu, HT
;
應用化學系
We have studied chemisorption and thermal decomposition of tert-butylamine (TBA), diethylamine (DEA), and methylethylamine (MEA) on Si(100)-(2 x 1) with synchrotron-based X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Adsorption at cryogenic temperature leads to molecularly intact chemisorption (dative-bonding via the nitrogen lone pair) and dissociative chemisorption via N-H scission, producing distinct N 1s peaks at binding energies of 401.1 and 398.2 eV, respectively. The corresponding change for C 1s core level is also significant, and a 0.9 eV shift toward lower binding energy is found for DEA, suggesting a high degree of charge redistribution between two adsorption configurations. Upon warming to room temperature, the adsorbed amines almost completely transform into dissociative chemisorbed forms. Thermal decomposition of TBA at elevated temperatures produces desorption species of isobutylene via gamma-H elimination, hydrogen cyanide, and H-2. In comparison, DEA and MEA decompose thermally to desorb imine via P-H elimination, ethylene via beta-H elimination, hydrogen cyanide, and H2. Eventually, silicon nitride and silicon carbide are formed. Distinct decomposition pathways lead to a C/N ratio variation among the products, with TBA yielding the lowest C/N ratio.
Chemical vapor deposition of tantalum carbide and carbonitride thin films from Me3CE=Ta(CH2CMe3)(3) (E = CH, N)
(2003)
Chang, YH
;
Wu, JB
;
Chang, PJ
;
Chiu, HT
;
應用化學系
Chemical vapor deposition (CVD) of thin films employing Me3CCH=Ta(CH2CMe3)(3) and Me3CN=Ta(CH2CMe3)(3) as the precursors has been carried out. TaC and TaCN films were deposited at relatively low temperatures (623-923 K). In comparison, using Me3CN=Ta(CH2CMe3)(3), the Ta=N bond did not undergo cleavage during the reaction and the N atom was incorporated into the film as nitride. The volatile components evolved were collected and examined by GC-MS, FT-IR, H-1 and C-13 NMR spectroscopy. Possible decomposition pathways of the tantalum complexes are proposed to rationalize the observation.
Correlation between N 1s XPS binding energy and bond distance in metal amido, imido, and nitrido complexes
(2003-07-28)
Wu, JB
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Lin, YF
;
Wang, JL
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Chang, PJ
;
Tasi, CP
Synchrotron-based X-ray photoelectron spectroscopy is used to measure N 1s binding energies of several metal amido, imido, and nitrido complexes of group 5 and 6 metals. The N 1s binding energy decreases as the formal M-N bond order increases. A simple correlation between the contraction of the M-N bond and the lowering of binding energy is also observed. This correlation supports a notion that the bonding character of a linear metal-imido linkage resembles that of a metal-nitrido linkage closely.
Metallo-organic chemical vapor deposition of tantalum carbide and tantalum nitride thin films from (BuCH)-Bu-t=Ta(CH2 Bu-t)(3) and (BuN)-Bu-t=Ta(CH2 Bu-t)(3).
(2002-04-07)
Chiu, HT
;
Chang, YH
;
Chang, PJ
;
Wu, JB
;
Peng, SM
Surface reaction of bis(tertbutylimido)bis(diethylamido)tungsten precursor on Si(100)-(2X1)
(2003-09-01)
Wu, JB
;
Yang, YW
;
Lin, YF
;
Chiu, HT
;
應用化學系
Thermal decomposition of a metal-organic chemical vapor deposition precursor, (t-BuN=)(2)W(-NEt2)(2), (bis(tertbutylimido)bis(diethylamido)tungsten, on Si(100) has been studied by means of synchrotron radiation-based x-ray photoemission spectroscopy and temperature programmed desorption spectroscopy. The, resultant thin films consist of tungsten metal, silicon carbides and silicon nitrides. Major desorption products, originated from ligand decomposition include imine (C2H5N=CHCH3) that is derived from beta-H elimination of diethylamido ligand, and isobutene (C4H8) that is generated from gamma-H elimination of t-butylimido ligands. The. transmetalation of the precursor leads to tungsten metal adsorption on Si(100); by contrast, tungsten nitrides, tungsten carbides and tungsten oxides are produced as the same precursor is decomposed on SiO2 surface. (C) 2003 American Vacuum Society.
Thermal decomposition mechanisms of tungsten nitride CVD precursors on Cu(111)
(2006-02-01)
Yang, YW
;
Wu, JB
;
Wang, JL
;
Lin, YF
;
Chiu, HT
Chemisorption and thermal decomposition of metallorganic chemical vapor deposition precursors, (t-BuN)(2)W(NHBu-t)(2), bis(tertbutyl imido) bis(tert-butylamido) tungsten (BTBTT) and (t-BuN)(2)W(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)(2)W(mu-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 alpha-H abstraction, isobutylene from gamma-H elimination, acetonitrile from beta-methyl elimination.. and molecular hydrogen. In addition to these desorption species, BTBDT produces hydrogen cyanide and imine (EtN = CHMe) via beta-H elimination, not possible with BTBTT due to the absence of beta-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. (c) 2005 Elsevier B.V. All rights reserved.