Thermal decomposition mechanisms of tungsten nitride CVD precursors on Cu(1 1 1) Export

@article{90, 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(1 1 1) 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(1 1 1) 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([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.}, author = {Yang, Yaw-Wen and Wu, Jin-Bao and Wang, Jelin and Lin, Yi-Feng and Chiu, Hsin-Tien}, citeulike-article-id = {1198287}, citeulike-linkout-0 = {http://dx.doi.org/10.1016/j.susc.2005.12.004}, citeulike-linkout-1 = {http://www.sciencedirect.com/science/article/B6TVX-4HWXN26-1/2/89da999339a2959af8f0de07b9d8b0d2}, day = {1}, doi = {10.1016/j.susc.2005.12.004}, journal = {Surface Science}, keywords = {chemical-vapor-deposition, tungsten-nitride, xps}, month = {February}, number = {3}, pages = {743--754}, posted-at = {2007-03-30 15:56:19}, priority = {0}, title = {Thermal decomposition mechanisms of tungsten nitride CVD precursors on Cu(1 1 1)}, url = {http://dx.doi.org/10.1016/j.susc.2005.12.004}, volume = {600}, year = {2006} }

TY - JOUR ID - 90 L3 - citeulike-article-id:1198287 N2 - 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(1 1 1) 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(1 1 1) 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([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. IS - 3 JF - Surface Science EP - 754 TI - Thermal decomposition mechanisms of tungsten nitride CVD precursors on Cu(1 1 1) VL - 600 SP - 743 KW - chemical-vapor-deposition KW - tungsten-nitride KW - xps AU - Yang, Yaw-Wen AU - Wu, Jin-Bao AU - Wang, Jelin AU - Lin, Yi-Feng AU - Chiu, Hsin-Tien PY - 2006/02/01/ UR - http://dx.doi.org/10.1016/j.susc.2005.12.004 ER -