Low-temperature thermolysis behavior of tetramethyl- and tetraethyldistibines
In: Journal of the american Society of Mass Spectrometry, Jg. 19 (2008) ; Nr. 9, S. 1336-1342
Zeitschriftenaufsatz / Fach: Chemie
he thermolysis behavior of tetramethyl- and tetraethyldistibine (Sb2Me4 and Sb2Et4) was investigated using a mass spectrometer coupled to a tubular flow reactor under near-chemical vapor deposition (CVD) conditions. Sb2Me4 undergoes a gas-phase disproportionation with an estimated activation energy of 163 kJ/mol. This reaction leads to the formation of methylstibinidine, SbMe, that reacts on the surface to produce antimony film and SbMe3. Unfortunately, this clean decomposition pathway is limited to a narrow temperature range of 300–350 °C. At temperatures exceeding 400 °C, SbMe3 decomposes following a radical route with a consequent risk of carbon contamination. In contrast, Sb2Et4 disproportionates at the hot wall of the reactor. According to mass-spectrometric data, this reaction is significant starting at a temperature of 100 °C, with an apparent activation energy of 104 kJ/mol. Within the temperature range of 100–250 °C, the precursor decomposition leads to the formation of antimony films and SbEt3, whereas different molecular reaction pathways are significantly activated above 250 °C. The use of Sb2Et4 lowers the risk of carbon contamination compared to Sb2Me4 at high temperature. Therefore, Sb2Et4 is a promising CVD precursor for the growth of antimony films in the absence of hydrogen atmosphere in a wide temperature range.