Gas-phase Reaction Kinetics of 1-Methylsilacyclobutane in a Hot-wire Chemical Vapor Deposition Reactor
Date
2015-04-21
Authors
Badran, Ismail
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Abstract
Thin films made of silicon carbide (SiC) play an important role in the
manufacturing of solar cells, lithium-ion batteries, and microelectronics. Recently,
there was a growing interest in fabricating SiC’s using hot-wire chemical vapor
deposition (HWCVD). Particularly, using single-source precursors that contain both
carbon and silicon. 1-methyl-1-silacyclobutane (MSCB) is a four-membered ring
compound that is characterized by its high ring-strain which facilitate its thermal
decomposition on the hot-wire. In order to utilize MSCB in an industrial HWCVD
reactor, its reaction kinetics in the gas phase needs to be comprehended.
Vacuum ultraviolet laser (VUV) single photon ionization (SPI) in tandem with timeof-
flight mass spectrometry (TOF-MS) was used to study the kinetics of MSCB
under typical HWCVD conditions. A new analytical method was developed solely
for this study. MSCB was synthesized in situ. The steady state approximation was
assumed in order to derive rate constants formulations, in which the kinetic data
were analyzed and fit.
Results: The rate constants for the individual decomposition routes along with
their respected activation energies were determined. Both the temperature and
pressure dependence on the rate constant were investigated. The activation
energies for the HWCVD decomposition of MSCB were lower than the
theoretically calculated ones, or the ones obtained from the thermal pyrolysis,
indicating a catalytic behavior on the hot-wire. However, the activation energies
were slightly higher than the ones obtained from the HWCVD primary
decomposition under a collision-free environment. This infer that the reactions
inside the HWCVD reactor were a mix between a heterogeneous decomposition
on the hot-wire, followed by homogeneous secondary reactions in the gas-phase.
The study shapes a new methodology to study the kinetics of the complex
reactions involved in the HWCVD reactor.