Kinetics and mechanism of silicon dioxide deposition through thermal pyrolysis of tetraethoxysilane

Intrinsic silicon dioxide deposition rate dependences from tetraethoxysilane (TEOS) thermal pyrolysis were measured in an experimental cold wall low-pressure chemical vapor deposition reactor designed to minimize reactant depletion and gas-phase reactions. The apparent activation energy of 90 kJ mol−1±16 kJ mol−1 over the range of temperatures from 873 to 1073 K is significantly lower than that typically measured in commercial or development-scale hot wall reactors. The reaction rate exhibits a first order dependence on TEOS pressure. Film deposition proceeds without a nucleation-induced incubation period. Interpretation of deposited film profiles in high aspect ratio trenches through rigorous ballistic transport-reaction simulation reveals that deposition most likely occurs through a heterogeneous mechanism in which strong readsorption of the byproducts of TEOS decomposition inhibits silicon dioxide deposition.