Kinetic study on heterogeneous nucleation and incubation period during chemical vapor deposition

Autor: Kohei Shima, Yuhei Otaka, Noboru Sato, Yuichi Funato, Yasuyuki Fukushima, Takeshi Momose, Yukihiro Shimogaki
Rok vydání: 2023
Předmět:
Zdroj: The Journal of Chemical Physics. 158:124704
ISSN: 1089-7690
0021-9606
DOI: 10.1063/5.0133157
Popis: The kinetics of heterogeneous nucleation during chemical vapor deposition (CVD) is still unclear despite its importance. Nucleation delay is often observed in many CVD processes, which is known as the incubation period ( τi). In this study, the effects of concentration ( C) and sticking probability ( η) of film-forming species on τi were formulated based on our kinetic model. To discuss the kinetics, [Formula: see text] with the rate dimension was used and formulated using C and η. Because η onto heterogeneous surfaces ( ηhetero) is difficult to evaluate, the study was initiated with η onto homogeneous surfaces ( ηhomo), followed by a discussion on its reasonability. The formulation was validated using the experimental dataset for SiC-CVD from CH3SiCl3/H2 onto BN underlayers because CVD involves multiple film-forming species with different ηhomo ranging from 10−6 to 10−2 and thus is a suitable system for studying the effect of ηhomo. High-aspect-ratio (1000:1) parallel-plate microchannels consisting of τi-involving BN and a τi-free Si surface were utilized to separate these film-forming species along the microchannel depth. τi was exceptionally long, up to several hours, depending on the CVD conditions. [Formula: see text] was found to be proportional to C n, where n is the reaction order. n was quantified as ≈1.6, suggesting the initial nucleation was triggered by the impingement of two adspecies in the second order and lowered possibly by the discrepancy between C in the gas-phase and that actually producing adspecies on the surface. [Formula: see text] was also found to be proportional to ηhomo. The exceptionally long τi was likely originated from the significantly lower ηhetero than ηhomo and the higher activation energy for ηhetero than that for ηhomo.
Databáze: OpenAIRE
Externí odkaz: