Surface Reaction Probabilities of Silicon Hydride Radicals in SiH₄/H₂ Thermal Chemical Vapor Deposition

Abstract

Surface reaction probabilities of silicon hydride radicals are correlated from measurements of the film thickness profile in trench and the deposition rate in thermal chemical vapor deposition of the SiH 4 /H 2 system at 871-913 K. Correlated radical reactive sticking probability RSC rd increases linearly with the fraction of dangling bond φ. Experimental data of RSC rd vs φ in SiH 4 / H 2 and SiH 4 /Ar systems fall on the same line when the deposition temperature is the same. The extrapolated RSC rd at φ ) 1 of the SiH 4 /H 2 system is unity, which indicates that radicals deposit as soon as they impinge on the surface that contains only bare Si atoms. The growing surface reactivity is less than 1 owing to chemisorbed hydrogen. The silicon surface is more passivated in the SiH 4 /H 2 system, compared with the SiH 4 /Ar system, since molecular hydrogen (sticking coefficient 3.57 × 10 -6 ) enhances the hydrogen coverage. The radical reaction probability on a hydrogen-saturated Si surface is the RSC rd value extrapolated at φ ) 0. The activation energy for radical reaction probability with hydrogen-saturated surface is 4.91 ( 0.06 kcal. CRESLAF simulation results, using this revised surface reaction mechanism and the gas-phase reaction mechanism of Ho, Coltrin, and Breiland, indicate the influences of radicals originate from H 2 -SiSiH 2 , since its concentration is much higher than other radical species.

Kinetics of Silane Decomposition in High-Pressure Confined Chemical Vapor Deposition of Hydrogenated Amorphous Silicon

“…Whether the homogeneous or heterogeneous mechanism is predominantly responsible for silicon deposition is subject to debate. Some researchers believe homogeneous initiation of the growth process occurs wherein higher-order silanes (disilane and trisilane) and/or silylenes formed in the gas phase stick to the surface to deposit a semiconductor film. − , Others believe heterogeneous decomposition of silane at the surface occurs to deposit the film. , The relative contributions of the homogeneous and heterogeneous reactions to film growth depend on deposition temperature, pressure, and the surface-to-volume ratio of the reactor. , In this study, we present the kinetics of film growth via confined HPCVD in a microcapillary, which results in the formation of optical fibers. We also show via reactive molecular dynamics simulations that in the confined HPCVD process, heterogeneous thermal decomposition of silane at the amorphous silicon surface is the dominant mechanism for deposition of the a-Si:H film due to the very high surface area to volume ratio present in the confined geometry.…”

“…Some researchers believe homogeneous initiation of the growth process occurs wherein higher-order silanes (disilane and trisilane) and/or silylenes formed in the gas phase stick to the surface to deposit a semiconductor film. [12][13][14][15][16]26 Others believe heterogeneous decomposition of silane at the surface occurs to deposit the film. 20,23 The relative contributions of the homogeneous and heterogeneous reactions to film growth depend on deposition temperature, pressure, and the surfaceto-volume ratio of the reactor.…”

Amorphous carbon step coverage improvement applied to advanced hard mask for lithographic application

“…On the other hand, another C 7 H 8 base a-C is also taken into consideration for S/C performance investigation (Table 1). In general, film surface coverage has a definitely linear relationship with sticking efficiency, and higher sticking coefficient means more opportunity for C radical to adsorb on the film surface [2][3][4]. In previous experiment [5], it was indicated that a clear correlation exists between the ratio of C/H in hydrocarbon species and the sticking efficiency for the reaction behavior on hydrogenated diamond: the sticking efficiency enhances with C/H ratio increases.…”