Density evaluation of remotely-supplied hydrogen radicals produced via tungsten filament method for SiCl₄ reduction

Abstract

Effect of the hydrogen radical on the reduction of a silicon tetrachloride (SiCl 4 ) source was studied. The hydrogen radicals were generated using a tungsten (W) filament in a generation chamber, and were remotely supplied to another reaction chamber. The density of the hydrogen radical was estimated from the optical transmittance of 600-nm-wavelength light through phosphate glass doped with tungsten oxide (WO 3 ). Lifetime of the hydrogen radical seemed sufficiently long, and its density as supplied to the reaction chamber was estimated to be on the order of 10 12 cm %3 . Signal intensity of the peak corresponding to SiCl 4 (m/z = 170) detected by quadrupole-mass measurement was confirmed to decrease owing to the reaction with the remotely-supplied hydrogen radical. This indicates the possibility that chemically-stable SiCl 4 , as one of the by-products of the Siemens process, can be reduced to produce silicon.

Epitaxial Thin Film Growth of Perovskite Hydrides MLiH3 (M : Sr, Ba) for the Study of Intrinsic Hydride-Ion Conduction

“…Because we generate H-radicals by flowing H 2 over a hot W filament, the filament temperature T f controls the amount of H-radicals in the reaction atmosphere, with higher T f generating more radicals. 31,32 Here, we compare the reaction atmosphere at T f = ambient temperature, 1200, and 1700 °C, generating H 2 reaction atmospheres with no Hradical (H 0 ), low amount of H-radials (H low ), and high amount of H-radicals (H high ), respectively.…”

“…Next, we discuss the effects of H-radicals on the product film integrity by comparing the surfaces of the BaLiH 3 (100) thin films grown on the MgAl 2 O 4 (100) substrate at T dep = 150 °C in molecular H 2 reaction atmospheres with different amounts of H-radicals. Because we generate H-radicals by flowing H 2 over a hot W filament, the filament temperature T f controls the amount of H-radicals in the reaction atmosphere, with higher T f generating more radicals. , Here, we compare the reaction atmosphere at T f = ambient temperature, 1200, and 1700 °C, generating H 2 reaction atmospheres with no H-radical ( H 0 ), low amount of H-radials ( H low ), and high amount of H-radicals ( H high ), respectively.…”

Effective silicon production from SiCl4 source using hydrogen radicals generated and transported at atmospheric pressure

“…To improve the Si yield of the Siemens method, we have focused on hydrogen radicals (H-radicals) as a reducing agent [5,6]. H-radicals have been used in some chemical vapor deposition processes, including those leading to the deposition of amorphous or polycrystalline Si [7,8] and diamond thin films [9,10].…”

“…The distance between the generating and detection points was 50 cm, which implies an availability of H-radical for the Siemens method. In a previous study, we successfully generated and transported H-radicals using a filament method and reduced SiCl 4 with the remotely supplied H-radicals under relatively low pressures of approximately 1-10 kPa [6]. The density of hydrogen radical should decrease with an increase of pressure due to three-body recombination (H + H + M (H 2 ) → H 2 + M (H 2 )) [12,13].…”