Manufacture of Granular Polysilicon from Trichlorosilane in a Fluidized‐Bed Reactor

Abstract

Manufacturing of polysilicon by chemical vapor deposition from SiHCl 3 in a fluidized-bed reactor was studied. The effects of reaction temperature, H 2 /SiHCl 3 ratio, gas velocity, and seed particle loading were evaluated. The outlet gas composition was analyzed by gas chromatography. The physical features of the product particles were determined by scanning electron microscopy and laser particle size analyzer. Well-grown product particles were obtained. The temperature and H 2 /SiHCl 3 ratio significantly affected conversion, yield, and selectivity, which were less affected by gas velocity and seed particle loading at higher temperatures. The surface reaction kinetics determined the product yield only at lower temperatures, and thermodynamic equilibrium was approached at temperatures above 900°C.

Thermodynamic analysis of manufacturing polysilicon from SiHCl3, SiCl4 and H2

“…Some of these species are not included in other databases. Li [18] and Kang [19] SiH 2 Cl 2 Peng [20] and He [21] SiH 2 Cl 2 , SiH 3 Cl Wang [4] SiH 2 Cl 2 , SiCl 2 Xu [22] and Miao [23] SiH 2 Cl 2 , SiH 3 Cl, SiCl 2 Niederkorn [6] SiH 2 Cl 2 , SiH 3 Cl, SiCl 2 , SiCl, SiH 4 Sirtl [5] SiH 2 Cl 2 , SiH 3 Cl, SiCl 2 , SiCl, SiH 4 , SiCl 3 Chernyavsky [7] and Diana [8] SiH 2 Cl 2 , SiH 3 Cl, SiCl 2 , SiCl, SiH 4 , SiCl 3 , some other species only existing at high temperature and radicals such as Si(g), SiH, H, Cl NIST-JANAF thermochemical tables [10] Matheson gas data book [11] Thermochemical data of elements and compounds [12] HSC Data compilation tables of properties of pure compounds [13] Aspen Gmelin handbook of inorganic and organometallic chemistry [14] Chemkin Practical handbook of thermodynamic data for inorganic compounds [15] Others [16,17] Thus, JANAF is recommended as a reliable database for C p data of the Si-H-Cl system.…”

“…of SiHCl 3 (X) is significantly lower than the equilibrium value. The Si-H-Cl experimental system reaches thermodynamic equilibrium at T N 1000°C [4]. The inconsistencies between the experimental and equilibrium conversions are caused by the measuring method.…”

“…5(d), the temperature and feed composition have significant effects 3.2.2. Feasibility of zero net by-production of SiCl 4 In the Siemens process, two approaches are used in the treatment of SiCl 4 : one is to convert SiCl 4 to other chemical products such as white carbon black, and the other is to convert it to SiHCl 3 by hydrogenation, which is then used as feed of the bell jar reactor [29]. The thermodynamic calculations show that it is feasible to directly mix the byproduct SiCl 4 in the feed to realize net zero SiCl 4 by-production.…”

“…In the fluidized bed process, the Si-H-Cl system is usually close to thermodynamic equilibrium because the seed particles provide very large area of reaction surface [4]. Therefore, a reliable thermodynamic analysis is very important for the design of a fluidized bed process.…”

“…In the Si-H-Cl system at conditions relevant for silicon production, silicon exists as solid state and the gas phase may contain H 2 , HCl, SiCl 4 , SiCl 3 , SiCl 2 , SiCl, SiH 4 , SiHCl 3 , SiH 2 Cl 2 , SiH 3 Cl and some radical species. Different sets of species have been used in thermodynamic analysis of the Si-H-Cl system in the literature [4][5][6][7][8][18][19][20][21][22][23], as listed in Table 2.…”