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Production of polycrystalline silicon by pyrolysis of silane.
Production of polycrystalline silicon by pyrolysis of silane.
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机译:通过硅烷热解生产多晶硅。
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摘要
Silicon of high purity is made by decomposing silane in a fluidized bed reactor. To obtain good process economics, two modes of operation are used. In a first mode, the reactor is operated under high productivity conditions which also result in co-production of silicon dust or fines. The dust on the particles can cause problems in handling. For example, in bagging the particles, or removing the particles from a bag, the dust can become airborne from the larger particle surfaces and form an objectionable cloud of silicon dust. The invention provides a method for uniting dust to the larger silicon particles. In a second process mode, a thin (0.1-5.0 micron) layer of high purity silicon is deposited on the dust laden particles. This second mode is most preferably carried out by (a) treating the dust-laden particles with a deposition gas comprising 1 to 5 mole % silicon admixed with an inert carrier gas such as hydrogen, (b) in a fluidized bed reactor, and (c) at a process temperature of 620. degree.650° C. The product polysilicon is composed of free flowing, approximately spherical particles having a size distribution of 150-1500 microns, an average size of 650-750 microns and has a particle bulk density of 2.3 grams per cubic centimeter, a bulk density of about 1360 kg/m.sup.3 and a silicon surface dust content of less than about 0.08 wt. %.
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机译:高纯度的硅是通过在流化床反应器中分解硅烷而制得的。为了获得良好的过程经济性,使用了两种操作模式。在第一模式中,反应器在高生产率条件下操作,这也导致硅粉或细粉的联产。颗粒上的灰尘可能会导致处理问题。例如,在将颗粒装袋或从袋子中取出颗粒时,灰尘可能会从较大的颗粒表面浮空,并形成令人讨厌的硅尘云。本发明提供了一种将灰尘结合到较大的硅颗粒上的方法。在第二种处理方式中,高纯度硅薄层(0.1-5.0微米)沉积在载有灰尘的颗粒上。最优选通过以下方式进行第二种方式:(a)在流化床反应器中,用含1至5摩尔%的硅与惰性载气(例如氢气)混合的沉积气体处理含尘颗粒,(b) c)在620°C 650°C的工艺温度下。产物多晶硅由自由流动的近似球形颗粒组成,其粒径分布为150-1500微米,平均粒径为650-750微米,并且具有颗粒体积密度为每立方厘米2.3克,堆积密度为约1360kg / m 3,硅表面粉尘含量小于约0.08wt。%。 %。
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