铸造多晶硅的制备与研究

Preparation and research of casting polysilicon

当今多晶硅已成为最主要的光伏材料,利用定向凝固工艺生产铸造多晶硅铸锭已成为业界广为采用的方法,但目前利用定向凝固工艺生产出来的多晶硅铸锭仍存在较多的缺陷,例如材料利用率低以及组织不均匀等问题。为了进一步优化铸造工艺,采用自行设计的真空电磁感应熔炼炉及定向凝固炉进行了多晶硅定向凝固实验。重点对比研究了石英坩埚和石英陶瓷坩埚对铸锭质量的影响。研究表明相对于石英坩埚而言,具有涂层的石英陶瓷坩埚不但可以防止铸锭产生裂纹,而且铸造出的多晶硅铸锭具有表面质量好以及相对发达粗大的柱状晶组织,平均晶粒尺寸为3～4mm。同时氮化硅涂层可以有效地降低铸锭中杂质氧的含量。

Today polysilicon has become the most important PV materials.The production of casting polysilicon ingot by directional solidification process has become a widely used method,but polycrystalline silicon ingots which are got by this process still have some defects.For example,low materials utilization,heterogeneous organization and so on.In order to further optimize the casting process,in this paper,self-designed vacuum induction melting furnace and directional solidification furnace were used for directional solidification experiments.The effect of quartz crucible and quartz ceramics crucible on ingot quality was investigated.The results showed that ingot with better surface quality and relatively well-developed coarse columnar grain structure can be obtained by use of silica ceramic crucibles coated high-purity silicon nitride.The average grain size of ingot is 3-4mm.Meantime,nitride coatings can also effectively reduce the oxygen impurity content in silicon ingot.