多晶硅定向生长的实验研究

Research on Directional Growth of Polycrystalline Silicon

以埚底料为原料进行定向凝固实验,从晶体生长和提纯的角度分析,拉伸速度为20μm/s是较优的实验条件。根据多晶硅锭纵截面的腐蚀照片和XRD晶体取向分析得出,底部定向生长的效果明显,<111>方向是晶体生长的主要方向,单向生长比较明显,铸锭中上部晶体取向变得相对混乱。此外,还利用晶体的淘汰机制和合并机制分析了晶体生长的过程。

The pot bottom material was placed in self-assembled directional solidification furnace and the experiment was carried out. According to the analysis on silicon surface appearances and impurity purification, it was observed that the optimal pulling rate was 20 um/s. Crystal growth was studied using etched images along longitudinal section and X-ray diffraction （XRD）. Crystal directional growth was obvious and polycrystalline silicon mainly grew along 〈 111〉 orientation at the bottom of silicon ingot. But the crystals grew into disorder and larger in grain size at the middle and top of silicon ingot. In this paper, the crystal growth process was reasonably explained by the crystal elimination rule and the columnar crystals merge mechanism.