多晶硅锭的制备及其形貌组织的研究

研究了采用定向凝固法制备多晶硅锭的凝固速率与表面形貌、晶粒尺寸以及显微组织缺陷的关系。找出了晶锭不出现细晶的临界生长速度 ,并对固液界面形状进行了探讨。多晶硅锭的制备工艺主要包括定向凝固法及浇铸法。采用定向凝固法制备多晶硅锭 ,通过改变降埚速率控制晶体生长速度 ,进而找出晶粒大小与降埚速率的关系 ;同时通过改变石英坩埚、石墨托厚度 ,冷源半径等几何参数来达到控制固 液界面形状的目的。

Preparation of Polycrystalline Silicon Ingot and Its Microstructure

Polycrystalline silicon ingots were prepared by the method of directional solidification. The relationship between solidification rate and surface morphotogy, grain size and microstructure was studied. Results show that there exist a critical growth rate, if the actual growth rate is higher than that, fine grained structure will be obtained. In addition, the solid liquid interface was discussed. The production process for making poly silicon mainly includes directional solidification and casting methods. In our laboratory the directional solidification technique was used to obtain poly silicon, by changing decreasing ratio to control crystal growth rate, so the relationship between grain size and decreasing ratio was found. In addition, the solid liquid interface shape was controlled by changing geometric parameters, such as quartz crucible, graphite support thickness and cooling radius.