SiC单晶生长的热场模拟及其在籽晶固定方面的应用

Thermal Simulation of SiC Single Crystal Growth Process and Its Applications for Seed Crystal Fixation

热场模拟在物理气相输运法(PVT法)制备SiC单晶工艺的改进中起着重要的作用。实验中发现,SiC晶体生长表面可能会起伏不平,导致生长的晶体质量下降。经分析可知,籽晶固定过程中籽晶背面形成的气孔是造成晶体生长表面起伏不平的主要因素。热场模拟发现,在籽晶背面有气孔处,籽晶生长面温度较高。气孔宽度、籽晶厚度及粘结剂厚度影响籽晶表面气孔中心与气孔边缘的温差。减小气孔、增厚籽晶可有效减小籽晶表面气孔中心与气孔边缘的温差,是改善晶体生长面质量的两个有效途径。

Thermal simulation played an important role in the improvement of the growth process for preparing SiC single crystals by PVT method. It was found that the surfaces of grown SiC crystals might become uneven, which would result in a decrease of grown crys- tal quality. The analysis showed that bubbles at the back of seed crystal, which formed during the fixation process, was the major cause of the unevenness at the surface of a grown crystal. Thermal simulation showed that the temperature at the growing surface of seed crys- tal was higher at bubble places. The temperature difference between the bubble center and the bubble edge at the surface of seed crystal was influenced by bubble width, seed crystal thickness and adhesive layer thickness. Minimizing the width of bubbles and increasing the thickness of seed crystals were two effective ways for reducing the temperature difference between the bubble center and the bubble edge at the surface of seed crystal, thus improving the quality of the crystal growing surfaces.