Mist CVD生长的雾滴迁移与早期沉积研究

Droplet migration and early deposition of Mist CVD

第三代半导体材料α-Ga_(2)O_(3)因其超宽带隙(5.3 eV)和超高巴利加优值(6726)在制造高功率器件等电子器件方面更具优势。在α-Ga_(2)O_(3)的诸多生长方法中,Mist CVD简化了前体输运,是亚稳相薄膜较有前景的生长技术。针对早期雾滴分布会制约薄膜质量的问题,使用计算流体力学(CFD)对α-Ga_(2)O_(3)的水平热壁Mist CVD系统进行了多相流反应的瞬态数值仿真研究。基于雾滴迁移与气化模型,研究影响雾滴蒸发时间的因素,解释了雾滴迁移长度对初始外延质量和平均生长速率的作用。在影响α-Ga_(2)O_(3)薄膜生长分布的诸多变量中,对衬底温度、衬底位置及衬底角度等关键参数进行了优化。结果表明,26.5°的衬底角度、距离出口78 cm的衬底位置和550℃的衬底温度具有较好的雾滴迁移分布,是有利于薄膜成核生长的优化条件,为实际生长与制备提供生长参数。

The third generation semiconductor materialα-Ga_(2) O_(3) has advantages in manufacturing high-power and other electronic devices due to its ultra-wide band gap(5.3 eV)and ultra-high Baliga figure of merit(6726).Among various methods for growingα-Ga_(2) O_(3) thin films,Mist CVD simplifies precursor transport,making it a promising growth technique for the metastable phase thin films.Due to the limitation of early droplet distributions on the quality of the film,transient numerical simulations of multiphase flow reactions in the horizontal hot wallα-Ga_(2) O_(3) miss CVD system were conducted with computational fluid dynamics(CFD).Based on the model of the droplet migrations and gasification,the factors affecting droplet evaporation time were studied,and the effect of the droplet migration length on the initial epitaxial quality and average growth rate of thin films was disclosed.Among many variables that affect theα-Ga_(2) O_(3) thin film growth distribution,the key parameters such as substrate temperatures,substrate positions,and substrate angles were optimized.The results indicate that parameters like the substrate angle of 26.5°,the substrate position of 78 cm away from the outlet,and substrate temperature of 550℃lead to good droplet migrations and distributions,which are the optimized conditions for thin films nucleation and growth.This work provides growth parameters for the actual growth and preparation.