150mm高质量15kV器件用4H-SiC同质外延生长

150 mm High-Quality 4H-SiC Homoepitaxial Growth for 15 kV Devices

采用化学气相沉积法进行6英寸(1英寸=2.54 cm)厚层4H-SiC同质外延片的快速生长,通过对工艺中预刻蚀、碳硅比(C/Si)和温度等关键参数优化,有效降低了厚层外延片表面缺陷密度。同时,采用傅里叶变换红外法、汞探针电容电压法和表面缺陷测试仪对厚层4H-SiC同质外延片各项参数进行表征。结果表明,生长的厚150μm外延层表面缺陷(三角形、掉落物以及掉落物引起的三角形)密度可降低至0.5 cm^(-2)。外延片厚度均匀性为0.66%,外延层氮(N)掺杂浓度为2×10^(14) cm^(-3),N掺杂浓度均匀性为1.97%。此外,通过生长前对系统进行烘烤处理有效降低了反应腔系统的背景浓度,连续生长10炉次低掺杂浓度外延片,片间N掺杂浓度均匀性为4.56%,大大提高了炉次间的掺杂浓度均匀性。通过对工艺参数进行优化及外延前烘烤系统的方式,成功制备了150 mm高质量15 kV器件用4H-SiC同质外延片。

The fast growth of 6-inch(1 inch=2.54 cm) thick 4 H-SiC homoepitaxial wafers was carried out by chemical vapor deposition method.The key parameters such as pre-etching,carbon to silicon ratio(C/Si) and temperature were optimized to effectively reduce the density of surface defects of the thick epitaxial wafers.Meanwhile,Fourier transform infrared method,mercury probe capacitance voltage method and surface defect tester were used to characterize various parameters of the thick layer 4 H-SiC homoepitaxial wafers.The results show that the density of surface defects(triangles,falling objects,and triangles caused by falling objects) of the grown epitaxial layer with a thickness of 150 μm can reduce to 0.5 cm^(-2).The thickness uniformity of the epitaxial wafer is 0.66%,the nitrogen(N) doping concentration of the epitaxial layer is 2×10^(14) cm^(-3),and the N doping concentration uniformity is 1.97%.In addition,by baking the system before growth,the background concentration of the reaction chamber system was effectively reduced.The low doping concentration epitaxial wafers were grown continuously for 10 runs.The uniformity of the N doping concentration between the wafers is 4.56%,which greatly improves the doping concentration uniformity of different runs.By optimizing the process parameters and the method of pre-epitaxially baking the system,150 mm high-quality 4 H-SiC homoepitaxial wafers for 15 kV devices were successfully prepared.