6英寸碳化硅外延片小坑缺陷研究

Study on Pit Defects of 6-Inch Silicon Carbide Epitaxial Wafer

随着碳化硅(SiC)功率器件在新能源汽车、光伏产业、高压输电和智能充电桩等下游领域需求的爆发式增长,对高质量、低缺陷密度SiC外延材料提出了迫切需求。有研究表明,小坑缺陷可能引起器件漏电流增大,影响SiC金属氧化物半导体场效应晶体管(MOSFET)栅氧可靠性,因此对外延材料小坑缺陷的研究成为热点之一。采用单片水平式SiC外延设备,在6英寸(1英寸=2.54 cm)偏4°SiC衬底上生长4H-SiC外延层,系统研究了外延工艺对小坑缺陷的影响。采用表面缺陷测试仪对外延层小坑缺陷形貌和数量进行表征,利用表面缺陷测试仪的同步定位系统研究了小坑缺陷的起源与形成机理。研究结果表明,通过优化碳硅比和生长温度,有效降低了4H-SiC外延层小坑缺陷密度,小坑缺陷密度可控制在25 cm^(-2)以下,实现了低缺陷密度的高质量外延材料生长。

With the explosive growth of demand for silicon carbide(SiC)power devices in downstream areas such as new energy vehicles,photovoltaic industry,high voltage power transmission and smart charging piles,there is an urgent need for SiC epitaxial materials with high-quality and low defect density.Some studies have shown that the small pit defects may cause the increase of device leakage current and affect the gate oxide reliability of SiC metal-oxidesemiconductor field effect transistor(MOSFET),so the study on pit defects in epitaxial materials has become one of the hot spots.The 4H-SiC epitaxy layer was grown on a 6-inch(1 inch=2.54 cm)SiC substrate at 4°off-axis by the monolithic horizontal SiC epitaxy equipment,the effect of epitaxy process on small pit defects was systematically studied.The morphology and quantity of pit defects on the epitaxial layer were characterized by using the surface defect tester,and the origin and formation mechanism of pit defects were studied by using the synchronous positioning system of surface defect tester.The study results show that by optimizing the C/Si ratio and the growth temperature,the pit defect density of 4H-SiC epitaxial layer is effectively reduced and can be controlled below 25 cm^(-2),which realizing the growth of high-quality epitaxial materials with low defect density.