重掺杂P型SiC的熔融KOH刻蚀行为研究

Molten KOH Etching Behaviors of Heavily Doped P-Type SiC

本文采用熔融KOH刻蚀方法详细研究了液相法生长的重掺杂P型6H-SiC晶体中的位错情况,探究了时间、温度变化对液相法生长的重掺杂P型6H-SiC晶片表面刻蚀的影响。当提高腐蚀时间或腐蚀温度时,晶片表面的腐蚀坑尺寸均表现出不同程度的增加,过高的温度及长时间刻蚀均导致过腐蚀现象的发生。根据不同腐蚀条件下腐蚀坑的形貌与分布,确定出刻蚀重掺杂P型6H-SiC晶片的最佳工艺参数。利用晶片在不同温度下的腐蚀速率变化关系及阿伦尼乌斯公式计算出晶体的反应活化能为10.59 kcal/mol。最后,对穿透型螺位错(TSD)和穿透型刃位错(TED)的形貌、尺寸和内部结构进行了详细的表征和分析,结果表明P型6H-SiC晶体中腐蚀坑的倾角与腐蚀时间无关。

In this paper,the dislocations in heavily doped P-type 6H-SiC crystals grown by liquid phase method have been studied in detail by melt KOH etching method.The effects of etching time and temperature on the surface etching of the heavily doped P-type 6H-SiC wafers grown by liquid phase method were investigated.The increase of etching temperature or etching time enlarge the etching pit size on the wafer surface,and the over etching happen at over temperature and long etching time.The optimal parameters for etching heavily doped P-type 6H-SiC wafers were determined according to the morphology and distribution of etching pits under different etching conditions.The reaction activation energy of the heavily doped P-type 6H-SiC crystal is calculated to be 10.59 kcal/mol through the etching rate variation relationship of the wafers at different temperatures and Arrhenius formula.Finally,the detailed characterizations on the morphologies,sizes and internal structures of threading screw dislocation(TSD)and threading edge dislocation(TED)in the wafers indicate that the inclination angle of etching pits in P-type 6H-SiC crystals is independent of the etching time.