8英寸导电型4H-SiC单晶衬底制备与表征

使用物理气相传输法(PVT)通过扩径技术制备出直径为209 mm的4H-SiC单晶,并通过多线切割、研磨和抛光等一系列加工工艺制备出标准8英寸SiC单晶衬底。使用拉曼光谱仪、高分辨X射线衍射仪、光学显微镜、电阻仪、偏光应力仪、面型检测仪、位错检测仪等设备,对8英寸衬底的晶型、结晶质量、微管、电阻率、应力、面型、位错等进行了详细表征。拉曼光谱表明8英寸SiC衬底100%比例面积为单一4H晶型;衬底(004)面的5点X射线摇摆曲线半峰全宽分布在10.44″~11.52″;平均微管密度为0.04 cm^-2;平均电阻率为0.020 3 Ω·cm。使用偏光应力仪对8英寸SiC衬底内部应力进行检测表明整片应力分布均匀,且未发现应力集中的区域;翘曲度(Warp)为17.318 μm,弯曲度(Bow)为-3.773 μm。全自动位错密度检测仪对高温熔融KOH刻蚀后的8英寸衬底进行全片扫描,平均总位错密度为3 293 cm^-2,其中螺型位错(TSD)密度为81 cm^-2,刃型位错(TED)密度为3 074 cm^-2,基平面位错(BPD)密度为138 cm^-2。结果表明8英寸导电型4H-SiC衬底质量优良,同比行业标准达到行业先进水平。

Fabrication and Characterizations of 8-Inch n Type 4H-SiC Single Crystal Substrate

A SiC single crystal boule with a diameter of 209 mm was grown by physical vapor transport (PVT) method with a diameter expansion technique. Standard 8-inch SiC single crystal substrates were fabricated by using the processes of multi-wire sawing, grinding, polishing and cleaning. Crystal polytype, crystal quality, micropipes, resistivity, stress, wafer shape, dislocation of a randomly selected 8-inch substrate were characterized by Raman spectrometer, high-resolution X-ray diffractometer, optical microscope, resistivity tester, polarization stress meter, wafer flatness tester, and dislocation detector. Raman spectra show that 8-inch substrate consists only 4H polytype. X-ray rocking curves illustrate full-width at half-maximum of the (004) peak between 10.44″ and 11.52″. Micropipe density is 0.04 cm^-2 and the average resistivity is 0.020 3 Ω·cm. There is no stress concentration zone in the substrate with an evenly distributed stress. Warp and bow are 17.318 μm and -3.773 μm, respectively. The average dislocation density is 3 293 cm^-2 by scanning the full area of the molten KOH etched 8-inch substrate, among which the density of threading screw dislocation(TSD), threading edge dislocation(TED) and basal plane dislocation(BPD) are 81 cm^-2, 3 074 cm^-2 and 138 cm^-2, respectively. All results indicate the high quality of the 8-inch n type 4H-SiC substrate, which reaches world-class levels according to the comparsion with the industry standards.