高纯半绝缘SiC电阻率影响因素

采用物理气相传输(PVT)法进行高纯半绝缘SiC晶体生长,利用高温真空解吸附以及在系统中通入HCl和H2的方法,有效降低了系统中N、B和Al等杂质的背景浓度。使用二次离子质谱(SIMS)对晶体中杂质浓度测试,N、B和Al浓度分别小于1×1016、1×1015和2×1014 cm-3。对加工得到的晶片进行测试,全片的电阻率均在1×1010Ω·cm以上,微管密度小于0.02 cm-2,(004)衍射面的X射线摇摆曲线半高宽为34″。结果表明,该方法可以有效降低SiC晶体中N、B和Al等杂质浓度,提升SiC晶片的电阻率。使用该方法成功制备了4英寸(1英寸=2.54 cm)高纯半绝缘4H-SiC晶体。

Influence Factors of High Purity Semi-Insulating SiC Resistivity

The SiC crystal with high purity semi-insulation was grown by the physical vapor transfer(PVT)method.By the high temperature vacuum desorption and injecting HCl and H2 into the system,the background concentrations of N,B,Al and other impurities in the system are decreased effectively.The concentrations of the impurities in the crystal were measured by the secondary ion mass spectrometry(SIMS).The concentrations of N,B and Al are lower than1×1016,1×1015 and 2×1014 cm-3,respectively.To test the processed wafer,the resistivity of whole wafer is above 1×1010Ω·cm,the micropipe density is below 0.02 cm-2,and the full width at half maximum of X-ray rocking curve for(004)diffraction plane is 34″.The results show that the method can effectively reduce the concentrations of N,B,Al and other impurities in the SiC crystal,and the resistivity of the SiC wafer is obviously improved.The 4 inches(1 inch=2.54 cm)high-purity semi-insulating 4 H-SiC crystal was successfully prepared by the method.