Characterization And Distribution Law Of Micropipes In Silicon Carbide Bulk

Silicon carbide as the third era semiconductor has excellent properties such as high power, high temperature, high breakdown voltage.The devices made of Silicon carbide could be used in extreme condition. The growth process and properties of silicon carbide were disscussed in this paper, especially the defects which affect the quality of SiC bulk .Micropipe was considered to be the most serious defect which was the most importance in this research.Raman spectroscopy applied to identify polytype in SiC single crystal grown by the seeded sublimation technique and the rocking curves of several specimens measured by DCXRD diffractometry and the micropipe observed in optical microscopy and SEM were used to determine the polytype and quality of the wafer as well as defects categories. The splitting of micropipe and the formation of hexagonal voids were observed to partly speculate their formation mechanism. The number of mps before etching was approximately the same as that after etching observed using optical microscopy that demonstrated optical microscopy could be used to observe nearly all the micropipes without etching. The experiment was designed with different observation region and point selection method in several 2-inch SiC wafers to calculate the micropipe density error between reality value and calculation value. The result revealed the micropipe distributed along annularity and the observation area and the number of points selected also affected results. Uniformity point selection was used to calculate micropipe density more accurately. The statistics about the distribution of the micropipe diameter in a 2-inch SiC wafer showed that the diameter of micropipe was between 0.7 micrometer and 15.4 micrometer with Gauss distribution, and the maximum number was in the space interval of 3 to 3.5 millimeter.The research about silicon carbides was at the initial stage, especially the characterization, formation mechanism and distribution of defects. The mechanism of the splitting of micropipe and hexagonal void formation needed further analyse both in theory and experiment . There was less data about the distribution of micropipe density and the diameter for the different crystal plane that needed further study.