Analysis and Review of Influencing Factors of SiC Homo-Epitaxial Wafers Quality
The performance and lifetime of silicon carbide(SiC)devices are directly affected by the quality of SiC epitaxial films.On the one hand,the quality of SiC epitaxial films is affected by the quality of substrates.For examples,the stacking faults(SF)in substrates penetrate into the epitaxial layer,forming bar-shaped stacking faults(BSF),and the threading screw dislocation(TSD)penetrate into the epitaxial layer to form pits or Frank-type stacking faults(Frank SF).On the other hand,the quality of SiC epitaxial films is also influenced by the epitaxial growing process.For examples,basal plane dislocation(BPD)in the substrate form ∑-basal plane dislocation(∑-BPD)in the epitaxial layer under thermal stress or other unstable conditions,the TSD and threading edge dislocation(TED)in the substrate may be etched and derived into pits,and SF and silicon droplets may also be produced.Therefore,high quality SiC substrates and optimized epitaxial growing process are both crucial for obtaining high-quality silicon carbide epitaxial wafers.In this article,based on the SiC epitaxial films grown on 6 inch SiC substrates batch-produced by TankeBlue Company,the defects reproducing process in substrates during epitaxial growing were analyzed,and the formation mechanism and controlling technology of common defects such as BPD,SF,silicon droplets and pits were overviewed.The generation mechanism of ∑-BPD and its eliminating methods were also explored.Finally,we obtained the mass-production technologies of SiC epitaxial films with good thickness and concentration uniformity,and low defect density,which are qualified for making 650 and 1 200 V SiC-based MOSFETs.
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