Homoepitaxial Growth of 8-Inch 200 μm 4H-SiC Thick Film for Ultra-High Voltage and High-Current Power Devices

doi:10.16553/j.cnki.issn1000-985x.2025.0197

Abstract

Abstract: The epitaxial growth of 4H-SiC thick films was investigated to meet the requirements for ultra-high-voltage and high-current power devices. Key parameters，including the uniformity of the epitaxial layer's doping concentration and thickness，the suppression of surface defect density，and the enhancement of minority carrier lifetime were explored. The results demonstrate that the uniformity of the epitaxial layer's thickness and doping concentration can be significantly improved through optimized reactor design combined with precise process control. Furthermore，strict control of triangle defects of p-type epi-layer and downfalls during epitaxy is identified as a critical technique for reducing surface defect density and increasing the usable wafer area，which also contributes substantially to the improvement of minority carrier lifetime. High-quality 8 inch 4H-SiC homoepitaxial thick films were successfully fabricated，achieving a thickness of 200 μm with a doping concentration of 1.9×10¹⁴ cm^-3. The thickness non-uniformity is measured at 0.95%，and the doping concentration non-uniformity is 3.92%. A usable area of 46.5% is obtained for the IGBT structure （based on a 10 mm×10 mm die size），while the diode structure achieve a remarkably high usable area of 96.9%. Minority carrier lifetimes exceeding 5 μs are recorded for both structures. The epitaxial layers were characterized by AFM，which reveal low surface roughness and excellent morphology. This study presents an effective technical approach for producing SiC homoepitaxial thick films with high uniformity，low defect density，and extended minority carrier lifetime. The methodology is demonstrated to be of significant importance for the development of SiC ultra-high-voltage devices （such as IGBT） and their industrial applications in sectors such as novel energy storage systems and smart grids.

Key words: SiC; homoepitaxy; thick film; ultra-high-voltage power device; surface defect; minority carrier lifetime

CLC Number:

O484.1

CAI Zidong, JIANG Yitian, YE Zheng, WU Zihao, FANG Yutao, XIA Yun, CHEN Gang, HU Haolin, WAN Yuxi. Homoepitaxial Growth of 8-Inch 200 μm 4H-SiC Thick Film for Ultra-High Voltage and High-Current Power Devices[J]. Journal of Synthetic Crystals, 2026, 55(2): 264-273.

Figures/Tables 8

Fig.1 Schematic diagram of epi-structures. （a） IGBT structure；（b） diode/MOSFET structure

Fig.2 Characterization data of thick film epitaxial layer thickness. Cross-sectional SEM image （a） of IGBT structure and statistical data of thickness （b） measured by SEM；total epitaxial thickness （c） and thickness （d） of n-type doped epitaxial layer obtained after FT-IR testing and fitting of IGBT structure epitaxial wafer

Fig.3 Doping concentration data of thick film epitaxial layer. （a） n-type doped layer on a single wafer，showing a mean value of 1.94×1014 cm-3 and a non-uniformity of 3.92%；（b） results for eight consecutive wafers from the same batch

Fig.4 SIMS measurement results of Al doping in the p-type SiC epitaxial layer

Fig.5 Surface defect of p-type epitaxial and thick film epitaxial layers. （a） p-type epitaxial layer before optimization；（b） p-type epitaxial layer after optimization；（c） IGBT structure grown on pre-optimized p-type epitaxial layer；（d） IGBT structure grown on optimized p-type epitaxial layer；（e） diode/MOSFET structure epitaxial wafer

Fig.6 Schematic diagram of defects in IGBT epi-structure wafer，where dashed box shows an enlarged view of a triangular defect caused by downfall，and solid box displays BPD and other defects derived from the triangular defect

Fig.7 Minority carrier lifetime measurements of thick film epitaxial layer. （a） IGBT epitaxial wafer；（b） diode/MOSFET epitaxial wafer

Fig.8 AFM images of thick film epitaxial layer. Center region （a） and edge region （b） for IGBT epi-structure；center region （c） and edge region （d） for diode/MOSFET epi-structure

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