Growth of Large Diameter 6H SI and 4H n+ SiC Single Crystals
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1246-B01-01
Growth of Large Diameter 6H SI and 4H n+ SiC Single Crystals Avinash Gupta, Ping Wu, Varatharajan Rengarajan, Xueping Xu, Murugesu Yoganathan, Chris Martin, Ejiro Emorhokpor, Andy Souzis, Ilya Zwieback and Tom Anderson II-VI Incorporated, Wide Bandgap Materials Group. 20 Chapin Road, PO Box 840, Pine Brook, NJ 07058, U.S.A.
ABSTRACT SiC single crystals are grown at II-VI by the seeded sublimation technique. The process has been scaled up and optimized to support commercial production of high-quality 100 mm diameter, Semi-Insulating (SI) 6H substrates and 100 mm 4H n+ substrates. The growth process incorporates special elements aimed at achieving uniform sublimation of the source, steady growth rate, uniform doping and reduced presence of background impurities. Semi-insulating 6H substrates are produced using precise vanadium compensation. Vanadium doping is optimized to yield SI material with very high resistivity and low capacitance. Crystal quality of the substrates is evaluated using a wide variety of techniques. Specific defects, their interaction and evolution during growth are described with emphasis on micropipes and dislocations. The current quality of the 6H SI and 4H n+ crystals grown at II-VI is summarized.
INTRODUCTION Over the last decade, remarkable progress has been achieved in the development of AlGaN-based RF/microwave devices and SiC-based power switching devices. In these epitaxial devices, single crystals of silicon carbide, semi-insulating 6H/4H and electrically conductive 4H n+, serve as lattice-matched, high thermal conductivity substrates. The design of the AlGaN devices requires on-axis Semi-Insulating (SI) substrates having high electrical resistivity and low capacitance. The design of SiC power switching devices requires 4°-offcut 4H n+ substrates with the resistivity of about 20 mΩ·cm. These devices are at the stage where considerations of yield, reliability and cost become dominant. This has led to demands for affordable SiC substrates of 100 mm diameter (150 mm in the future) having high crystal quality. Recently, 100 mm semi-insulating (SI) and 4H n+ substrates have been introduced to the market and are gradually replacing 3” substrates, which were launched only several years earlier. Over the last five years, II-VI has successfully developed 100 mm SiC substrates, both 6H SI and 4H n+, which became standard commercial products of the Company. This paper reviews growth of large-diameter SiC crystals at II-VI and discusses characteristic crystal defects and their evolution during growth.
SiC SUBLIMATION GROWTH II-VI applies its advanced sublimation process [1] for the growth of large-diameter 6H and 4H crystals. Independent of the crystal type, the growth process utilizes high-purity SiC source and employs special procedures for the reduction of background contamination with emphasis on boron and, in the case of semi-insulating crystals, nitrogen. The SiC source is synthesized at II-VI in a separate process from the semiconductor-purity starting components - elemental s
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