A Crucible Design for Growing p-Type SiC with Improved Release Uniformity of Al Source

The n-channel SiC Insulated Gate Bipolar Transistor (IGBT) devices have emerged as a prominent contender in the domain of contemporary high-efficiency power electronic systems, predominantly due to their superior electrical properties. The fabrication of n-channel SiC IGBTs necessitates the use of p-type SiC substrates with low resistivity. The presence of foreign polytypes, inhomogeneous doping, and difficulties in achieving heavy dopant in p-type doped SiC present significant challenges for the growth of p-type SiC boules using the Physical Vapor Transport (PVT) method. Achieving uniform doping within the crystal is of critical importance, which necessitates the creation of a low-temperature region for the uniform release of the aluminum (AI) source, while still maintaining the appropriate SiC growth temperature. This ensures uniform Al doping into SiC single crystals and enhances the uniformity of the resistivity. The objective of this paper is to present a novel crucible structure specifically designed to obtain p-type 4H-SiC single crystals with uniform resistivity. The feasibility of the proposed crucible structure is evaluated through numerical simulation. Furthermore, the thermal field structure and gas species transfer process within the crucible have been simulated using the VR™-PVT software. The numerical simulation results demonstrate that the SiC growth chamber is maintained at an appropriate temperature for crystal growth, while the temperature of the Al dopant is at the suitable decomposition temperature to ensure the continuous release of the Al doping source and uniform doping of Al into SiC. Resistivity uniformity can be effectively improved by using 150 mm long extension rods and by moving the crucible upwards.