Growth of High Quality and Low Resistivity Φ100mm p-type 4H-SiC Single Crystal

Abstract

To fabricate n-channel SiC Insulated Gate Bipolar Transistor (IGBT) devices, p-type SiC wafers with low resistivity are demanded. Recently, several groups reported the growth of p-type SiC, however, there are still some challenges to grow p-type 4H-SiC by PVT method, such as foreign polytype in heavily p-type doped SiC, doping inhomogeneous, higher resistivity and so on. In our previous study, our group found when Al doping concentration was above 4.0E18cm-3, foreign polytypes will easily appear in the 4H-SiC boules, which severely degrades crystal quality.In this work, numerical simulation and experiment are combined to study the growth of p-type SiC. Numerical simulation calculation is carried out by VRTM-PVT SiC software. The temperature field and growth gas species flow transport in the crucible are studied. To ensure the continuous release of Al dopants, a lower growth temperature was necessary to avoid the concentrated release of Al dopants at early growth stage. In addition, according to our stimulation results, the crystal growth rate under 10 mbar pressure is about 3.5 times than that under 100 mbar pressure at the same heating conditions. Consequently, to make the crystal growth have a reasonable growth rate, low background pressure is demanded. Moreover, by conducting systematic research on the dynamic material transport path, the position of the dopant source is determined to ensure the uniform release of the Al source at different growth periods. Based on the above proposal, Φ100 mm p-type SiC single crystal is grown by PVT method with Al4C3 as dopant. SIMS results show the Al concentration in SiC is 2.9E19cm-3. Raman spectroscopy mapping result indicates that p-type SiC is totally 4H-SiC and no other foreign polytype exist. The full width at half maximum (FWHM) of (004) X-ray rocking curve is 28 arcsec, indicating p-type 4H-SiC is of high crystalline quality. Resistivity mapping result shows that the resistivity deviation is 23.51% with the lowest resistivity 0.30 Ωcm.