High-Dose Phosphorus-Implanted 4H-SiC: Microwave and Conventional Post-Implantation Annealing at Temperatures ≥ 1700°C

Semi-insulating 4H-SiC aY0001aY (c) wafers have been phosphorus ion implanted at 500A degrees C to obtain phosphorus box depth profiles with dopant concentration from 5 x 10(19) cm(-3) to 8 x 10(20) cm(-3). These samples have been annealed by microwave and conventional inductively heated systems in the temperature range 1700A degrees C to 2050A degrees C. Resistivity, Hall electron density, and Hall mobility of the phosphorus-implanted and annealed 4H-SiC layers have been measured in the temperature range from room temperature to 450A degrees C. The high-resolution x-ray diffraction and rocking curve of both virgin and processed 4H-SiC samples have been analyzed to obtain the sample crystal quality up to about 3 mu m depth from the wafer surface. For both increasing implanted phosphorus concentration and increasing post-implantation annealing temperature the implanted material resistivity decreases to an asymptotic value of about 1.5 x 10(-3) Omega cm. Increasing the implanted phosphorus concentration and post-implantation annealing temperature beyond 4 x 10(20) cm(-3) and 2000A degrees C, respectively, does not bring any apparent benefit with respect to the minimum obtainable resistivity. Sheet resistance and sheet electron density increase with increasing measurement temperature. Electron density saturates at 1.5 x 10(20) cm(-3) for implanted phosphorus plateau values a parts per thousand yen4 x 10(20) cm(-3), irrespective of the post-implantation annealing method. Implantation produces an increase of the lattice parameter in the bulk 4H-SiC underneath the phosphorus-implanted layer. Microwave and conventional annealing produce a further increase of the lattice parameter in such a depth region and an equivalent recovered lattice in the phosphorus-implanted layers.