Characterization of 4H-SiC Lattice Damage after Novel High Energy Ion Implantation

A multi-energy implantation system has been developed for deep implantation of dopant atoms (Al, B, N, P) in 4H-SiC wafers to fabricate deep junctions for medium and high voltage devices. Energies used range from 13MeV to 66MeV, far higher than those used in conventional implantations. Therefore, lattice damage induced by the implantation process and the recovery by annealing must be characterized in detail for understanding the nature of damage, extent of recovery and its possible effect on device properties. To this end, 4H-SiC wafers with 12 um epilayer were implanted by 13.8 MeV to 65.7 MeV Al and N ions using the multi-energy implantation system. Samples were implanted in the form of alternative Al and N pillars or blanket co-implanted with Al and N. The nature of strains induced by the implantation process in as-implanted and post-annealed samples were investigated using Synchrotron X-ray Rocking Curve Topography (SXRCT) and Reciprocal Space Map (RSM). As-implanted samples are characterized by tensile strains. By comparing samples implanted with different fluences, we have confirmed that implantation with higher total fluence introduces higher levels of strains in the 4H-SiC epilayer.