Analysis of Strain in Ion Implanted 4H-SiC by Fringes Observed in Synchrotron X-Ray Topography

A novel high energy implantation system has been successfully developed to fabricate 4HSiC superjunction devices for medium and high voltage via implantation of dopant atoms with multienergy ranging from 13 to 66 MeV. Level of energy used is significantly higher than that of conventional implantation, so lattice damage caused by such implantation must be characterized in detail to enhance the understanding of the nature of the damage. In regard to this, by employing the novel high energy system, 4H-SiC wafer with 12 μm epilayer was blanket implanted by 13.8 to 65.7 MeV Al atoms and energy range up to 42.99 MeV N atoms. The lattice damages induced by the implantation were primarily characterized by Synchrotron X-ray Topography. Multiple asymmetric diffraction peaks with an angular separation of only 2” (arcseconds) were shown in the topographs, indicating inhomogeneous strain distribution across the implanted layer. The strain profile of the implanted layer was obtained by Rocking-curve Analysis by Dynamical Simulation (RADS).