Stress mapping of SiC wafers by synchrotron white beam X-ray reticulography

Synchrotron white beam x-ray reticulography has been used to quantitatively map the residual stress/strain in SiC wafers. The basic principle of our study is that there exists a relationship between the stress state in a crystal and the local lattice plane orientation and that this relationship can be exploited in order to determine the full strain tensor as a function of position inside the crystal. The theoretical background involved in stress mapping using synchrotron white beam x-ray reticulography is introduced based on the change of the normal to a lattice plane due to the distortion associated with the residual strain. The stress in a region of a commercial 4H silicon carbide wafer has been studied using this technique and the results are discussed. This technique can in principle be used in any single crystal material.