Development of High-Resolution Nuclear Emulsion Plates for Synchrotron X-Ray Topography Observation of Large-Size Semiconductor Wafers

Characterization of defects in semiconductor wafers is essential for the development and improvement of semiconductor devices, especially power devices. X-ray topography (XRT) using synchrotron radiation is a powerful methods used for defect characterization. To achieve detailed characterization of large-size semiconductor wafers by synchrotron XRT, we have developed nuclear emulsion plates reaching a high-resolution and wide dynamic range. We have shown that higher-resolution XRT images could be obtained using emulsions with smaller iodobromide crystals, and demonstrated clear observation of threading edge dislocations in a SiC epitaxial layer having small contrast. Furthermore, we demonstrated XRT image acquisition for almost all of a 150-mm SiC wafer with one plate. Our development will contribute to advances in electronic materials, especially in the field of power electronics, in which defect characterization is important for improving the performance and yield of devices.