Non-Destructive Evaluation of SiC wafer for Power Device Defect detection in μm~nm scale using optical analytical technique
Author: N. NAKA; T. SHIMIZU; H. BABA; T. NUMATO; J. AOYAMA; S. AWATA; T. HATAYAMA – Nobuyuki NAKA, Tomoya SHIMIZU, Hiroki BABA, Tomoko NUMATO, Junichi AOYAMA, Shogo AWATA and Tomoaki HATAYAMA Power devices using Silicon Carbide (SiC) are already commercialized and are moving into mass production, but commercial SiC wafers have several types of defects. It is important to have techniques for analyzing a variety of defects, because these defects decrease the yield ratio of SiC devices. In this paper, we did complex analysis on sub-millimeter- and nanometer-scale defects and stress in epitaxial / bulk SiC wafers. The laser scattering method can detect submicronsized defects on the entire surface of a 4-inch (10.16 cm) wafer in about 3 minutes. Our original CathodeLuminescence (CL) imaging system can evaluate nanometer-sized crystal defects using a submillimeter-scale panchromatic image acquired in a short time, and PhotoLuminescence (PL) lifetime measurements help us understand carrier lifetime. Furthermore, we show that Raman spectroscopy can evaluate stress distribution around defects detected in CL images in a non-destructive manner.