Observation of in-plane shear stress fields in off-axis SiC wafers by birefringence imaging

Abstract

For the nondestructive characterization of SiC wafers for power device application, birefringence imaging is one of the promising methods. In the present study, it is demonstrated that birefringence image contrast variation in off-axis SiC wafers corresponds to the in-plane shear stress under conditions slightly deviating from crossed Nicols according to both theoretical consideration and experimental observation. The current results indicate that the characterization of defects in SiC wafers is possible to achieve by birefringence imaging.

Effects of proton implantation for expansion of basal plane dislocations in SiC toward suppression of bipolar degradation: review and perspective

“…[8][9][10] Therefore, development of wafer inspection technologies has been explored to screen through poor quality wafers. 7,[10][11][12][13][14][15][16][17][18] Over the past two decades, basal plane dislocations (BPDs) in 4H-SiC substrates have emerged as crucial defects in SiC wafers. Bipolar degradation in 4H-SiC PN diodes has emerged as a significant concern affecting their operational longevity.…”