BS IEC 63068-2:2019 pdf free.Semiconductor devices – Non-destructive recognition criteria of defects in silicon carbide homoepitaxial wafer for power devices.
General Defects with surface morphological features shall be detected by optical inspection method. The following descriptions concern such defects in n/n+-type 4H-SiC homoepitaxial wafers with an off-cut angle of 4° along the direction of [11 20]: — individual defects exhibiting hexagonal-shaped or round-shaped large holes on the wafer surface, e.g. micropipe (Figure A.1); — individual minute defects giving rise to a pit less than 50 .im in diameter on the wafer surface, e.g. TSD (Figure A.2), TED (Figure A.3); — individual linear defects extending in various directions, e.g. scratch trace (Figure A.4);
— individual planar defects providing needle-shaped features on the wafer surface, which extend along the off-cut direction, e.g. stacking fault complex (Figure A.7); — individual planar defects providing faintly-outlined features on the wafer surface, which extend diagonally to the off-cut direction, e.g. stacking fault (Figure A.5), propagated stacking fault (Figure A.6); — individual volume defects giving rise to triangle-shaped features on the wafer surface, which extend along the off-cut direction, e.g. polytype inclusion (Figure A.8); — individual volume defects, e.g. particle inclusions (Figure A.9), surface particle; — individual surface defects exhibiting obtuse triangle-shaped or trapezoid-shaped features on the wafer surface, e.g. bunched-step segment (Figure A.10). Defects without surface morphological features should be evaluated by other test methods such as photoluminescence and X-ray topography. Those defects include BPDs, TSDs without surface morphological features, TEDs without surface morphological features, stacking faults without surface morphological features, and propagated stacking faults without surface morphological features. 4.2 Principle A grey scale image (or colour image) is produced from the original digital image of defects on the wafer surface. This image is converted into a binary image (thresholding). The size and shape of defects are measured, and the distribution and number of defects within a specified area of wafer are calculated. First, an optical image of defects has to be captured and transformed into a digital format. An optical image is captured via an optical image sensor such as a charge-coupled device. Then, the obtained digital image is processed by manipulating the grey levels of the image. Through a specified scheme of image analysis, the image information is reduced to a set of values which are specific to the application. NOTE The size of planar and volume defects extending along the off-cut direction depends on the thickness of homoepitaxial layer. Details of such defects and the method of estimating the size of their optical images are described in 4.6.2 and Annex A, respectively.BS IEC 63068-2 pdf download.