As the critical dimensions of semiconductor manufacturing
processes gradually decrease, the requirements for production yield
management become increasingly stringent. During the manufacturing
process, there are many different types of defects, such as
micron-sized particles, millimeter-sized scratches, etc. Multiple
categories and different scales bring great challenges to the
detection and identification of defects. This paper provides a
full-flow surface defect identification method based on spot
scanning scattering for unpatterned wafers. First, an adaptive
threshold method with dynamic kernel windows is used to perform
line-by-line scanning inspection of the wafer Mercator image. The
3σ decision strategy is used to avoid the impact of defects
on background estimation and to improve detection sensitivity. After
morphological processing, connected domain analysis is performed to
obtain the defect mask, and feature information such as the shape,
size, and distribution of the defect is extracted. Finally, the
defect identification is performed by rules based binning, and the
identified defects are converted into wafer polar coordinate image
for display and analysis. In the experiments, the proposed method is
used to identify micron-scale particles as well as large scratches
on the millimeter scale for SiC wafers. Relative to the actual
production rate requirement of 20 wafers per hour, the analysis time
for a 6-inch wafer is 24.4 s, which can meet the
requirement. Meanwhile, the test results illustrate the
effectiveness of the method. The proposed method is recommended for
early-stage defect detection and identification of unpatterned
wafers.