Packaging the integrated circuit (IC) chip is a necessary step in the\nmanufacturing process of IC products. In general, wafers with the same size and process\nshould have a fixed number of packaged dies. However, many factors decrease the number\nof the actually packaged dies, such as die scratching, die contamination, and die breakage,\nwhich are not considered in the existing die-counting methods. Here we propose a robust\nmethod that can automatically determine the number of actual packaged dies by using\nmachine vision techniques. During the inspection, the image is taken from the top of the\nwafer, in which most dies have been removed and packaged. There are five steps in the\nproposed method: wafer region detection, wafer position calibration, dies region detection,\ndetection of die sawing lines, and die number counting. The abnormal cases of fractional\ndies in the wafer boundary and dropped dies during the packaging are considered in the\nproposed method as well. The experimental results show that the precision and recall rates\nreach 99.83% and 99.84%, respectively, when determining the numbers of actual packaged\ndies in the 41 test cases.
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