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Although the VLSI products produced in our manufacturing lines are mostly designed with 1 micron geometries, we expect the majority of products will shift to sub-micron design very soon. This article discusses results of our experiments to releaf human operators from the already difficult visual inspection tasks with a fully automated equipment. We have two groups of visual inspection tasks necessary on the VLSI manufacturing floor. One is Engineering Analysis and the other is in-line monitor, or Product Wafer Auditing. The former, Engineering Analysis, demands a variety of different measurements and inspections, such as line width, contact area, multilayer alignment precision and defect density. On the otherhand, Product Wafer Auditing, will need only one or two such functions per mo-nitoring point in the process, but will use the function more extensively, continuously, and repeatedly. In the manufacturing environment, where the ever pressing demand to increase yield is para-mount, it is crucial to reduce defect finding and analysing time. For that purpose, we need higher speed and accuracy for production wafer inspection than can be obtained with human inspectors. In this context, our experience on the KLA-2020, fully automated wafer inspection equipment has proven to be truely beneficial in the area of the following five different cases of evaluation of the KLA-2020, conducted in our plant. Case: 1. Visual inspection of the VLSI production wafer after aluminum dry-etching was studied in comparison with human operators. The result is that not only was the KLA-2020 much more thorough in detecting defects but also was much faster than any of the operators, by far. Case: 2. We applied the KLA-2020 to identify the cause of die, lost at probe test. We traced the killer defect, which was originated from the reticle. KLA-2020 is effective in reticle qualification. Case: 3. We found that the line-width instruments based upon laser scatterology cannot properly measure most of the dense 1 micron geometry of our VLSI devices. However, the KLA-2020 has provided excellent data of such Case: 4. During the course of process development, where the objective was to improve the LW uniformity within a production wafer, we found the efficiency and accuracy of the KLA-2020 were so good that the objective was met successfully in a very short time. In addition, the yield was improved remarkably. Case: 5. There have been no practical and simple methods to measure a small area in a pro-duction VLSI wafer. We will show the experimental results of measuring the area of contact holes in dropouts using the KLA-2020.
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