How mass metrology broke out of the cycle of complexity while maintaining the chip quality, yielding a new approach to semiconductor process monitoring.
Building semiconductors is an incredibly exacting process, with critical dimensions posing significant equipment challenges—and with the possibility that small process excursions can cause the yield to decrease. For this reason, it has always been important to measure and monitor the most critical process steps to ensure that no further processing is done on a faulty lot and so that equipment can be brought back into spec before any more lots are misprocessed.
As device structures become more complicated and require more process steps, process control becomes even more critical. Conventional metrology is challenged to characterize the tiny features with the required sensitivity. Fab metrology on simplified test structures or monitor wafers is not necessarily reflective of the actual structures. Lab metrology (e.g., TEM, XPS, etc.) is slow, expensive, and, of course, often destructive.
Process engineers have been looking for ways to break out of the cycle of complexity while maintaining the level of quality that chip users rely on. This search has yielded a new approach to semiconductor process monitoring that promises to be simpler, less expensive, and less time consuming than traditional approaches. It’s called mass metrology.
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