Setting quality control requirements to balance cycle time and yield — The single machine case

摘要

Control limits in use at metrology stations are traditionally set by yield requirements. Since excursions from these limits usually trigger machine stoppage, the monitor design has a direct impact on the station's availability, and thus on the product cycle time (CT). In this work we lay the foundation for a bi-criteria trade-off formulation between expected CT and die yield based on the impact of the inspection control limits on both performance measures. We assume a single machine plagued by a particle deposition process and immediately followed by a monitor step. We explore the impact of the upper control limit on the expected final yield on one hand, and on the distribution of the station time between consecutive stoppages on the other. The obtained model enables decision makers to knowingly sacrifice yield to shorten CT and vice versa.