Development of sample planning for wafer defect inspection

Sample planning for wafer defect inspection is a critical issue for reducing total cost. It is important to develop a cost-effective sampling plan. In the present study, using three parameters (gain, coefficient of gain variation, and payback period), an optimized sampling plan has been identified by principal component analysis. In particular, a robust sampling plan can be evaluated in terms of a coefficient of gain variation and a cost-effective sampling plan can be evaluated in terms of both gain and the payback period. This indicates that the optimal sampling plan must be designed from both economic and technical viewpoints to reduce the total inspection cost.