Capture rate enhance method of 0.1-mu m level defects by pattern-matching inspectors

In this paper, a method of enhancing the capture rate of 0.1-mum level defe cts by pattern-matching inspectors is studied from the viewpoint of image v ariances. By our method, defect inspection engineers can obtain quantitativ e information for enhancing the capture rate of 0.1-mum level defects on bo th actual devices and test element groups (TEGs). The inspection sensitivit ies were experimentally evaluated by using the detection rate of the defect s on an actual device and on the TEG. The image noise and the defect signal of the captured charge-coupled device (CCD) images of the same defect were quantitatively analyzed. The observed image noise and the defect signal ob ey a normal distribution. The capture rate calculated by our model, based o n normal distribution, almost agrees with the experimental data. Next, we p ropose a new criterion called the "practical capture rate" by uniting the c apture rate and the false count. The threshold value optimized from the vie wpoint of the practical capture rate agrees with empirical thresholds value set by our defect inspection engineers. Finally, as an example of capture rate enhancement, a unique TEG called TWICE (TEG with image contrast enhanc ing) for photoresist inspection is demonstrated.