Capture rate enhance method of 0.1-Μm level defects bypattern-matching inspectors

摘要

In this paper, a method of enhancing the capture rate of 0.1-Μmnlevel defects by pattern-matching inspectors is studied from thenviewpoint of image variances. By our method, defect inspection engineersncan obtain quantitative information for enhancing the capture rate ofn0.1-Μm level defects on both actual devices and test element groupsn(TEGs). The inspection sensitivities were experimentally evaluated bynusing the detection rate of the defects on an actual device and on thenTEG. The image noise and the defect signal of the capturedncharge-coupled device (CCD) images of the same defect werenquantitatively analyzed. The observed image noise and the defect signalnobey a normal distribution. The capture rate calculated by our model,nbased on normal distribution, almost agrees with the experimental data.nNext, we propose a new criterion called the “practical rapturenrate” by uniting the rapture rate and the false count. Thenthreshold value optimized from the viewpoint of the practical capturenrate agrees with empirical thresholds value set by our defect inspectionnengineers. Finally, as an example of capture rate enhancement, a uniquenTEG called TWICE (TEG with image contrast enhancing) for photoresistninspection is demonstrated