Capture rate enhancement method of 0.1 /spl mu/m-level defects by pattern matching inspectors

In this paper, a method of enhancing the capture rate of 0.1 /spl mu/m-level defects by pattern matching inspectors is studied from the viewpoint of image variances. The inspection sensitivities are experimentally evaluated by using the detection rate of the defects on an actual device and also on the TEG. The image noise and the defect signal of the captured CCD images of the same defect are quantitatively analyzed. The observed image noise and the defect signal obey a normal distribution. The capture rate calculated by our model, based on a normal distribution, almost agrees with the experimental data. In addition, as an example of capture rate enhancing, a unique TEG called TWICE is demonstrated. By our method, defect inspection engineers can obtain the key factors for enhancing the capture rate of 0.1 pm-level defects on both actual devices and TEGs.