Patent ID: 7817264
Filing Date: 2010-10-19
Classification: G01N

Abstract:
1. A method for preparing focus-adjustment data for a focusing lens system of an optical defect-inspection apparatus, said method comprising: positioning a wafer having a plurality of defects in place with respect to a focal plane defined by said focusing lens system; optically and electronically detecting the plurality of defects on said wafer; extracting a number of defects having a predetermined size among the plurality of defects; counting the number of defects having the predetermined size as defect-number data; repeating said positioning, said detecting, said extracting, and said counting whenever said focus-adjustment wafer is relatively shifted from said focal plane by a predetermined distance to be a different focus value; producing a defect-number distribution based on said defect-number data thus obtained; calculating a peak value of said defect-number distribution; and calculating a vertical offset value by comparing said peak value with a peak value of a defect-number distribution obtained in a similar manner to said method in an optical defect-inspection apparatus which is identical to said optical defect-inspection apparatus.