| 摘要 |
PURPOSE:To improve defect detecting precision by arranging plural focus offsets optionally. CONSTITUTION:Firstly, a focus is automatically adjusted in a reference focus position 14 by an automatic focusing offset unit. Secondly, focus offset values A, B are set and a focus position is switched sequently from 15 to 16, so that a focus can be adjusted properly to respective layers such as a wiring part 18 and a contact part, 19, and consequently, a failure to find a defect is eliminated and defect detecting precision is improved. |
