| 摘要 |
PURPOSE:To discriminate a defective chip immediately and accurately and reduce the testing time by a method wherein the patterns of at least three chips on a photomask are compared with each other and the defected chip is discriminated by detecting the difference between the compared patterns. CONSTITUTION:A chip 3, a chip 4 and a chip 11 on a photomask 7 are irradiated by a light beam 1, a light beam 2 and a light beam 10 respectively and the respective penetrating light beams 5, 6 and 12 are detected by a detector 8, a detector 9 and a detector 13. Moreover, the 1st electric output signal of the detector 8 is put into a differential device 14 and a differential device 15, and the 2nd electric output power of the detector 9 is put into the differential device 14 and a differential device 16 and the 3rd electric signal of the detector 13 is put into the differential device 15 and the differential device 16 respectively. When the chip 3 has a defect, for instance, output signals are given by the differential device 14 and the differential device 15 and no signal is given by the differential device 16. With this constitution, the defective chip can be discriminated by the output signals given by the differential device 14, the differential device 15 and the differential device 16. |
