| 摘要 |
PURPOSE:To perform positioning of high accuracy by using the first exposure mask and the second exposure mask which has a projected part extending from the reduced main part and the main part of an alignment mark for the former mask over the alignment mark. CONSTITUTION:The alignment mark 4 for the second exposure mask 7 is projected out of the algnment mark 5 for the first exposure mask 6 at the parts 10, and is small except them. The mark 4 is made to coincide, by the mark 5 for the mask 6, with a target mark formed on a semiconductor substrate. In other words, the center 8 of the mark 5 is made to agree with the center 9 of the mark 4. When the dimensional difference between the target mark on the semiconductor substrate and the projected parts 10 are determined with high accuracy, the masks can be superposed with high accuracy by the projected parts 10. Besides, the using order of the first and second masks can be exchanged to each other. |
