| 摘要 |
PURPOSE:To avoid the effect of residues on the mark and accurately align the mark by slightly shifting the scanning position of electron beam at every detection of the mark position. CONSTITUTION:An arm 2a of Y direction of a mark 2 is scanned in the X driection, and a regression line A of Y direction is obtained by scanning at a fixed distance X11, X21.... similarly, a regression line B of X direction is obtained by scanning at a fixed distance Y11, Y12... for an arm 2b of X direction. From calculation of the intersecting point of the lines A and B, a center P of the mark 2 can be detected. A wafer 1 is aligned based on the position P, and exposed. When the wafer 1 is aligned again in the optical system, beam scanning is conducted for X12, X22... Y12, Y22..., slightly shifted from the previous scanning positions. Therefore reflection electron signals are not distorted by oxide residues and etc. on the beam applying part, and the center P of the mark 2 can be detected accurately as before. In this way, the alignment mark is accurately aligned. |
