| 摘要 |
PURPOSE:To improve the accuracy of alignment by making end parts which are parallel to the arrangement direction of patterns have forms where diffracted light due to the above end parts is not detected in the square patterns of alignment marks which are arranged in a semiconductor wafer. CONSTITUTION:When a laser light strikes upon alignment marks 2 through an alignment optical device, diffracted lights take place and their lights ranging from primary to fourth degrees are detected in a photosensor. The angles theta of diffraction of the diffracted lights are expressed by the following relationship: THETA=Sin<-1>(Nlambda/P2) where N represents the order of diffraction; lambda represents wavelengths of the laser light. Patterns 2h have forms where irregularities 2i are prepared at end parts which are parallel to the arrangement direction. If periods P3 of the above irregularities 2i is 1/5 times periods P2 of the patterns 2h, the angles of diffraction of the primary degree diffracted light due to the irregularities 2i at the end parts are equal to those of the fifth degree diffracted light in the case of the period P2 and the primary degree diffracted light is not detected. Accordingly, even though the step coverage of an aluminum film in the vicinity of the end parts of the pattern 2h shows bilateral asymmetry, alignment can be performed correctly on the basis of detecting signals of the diffracted lights. |
