| 摘要 |
PURPOSE:To enable high-accuracy positioning by a method wherein rough positioning is carried out by fitting the relative position between the 0-degree diffracted light from a reticle and that from a substrate, and the photo intensity of the flux diffracted by a grating having a pitch of an integer multiple of that of interference fringes in measured by a photo detector. CONSTITUTION:Filtering is carried out on a spectrum surface by arranging a space filter 16 to Fourier transformation surfaces, and the pattern formed on a reticle 14 is filtered on the spectrum surface, thereby forming interference fringes on the wafer 18 surface. Then, photo intensity information showing the positional relation between the interference fringes and the grating is obtained by making beams diffracted by the grating on the wafer 18 interfere with each other. A sharp peak of photo intensity appears when the pitch of the grating is an integer multiple of that of the interference fringes. The photo intensity is observed by periodically varying the photo intensity at every pitch of the grating, thus showing the relative position between the interference fringes and the grating. Rough positioning of approx. 0.3mum is carried out by the same positioning as conventional; then, high-accuracy positioning can be accomplished in a short time with Moire fringes in a square bright pattern. |
