| 摘要 |
PURPOSE:To enable positioning having excellent accuracy even when light for sensing a position, the direction of which is not kept constant, is applied by synthesizing reflected images from each alignment mark on a mask and a wafer, on which the semitransparent alignment marks are formed, and conducting positioning so that the peak value of a syntherized brightness signal is maximized. CONSTITUTION:A mask 8, on which an alignment mark 7 composed of a material semitransparent to light is formed and which consists of a material transparent to light, is positioned between a wafer 5, on which another alignment mark 6 is formed, and a light source, the wafer 5 is irradiated with light through the mask 8 by the light source, reflected images from each alignment mark 7, 6 on the mask 8 and the wafer 5 are synthesized by using the technique of picture processing, and positioning is performed so that the peak value of the intensity distribution of a synthesized brightness signal is maximized. The semitransparent alignment mark 7 made up of a PSG film in film thickness of approximately 0.5mum is formed onto the mask 8 composed of quartz glass. Accordingly, even when light is applied obliquely and the intensity distribution of a brightness picture is asymmetrized, positioning having high accuracy can be conducted. |
