| 摘要 |
PURPOSE:To enable the accurate placing for patterning by detecting the predetermined interval between a mask and a wafer by detecting the light quantity of the laser beams of single wavelength which have passed a linear Fresnel zone target by which a reflective light on the wafer which is not given marks becomes maximum. CONSTITUTION:There are a mask 1 and a wafer 2, and a linear Fresnel zone plate 19 is formed on a mask surface. Laser beams (a) are projected to the mask 1 as parallel beams of wavelength lambda=0.6328mum and are focused at a point (A) on the wafer being distant from the mask with the predetermined distance (S) by diffraction determined by the predetermined linear Fresnel zone plates 19. At this time, if the distance between the mask and wafer varies with respect to (S), illumination (I) changes. Then for example, when S=10mum, a distribution of illumination distributes sharply within a range of 10+ or -2mum. Accordingly, the beams projected to the wafer for position detecting offer the maximum illumination and the maximum reflective light at a time when the beams are placed in the most appropriate position, therefore, positioning is done by focusing the above reflective lights (b) and detecting them. |
