| 摘要 |
PURPOSE:To eliminate the adverse influence of noise light so as to detect the relative positional deviation between a mask and wafer with high accuracy by oscillating an alignment luminous flux on the mask and wafer in a direction in which the oscillation is insensible from the detecting direction. CONSTITUTION:Alignment marks 5 on a mask 1 are scanned with a laser beam from a light source 10 by oscillating a mirror GM to which the laser loam is made incident through a collimator lens 12 and the transmit and diffracted luminous flux of the laser beam is made incident to an alignment mark 3 on the surface of a waver 2. The luminous flux made incident to the surface of the wafer 2 is condensed by means of a light receiving lens 13 and made incident to the surface of a detecting section 11. The luminous flux made incident to the section 11 is photoelectrically converted and an A/D-converting section 19 and computing means 20 find the relative in-plane positional deviation between the mask 1 and wafer 2 from the incident position of the alignment luminous flux to the detecting section 11. When the light noise caused by speckles is averaged by slightly oscillating the alignment luminous flux in a direction (y) which is insensible from the position detection, highly accurate positioning can be realized. |
