| 摘要 |
PURPOSE: To make use of an advantage that resolution and bright illumination by using a laser luminous flux are high by a method wherein the laser luminous flux is oscillated with reference to an alignment pattern so as to be irradiated, the image of reflected diffraction light is formed by an image formation optical system, the light is received and a composed signal is detected. CONSTITUTION: A beam of light which is radiated from a laser light source 1 is divided into two beams by a beam splitter 24, and one beam is used as a beam of light which illuminates a pattern of group of hyperbolas. The other beam of light which has been separated by the beam splitter 24 is incident on the hyperbola group pattern, and specularly reflected light illuminates an alignment pattern 40 on a wafer. The laser beam is deflected by a galvanomirror 2 so as to change an angle of incidence. The beam of light which has illuminated the alignment mark on the wafer at a variable angle of incidence is reflected by the pattern so as to be returned to an original optical path again, and it is reflected specularly by a hyperbola group pattern on a reticle. Then, the image of an alignment mark on the wafer is formed in a position in which the image of diffracted light from the reticle is formed on a line. |
