A wafer is aligned by using an alignment light having a longer wavelength than an exposure light. Exposure and alignment are effected through a common reduction lens. A wavefront aberration caused by the use of the long wavelength alignment light is compensated by a hologram. Thus, an alignment precision...http://www.google.es/patents/US4862008?utm_source=gb-gplus-sharePatente US4862008 - Method and apparatus for optical alignment of semiconductor by using a hologram
Method and apparatus for optical alignment of semiconductor by using a hologram
