A mark position determining apparatus used in an exposure system includes a laser light source for projecting a laser beam onto an alignment mark which is formed on a substrate to be exposed with a pattern and which has a center flat surface and a pair of side surfaces. A spatial filter is located to...http://www.google.es/patents/US5446542?utm_source=gb-gplus-sharePatente US5446542 - Mark position determining apparatus for use in exposure system
Mark position determining apparatus for use in exposure system
