Image plane positioner for semiconductor substrate photolithography - utilises two light beams in same plane, perpendicular to and intersecting at image plane centre

摘要

The device accurately positions the surface of a substrate (11) in the image plane (5) of a projecting objective lens (6) having a short focal distance, and can be used e.g., for the photolithographic transfer of structures onto semiconductor components. The device contains an illuminating system (1,2) which generates two light beams (3,4) and a photosensitive receiving system (9,10) for the light beams (7,8). Both these systems are external to the projecting objective lens (6). The two light beams (3,4) are placed in a plane which is pref. perpendicular to the image plane (5). The intersection between the two light beams (3,4) is situated in the centre of the image plane (15). A vertical shifting or a tilting of the substrate's (11) surface in relation to the image plane is detected with certainty.