Patent ID: 6541779
Filing Date: 2003-04-01
Classification: H01J

Abstract:
In a charged-particle-beam (CPB) microlithography apparatus including an illumination-optical system and a projection-optical system, a system for detecting a position of an alignment mark, the system comprising:a backscattered-electron (BSE) detector situated and configured to detect electrons backscattered from an irradiated alignment mark and output a corresponding BSE-data signal based on a quantity of backscattered electrons detected by the BSE detector; a detection-system selector situated to receive the BSE-data signal and configured to select, from among multiple candidate techniques for determining the position-of the alignment mark, a particular technique based on a characteristic of the BSE-data signal; and a controller configured to perform any of the candidate techniques, the controller being connected to the detection-system selector and configured to calculate, according to the selected technique and from the BSE-data signal, the position of the alignment mark.