MULTIPLE LAYER ALIGNMENT SENSING

摘要

Using an imaging system (104) in relation to a plurality of material layers (114, 116) is described, the material layers being separated by a distance greater than a depth of field of the imaging system. A focal plane (106) of the imaging system and a first (114) of the plurality of material layers are brought into correspondence. A first image including at least a portion of the first material layer (114) having a first feature of interest thereon (116) is stored. The focal plane (106) of the imaging system and a second (118) of the plurality of material layers are brought into correspondence. A second image including at least a portion of the second material layer (118) having a second feature of interest thereon (120) is acquired. The first and second images are processed for automatic computation of an alignment measurement between the first and second features of interest.