Method of detecting mask defects, a computer program and reference substrate

摘要

A method of detecting mask defects in which a reference substrate is patterned by the mask immediately after manufacture of the mask is disclosed. The reference substrate is stored in clean conditions while IC manufacture takes place. When a mask defect is suspected, a resist coated substrate, the test substrate, is patterned by exposure of the mask. The patterns on the reference substrate and the test substrate are compared to determine if there is a mask defect. The location of the mask defect can be found by scanning smaller areas of the patterns.