Patent ID: 6904164

Claim:
A method of inspecting the accuracy at which desired regions of a pattern formed by beam lithography are stitched on a material, which regions have been exposed successively to form said pattern comprising pattern elements which normally abut and align across exposure boundaries, said method comprising the steps of: selecting an inspected region containing at least two specified pattern elements existing in said exposed regions, said inspected region having at least one exposure boundary at which at least one stitching line exists between two normally abutting and aligned pattern elements; detecting signals arising from said inspected region; detecting positions of said specified pattern elements within said inspected region from said detected signals; obtaining data about a reference region corresponding to said inspected region and treating said data as reference data; finding positions of said specified pattern elements within said reference region from said reference data; and comparing said positions of said specified pattern elements within said reference region with said positions of said specified pattern elements within said inspected region, such that inspecting accuracy at which the exposed regions within said inspected region are stitched relative to the stitching of the exposed regions in the reference image is determined.