OVERLAY METROLOGY MARK

摘要

An overlay metrology mark for determining the relative position between two or more layers of an integrated circuit structure comprising a first mark portion associated with a first layer and a second mark portion associated with a second layer, wherein the first and second mark portions comprise geometrically similar periodic arrays of mark structures laid down such that the mark portions have patterns exhibiting rotational symmetry with the axes coincident when the mark is in correct alignment whereby the first mark portion overlays the second mark portion when in correct alignment to create an overlap region, but wherein the periodic array of the first mark portion is systematically shifted relative to the periodic array of the second mark portion to generate a Moiré fringe effect in at least a part of the overlap region. A method of marking and a method of determining overlay error are also described.