A sensor mark including: a substrate having: a deep ultra violet (DUV) radiation absorbing layer including a first material which substantially absorbs DUV radiation; and a protecting layer including a second material, wherein: the DUV radiation absorbing layer has a through hole in it; the protecting layer is positioned, in plan, in the through hole and the protecting layer in the through hole has a patterned region having a plurality of through holes; and the second material is more noble than the first material.