A method of inspecting a phase shift mask is disclosed. The method includes receiving a mask having an alternating phase shift pattern. The method also includes forming the alternating phase shift pattern on a wafer. The method further includes analyzing the alternating phase shift pattern on the wafer...http://www.google.com.au/patents/US7075639?utm_source=gb-gplus-sharePatent US7075639 - Method and mark for metrology of phase errors on phase shift masks
