Patent ID: 8828748

Claim:
A method of testing a lithography system comprising: (a) providing a workpiece having a layer of photosensitive material formed thereon; (b) providing a lithography mask comprising an attenuated phase shifting material comprising a pattern for a plurality of first vias in a first region and a pattern for a plurality of second vias in at least one second region, the first region having a first phase shift and the at least one second region having at least one second phase shift; (c) using the lithography system, exposing the layer of photosensitive material of the workpiece to energy through the lithography mask; (d) developing the layer of photosensitive material of the workpiece; (e) measuring features formed on the layer of photosensitive material from the pattern for the plurality of first vias and the pattern for the plurality of the second vias; and (f) determining an amount of focus level shift or an amount of dose shift of the lithography system from the measurements made.