Edge contrast: A new definition for comparative lithography tool characterization

A new definition called ‘‘edge contrast’’ is proposed for realistic resolution comparisons between tools of different beam technology. This new quantity does not pre‐empt the traditional intensity contrast definition, but extends it. Taken into account are both the intensity levels in areas to be exposed and not to be exposed, as well as the transition variations (edge slope) between them. As a result, it will be shown that, compared to light‐optical tools, electron beam systems have a resolving capability already superior in the range of feature dimensions well above 1 μm. A comparison on the basis of the intensity contrast definition would place the point of equivalency in the vicinity of 0.5 μm. The new definition is not only adequate to characterize the lithography tool, but also suitable to encompass the entire process chain provided the functional dependencies between the process parameters are known.