Our customers usually measure mask features in order to make a business decision, such as whether or not to ship a mask to a customer. A simple cost/benefit model for mask CD metrology shows there is an optimum measurement uncertainty which will maximize the expected benefit of this decision. The most significant components of this uncertainty are the chrome edge shape and errors in the image model and its input parameters. Correlations in the parameter errors can reduce the uncertainty in some common situations. The mask application, the lithography process, is topologically similar to the optical mask metrology process. The Neolithography model integrates mask metrology into the mask design and lithography optimization process, with many benefits. Process modeling, especially optical image formation, is critical to mask metrology and Neolithography. Evaluating the accuracy of such a model can be extremely difficult because high accuracy real test structures are rare.
Proceedings of the 188th PTB Seminar on CD Metrology; H. Bosse, B. Bodermann, W. Mirande` Editors; Physikalisch-Technische Bundesanstalt (PTB)
Optical Photomask CD Metrology at NIST, Proceedings of the 188th PTB Seminar on CD Metrology; H. Bosse, B. Bodermann, W. Mirande` Editors; Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, GE
(Accessed June 9, 2023)