Optical three-dimensional (3-D) nanostructure metrology utilizes a model-based metrology approach to determine critical dimensions (CDs) that are well below the inspection wavelength. A project at the National Institute of Standards and Technology is evaluating how to attain key CD and shape parameters from engineered in-die capable metrology targets. The performance of simplified models is validated using highly accurate, fully 3D simulations.
M. A. Henn, et al. Evaluating the effects of modeling errors for isolated finite three-dimensional targets. J. of Micro/Nanolithography, MEMS, and MOEMS, 16, 044001 (2017).