“…Thus, point-measurement techniques such as spectroscopic ellipsometry, 1-4 phase-sensitive ellipsometry, 5 laser reflectometry, 6,7 multi-beam interferometry, 8,9 and emission spectroscopy 10,11 have been successfully implemented. Typically, the structure height is measured at a single point or region of interest and information across the wafer is inferred assuming the process is uniform.…”