Metrology of optically-unresolved features using interferometric surface profiling and RCWA modeling.

Rigorous coupled wave analysis (RCWA) interprets 3D white-light interference microscopy profiles and reveals the dimensions of optically-unresolved surface features. Measurements of silicon etch depth of a 450-nm pitch grating structure correlate to atomic force microscopy with R(2)= 0.995 and a repeatability of 0.