The combination of SEM for high spatial resolution, images from multiple angles to provide 3D information, and commercially available stereo photogrammetry software for 3D reconstruction offers promise for dimensional metrology in 3D. A method is described to test 3D photogrammetry software by the use of virtual samples--mathematical samples from which simulated images are made for use as inputs to the software under test. The virtual sample is constructed by wrapping a rough skin with any desired power spectral density around a smooth near-trapezoidal line with rounded top corners. Reconstruction is performed with images simulated from different angular viewpoints. The software's reconstructed 3D model is then compared to the known geometry of the virtual sample. Three commercial photogrammetry software packages were tested. Two of them produced results for line height and width that were within close to 1 nm of the correct values. All of the packages exhibited some difficulty in reconstructing details of the surface roughness.
Proc. SPIE 9778
February 21-25, 2016
San Jose, CA
Metrology, Inspection, and Process Control for Microlithography XXX
critical dimension (CD), dimensional metrology, model-based metrology, scanning electron microscopy (SEM), simulation, stereo photogrammetry, surface roughness, virtual sample