Scatterometers and scatterometry methods using acoustic radiation

摘要

The acoustic scatterometer 502 has an acoustic source 520 operable to project acoustic radiation 526 onto periodic structures 538 and 540 formed on a substrate 536 . Acoustic detector 518 is operable to detect first order acoustic diffraction 528 diffracted by periodic structures 538 and 540 while distinguishing from specular reflection (zero order 532 ). Another acoustic detector 522 is again operable to detect +1 order acoustic diffraction 530 diffracted by the periodic structure while distinguishing it from specular reflection (0th order 532). The sound source and sound detector may be piezo transducers. The angle of incidence of the projected acoustic radiation 526 and the position of the detectors 518 and 522 are such that the detection of −1 and +1 order acoustic diffractions 528 and 530 is distinct from the 0th order specular reflection 532 . (538 and 540).