INSPECTION METHOD AND APPARATUS, LITHOGRAPHIC APPARATUS, LITHOGRAPHIC PROCESSING CELL AND DEVICE MANUFACTURING METHOD

摘要

A system is configured to measure two separately polarized beams upon diffraction from a substrate in order to determine properties of the substrate. Circularly or elliptically polarized light sources are passed via a fixed phase retarder in order to change the phase of one of two orthogonally polarized radiation beams with respect to the other of the two beams. The relative phases of the two radiation beams and other features of the beams as measured in a detector gives rise to properties of the substrate surface. [Fig.5]