Measuring contrast and critical dimension using an alignment sensor. Interuniversity Microelectronics Centre
A method can include directing radiation toward at least two targets using an optical scanning system so as to generate first and second portions of scattered radiation. A first target can include a plurality of first grating line structures including features having a first bias value. A second target can include a plurality of second grating line structures including features having a second bias value. The method can include detecting the first and second portions of scattered radiation, generating a first measurement signal indicative of a first target position based on the first bias ...