Abstract: A metrology system may include a controller coupled to a scanning metrology tool that images a sample in motion along a scan direction. The controller may receive an image of a metrology target on the sample from the scanning metrology tool, where the metrology target comprises a first measurement group including cells distributed along a transverse orthogonal to the scan direction, and a second measurement group separated from the first measurement group along the scan direction including a cells distributed along the transverse direction, the second measurement group. The controller may further generate at least a first metrology measurement based on at least one of the first set of cells in the first metrology group, and generate at least a second metrology measurement based on at least one of the first set of cells in the second metrology group.

Abstract: Metrology methods and tools are provided, which enhance the accuracy of the measurements and enable simplification of the measurement process as well as improving the correspondence between the metrology targets and the semiconductor devices. Methods comprise illuminating the target in a Littrow configuration to yield a first measurement signal comprising a ?1st diffraction order and a 0th diffraction order and a second measurement signal comprising a +1st distraction order and a 0th diffraction order, wherein the ?1st diffraction order of the first measurement signal and the +1st diffraction order of the second measurement signal are diffracted at 180° to a direction of the illumination, performing a first measurement of the first measurement signal and a second measurement of the second measurement signal, and deriving metrology metric(s) therefrom. Optionally, a reflected 0th diffraction order may be split to yield components which interact with the ?1st and +1st diffraction orders.