Patent ID: 7715007
Filing Date: 2010-05-11
Classification: G01B,G01N,G03F,H01L

Abstract:
1. A structure configured for overlay measurement on a sample, said structure comprising at least three pairs of diffractive structures of predetermined geometries, the diffractive structures of each pair being arranged with a predetermined different lateral shift between the diffractive structures, such that the diffractive structures of two of said at least three pairs are laterally shifted with respect to one another along an X-axis in opposite directions, and the diffractive structures of at least one other pair are laterally shifted with respect to one another along the X-axis by an additional distance Δx, where Δx is substantially smaller than a value of shifts of said two pairs, diffraction of incident light from said at least three pairs of diffractive structures being indicative of a lateral shift between layers in the sample.