Patent ID: 8363219

Claim:
A structure configured for overlay measurement on a sample, said structure comprising two pairs of diffractive structures of predetermined geometries, wherein said two pairs of diffractive structures are formed by two diffractive structures spaced-apart from one another along an X-axis and two diffractive structures spaced-apart from one another along a Y-axis, the diffractive structures of each pair are spaced-apart from one another along the Y-axis or the X-axis, respectively, and comprise patterns of features aligned along the X-axis or the Y-axis, respectively, with a predetermined lateral shift between the patterns in the structures in accordance with a predetermined model of simulated diffraction effects from incident light interaction with laterally shifted diffractive structures of a pair of such structures of said predetermined geometries, thereby enabling direct overlay measurement of a lateral shift between layers in the sample from diffraction of incident light from said two pairs of diffractive structures.