US Patent 7463367 Estimating overlay error and optical aberrations

Aberration marks, which may be used in conjunction with lenses in optical photolithography systems, may assist in estimating overlay errors and optical aberrations. Aberration marks may include an inner polygon pattern and an outer polygon pattern, wherein each of the inner and outer polygon patterns include a center, and two sets of lines and spaces having a different feature size and pitch that surround the outer polygon pattern. In some embodiments, the marks can be used with scatterometry or scanning electron microscope devices.