A method for determining an overlay offset may include, but is not limited to: obtaining a first anti-symmetric differential signal (ΔS1) associated with a first scatterometry cell; obtaining a second anti-symmetric differential signal (ΔS2) associated with a second scatterometry cell and computing an overlay offset from the first anti-symmetric differential (ΔS1) signal associated with the first scatterometry cell and the second anti-symmetric differential signal (ΔS2) associated with the second scatterometry cell.