US Patent 9123649 Fit-to-pitch overlay measurement targets

Various target configurations are disclosed. A target may include multiple lines spaced equally apart according to a pitch distance. The target may also include a first mark having at least one edge parallel to the lines, wherein the edge is configured to have at least one of: a periodically repetitive edge pattern having an amplitude that is a multiple of the pitch, a length that is a multiple of the pitch, or a thickness that is a multiple of the pitch. The target may further include a second mark having at least one edge parallel to the plurality of lines, wherein the edge is configured to have at least one of: a periodically repetitive edge pattern having a second amplitude that is a multiple of the pitch, a length that is a multiple of the pitch, or a thickness that is a multiple of the pitch.