Patent ID: 8564143

Claim:
An overlay mark, comprising: N (N≧2) groups of first x-directional linear patterns, wherein each group is defined from a different one of N pre-layers; N groups of second x-directional linear patterns of a current layer, wherein each group of second x-directional linear patterns is disposed together with one group of first x-directional linear patterns, wherein the second x-directional linear patterns and the first x-directional linear patterns are arranged alternately; N (N≧2) groups of first y-directional linear patterns, wherein each group is defined from a different one of the N pre-layers; and N groups of second y-directional linear patterns of the current layer, wherein each group of second y-directional linear patterns is disposed together with one group of first y-directional linear patterns, wherein the second y-directional linear patterns and the first y-directional linear patterns are arranged alternately.