Abstract: In an overlay measurement method, an overlay mark having programmed overlay values is provided. The overlay mark is scanned with an electron beam to obtain a voltage contrast image. A defect function that changes according to the overlay value is obtained from voltage contrast image data. Self-cross correlation is performed on the defect function to determine an overlay.

Abstract: A semiconductor device includes a substrate having a key region, a dummy active pattern on the key region, the dummy active pattern including a first impurity region and a second impurity region, a line structure provided on the first impurity region and extended in a first direction, a dummy gate electrode provided between the first and second impurity regions and extended in a second direction crossing the first direction, and a dummy contact disposed adjacent to a side of the line structure and connected to the second impurity region. The dummy contact includes a plurality of long contacts arranged in the second direction.