Abstract: An overlay marker adapted for use in fabricating a semiconductor device and a method of measuring overlay accuracy using the overlay marker are disclosed. The semiconductor device comprises sequentially disposed first, second, and third material layers, and the overlay marker comprises a primary marker and a secondary marker. The primary marker comprises a first pair of primary markers oriented in a first direction and disposed facing each other on the first material layer, and a second pair of primary markers oriented in a second direction and disposed facing each other on the second material layer. The secondary marker is disposed on the third material layer and comprises a first pair of secondary markers and a second pair of secondary markers.