A semiconductor device includes a first single crystal silicon layer including first transistors, a first alignment mark, and at least one metal layer overlying the first single crystal silicon layer for interconnecting the first transistors; a second layer overlying the at least one metal layer, wherein the second layer includes a plurality of second transistors; and a connection path connecting the first transistors and the second transistors and including at least a first strip, a second strip, and a through via connecting the first strip and the second strip, wherein the second strip is substantially orthogonal to the first strip and wherein the through via is substantially away from both ends of the first strip and both ends of the second strip.