An interconnect structure includes first, second, and third insulating layers, first, second, and third conductive lines, and first, second, third, and fourth conductive vias. The first conductive line is embedded in the first insulating layer. The second conductive line is embedded in the second insulating layer and comprises a first portion, a second portion, and a third portion. The third conductive line is embedded in the third insulating layer. The first and second conductive via are embedded in the first insulating layer. The third and fourth conductive via are embedded in the second insulating layer. A first cross-sectional area surrounded by the first conductive line, the first conductive via, the second conductive via, the first portion, and the second portion is substantially equal to a second cross-sectional area surrounded by the first portion, the third portion, the third conductive via, the fourth conductive via, and the third conductive line.