A method of manufacturing a semiconductor device, including: providing a substrate including a first cell and a second cell that are arranged in a first direction; forming a plurality of first metal strips extending in the first direction and arranged in a second direction on a first plane; forming a first trench over a boundary between the first cell and the second cell, wherein a bottom surface of the first trench is on a second plane over the first plane; filling the first trench with a non-conductive material, resulting in a separating wall which extends in the first direction; and forming a plurality of second metal strips extending in the second direction on a third plane over the second plane, wherein a first second metal strip and a second second metal strip separated from each other by the separating wall; wherein the second direction is orthogonal to the first direction.