A memory array has a plurality of conductor structures. Each conductor structure has a top wire segment extending in a first direction, a middle wire segment extending in a second direction at an angle from the first direction, a bottom wire segment extending in a direction opposite to the first direction, and a via connecting the top, middle, and bottom wire segments. A plurality of memory cells in an upper plane of the memory array are formed at intersections of the middle wire segment of each conductor structure with the top wire segments of neighboring conductor structures, and a plurality of memory cells in a lower plane are formed at intersections of the middle wire segment of each conductor structure with the bottom wire segments of neighboring conductor structures.