A three-dimensional memory device includes an alternating stack of insulating layers and electrically conductive layers located between line trenches, a first memory array region and a second memory array region, and a pair of dielectric wall structures located between the first line trench and the second line trench and between the memory array regions. Each layer within the alternating stack continuously extends between the first memory array region and the second memory array region in a connection region. The electrically conductive layers of the alternating stack have lateral extents that decrease with a distance from the substrate in a staircase region. Dielectric material plates interlaced with insulating plates or insulating layers are provided between the dielectric wall structures.