A three-dimensional semiconductor device comprising: an alternating stack of insulating layers and electrically conductive layers located over a substrate ; memory stack structures extending through the alternating stack and arranged in at least five rows that extend along a first horizontal direction; contact via structures arranged in a same number of rows as the memory stack structures and overlying the memory stack structures , each of the contact via structures being electrically connected to a semiconductor channel of a respective memory stack structure ; bit lines contacting a respective contact via structure and extending along a second horizontal direction that is different from the first horizontal direction, and arranged as a periodic array of bit lines having a bit line pitch along the first horizontal direction; a pair of wall-shaped via structures extending through the alternating stack, and laterally extending along the first horizontal direction, wherein the at least five rows of memory stack structures are located between the pair of wall-shaped via structures ; drain regions , each of the drain regions contacting a top end of a vertical semiconductor channel within a respective memory stack structure and electrically shorted to a respective contact via structure ; and contact pillars , each of the contact pillars contacting a top surface of a respective drain region and a bottom surface of a respective contact via structure ; the three-dimensional semiconductor device characterised in that each outermost row of the memory stack structures is laterally offset in opposite directions from a hexagonal two-dimensional array formed by inner rows of the memory stack structures along the first horizontal direction by a respective finite lateral offset distance. an alternating stack of insulating layers and electrically conductive layers located over a substrate ; memory stack structures extending through the alternating stack and arranged in at least five rows that extend along a first horizontal direction; contact via structures arranged in a same number of rows as the memory stack structures and overlying the memory stack structures , each of the contact via structures being electrically connected to a semiconductor channel of a respective memory stack structure ; bit lines contacting a respective contact via structure and extending along a second horizontal direction that is different from the first horizontal direction, and arranged as a periodic array of bit lines having a bit line pitch along the first horizontal direction; a pair of wall-shaped via structures extending through the alternating stack, and laterally extending along the first horizontal direction, wherein the at least five rows of memory stack structures are located between the pair of wall-shaped via structures ; drain regions , each of the drain regions contacting a top end of a vertical semiconductor channel within a respective memory stack structure and electrically shorted to a respective contact via structure ; and contact pillars , each of the contact pillars contacting a top surface of a respective drain region and a bottom surface of a respective contact via structure ; the three-dimensional semiconductor device characterised in that each outermost row of the memory stack structures is laterally offset in opposite directions from a hexagonal two-dimensional array formed by inner rows of the memory stack structures along the first horizontal direction by a respective finite lateral offset distance. <EOS>