In some embodiments, 3-dimensional semiconductor memory device includes a semiconductor substrate extending horizontally in a first direction and a second direction crossing the first direction. A stacked memory cell array is formed on the semiconductor substrate. The memory device further includes a separation pattern including a plurality of separation lines extending in the first direction and arranged in the second direction, and dividing the stacked memory cell array into a plurality of memory cell structures extending in the first direction and arranged in the second direction. An upper insulating layer is formed above the plurality of memory cell structures and separation lines, and a passivation layer is formed above the upper insulating layer. The passivation layer includes a plurality of first regions having a first vertical thickness. A plurality of gap regions in the passivation layer are formed between the plurality of first regions. The plurality of first regions vertically overlap the plurality of memory cell structures, and the plurality of gap regions vertically overlap the plurality of separation lines.