US Patent 11069698 Three-dimensional semiconductor memory device

A three-dimensional semiconductor memory device may include a first stack block including first stacks arranged in a first direction on a substrate, a second stack block including second stacks arranged in the first direction on the substrate, and a separation structure provided on the substrate between the first stack block and the second stack block. The separation structure may include first mold layers and second mold layers, which are stacked in a vertical direction perpendicular to a top surface of the substrate.