Semiconductor memory device with mold structure

Abstract

A mold structure includes gate electrodes stacked on a first substrate, a channel structure penetrating a first region of the mold structure to cross the gate electrodes, a first through structure penetrating a second region of the mold structure, and a second through structure penetrating a third region of the mold structure. The mold structure includes memory cell blocks extending in a first direction and spaced apart in a second direction, and a dummy block extending in the first direction and disposed between the memory cell blocks. Each of the memory cell and dummy blocks includes a cell region and an extension region arranged in the first direction. The first region is the cell region of one of the memory cell blocks, the second region is the extension region of the one of the memory cell blocks, and the third region is the extension region of the dummy block.