Semiconductor memory device and manufacturing method thereof

Abstract

The present disclosure provides a semiconductor memory device and a manufacturing method thereof. The manufacturing method includes: providing a substrate having a plurality of active areas; forming a plurality of bit line structures on the substrate, where the plurality of bit line structures are sequentially provided at intervals along a first direction; forming a dielectric layer on the substrate; etching the dielectric layer, to form a plurality of contact holes and a plurality of isolation structures, where each contact hole is between the adjacent bit line structures, the plurality of contact holes and the plurality of isolation structures are alternately provided along a second direction, the first direction is not parallel to the second direction; and forming an isolation layer on a side wall of each bit line structure and a side wall of each isolation structure.