3D memory device and manufacturing method thereof

The invention discloses a 3D memory device and a manufacturing method thereof. The manufacturing method comprises the following steps: forming a first etching stop layer on the surface of a substrate;forming a first insulating laminated structure on the first etching stop layer, wherein the first insulating laminated structure comprises a plurality of interlayer insulating layers and sacrificiallayers which are alternately stacked; forming a plurality of first channel holes penetrating through the first insulating laminated structure, the first channel holes extending to the surface of the first etching stop layer; and etching along the plurality of first channel holes to remove the first etching stop layer so as to form a plurality of first channel holes, the first channel holes extending into the substrate, and forming channel columns in the first channel holes. Through the first etching stop layer formed on the surface of the substrate, when the first channel hole is formed, the first etching stop layer is