US Patent 11980030 Three-dimensional memory device and fabrication method thereof

Three-dimensional (3D) NAND memory devices and methods are provided. In one aspect, a 3D NAND memory device includes a substrate, core regions, isolation regions, a layer stack, channel structures, and an isolation structure. Each core region is surrounded by one or more of the isolation regions. The layer stack is formed in each core region and includes first dielectric layers and conductor layers that are alternatingly stacked over each other. The channel structures are formed through the layer stack. The isolation structure is formed in one or more of the isolation regions, and includes second dielectric layers and third dielectric layers that are alternatingly stacked over each other.