Methods and structures of a three-dimensional memory device are disclosed. In an example, the memory device includes a substrate and a first alternating conductor/dielectric stack disposed on the substrate and a dielectric layer disposed over the first alternating conductor/dielectric stack. A second alternating conductor/dielectric stack is disposed on the dielectric layer. The NAND memory device includes one or more array common source contacts extending orthogonally with respect to the surface of the substrate through the first layer stack and the second layer stack, wherein at least one of the one or more array common source contacts includes a first conductive contact and a second conductive contact that is disposed over and electrically connected with the first conductive contact.