As shown in FIG. 7, the second initial conductive layer 80 may be removed by a certain thickness with CMP, such that a retained second initial conductive layer 80 forms the second conductive layer 81, and the second conductive layer 81 and the first conductive layer 31 are connected into a whole to form a BL contact layer 90.

In the embodiment, through planarization on a top surface of the second initial conductive layer 80 with the CMP, the top surface of the BL contact layer 90 formed by the first conductive layer 31 and the second conductive layer 81 is parallel to a horizontal plane, thereby avoiding the height difference between BLs subsequently formed on the BL contact layer and ensure the performance of the BLs.

It is to be noted that the top surface of the BL contact layer 90 may be higher than the top surface of the first conductive layer 31, and may also be flush with the top surface of the first conductive layer 31 in the embodiment.

In some embodiments, after the step that the second initial conductive layer is removed by a certain thickness, such that a retained second initial conductive layer forms the second conductive layer, and the second conductive layer and the first conductive layer are connected into a whole to form a BL contact layer, the manufacturing method further include the following step.

As shown in FIG. 8, a BL conductive layer 100 and a second mask layer with a pattern 110 that are stacked sequentially are formed on the BL contact layer 90.