In this embodiment, the procedure of forming the first hard mask layer 700 includes: sequentially forming a first hard mask material layer 710 and a first organic mask material layer 720 on a surface of the first sublayer of non-metal conductive material 310a, wherein the first hard mask material layer 710 is formed using silicon oxide or other insulation materials, the first organic mask material layer 720 is formed using organic materials containing silicon; forming the first hard mask layer 70 consisting of the first hard mask material layer 710 and the first organic mask material layer 720; then, coating a layer of photoresist on the first organic mask material layer 720 to form a first photoresist layer (not shown), and patterning the first photoresist layer by a photolithography process, the patterned first photoresist layer having a first graphical target pattern defining the bitline structure 900; finally, with the first photoresist layer serving as a mask, etching the first hard mask material layer 710 and the first organic mask material layer 720 to transfer the first graphical target pattern to the first hard mask layer 700. In addition, after the bitline structure 900 is formed, removing the first organic mask material layer 720 and the first photoresist layer, and retaining only the first hard mask material layer as the first hard mask layer.

Step 3: forming the second sublayer 320 of the non-metal conductive layer. In one of the embodiments, the step of forming the second sublayer 320 of the non-metal conductive layer includes:

forming a second sublayer of non-metal conductive material 320a, with which the bitline contact hole 200 is filled and the surface of the first hard mask layer 700 is covered;