2) Referring to FIG. 11, with the metal conductive layer 400 serving as an etch stop layer, using the second hard mask layer 800 as a mask to etch the insulation layer 500 to transfer the second graphical target pattern to the insulation layer 500. In this embodiment, a fluorine-containing etching is used to etch the insulation layer 500, fluorine-containing etching gases include one or more of octafluorocyclobutanne, octafluorocyclopentene, and hexafuorobutadiene. After the insulation layer 500 is etched, the second hard mask layer 800 is removed.

3) Referring to FIG. 12, with the insulation layer 500 serving as a mask, etching the metal conductive layer 400 and the non-metal conductive layer 300 to form the bitline structure 900. In this embodiment, the procedure of etching the metal conductive layer 400 and the non-metal conductive layer 300 is mainly as follows.

Firstly, with the metal barrier material layer 410 serving as an etching stop layer, the insulation layer 500 is used as a mask to etch the metal material layer 420 to transfer the second graphical target pattern to the metal material layer 420; in this embodiment, the metal material layer 420 is made of tungsten, and thus, an etching gas containing silicon hexafluoride may be used to etch the metal material layer 420 in this step.