Semiconductor structure and manufacturing method thereof

A manufacturing method of a semiconductor structure, comprising:

• providing a substrate, the substrate comprising a polysilicon layer, a first conductive layer, a first dielectric layer, a mask layer, and a sacrificial layer sequentially formed thereon, wherein the sacrificial layer has a plurality of first trenches distributed at intervals and the polysilicon layer is electrically connected to an Active Area in the substrate;
• forming a first insulating layer on the sacrificial layer, the first insulating layer covering a top surface of the sacrificial layer, a bottom of the first trench, and sidewalls of the first trench;
• forming a protective layer, the protective layer only covering a surface of the first insulating layer above the top surface of the sacrificial layer;
• removing the first insulating layer located at the bottom of the first trench;
• removing the protective layer, part of the first insulating layer, the sacrificial layer, and part of the mask layer to form a first pattern layer;
• and
• removing part of the first dielectric layer, part of the first conductive layer, and part of the polysilicon layer by using the first pattern layer as a mask to form a bit line structure.