Semiconductor structure and manufacturing method thereof

A manufacturing method of a semiconductor structure, comprising:

• providing a substrate comprising active regions and isolation regions;
• forming first trench structures on the substrate, the first trench structure passing through the active region and the isolation region;
• forming bit line contact structures in the first trench structures, wherein an upper surface of the bit line contact structure is lower than an upper surface of the substrate;
• forming bit line structures on the bit line contact structures, wherein the first trench structure is filled up with the bit line contact structure and the bit line structure, and at least part of the bit line structure is positioned in the first trench structure;
• forming bit line protection structures on the bit line structures, wherein the bit line protection structure at least covers an upper surface of the bit line structure, and a second trench structure is provided between adjacent bit line protection structures;
• and
• forming capacitor contact assemblies each comprising a first capacitor contact structure positioned in the second trench structure and a second capacitor contact structure covering an upper surface and part of a side wall of the first capacitor contact structure;
• and, wherein
• forming the first trench structures on the substrate comprises:
• forming a stress buffer material layer, an etching blocking material layer and a first mask material layer in sequence on the substrate;
• patterning the first mask material layer to form a first mask layer;
• and
• etching part of the etching blocking material layer, part of the stress buffer material layer and part of the substrate by taking the first mask layer as a mask,
• wherein the rest of the etching blocking material layer constitutes an etching blocking layer, and the rest of the stress buffer material layer constitutes a stress buffer layer;
• after the first trench structures are formed and before the bit line contact structures are formed in the first trench structures, further comprising:
• removing the first mask layer;
• and
• forming first side wall protection layers which cover side walls of the first trench structures.