Semiconductor structure and formation method thereof

A formation method of a semiconductor structure, comprising:

• providing a base, wherein a laminate structure is formed on the base and comprises a plurality of channel laminates sequentially stacked from bottom to top, each of the plurality of channel laminate comprises a sacrificial layer and a first channel layer located on the sacrificial layer, the first channel layer extends along a horizontal direction, and a direction parallel to the base and perpendicular to the horizontal direction is a longitudinal direction;
• forming a dummy gate structure stretching across the laminate structure on the base;
• forming grooves in parts, on two sides of the dummy gate structure, of the laminate structure;
• forming a source/drain structure in the groove, wherein the source/drain structure comprises a first source/drain doped layer covering a side wall of the first channel layer exposed out of the groove;
• removing the dummy gate structure and forming a gate opening to expose a channel laminate;
• removing the sacrificial layer in the channel laminate via the gate opening, such that adjacent first channel layers as well as the base and the first channel layer adjacent to the base are surrounded to form a through groove;
• forming gate structures in the gate opening and the through groove to surround the first channel layer;
• and
• forming source/drain plugs on two sides of the gate structure, wherein the source/drain plug is in contact with a top of the source/drain structure, and the source/drain plug is further in contact with at least one of a longitudinal side wall facing away from the gate structure, a side wall along a horizontal first side and a side wall along a horizontal second side of the first source/drain doped layer.