Semiconductor structure with increased channel length and method for forming the same

A method for forming a semiconductor structure, comprising:

• forming a substrate, wherein the substrate comprises a body part and a protrusion part located on a surface of the body part;
• forming a gate electrode located on the body part and distributed around sidewalls of the protrusion part;
• and
• forming a first doped region and a second doped region located in the body part and distributed at two opposite sides of the gate electrode;
• before forming the first doped region and the second doped region located in the body part and distributed at the two opposite sides of the gate electrode,
• forming a first dielectric layer covering the gate electrode;
• and
• implanting a first doping ion into the body part at two opposite sides of the protrusion part to form second lightly doped regions;
• after forming the first doped region and the second doped region located in the body part and distributed at the two opposite sides of the gate electrode,
• forming a second dielectric layer covering the surface of the body part, a surface of the first dielectric layer, and a surface of the insulating layer;
• etching the second dielectric layer, the first dielectric layer and the insulating layer to form a first through hole exposing the first lightly doped region in the protrusion part, a second through hole exposing the first doped region in the body part, a third through hole exposing the second doped region in the body part, and fourth through holes exposing the gate electrode;
• and
• forming a first plug electrically connected to the first lightly doped region, a second plug electrically connected to the first doped region, a third plug electrically connected to the second doped region, and fourth plugs electrically connected to the gate electrode by filling a conductive material into the first through hole, the second through hole, the third through hole and the fourth through holes.