Semiconductor structure and forming method thereof

A forming method of a semiconductor structure, comprising:

• providing a base, comprising a target layer configured to form a target pattern;
• forming mandrel lines that extend along a first direction and are arranged at intervals along a second direction on the base, wherein the second direction is perpendicular to the first direction, and wherein opposite sidewalls of adjacent mandrel lines in the second direction are a first sidewall and a second sidewall;
• forming a sacrificial spacer on a sidewall of the mandrel line;
• after forming the sacrificial spacer, forming a sacrificial layer extending along the first direction on a part of the base between adjacent sacrificial spacers, wherein the sacrificial layer covers a sidewall of a sacrificial spacer located on the first sidewall, and is spaced apart from a sacrificial spacer located on the second sidewall;
• forming a filling layer on the base exposed by the mandrel line, the sacrificial spacer, and the sacrificial layer;
• removing the sacrificial layer, to form an opening in the filling layer;
• removing the sacrificial spacer, wherein the opening and the first sidewall form a trench;
• forming a third blocking groove running through the mandrel line along the second direction;
• forming a mask spacer on a sidewall of the trench, wherein the mask spacer is further filled between the sidewall of the mandrel line and the filling layer, and the mask spacer located on the sidewall of the trench forms a first groove, mask spacers located in the third blocking groove are in contact with each other, and the mask spacers located in the third blocking groove are used as a third cutting layer cutting the mandrel line along the first direction;
• forming a second groove running through the filling layer between the sidewall of the trench and the mask spacer located on the second sidewall;
• removing the mandrel line, to form a third groove, wherein a cutting layer is formed in at least one of the third groove, the second groove, and the first groove, and the cutting layer cuts the corresponding groove along the first direction;
• and
• patterning the target layer below the third groove, the second groove, and the first groove using the cutting layer, the mask spacer, and the filling layer as a mask, to form the target pattern.

A semiconductor structure, comprising:

• a base, comprising a target layer configured to form a target pattern;
• mandrel lines, located on the base, wherein the mandrel lines extend along a first direction and are arranged at intervals along a second direction, wherein the second direction is perpendicular to the first direction, and opposite sidewalls of adjacent mandrel lines in the second direction are a first sidewall and a second sidewall, a part of the mandrel line is doped with ion and used as a third cutting layer configured to cut the mandrel line along the first direction;
• a filling layer, located on the base exposed by the mandrel lines, wherein a trench running through a part of the filling layer is formed between adjacent mandrel lines in the second direction, and the trench exposes the first sidewall and is spaced apart from the second sidewall;
• a mask spacer, located on a sidewall of the trench and between a sidewall of the mandrel line and the filling layer, wherein the mask spacer located on the sidewall of the trench forms a first groove, and the first groove is spaced apart from the mandrel lines by the mask spacer;
• a second groove, running though the filling layer between the first groove and the mask spacer located on the second sidewall, wherein the mandrel line is configured to occupy space for forming a third groove;
• and
• a cutting layer, running through at least one of the mandrel line, the second groove, and the first groove along the second direction, wherein the cutting layer is configured to cut the corresponding groove along the first direction.