Semiconductor structure and manufacturing method thereof

A method of manufacturing a semiconductor structure, comprising:

• providing a substrate, the substrate comprising active regions arranged at intervals and an isolation structure located between the active regions;
• patterning the active region and the isolation structure, and forming a word line trench, the word line trench extending along a first direction, and a sidewall of the word line trench exposing the active region and the isolation structure;
• performing corner rounding at least once on the active region and the isolation structure exposed by the sidewall of the word line trench, such that a first height difference is formed in a second direction between the active region and the isolation structure exposed by the sidewall of the word line trench, the second direction being parallel to the substrate and perpendicular to the first direction;
• and
• forming, upon completion of the corner rounding, a word line filling the word line trench.

A semiconductor structure, comprising:

• a substrate, comprising active regions arranged at intervals and an isolation structure located between the active regions;
• a word line trench, penetrating through the active region and the isolation structure along a first direction;
• and
• a word line, located in the word line trench,
• wherein on a section parallel to a second direction, a first height difference is formed between the active region and the isolation structure;
• and the second direction is parallel to the substrate and perpendicular to the first direction, and
• wherein the active region comprises a recess, a side of the recess contacts the word line, and along the first direction, a width of the word line which contacting the recess is greater than a width of the word line which contacting the isolation structure.