Semiconductor structure and method for forming semiconductor structure

A method for forming a semiconductor structure, comprising:

• providing a substrate comprising a first surface and a second surface opposite to the first surface, wherein the substrate comprises a plurality of active areas separated from each other and arranged along a first direction, the active areas are disposed in parallel along a second direction, and the first direction is disposed perpendicular to the second direction;
• forming a plurality of first recesses in the substrate, wherein the first recesses stretch from the first surface to the second surface, and the first recesses are arranged along the second direction and run through an active area along the first direction;
• forming an initial word line gate structure in a first recess, wherein the initial word line gate structure comprises a first side wall and a second side wall opposite to the first side wall, and the first side wall and the second side wall are respectively adjacent to the active area;
• removing the first side wall and a part of the active area adjacent to the first side wall to form a word line gate structure and to form a second recess between the word line gate structure and the active area;
• forming a first isolation structure in the second recess;
• forming a plurality of capacitor structures on the first surface of the substrate, wherein each of the capacitor structures is electrically coupled with an active area adjacent to the second recess;
• and
• forming a plurality of bit lines on the second surface of the substrate, wherein the bit lines are arranged along the first direction and parallel to the second direction.