Semiconductor structure and forming method thereof

A semiconductor structure forming method, comprising:

• forming a trench by etching a pad layer, wherein the trench passes through the pad layer along a direction;
• depositing a gate on the pad layer, wherein the gate is in T-shape and extends into the trench;
• depositing a protecting layer on the pad layer and the gate;
• and
• forming two protecting parts by etching the protecting layer to remove a bottom part and a top part of the protecting layer, the two protecting parts respectively covering two side walls and a first metal layer of the gate disposed between the two protecting parts;
• wherein, the gate comprises:
• a first part disposed on the pad layer, and comprising the two side walls and the first metal layer;
• and
• a second part connected to the first part, and located in the trench.

A semiconductor structure, comprising:

• a pad layer;
• a trench passing through the pad layer along a direction;
• a gate being in T-shape, disposed on the pad layer, and extending into the trench, the gate comprising:
• a first part disposed on the pad layer, and comprising two side walls and a first metal layer;
• and
• a second part connected to the first part, and located in the trench;
• and
• two protecting parts respectively covering the two side walls to isolate the first metal layer from an outside.