Semiconductor structure with dielectric fin structure and method for manufacturing the same

A semiconductor structure, comprising:

• a substrate;
• first nanostructures and second nanostructures formed over the substrate;
• a first dielectric fin structure formed between the first nanostructures and the second nanostructures, wherein the first dielectric fin structure comprises a first core portion, first connecting portions sandwiched between the first nanostructures and the first core portion, and second connecting portions sandwiched between the second nanostructures and the first core portion;
• and
• a gate structure comprising a first portion and a second portion, wherein the first portion of the gate structure is formed around the first nanostructures and the first connecting portions, and the second portion of the gate structure is formed around the second nanostructures and the second connecting portions.

A method for manufacturing a semiconductor structure, comprising:

• alternately stacking first semiconductor material layers and second semiconductor material layers to form a semiconductor stack over a substrate;
• patterning the semiconductor stack to form a first fin structure and a second fin structure;
• forming a first dielectric fin structure in a first space between a second sidewall of the first fin structure and a first sidewall of the second fin structure;
• removing the first semiconductor material layers of the first fin structure to form first nanostructures exposed by a first gate trench;
• trimming the first dielectric fin structure to form first connecting portions connected to the first nanostructures;
• and
• forming a first portion of a gate structure in the first gate trench,
• wherein the first portion of the gate structure covers top surfaces and bottom surfaces of the first connecting portions of the first dielectric fin structure and surrounds the first nanostructures.