Semiconductor structure with isolation feature

A semiconductor structure, comprising:

• a backside dielectric layer;
• first nanostructures and second nanostructures extending in a first direction over the backside dielectric layer;
• a gate structure over the backside dielectric layer and wrapping around the first nanostructures and the second nanostructures and extending in a second direction;
• a gate spacer on a sidewall of the gate structure;
• a first source/drain structure over the backside dielectric layer and connected to the first nanostructures;
• a second source/drain structure over the backside dielectric layer and connected to the second nanostructures;
• a backside source/drain isolation feature extending in the first direction and separating the first source/drain structure and the second source/drain structure, wherein the backside source/drain isolation feature comprises:
• a liner layer over a sidewall of the first source/drain structure and a sidewall of the second source/drain structure;
• and
• an isolation material surrounded and covered by the liner layer;
• and
• a source/drain conductive contact over the first source/drain structure and laterally spaced apart from the gate structure by the gate spacer, wherein the source/drain conductive contact is at a first side of the first source/drain structure, while the backside dielectric layer is at a second side of the first source/drain structure opposite to the first side.

A semiconductor structure, comprising:

• first nanostructures;
• a first gate structure wrapping around the first nanostructures;
• a first source/drain structure attached to the first nanostructures in a first direction;
• second nanostructures;
• a second gate structure wrapping around the second nanostructures;
• a second source/drain structure attached to the second nanostructures in the first direction;
• a source/drain isolation feature sandwiched between the first source/drain structure and the second source/drain structure in a second direction different from the first direction;
• and
• a source/drain contact extending in the second direction and vertically overlapping the first source/drain structure, the second source/drain structure, and the source/drain isolation feature, wherein the source/drain contact comprises aluminum (Al), copper (Cu), tungsten (W), titanium (Ti), tantalum (Ta), titanium nitride (TiN), cobalt, tantalum nitride (TaN), nickel silicide (NiS), cobalt silicide (CoSi), copper silicide, tantalum carbide (TaC), tantalum silicide nitride (TaSiN), tantalum carbide nitride (TaCN), titanium aluminide (TiAl), or titanium aluminum nitride (TiAlN).