Semiconductor Device with Backside Power Rail and Method for Forming the Same

A method, comprising:

• providing a structure having a frontside and a backside, the structure including a substrate at the backside of the structure and a fin at the frontside of the structure, wherein the substrate includes a sacrificial feature under the fin, and wherein the fin includes a plurality of sacrificial layers and a plurality of channel layers alternately arranged;
• recessing the fin from the frontside of the structure, thereby exposing the sacrificial feature in a source/drain (S/D) region;
• forming an S/D epitaxial feature above the sacrificial feature;
• thinning down the structure from the backside of the structure until the sacrificial feature is exposed;
• etching the sacrificial feature from the backside of the structure to form a trench exposing the S/D epitaxial feature;
• depositing a conductive feature in the trench;
• and
• forming a metal wiring layer on the backside of the structure, wherein the metal wiring layer electrically couples to the S/D epitaxial feature through the conductive feature.

A semiconductor structure, comprising:

• first and second source/drain (S/D) epitaxial features;
• one or more channel structures connecting the first and second S/D epitaxial features;
• a gate structure engaging the one or more channel structures, wherein the first and second S/D epitaxial features, the one or more channel structures, and the gate structure are at a frontside of the semiconductor structure;
• a metal wiring layer at a backside of the semiconductor structure;
• and
• a conductive feature connecting the metal wiring layer and the first S/D epitaxial feature, wherein the conductive feature extends to a position directly under the one or more channel structures.