Semiconductor devices with backside power rail and methods of fabrication thereof

A semiconductor device, comprising:

• a first dielectric feature and a second dielectric feature;
• a first source/drain feature, wherein the first source/drain feature is a bar-shaped epitaxial feature having a first side surface facing the first dielectric feature, a second side surface facing the second dielectric feature, and a bottom surface connecting the first side surface and second side surface;
• and
• a conductive feature having a first sidewall portion and a second sidewall portion, and a body portion connecting the first sidewall portion and second sidewall portion, wherein the first sidewall portion of the conductive feature is disposed between the first dielectric feature and the first side surface of the first source/drain feature, the second sidewall portion of the conductive feature is disposed between the second dielectric feature and the second side surface of the first source/drain feature, and the body portion is disposed on the bottom surface of the first source/drain feature.

A method for forming a semiconductor device, comprising:

• forming an epitaxial source/drain feature having a top surface, a bottom surface, and a first side surface connecting the top surface and the bottom surface;
• depositing a dielectric fill material in contact with the first side surface of the epitaxial source/drain feature;
• etching back the dielectric fill material to expose the top surface of the epitaxial source/drain feature;
• depositing a contact etch stop layer (CESL), wherein the CESL is in contact with the top surface of the epitaxial source/drain feature;
• forming a first conductive feature over the top surface of the epitaxial source/drain feature;
• and
• forming a second conductive feature below the bottom surface of the epitaxial source/drain feature.