Source/drain contacts and methods of forming same

A device comprising:

• a device layer comprising a transistor;
• and
• a backside interconnect structure on a backside of the device layer, the backside interconnect structure comprising:
• a semiconductor material;
• a first insulating material, wherein the first insulating material contacts a gate stack of the transistor and the semiconductor material;
• a contact extending through the first insulating material to a first source/drain region in the device layer;
• and
• a conductive line electrically connected to the first source/drain region by the contact.

A method comprising:

• forming a device layer on a semiconductor substrate, the device layer comprising a plurality of transistors, wherein forming the device layer comprises:
• etching a first recess in the semiconductor substrate;
• epitaxially growing a sacrificial semiconductor material in the first recess;
• and
• epitaxially growing a first source/drain region over the sacrificial semiconductor material in the first recess;
• and
• forming a backside interconnect structure on a backside of the device layer, wherein forming the backside interconnect structure comprises:
• removing a portion of semiconductor substrate to expose the sacrificial semiconductor material;
• depositing a first dielectric layer over remaining portions of the semiconductor substrate and around the sacrificial semiconductor material;
• removing the sacrificial semiconductor material to expose the first source/drain region, wherein the remaining portions of the semiconductor substrate masks a second source/drain region while removing the sacrificial semiconductor material;
• and
• after removing the sacrificial semiconductor material, forming a source/drain contact to first source/drain region.