Backside contact with air spacer

A method comprising:

• applying an etching process to remove a dummy contact structure from a backside of a substrate and expose a source/drain region at a bottom of a trench;
• depositing a sacrificial layer on sidewalls of the trench;
• depositing a dielectric layer on the sacrificial layer;
• filling the trench with a conductive material;
• and
• removing the sacrificial layer.

A semiconductor structure comprising:

• a substrate having a frontside and a backside;
• a transistor formed on the frontside of the substrate, the transistor comprising a source/drain region;
• a contact extending from a bottom of the source/drain region to the backside of the substrate, wherein the contact is in direct contact with the source/drain region;
• and
• a first dielectric layer positioned along sides of the contact;
• an air gap positioned between the first dielectric layer and a second dielectric layer.