Conductive features of semiconductor device and method of forming same

A method comprising:

• depositing a first dielectric material over a substrate;
• depositing a first barrier layer over the first dielectric material;
• depositing a conductive material over the first barrier layer;
• etching a plurality of recesses extending through the conductive material and the first barrier layer;
• selectively depositing a protective material on exposed surfaces of the conductive material and the first barrier layer, wherein the first dielectric material is free of the protective material;
• and
• depositing a liner layer on the protective material and the first dielectric material.

A structure comprising:

• a first conductive feature and a second conductive feature over a first dielectric layer, wherein the first conductive feature and the second conductive feature each comprise:
• a barrier layer over the first dielectric layer;
• a conductive layer over the barrier layer;
• and
• a capping layer on sidewalls of the barrier layer and the conductive layer;
• a liner layer extending on a sidewall of the first conductive feature, a sidewall of the second conductive feature, and a top surface of the first dielectric layer;
• and
• a second dielectric layer extending from the liner layer on the sidewall of the first conductive feature to the liner layer on the sidewall of the second conductive feature, wherein the second dielectric layer extends over an air gap.