Interconnect Structure and Method of Forming the Same

A semiconductor device, comprising:

• a first dielectric layer;
• a second dielectric layer over the first dielectric layer;
• a third dielectric layer over the second dielectric layer;
• a fourth dielectric layer over the third dielectric layer;
• a first conductive feature in the fourth dielectric layer and the third dielectric layer, the third dielectric layer physically contacting the first conductive feature;
• a second conductive feature in the second dielectric layer extending from the first conductive feature and through the first dielectric layer;
• a gap between the first conductive feature and the fourth dielectric layer and between the second conductive feature and the second dielectric layer, the gap contacting a surface of the first conductive feature over the third dielectric layer and a surface of the second conductive feature below the third dielectric layer;
• and
• a fifth dielectric layer over the fourth dielectric layer, the first conductive feature, and the gap.

A semiconductor device, comprising:

• a first dielectric layer;
• a second dielectric layer over the first dielectric layer;
• a third dielectric layer over the second dielectric layer;
• a first conductive feature extending through the third dielectric layer and the second dielectric layer and into the first dielectric layer, the second dielectric layer physically supporting the first conductive feature, an air gap contacting a first sidewall surface of the first conductive feature above the second dielectric layer and extending between the first sidewall surface of the first conductive feature and the third dielectric layer, the air gap further contacting a second sidewall surface of the first conductive feature below the second dielectric layer and extending between the second sidewall surface and the first dielectric layer;
• and
• fourth dielectric layer over the first conductive feature and the third dielectric layer.