An interconnect structure includes a first low-k dielectric layer formed over a substrate. A first metal line is disposed in the first low-k dielectric layer. The first metal line includes a first conductive body with a first width and an up landing pad with a second width. The first width is smaller than the second width. The interconnect structure further includes a first air-gap adjacent to sidewalls of the first conductive body. The interconnect structure also includes a second low-k dielectric layer formed over the first low-k dielectric layer and a first via in the second low-k dielectric layer and disposed on the up landing pad.