Semiconductor device comprising air gaps having different configurations

A semiconductor device comprising:

• a first interlayer dielectric layer disposed over a substrate;
• metal wirings embedded in the first interlayer dielectric layer, the metal wirings being arranged with a first space or a second space between the metal wirings, the second space having a greater length than the first space;
• a second interlayer dielectric layer disposed over the first interlayer dielectric layer and the metal wirings;
• an etch-stop layer disposed between the first interlayer dielectric layer and the second interlayer dielectric layer;
• a first air gap formed by the second interlayer dielectric layer and formed in a first area sandwiched by adjacent two metal wirings arranged with the first space;
• and
• a second air gap formed by the second interlayer dielectric layer and formed in a second area sandwiched by adjacent two metal wirings arranged with the space more than the first space therebetween,
• wherein no etch-stop layer is disposed over at least one of the metal wirings in the first area.

A semiconductor device, comprising:

• a first air gap provided between first wirings, in a first wiring layer, arranged adjacent to each other with a space S1;
• a second air gap provided between second wirings, in the first wiring layer, arranged adjacent to each other with a space S2 larger than S1, wherein:
• the first air gap has a longer-side length along a first direction and a shorter-side width along a second direction perpendicular to the first direction in plan view,
• the second air gap has a first side length along the first direction and a second-side length along the second direction in plan view, and
• a ratio of the longer-side length and the shorter-side width of the first air gap is greater than a ratio of the first-side length and the second-side length of the second air gap.