Semiconductor device with filling layer

1 . A semiconductor device, comprising:

a substrate;

a plurality of conductive layers positioned on the substrate;

a filling layer positioned between the plurality of conductive layers, wherein the filling layer comprises boron carbonitride;

a dielectric layer positioned on the plurality of conductive layers and the filling layer;

an air gap positioned in the filling layer and sealed by the dielectric layer, wherein a bottom of the air gap is positioned above a bottom surface of the filling layer, such that the bottom of the air gap is sealed by the filing layer; and

a plurality of hard mask layers positioned between the dielectric layer and the plurality of conductive layers and surrounding the filling layer, wherein a top portion of the air gap and top surfaces of the hard mask layers are coplanar.

2 . The semiconductor device of claim 1 , wherein a ratio of a distance between the plurality of conductive layers to a width of the air gap is between about 50 and about 5.

3 . The semiconductor device of claim 2 , wherein the plurality of conductive layers comprise tungsten, cobalt, zirconium, tantalum, titanium, aluminum, ruthenium, copper, metal carbides, metal nitrides, transition metal aluminides, or a combination thereof.

4 . The semiconductor device of claim 3 , wherein the plurality of hard mask layers comprise silicon oxide, silicon nitride, silicon oxynitride, or silicon nitride oxide.

5 . The semiconductor device of claim 4 , wherein the dielectric layer comprises silicon oxide, silicon nitride, silicon oxynitride, silicon nitride oxide, undoped carbonitride, or doped carbonitride.

6 . The semiconductor device of claim 4 , wherein the dielectric layer comprises p-type dopants or n-types dopants.

7 . The semiconductor device of claim 1 , further comprising a space extended between the hard mask layer and between the conductive layers to expose the substrate, wherein the filing layer is filled into the space to form the air gap within the space.