Patent ID: 7294568

Claim:
A method comprising: depositing a layer of a dielectric material over at least a portion of a surface of an underlying layer; depositing a layer of a sacrificial material over the dielectric layer; depositing a layer of a permeable material over the sacrificial layer, the permeable layer having a thickness of less than approximately 250 nm and internal compressive stresses of less than approximately 200 MPa, wherein internal stresses in the permeable layer are tensile; forming a trench and a via, the trench extending through at least the permeable layer and to the sacrificial layer, the via having one end opening into the trench and an opposing end extending down to a conductor in the underlying layer; depositing a conductive material within the via and the trench; and thermally decomposing the sacrificial layer to allow the sacrificial material to escape through the permeable layer to form air gaps surrounding at least portions of the conductive material within the trench.