Method of forming air gaps in a dielectric material using a sacrificial film

A method comprising:

• forming a trench and a via in a layer of dielectric material, the via having one end opening into the trench and an opposing end extending down to a conductor in an underlying layer;
• depositing a layer of a sacrificial material over the dielectric material layer and over surfaces of the trench and via;
• etching the sacrificial material layer to remove at least a portion of the sacrificial material layer overlying the conductor in the underlying layer;
• depositing a layer of a conductive material over the sacrificial material layer and the conductor in the underlying layer;
• removing excess conductive material and excess sacrificial material from an upper surface of the dielectric material layer;
• depositing a layer of a porous dielectric material over the upper surface of the dielectric material layer and exposed portions of the conductive and sacrificial material layers;
• and
• removing the sacrificial material to form air gaps surrounding the conductive material within the trench and the via.