Patent ID: 7078352

Claim:
A method for making airgaps in a stack of layers of a semiconductor device, said stack of layers comprising: a first dielectric material, which is resistant to a first etching composition; and a second dielectric material disposed upon said first dielectric material, wherein said method comprises the steps of: etching, with a second etching composition, at least one hole in said stack of layers; performing a conversion step comprising at least one of (i) chemically converting and (ii) mechanically converting said first dielectric material on respective sidewalls of said at least one hole, at least locally, into a converted, dielectric material that is etchable by said first etching composition; depositing an electrically conductive material in said at least one hole; removing an overburden of said conductive material to expose at least a portion of the converted dielectric material; and removing said converted dielectric material using said first etching composition.