US Patent 7094669 Structure and method of liner air gap formation

A structure and method of a semiconductor device with liner air gaps next to interconnects and dielectric layers. A dielectric layer is formed over a lower dielectric layer and a lower interconnect over a substrate. We form an interconnect opening in the dielectric layer. The opening has sidewalls of the dielectric layer. A sacrificial liner is formed over the sidewalls of the interconnect opening. An upper interconnect is formed that fills the opening. We remove the sacrificial liner/spacers to form (air) liner gaps.