Interconnect structures having permeable hard mask for sealing air gap contained by conductive structures

摘要

A method for forming a semiconductor structure includes forming a sacrificial layer over a substrate. A first dielectric layer is formed over the sacrificial layer. A plurality of conductive structures are formed within the sacrificial layer and the first dielectric layer. The sacrificial layer is treated through the first dielectric layer, at least partially removing the sacrificial layer and forming at least one air gap between two of the conductive structures. A surface of the first dielectric layer is treated, forming a second dielectric layer over the first dielectric layer, after the formation of the air gap. A third dielectric layer is formed over the second dielectric layer. At least one opening is formed within the third dielectric layer such that the second dielectric layer substantially protects the first dielectric layer from damage by the step of forming the opening.