Replacement contact cuts with an encapsulated low-k dielectric

Abstract

Interconnect structures and methods of forming an interconnect structure. A sacrificial contact is arranged between a first gate structure and a second gate structure. The sacrificial contact extends vertically to a source/drain region. A section of the sacrificial contact is removed to form a cut opening extending vertically to the source/drain region. A first dielectric layer is deposited in the cut opening, and is then partially removed to open a space in the cut opening that is arranged vertically above the first dielectric layer. A second dielectric layer is deposited that fills the space in the cut opening and forms a cap on the first dielectric layer. The first dielectric layer has a first dielectric constant, and the second dielectric layer has a second dielectric constant that is greater than the first dielectric constant.