Fully aligned interconnects with selective area deposition

Abstract

Interconnect structures and methods for forming the interconnect structures generally include forming a dielectric layer over a substrate. The dielectric layer includes a dielectric layer top surface. A metal line is formed in the dielectric layer. The metal line includes a sacrificial upper region and a lower region. The sacrificial upper region is formed separately from the lower region and the lower region includes a lower region top surface positioned below the dielectric layer top surface. The sacrificial upper region is removed, thereby exposing the lower region top surface and forming a trench defined by the lower region top surface and sidewalls of the dielectric layer. An interconnect structure is deposited such that at least a portion of the interconnect structure fills the trench, thereby defining a fully aligned top via.