Dielectric damage-free dual damascene cu interconnects without barrier at via bottom

Abstract

Techniques for dielectric damage-free interconnects are provided. In one aspect, a method for forming a Cu interconnect structure includes: forming a via and trench in a dielectric over a metal line M; depositing a first barrier layer into the via and trench; removing the first barrier layer from the via and trench bottoms using neutral beam oxidation, and removing oxidized portions of the first barrier layer such that the first barrier layer remains along only sidewalls of the via and trench; depositing Cu into the via in direct contact with the metal line Mto form a via V; lining the trench with a second barrier layer; and depositing Cu into the trench to form a metal line M. The second barrier layer can instead include Mn or optionally CuMn so as to further serve as a seed layer. A Cu interconnect structure is also provided.