HIGH ASPECT RATIO VIA FILL PROCESS EMPLOYING SELECTIVE METAL DEPOSITION AND STRUCTURES FORMED BY THE SAME

A method of forming a semiconductor structure includes forming a semiconductor device over a substrate, forming a combination of a connection-level dielectric layer and a connection-level metal interconnect structure over the semiconductor device, where the connection-level metal interconnect structure is electrically connected to a node of the semiconductor device and is embedded in the connection-level dielectric layer, forming a line-and-via-level dielectric layer over the connection-level dielectric layer, forming an integrated line-and-via cavity through the line-and-via-level dielectric layer over the connection-level metal interconnect structure, selectively growing a conductive via structure containing cobalt from a bottom of the via portion of the integrated line-and-via cavity without completely filling a line portion of the integrated line-and-via cavity, and forming a copper-based conductive line structure that contains copper at an atomic percentage that is greater than 90% in the line portion of the integrated line-and-via cavity on the conductive via structure.