Stress relaxation, selective nitride phase removal

A method for forming a dielectric cap layer over an interconnect layer formed by a back-end-of-the-line (BEOL) interconnect process, the interconnect process including: lithography, reactive ion etching (RIE), metal filling of BEOL conductors, and chemical-mechanical polishing (CMP), wherein a sacrificial material resides between conductors of the interconnect layer, and wherein the dielectric cap layer is made porous through an oxidation process.