Air-gaps in 0.3 mu m electrical interconnections

A copper/air-gap interconnection structure using a sacrificial polymer and SiO2 in a damascene process has been demonstrated. The air-gap occupies the entire intralevel volume with fully densified SiO2 as the planar interleve l dielectric, The copper was deposited by physical vapor deposition and pla narized by chemical-mechanical planarization. The Ta/Cu barrier/seed layer was deposited by physical vapor deposition; the bulk copper was electrochem ically deposited. The resulting structure has an effective intralevel diele ctric constant of 2.19.