Interconnect structure formed in porous dielectric material with minimized degradation and electromigration

Abstract

For fabricating an interconnect structure within an interconnect opening formed within a porous dielectric material, the interconnect opening is initially formed within a low-K precursor material that is not completely cured. The interconnect opening is then filled with a conductive fill material being contained within the interconnect opening and with a top surface of the conductive fill material within the interconnect opening being exposed. A capping material is formed on the top surface of the conductive fill material, and the capping material is an amorphous alloy or is a microcrystalline alloy having stuffed grain boundaries. A thermal curing process is then performed for curing the low-K precursor material to become a porous low-K dielectric material. The capping material on the top surface of the conductive fill material is impervious to at least one of oxygen, carbon, hydrogen, chlorine, and porogen fragments that are generated as out-gassing volatile by-products from the low-K precursor material during the thermal curing process to preserve the integrity of the interconnect structure. In another aspect for fabricating an interconnect structure, an interconnect opening is formed within a porous dielectric material with opened pores at sidewalls of the interconnect opening. A diffusion barrier material is formed at a bottom wall of the interconnect opening. The diffusion barrier material is then sputtered away from the bottom wall of the interconnect opening and onto the sidewalls of the interconnect opening to substantially fill the opened pores at the sidewalls with the diffusion barrier material. The interconnect opening is then filled with a conductive fill material after the opened pores at the sidewalls of the interconnect opening are filled with the diffusion barrier material.