Methods for forming self-aligned conductive pillars on interconnects

Abstract

Methods, of forming a self-aligned conductive pillar (16) on an interconnect (12) on a body (10) having semiconducting surfaces. A first mask (24) defines an inverse pattern for formation of an interconnect (12). The interconnect (12) is formed by additive metallization processes. A second mask (26) is formed over portions of the first mask (24) and the interconnect (12). Sidewalls of the first mask (24) which define at least one side of side of said interconnect (12) serve to also define at least one side of said conductive pillar (16). The second mask (26) also defines at least one side of the conductive pillar (16). The conductive pillar (16) is formed by additive metal deposition processes. The conductive pillar (16) is thus self-aligned to the interconnect (12) on which it is formed. A cladding layer of tungsten (40) can be used on the multiple layers of seed layer (22), e.g. molybdenum coated with thin copper, of copper interconnects (12/14), and of conductive pillars (16/18). Feed layer of nickel and gold interconnect are also disclosed.