Density-graded adhesion layer for conductors

Abstract

Density-graded adhesion layers on conductive structures within a microelectronic package substrate are described. An example is a density-graded adhesion layer that includes a dense region proximate to a conductive structure that is surrounded by a less dense (or porous) region adjacent to an overlying dielectric layer. Providing such a graded adhesion layer can have a number of benefits, which can include providing both mechanical connections for improved adhesion with a surrounding dielectric layer and provide hermetic protection for the underlying conductive structure from corrosive species. The adhesion layer enables the conductive structure to maintain its as-formed smooth surface which in turn reduces insertion loss of signals transmitted through the conductive structure.