A line trough and a via cavity are formed within a dielectric layer comprising a fluorosilicate glass (FSG) layer. A fluorine depleted adhesion layer is formed within the line trough and the via cavity either by a plasma treatment that removes fluorine from exposed surfaces of the FSG layer, or by deposition of a substantially fluorine-free dielectric layer. Metal is deposited within the line trough and the via cavity to form a metal line and a metal via. The fluorine depleted adhesion layer provides enhanced adhesion to the metal line compared with prior art structures in which a metal line directly contacts a FSG layer. The enhanced adhesion of metal with an underlying dielectric layer provides higher resistance to delamination for a semiconductor package employing lead-free C4 balls on a metal interconnect structure.