The invention provides for a back-end metallisation process in which a recess is filled with copper and which includes the step of forming a plating base on the surfaces of the recess for the subsequent galvanic deposition of the said copper, and wherein subsequent to the formation of the plating base, but prior to the galvanic deposition of the copper, a modifying agent is introduced to the recess and which serves to absorb in the surface regions not covered by the plating base and to thereby modify the surface to promote copper growth thereon so as to effectively repair the initial plating base before the copper plating fill commences.