Acidic aqueous composition for electrolytically depositing a copper deposit

The invention relates to an acidic aqueous composition for electrolytic copper plating, the composition comprising(i) copper (II) ions,(ii) one or more than one suppressor consisting of or comprisingone single N-heteroaromatic mono-ring, said mono-ring comprising at least two ring nitrogen atoms and more than one substituent covalently connected to one of said ring nitrogen atoms and/or a ring carbon atom, wherein said substituent independently is or comprisesone or more than one linear or branched polyalkylene glycol moiety, and/orone or more than one linear or branched polyalkylene glycol block polyalkylene glycol, or random polyalkylene glycol moiety,with the proviso thatif said suppressor comprises a OH group, then it is a terminal OH group of said polyalkylene glycol moiety, polyalkylene glycol block polyalkylene glycol, and random polyalkylene glycol moiety, respectively, andsaid suppressor does not comprise NH2 groups, halogen atoms, and sulfur atoms;a method of electrolytic copper plating using the acidic aqueous composition; and specific suppressors as defined above.