The subject-matter of the present invention is a composition especially intended for filling, by the electroplating of copper, a cavity in a semiconductor substrate such as a “through-via” structure for the production of interconnects in three-dimensional integrated circuits.According to the invention, this composition comprises in solution in a solvent: copper ions in a concentration lying between 45 and 1500 mM; a complexing agent for the copper consisting of at least one compound chosen from aliphatic polyamines having 2 to 4 amino groups, preferably ethylenediamine, in a concentration lying between 45 and 3000 mM; the molar ratio between the copper and said complexing agent lying between 0.1 and 5; thiodiglycolic acid in a concentration lying between 1 and 500 mg/l; and optionally a buffer system, in particular ammonium sulfate, in a concentration lying between 0.1 and 3M.