Direct plating of Cu on ALD TaN for 45nm node Cu BEOL metallization

Direct electro-deposition of a highly conformal and adherent Cu seed on ALD TaN by means of electro-grafting technique is presented. Both the adhesion of Cu seed to the underlying ALD TaN and EM lifetime performance were greatly enhanced by electro-grafting process, while the benefit of low via and line resistance of ALD TaN were maintained. This direct plated Cu seed layer on ALD TaN was demonstrated to successfully extend the current ECP to 45nm-node metallization and beyond.