A study has been made of effects of current waveform. and bath temperature in a copper sulfate bath without any organic additives on characteristics of copper electrodeposits for ULSI. The surface morphology, crystallographic texture and gap-fill of electrodeposits are influenced by the bath temperature and current waveform. The reverse pulse current (RPC) and pulse current (PC) are more likely to give rise to the epitaxial growth of electrodeposits than the direct current (DC). RPC gives rise to the minimum surface asperities for 1 mum thick deposits, but the roughest surface morphologies for 10 mum thick deposits. RPC and PC give rise to the stronger <111> textures than DC. A bath temperature of 60degreesC or higher and RPC result in the best gap-fill performance for trenches of 6 in aspect ratio.