Leveling and microstructural effects of additives for copper electrodeposition

The roles of two model additives, bis(3-sulfopropyl) disulfide (SPS) and Ja nus Green B (JGB), in the deposition of copper from an acid-copper sulfate electrolyte containing polyethylene glycol (PEG) and Cl- were studied by de position on microprofiled electrodes, scanning electron microscopy (SEM), a nd transmission electron microscopy(TEM). It was found that leveling occurs only when all four additives are present, suggesting that additive-additiv e interactions are important to the leveling mechanism. Moreover, an optima l flux of the active leveling agent exists, an effect that may be explained by the classical diffusion-adsorption theory of leveling. SEM and TEM micr ographs show that the additive SPS removes the columnar structure of the de posit and effects micron-sized, unoriented grains provided PEG and Cl- are present; the subsequent addition of JGB decreases the grain size of the fil m significantly. (C) 1999 The Electrochemical Society. S0013-4651(98)10-025 -3. All rights reserved.