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A multi-ion deposition model, based on constant applied voltage, was used to calculate the current distribution for anisotropic deposition in electrolyte composed of CuSO4 and H2SO4. The bulk species concentration was calculated by Pitzer’s model, including consideration of partially dissociated CuSO4false(normalaqfalse) and HSO4−. It was found, in some cases with high H2SO4 concentration, that the dissociation of CuSO4false(normalaqfalse) was higher than in the pure CuSO4 solution because of excess H+ ions. Further deposition modeling shows that H2SO4 and CuSO4 play different roles in anisotropic deposition. High H2SO4 concentration improves deposition uniformity but suppresses the filling ability. However, CuSO4 plays a role inverse to that of H2SO4. A moderate electrolyte composition for anisotropic deposition is thus suggested to be 0.1-0.3 M CuSO4 and 0.6-1 M H2SO4. © 2002 The Electrochemical Society. All rights reserved.

Uneven adsorption of polyethylene glycol (PEG) along a submicron feature enabling the occurrence of void-free deposition has been identified and we have developed a simplified 1-D model to explain the phenomenon based on the distribution of hydrodynamic driving force along the trench depth. We also verified this new model based on the uneven PEG adsorption via an electrochemical quartz crystal microbalance study. The model shows that with only moderate PEG concentration, void-free deposition can be realized. Some parameters used in the modeling were developed from chronopotentiometry and rotating disc electrode experiments.

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