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The mechanism of copper deposition in a sulphuric acid–sulfate bath in the presence of chlorides was investigated by electrochemical impedance measurements. A model where the chloride ions added to a sulphuric acid–sulfate copper-plating bath have a catalytic action not limited by mass transport has been proposed. This shows that the observed mass transport limitation is due to the diffusion of cupric ions and that, at high current densities, the copper deposition is mainly due to a mechanism involving CuCl formation on the electrode.

The mechanism of copper deposition in a sulphuric acid–sulfate bath in the presence of chlorides was investigated by electrochemical impedance measurements. A model where the chloride ions added to a sulphuric acid–sulfate copper-plating bath have a catalytic action not limited by mass transport has been proposed. This shows that the observed mass transport limitation is due to the diffusion of cupric ions and that, at high current densities, the copper deposition is mainly due to a mechanism involving CuCl formation on the electrode.

Electroacoustic admittance measurements were performed on copper bath solutions containing additives that are used in the copper damascene process. Preliminary results have shown that an electroacoustic admittance parameter can be defined that varies with additive concentration. It is proposed that quartz resonators may be suitable sensors for monitoring copper bath additives.

Electroacoustic admittance measurements were performed on copper bath solutions containing additives that are used in the copper damascene process. Preliminary results have shown that an electroacoustic admittance parameter can be defined that varies with additive concentration. It is proposed that quartz resonators may be suitable sensors for monitoring copper bath additives.

Electrochemical impedance measurements were performed on copper bath solutions during copper deposition and subsequent aging of the bath. The results show a correlation between the low-frequency capacitive loop of the electrochemical impedance and copper deposit roughness. The deposit became smoother as the bath aged and reached an optimal value, after which the deposit became rougher. The optimal surface smoothness correlated with a minimum in the low-frequency capacitive loop diameter of the impedance. The results suggest that electrochemical impedance measurements may be used to monitor changes in the copper bath that affect copper deposit quality and superfilling capability.

Electrochemical impedance measurements were performed on copper bath solutions during copper deposition and subsequent aging of the bath. The results show a correlation between the low-frequency capacitive loop of the electrochemical impedance and copper deposit roughness. The deposit became smoother as the bath aged and reached an optimal value, after which the deposit became rougher. The optimal surface smoothness correlated with a minimum in the low-frequency capacitive loop diameter of the impedance. The results suggest that electrochemical impedance measurements may be used to monitor changes in the copper bath that affect copper deposit quality and superfilling capability.

Abstract We apply a 2 5−1 fractional factorial Design of Experiments (DoE) test plan in order to discriminate the direct effects and interactions of five factors on the water management of a 500 We PEMFC stack. The stack is submitted to current steps between different operating levels and several responses are extracted for the DoE analysis. A strong ageing effect on stack and cell performances is observed. Therefore, in order to perform the DoE analysis, responses which values are too strongly affected by ageing are “corrected” prior to the analysis. A “virtual” stack, considered as “healthy”, is also “reconstructed” by “putting in series” the cells exhibiting very low performance drop. The results show that stacks and cells' resistivities are mostly impacted by direct effects of both temperature and cathodic inlet relative humidity and by compensating interaction between temperature and anodic overstoichiometric ratio. It also appears that two responses are able to distinguish a “healthy” stack from a degraded stack: heterogeneities in cell voltages and cell resistivities distributions. They are differently impacted by considered effects and interactions. Thus, a customised water management strategy could be developed, depending on the stack's state of health to maintain it in the best possible operating conditions.

Abstract We apply a 2 5−1 fractional factorial Design of Experiments (DoE) test plan in order to discriminate the direct effects and interactions of five factors on the water management of a 500 We PEMFC stack. The stack is submitted to current steps between different operating levels and several responses are extracted for the DoE analysis. A strong ageing effect on stack and cell performances is observed. Therefore, in order to perform the DoE analysis, responses which values are too strongly affected by ageing are “corrected” prior to the analysis. A “virtual” stack, considered as “healthy”, is also “reconstructed” by “putting in series” the cells exhibiting very low performance drop. The results show that stacks and cells' resistivities are mostly impacted by direct effects of both temperature and cathodic inlet relative humidity and by compensating interaction between temperature and anodic overstoichiometric ratio. It also appears that two responses are able to distinguish a “healthy” stack from a degraded stack: heterogeneities in cell voltages and cell resistivities distributions. They are differently impacted by considered effects and interactions. Thus, a customised water management strategy could be developed, depending on the stack's state of health to maintain it in the best possible operating conditions.