In the present work, tantalum (Ta) and copper (Cu) chemical mechanical polishing (CMP) has been carried out using a polishing slurry containing 2 wt% alumina (abrasive), 1 wt% potassium carbonate (oxidizer), and 0.25 wt% each urea and citric acid (additives). The Cu removal rate (RR) decreases with an increase in pH and is found to be minimum at pH 11 while Ta RR increases till neutral pH and then decreases till pH 11 having maximum RR at pH 7. Ta to Cu removal rate selectivity of 1:1.02 is attained at pH 11. Other parameters such as the effect of additives concentration, applied pressure, and platen rotational speed are also studied and results are reported to get a clear scenario. Surface charge analysis reveals that with change in pH, zeta potential alters and 30mV zeta potential is found at pH 11 which confirms the stability of the formulated slurry. To comprehend the removal mechanism of the metals, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) are employed. The same trend is encountered for both corrosion current density (Icorr) and film resistance (Rfilm)values resulting from Tafel and EIS. Based on the research conducted a plausible material removal mechanism is suggested.

中文翻译：

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用于选择性去除阻挡层金属的有机添加剂碱性氧化铝浆料

在目前的工作中，钽 (Ta) 和铜 (Cu) 化学机械抛光 (CMP) 使用含有 2 wt% 氧化铝（磨料）、1 wt% 碳酸钾（氧化剂）和 0.25 wt%每种尿素和柠檬酸（添加剂）。Cu 去除率 (RR) 随着 pH 值的增加而降低，发现在 pH 11 时最小，而 Ta RR 增加至中性 pH，然后降低至 pH 11，在 pH 7 时具有最大 RR。Ta 对 Cu 去除率的选择性为 1在 pH 值为 11 时达到：1.02。还研究了添加剂浓度、施加压力和压板转速等其他参数的影响，并报告了结果以获得清晰的场景。表面电荷分析表明，随着 pH 值的变化，zeta 电位发生变化，在 pH 11 时发现 30mV zeta 电位，这证实了配制浆料的稳定性。为了理解金属的去除机制，采用动电位极化和电化学阻抗谱 (EIS)。由 Tafel 和 EIS 得出的腐蚀电流密度 (Icorr) 和薄膜电阻 (Rfilm) 值也存在相同的趋势。基于所进行的研究，提出了一种合理的材料去除机制。