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在Co化学机械抛光(CMP)过程中,Co的化学反应活性强于Cu,Co/Cu界面存在较大的电化学腐蚀电位差。采用动电位扫描电化学技术,表征金属铜钴表面的电化学反应。采用降低Cu/Co接触腐蚀电位差的方法,表征铜钴电偶腐蚀。研究了阻挡层CMP中影响铜钴电偶腐蚀的几个因素:pH值、H_2O_2和FA/O螯合剂;并对其控制机理进行了深入的研究。实验结果表明:pH值对钴的腐蚀电位影响较大,对铜的腐蚀电位影响不大,随着pH值的增加降低了铜和钴的腐蚀电位差;在碱性环境下,H_2O_2可降低Cu和Co的腐蚀电位差(最小可降到3 mV),可有效抑制Cu和Co之间电偶腐蚀现象的产生;在H_2O_2基电解液中添加适量的FA/O螯合剂有助于降低Cu和Co的腐蚀电位差,对抑制Cu和Co电偶腐蚀现象的产生具有重大的作用。
During the chemical mechanical polishing (CMP) process, the chemical reactivity of Co is stronger than that of Cu, and the electrochemical corrosion potential difference exists at the Co / Cu interface. Electrokinetic potential scanning electrochemical technique was used to characterize the electrochemical reaction on the copper-cobalt surface. The method of reducing the potential difference of Cu / Co contact corrosion was used to characterize the copper-cobalt galvanic corrosion. Several factors influencing the corrosion of copper and cobalt in the barrier CMP were studied: pH value, H_2O_2 and FA / O chelating agent. The control mechanism was further studied. The experimental results show that pH value has a significant effect on the corrosion potential of cobalt, but has little effect on the corrosion potential of copper. With the increase of pH value, the corrosion potential difference between copper and cobalt is reduced. In alkaline environment, H_2O_2 can reduce Cu And Co corrosion potentials (the minimum can be reduced to 3 mV), which can effectively inhibit the galvanic corrosion between Cu and Co. Addition of proper amount of FA / O chelating agent to H 2 O 2 -based electrolyte can reduce the Cu and Co corrosion potential difference, the inhibition of Cu and Co galvanic corrosion phenomenon has a major role.