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在阻挡层化学机械抛光(CMP)过程中,阻挡层材料钽(Ta)易与铜(Cu)发生电偶腐蚀。针对这一问题,通过电化学分析方法研究了碱性抛光液中非离子表面活性剂对铜钽腐蚀电位的影响;通过CMP实验研究了非离子表面活性剂对铜钽去除速率的影响。结果表明,随着非离子表面活性剂体积分数增加至9%,铜钽的腐蚀电位均降低。最终确定最佳非离子表面活性剂的体积分数为6%。此时,在静态条件下,铜钽电极之间的电位差为1 m V;在动态条件下,铜钽电极之间的电位差为40 m V,可极大地减弱铜钽电偶腐蚀。同时,铜钽的去除速率分别为47 nm·min-1和39 nm·min-1,铜钽去除速率选择比满足阻挡层CMP要求。
Tantalum (Ta), a barrier material, is susceptible to galvanic corrosion with copper during barrier chemical mechanical polishing (CMP). In response to this problem, the influence of nonionic surfactants in alkaline polishing solution on the corrosion potential of copper and tantalum was investigated by electrochemical analysis. The effects of nonionic surfactants on the removal rate of copper and tantalum were investigated by CMP. The results show that as the volume fraction of nonionic surfactant increases to 9%, the corrosion potential of copper and tantalum decreases. The volume fraction of the best non-ionic surfactant was finally determined to be 6%. In this case, the potential difference between copper and tantalum electrodes is 1 mV under static conditions; under dynamic conditions, the potential difference between copper and tantalum electrodes is 40 mV, which can greatly reduce the corrosion of copper and tantalum. At the same time, the removal rates of copper and tantalum are 47 nm · min-1 and 39 nm · min-1, respectively, and the copper-tantalum removal rate selectivity meets the CMP requirement.