碱性抛光液中表面活性剂对铜钽的电偶腐蚀

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 mV;在动态条件下,铜钽电极之间的电位差为40 mV,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.

Galvanic Corrosion Between Copper and Tantalum in the Surfactant Based Alkaline Polishing Slurry

In the process of chemical mechanical polishing (CMP) of the barrier layer,the barrier layer material tantalum is prone to galvanic corrosion with copper.In order to solve the problem,the effects of the nonionic surfactant in alkaline polishing slurries on the corrosion potentials of Cu and Ta were analyzed through the electrochemical analysis method,and the effects of the nonionic surfactant on the removal rate of Cu and Ta were studied through CMP experiment.The results indicate that the corrosion potential of Cu and Ta both decrease when the volume fraction of the nonionic surfactant increases to 9％.It eventually determines that the best volume fraction of the nonionic surfactant is 6％.At this point,the potential difference between Cu and Ta is 1 mV and 40 mV under static condition and dynamic condition,respectively.The galvanic corrosion between Cu and Ta is greatly weakened.At the same time,the removal rates of Cu and Ta are 47 nm· min-1 and 39 nm· min-1,respectively.And the selection ratio of Cu and Ta meets the requirements of CMP of the barrier layer.