集成电路钴化学机械抛光缺陷控制的研究进展

钴(Co)因拥有较低的电阻率、良好的热稳定性、与Cu黏附性好等优点，可以替代钽(Ta)成为铜(Cu)互连结构的阻挡层；当特征尺寸减小到10 nm后，由于Co良好的抗电迁移能力，可以在很薄的阻挡层上实现无空隙填充，作为理想的互连金属候选材料，表现出了巨大的应用潜力。但由于Co的反应活性较强，以及不同金属材料之间的腐蚀电位差异，在化学机械抛光(CMP)过程中容易形成点蚀和电偶腐蚀缺陷，严重影响器件的性能，而成为研究的热点。综合分析近年来关于钴CMP过程中表面缺陷的产生及控制的相关研究，重点分析抛光液中的络合剂、缓蚀剂等成分对于钴表面缺陷的产生以及控制的作用机制；指出在碱性环境下，选择合适的缓蚀剂和络合剂以及利用不同缓蚀剂的协同作用，可以有效控制点蚀缺陷的发生，并指出量子化学可从分子层面上定性定量地分析抛光液中各试剂的相互协同机制，为抛光液的设计提供理论支撑。

Research Progress of Cobalt CMP Defect Control in Integrated Circuits

Cobalt (Co) can replace Tantalum (Ta) as the barrier layer of copper (Cu) interconnection structure because of its low resistivity,good thermal stability and better adhesion to Cu.With the feature size decreased to 10 nm and less,Co will replace Cu as a new interconnect metal material,because of its good electromigration resistance and the ability to achieve void free filling on a very thin barrier layer,which has shown great potential for application.However,due to the strong reaction activity of Co and the difference of corrosion potential between different metal materials,pitting corrosion and galvanic corrosion defects are easy to form in the process of Cobalt CMP,which seriously affects the performance of the devices.The research status of the generation and control of surface defects in cobalt CMP process in recent years was comprehensively analyzed.The action mechanism of complexing agent and corrosion inhibitor in polishing solution was emphatically described.It was pointed out that under alkaline environment,the occurrence of pitting defects can be effectively controlled by selecting appropriate corrosion inhibitors and complexing agents,as well as by using the synergistic effect of different corrosion inhibitors.It was also pointed out that quantum chemistry can qualitatively and quantitatively analyze the synergistic mechanism of various reagents in the polishing solution from the molecular level,providing theoretical support for the design of polishing solution.