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钴(Co)作为10 nm及以下技术节点的铜互连极大规模集成电路(GLSI)的新型阻挡层材料,在阻挡层化学机械抛光(Chemical-Mechanical Polishing,CMP)中易与铜(Cu)发生电偶腐蚀。本文采用电化学、CMP、静态腐蚀实验以及SEM表征方法,研究了弱碱性抛光液中螯合剂和氧化剂在Co/Cu电偶腐蚀中的协同作用。研究表明:抛光液中的氧化作用,使得Co和Cu表面生成一层由氧化物及氢氧化物组成的钝化膜,抑制了Co和Cu的静态腐蚀;多羟多胺螯合剂浓度增加,抛光液p H升高,Co和Cu表面钝化膜的生成加快;CMP过程中,Co和Cu腐蚀电位均有明显降低,去除速率均加快。抛光液组分为1.5 ml·L-1 H2O2、0.1 wt%FA/O螯合剂、30 wt%AEO-9、5 wt%硅溶胶时,Co的腐蚀电位低于Cu的腐蚀电位;研磨状态下,Co/Cu腐蚀电位差降到-6 m V,电偶腐蚀电流很小,极大地减弱Co/Cu电偶腐蚀。同时,Co的去除速率为130nm·min-1,Cu的去除速率为76.5 nm·min-1,Co与Cu的静态腐蚀均不明显,可以很好地满足阻挡层CMP要求。
Cobalt (Co) is a new type of barrier material of copper interconnected very large scale integrated circuit (GLSI), which is a technology node of 10 nm and below. It is easy to react with copper (Cu) in barrier layer chemical mechanical polishing (CMP) Galvanic corrosion occurred. In this paper, the synergistic effect of chelating agent and oxidant on the galvanic corrosion of Co / Cu was studied by means of electrochemical, CMP, static corrosion experiments and SEM characterization. The results show that the oxidation of polishing solution causes the surface of Co and Cu to form a passivation film composed of oxide and hydroxide, which inhibits the static corrosion of Co and Cu. The concentration of polyhydroxy polyamine chelating agent is increased and polished Liquid p H increased, the formation of passivation film on the surface of Co and Cu accelerated. During the CMP process, the corrosion potential of Co and Cu decreased significantly and the removal rate accelerated. The corrosion potential of Co was lower than that of Cu when the polishing solution was composed of 1.5 ml·L-1 H2O2 and 0.1 wt% FA / O chelating agent, 30 wt% AEO-9 and 5 wt% , Co / Cu corrosion potential difference down to -6 m V, galvanic corrosion current is very small, greatly reducing Co / Cu galvanic corrosion. At the same time, the removal rate of Co is 130 nm · min-1 and the removal rate of Cu is 76.5 nm · min-1. The static corrosion of Co and Cu are not obvious, which can well meet the requirements of barrier CMP.