单烷基磷酸酯钾盐和烷基糖苷对钴互连化学机械抛光的影响

Effect of potassium monoalkyl phosphate and alkyl polyglucoside on chemical mechanical polishing ofcobalt interconnect

[目的]目前钴(Co)互连化学机械抛光(CMP)使用的传统唑类抑制剂(如苯并三氮唑)一般有毒性,会对环境造成危害。[方法]在以甘氨酸为配位剂、过氧化氢为氧化剂和SiO_(2)(平均粒径60 nm)为磨料的情况下,添加阴离子型表面活性剂单烷基磷酸酯钾盐(MAPK)和非离子型表面活性剂烷基糖苷(APG)作为抑制剂,得到绿色环保的抛光液。先从Co的去除速率和静态腐蚀速率、抛光液的润湿性及抛光后Co的表面品质入手,研究了MAPK与APG对Co互连CMP的影响。接着通过电化学分析和密度泛函理论分析,构建出两种表面活性剂在Co表面的吸附模型,探讨了它们对Co互连CMP的影响机制。[结果]MAPK与APG复配时抛光液的润湿性最好,Co镀膜片在CMP过程中的去除速率和静态腐蚀速率分别为454 nm/min和1 nm/min,抛光后表面品质良好,无腐蚀缺陷。[结论]MAPK和APG都较环保,有望替代传统抑制剂用于钴互连化学机械抛光。

[Introduction]The traditional zole compounds(such as benzotriazole)currently used as inhibitors in chemical mechanical polishing(CMP)of cobalt(Co)interconnect are usually toxic and harmful to the environment.[Method]An environment-friendly polishing slurry was obtained by adding potassium monoalkyl phosphate(an anionic surfactant,coded as MAPK)and alkyl polyglucoside(a nonionic surfactant,coded as APG)as inhibitors to a basic slurry containing glycine as complexing agent,hydrogen peroxide as oxidant,and SiO_(2)with an average particle size of 60 nm as abrasive.The effects of MAPK and APG on the CMP of Co interconnect was studied from the aspects of removal rate and static corrosion rate of Co,surface tension of slurry,and surface quality of CMPed Co.The adsorption models for the two surfactants onto Co surface were established by electrochemical analysis and density functional theory analysis,and their influencing mechanisms on CMP of Co interconnect were discussed.[Result]The polishing slurry featured the optimal wettability when MAPK and APG were both used.The removal rate and static corrosion rate of Co-coated sheet during CMP in the slurry containing MAPK and APG was 454 nm/min and 1 nm/min,respectively.The surface of Co was good without any corrosion defects after CMP.[Conclusion]Both MAPK and APG are environmentally friendly and are expected to replace the traditional inhibitors for chemical mechanical polishing of cobalt interconnects.