Effect of potassium monoalkyl phosphate and alkyl polyglucoside on chemical mechanical polishing of cobalt interconnect
[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 SiO2 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.
cobalt interconnectionchemical mechanical polishingpotassium monoalkyl phosphatealkyl polyglucosideremoval ratedensity functional theory
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