Study On Weakly Alkaline Basic Chemical Mechanical Planarization Materials And Mechanism For Integrated Circuit Cobalt Plugs

Since entering the technology node of 10nm and below,the conventional tungsten(W)plug can not meet development requirements due to the high resistivity,so it is replaced by cobalt(Co)material with low resistivity(?6.64??·cm).Chemical mechanical polishing(CMP)is one of the most effective methods to achieve local and global planarization of wafer surface.Co CMP requires a high Co removal rate(RR)and a low Co dissolution rate(DR).In this paper,the research is carried out from the weakly alkaline polishing solution.The research results have important guiding significance for realizing the localization of cobalt plug polishing slurry.The specific results are as follows:1.In view of corrosiving equipment of internationally common acid polishing slurry of Co and low polishing rate of weakly alkaline polishing slurry,the effects and the mechanism of different p H values on Co RR/DR were studied.Then the weakly alkaline Co CMP technology route with p H=8 was established.2.In view of the problem which is lower RR and Co/liner,higher DR in Co plug planarization,the nano-silica colloidal abrasive?polyhydroxypolyamine complexation agent(FA/O II chelating agent)?oxidant H₂O₂ and corrosion inhibitor TT-LYK on Co CMP were studied in p H=8.The distribution ratio of the polishing slurry:3wt%abrasive?20ml/L chelating agent FA/O II?5ml/L oxidant H₂O₂ and 0.2wt%corrosion inhibitor TT-LYK at p H=8 was verified to increase Co RR(?500nm/min)and Co/liner removal selectivity(103:1),decrease Co DR(?0nm/min).3.In view of the imperfect mechanism of Co plug removal mechanism,electrochemical experiments?X-ray photoelectron spectroscopy(XPS)and UV-Vis detections revealed that the removal of Co is accelerated by the formation of soluble Co-FA/O II during Co CMP.4.In view of the problem of poor quality of Co surface after polishing,the effect of TT-LYK,a corrosion inhibitor based on physical adsorption,on the surface quality of Co was studied.The surface morphology of Co was analyzed by scanning electron microscopy(SEM)and atomic force microscopy(AMF).It achieves Co surface roughness to reach 0.423nm,and provides theoretical and technical support for the technology of Co-plug CMP of 10 nm and below.