Under The Condition Of Alkaline Research On Chemical Mechemical Polishing Of Barrier Layer Material Co For Cu Interconnection

With the development of microelectronic technology,in order to ensure the performance of device and reduce the resistance of interconnects,the thickness of barrier layers and copper seed crystal must be decreased?<5nm?.So the requirements of ultra-thin Cu barrier material behavior are increasing.Owing to the excellent pHysical and chemical properties,cobalt has been selected as one of the most promising candidates of barrier metals for the next-generation ultra-large scale integrated circuits.However,there is poor of report about chemical mechanical polishing?CMP?of Co based barrier.The chemical corrosion,galvanic corrosion and removal mechanism of chemical mechanical polishing of Co need to be studied.This work has significant meaning in both scientific research and potential application of novel CMP process of Co based barrier layer.This paper analyzed the feasibility of alkaline polishing in theroy.In order to obtain the faster removal rates and better surface quality of material Co,this paper researched the polishing process and polishing slurry composition..Experimental results indicated that get best surface roughness?3.39nm,the scanned area was10?m×10?m?and higher polishing rate?56.7 nm/min?,the optimal parameters were:pressure,1.5psi;slurry flow rate,150 ml/min;polishing head speed,60 rpm;platen speed,65 rpm.In order to enhance the material removal is by modifying its chemical and mechanical properties using Hydrogen peroxide?H202?and FA/O I complexing agents.This paper investigated the effect of FA/O I and H₂0₂ on Co material removal rate?MRR?and polarization curve.It was revealed that Co RR first linearly increased then slowly decreaseed with the increasing H₂0₂ probably due to the formation of uniform Co oxides on the surface during polishing.And their corrosion behaviors and states of surface oxidation were analyzed.The result shows that,with the increase of chelating agent concentration,the open circuit potential is reduced,it shows that the electrochemical reaction is strong in the slurry,the complexing action is enhanced,and to some extent,that improves the Co corrosion rate.In addition,by adjusting the concentration of FA/O I and H₂0₂,Co and Cu polishing rate can be adjusted to1:1.5.The fact that FA/O I can inhibit Co and Cu galvanic corrosion.In this paper,the non-ionic surfactant were used to improve the Co CMP performance.Especially the addition of non-ionic surfactant can lead tosignificantly improvement of the surface roughness.