Study On Selectivity Of Cu,Ru And TaN In GLSI Copper Interconnct Ru Barrier CMP

At present,the key technology nodes of Giant Large Scale Integrated circuit(GLSI)have been reduced to below 10 nm.At this technology node,the traditional barrier layer tantalum/tantalum nitride(Ta/Ta N)can no longer meet the need of integrated circuit multilayer wiring development.Metal ruthenium(Ru)has gradually become the first choice for many barrier materials due to its low resistivity and high stability.However,the hardness and inertness of the Ru are extremely high.The removal rate is low during the chemical mechanical planarization(CMP)of the integrated circuit,and the removal selectivity is poor between Cu and Ru.It is easy to further aggravate the dishing and erosion depth in the Ru barrier CMP,which greatly affects the reliability and yield of chip.Therefore,in this paper,studied the removal rate selectivity between the barrier layer material Ru/Ta N and the wiring layer material Cu involved in the ruthenium barrier CMP from the perspectives of CMP theory,materials,and process.The main contents were as follows:1.The effect of p H value on removal rate selectivity of Cu,Ru and Ta N was studied.Under different p H values(4,6,8,9,10),the removal rates and removal rate selectivity of Cu,Ru and Ta N were tested respectively,indicating that the weakly alkaline environment was more conducive to improve the removal rate selectivity of the barrier layer to Cu,and the removal selectivity of the barrier layer to Cu was the highest when the p H value was 9.The Cu/Ru corrosion potential and zeta potential of slurry under different p H values were further tested,and the results showed that the Cu/Ru corrosion potential difference under weak alkaline condition was small,and the slurry was relatively stable.2.Under the guidance of mass transfer theory,oxidation-passivation theory and complex-adsorption theory,the effects of slurry composition on the removal rate selectivity of Cu,Ru and Ta N were studied from the aspects of dynamic polishing and electrochemical corrosion,including abrasives,oxidants,complexing agents,and inhibitors.The results showed that the too lower or too higher abrasive concentration was not conducive to the removal of materials,5wt%is selected as the best abrasive concentration;the addition of H₂O₂can initially increase the removal rate of Cu,Ru,Ta N and the removal rate selectivity of barrier layer to Cu.Guanidine carbonate(GC)as a complexing agent can further improve the removal rate of the barrier material,while the inhibitor 1,2,4 triazole(TAZ)can selectively inhibit the removal of Cu.3.The complexation of guanidine ion on metal oxides and the adsorption-passivation of 1,2,4-triazole(TAZ)on Cu were used to realize the controllable removal rate selectivity of Cu,Ru and Ta N.The dishing and erosion on the surface of ruthenium barrier pattern wafer before and after CMP were tested.Using scanning electron microscopy(SEM)and X-ray photoelectron spectrometer(XPS)on the surface morphology and elemental analysis,revealed the Cu,Ru,Ta N CMP removal mechanism,it indicated the existence of GC can accelerate the surface of the three kinds of materials corrosion rate,and the existence of Cu-TAZ passivation layer can effectively protect the surface of Cu and inhibit copper removal.