Study On The Galvanic Corrosion In Barrier Chemical Mechanical Planarization Of Great Large Scale Intergration With Copper Wiring

The chemical mechanical planarization(CMP)is one of the key technology in the manufacture of large scale integrated circuit.Tantalum was widely used as barrier material in copper interconnection because of its'high stability,high electrical conductivity and the inertia for copper.Chemical reaction activity of copper was higher than tantalum which formed difference of corrosion potential on the interface of copper and tantalum.Galvanic corrosion occurred when two copper and tantalum contacted in the slurry during the process of barrier layer CMP.The galvanic corrosion seriously influenced on the reliability and yield and integrity of the device and restricted the further development of microelectronics technology.Therefore,this paper researched the galvanic corrosion which was the most serious in the interface corrosion and the contents of research is as follows:First,a kind of alkaline polishing slurry without oxidant and inhibitors was determined according to the removal rate of copper and tantalum from CMP experiment.On the basis of this polishing slurry,the galvanic corrosion between copper and tantalum affected by the composition of polishing slurries,including FA/O chelating agent of type I and type II and nonionic surfactant and the pH value of polishing slurry was studied combining static and dynamic electrochemical methods.The passivation and corrosion state on the surface of copper and tantalum were analyzed by combining dynamic and static electrochemical polarization curve.According to the influence of pH and components of the slurries on the passivation and corrosion performance on the surface of copper and tantalum,the corrosion potential of copper and tantalum could be controlled by adjusting the pH or concentration of the slurry components.Therefore,the galvanic corrosion between copper and tantalum was inhibited.The results of experiment show that the ratio of copper and tantalum is 1:1,the removal rate of copper reached 245?/min and the tantalum reached 260?/min when the volume fraction of FA/O I chelating agent is 5%and the volume fraction of FA/O II chelating agent is 0.2%and the volume fraction of nonionic surfactant is 6%.It achieved the correction of dishing and erosion.The rates of static corrosion are small.And the corrosion potential difference of copper and tantalum was close to 0mV and the current density of galvanic corrosion was 7.86?A·cm~-22 that the galvanic corrosion realized controllable.The research results about galvanic corrosion had great guiding significance and it further promoted the industrialization process of FA/O alkaline barrier polishing slurries.