Investigation On Electrochemical Properties Of Novel Barrier Layer Ru Chemical Mechanical Polishing For Great Large Scale Intergration With Multilayer Copper Interconnection

With the continuous development of the integrated circuits?IC?,the feature size continues to decrease,and current technical node has been down to 14nm below.Due to the lower resistivity,directly plated to copper?Cu?and effectively reducing the thickness of the barrier laye,the new material ruthenium?Ru?can replace the traditional tantalum?Ta?as popular materials of a new generation copper interconnection diffusion barrier.Chemical mechanical polishing?CMP?is the key technology to realize the planarization of Ru-based barrier layer.There is a large corrosion potential difference between Ru and Cu during Ru CMP,which makes serious electrochemical corrosion and affects device reliability when contacts with polishing slurry.Therefore,Ru/Cu interface corrosion?Ru corrosion and galvanic corrosion?problem is further studied in the Ru-based barrier CMP.The main contents are as follows:In this paper,the weak alkaline route based on chemical action is through a series of electrochemical experiments research,using the method of oxidation passivation and strong chelating adsorption.According to the Nernst equation,the mechanism of pH,oxidant,chelating agent and surfactant on electrochemical corrosion mechanism of Ru and the galvanic corrosion inhibition between Ru/Cu were revealed.The results show that the pH value of Ru corrosion film have great influence in alkaline conditions can effectively alleviate the galvanic corrosion between Ru/Cu,and selected 9 as pH in the experiments of this topic.The corrosion resistance of hydrogen peroxide was effectively improved by using the oxidation passivation of hydrogen peroxide.The corrosion potential of Cu was close to Ru,and the corrosion potential difference between Ru/Cu decreased first and then increased.On the basis of oxidative passivation,FA/OII was added,the use of polyhydroxy polyamine chelating agent strong chelation,chelating metal ions,dissolved passivation film,promote anodic reaction,effective selective reduction the corrosion potential of Ru close to Cu,to further reduce the corrosion potential between Ru/Cu.At the same time,the self-developed FA/OI nonionic surfactant was used to control the dissolution of Ru and Cu surface passivation films,and the adsorption mechanism was analyzed.The eventual establishment of a FA/O alkaline barrier slurry,H₂O₂ in 3ml/L,FA/O II 1ml/L FA/OI as chelating agent,nonionic surfactant 20ml/L Ru/Cu can effectively inhibit the serious phenomenon of the corrosion,corrosion potential difference between Ru/Cu to reach2.8mV.The study of paper can lay a theoretical foundation for further study on Ru CMP polishing slurry.