Study On The CMP Rate Selection Tatio Of New Barrier Layer Ruthenium And Copper In GLSI

With the development of integrated circuit?IC?industry,the feature size of the device is decreasing,the IC preparation technology is facing new challenges.When the technology node is less than 14nm,the traditional barrier material tantalum/tantalum nitride?Ta/TaN?will affect the signal transmission speed in copper?Cu?interconnects.In order to reduce the interconnect delay signal,a new type of barrier material was need to replace the traditional barrier material?Ta/TaN?.platinum ruthenium?Ru?with the physical properties of high melting point and low resistivity,while Ru and Cu can realize the direct plating process,plating Cu seed layer can be omitted and the reliability will be improved.However,the chemical properties of Ru are stable and the hardness is larger,so it is very important to study the chemical mechanical polishing?CMP?of Ru,and it is also critical to study the rate selectivity ratio of Ru and Cu in CMP process.In order to get the appropriate rate selection ratio of Ru and Cu in CMP process,Firstly,the influence of process parameters on the CMP of Ru and Cu was studied,a set of optimal process parameters was selected for the experiment.Then the effect of different abrasive concentration on the CMP of Ru and Cu was studied.Because of the difference between the two properties,the hardness of Ru is higher and it is hard to be oxidized,Cu is easy to be oxidized and the hardness is small,so VCu is much larger than VRu.In order to improve the V_Ru,it is necessary to add an oxidant in the CMP.Firstly,H₂O₂ was chosen as oxidant,the effects of pH and concentration of H₂O₂ on Ru of CMP were also studied,it is concluded that the maximum removal rate of Ru can be obtained in alkaline environments,especially at pH 10.Then the effects of H2O2 and FA/O I on the CMP of Ru and Cu were studied,although FA/O I can reduce galvanic corrosion between Ru and Cu,but when V_Ruu reached 38nm/min,the V_Cu can reach to more than 400nm/min under the same condition,and it can not reach the appropriate rate selection ratio.In order to further improve V_Ru,NaClO was chosen as oxidant,and the effect of pH and concentration of NaClO on Ru of CMP was studied,Ru can reach the highest removal rate in alkaline environment,and the effects of NaClO and FA/O I on the CMP of Ru and Cu were studied,when V_Ru was 53.8nm/min,V_Cu was 260.4nm/min,the rate selection ratio has some optimization,the removal rate of Ru and Cu was adjusted by the addition of an anti reagent benzotriazole three?BTA?.The addition of BTA can significantly reduce the V_Cu,reduce the V_Ru by a small margin,and finally,by adjusting the amount of BTA,the V_Ru and V_Cu can reach the appropriate rate selection ratio?1.15:1?.