Stability Of The Alkaline Copper CMP Slurry

Integrated Circuit is developing rapidly according to Moore's law.The integration level is Higher and higher,the feature sizes is smaller and smaller,the wafer area is larger and larger,all benefit from the rapid development of precision machining technology.Chemical mechanical planarization?CMP?is the only way to achieve global planarization in copper interconnect process.And the slurry is the main consumable material in the CMP process,its performance determines the planarization efficiency of the whole wafer directly.The alkaline slurry for copper interconnect polishing invented by microelectronics technology and material institute,Hebei University of Technology,its compositions are sample without BTA which is international general but poisonous and difficult to clean,it has a good performance.The dishing,erosion and surface roughness value can reach the international advanced level.And its causticity is weak for the equipments,it is friendly to environment,which makes it promote the development of electronic technology.The oxidant used in slurry is H2O2,which is the first selection of oxidant,because it has a good oxidability and it doesn't pollute materials and environment.But since the stability of H2O2is not good,especially add H2O2 to alkaline polishing slurry,it's easy to decompose and react with other compositions,which leads to the stability of alkaline polishing slurry deteriorate.The slurry is out of function less than 48 hours,which has become a key problem that must be solved.This paper analyses the effect of different components on stability in the invented alkaline slurry.The surfactant has positive effect on stability.Then add other additives to slurry,including a little of BTA,pH regulator--phosphoric acid and glycine reagent,observe their effect on stability.According to the experiments,BTA and phosphoric acid have a positive effect on the stability.This paper also research the Abrasive-Free CMP?AFP?and sterilization and algae killing of CMP slurry.Because there is no abrasive colloid in AFP slurry,the stability of abrasive colloid could not be considered.The research of sterilization and algae killing of CMP slurry can eliminate and reduce the effect of fungi and algae on stability.The two aspects research has great significance on the stability of alkaline slurry.According to the research on stability of alkaline slurry.Original slurry is stable for more than twelve months,the stability of using slurry for P₁ and P₂ can be increased by double.