Study On Material Removal Rateselectivity In GLSI Copperinterconnect Barrier Cobalt CMP

Integrated circuits(ICs) are the foundation for realizing the intelligence and informationization of today's society.Chemical mechanical planarization(CMP)is one of the key process technologies for IC fabrication,and it is the only technology that can achieve global and local flattening.At 14 nm and below,the Co/TaN with its excellent diffusion barrier and adhesion to Cu,is one of the most competitive new barrier materials.As the feature size of the device shrinks,the thickness of the barrier layer decreases.At the14 nm technology node,the thickness of the barrier layer Co and TaN are 2nm and 3nm,respectively.In the barrier CMP process of the IC process,there is Cu/Co.The problem of/TaN removal rate and removal rate selectivity is difficult to control,which seriously affects the yield of the polished sheet and restricts the development of the integrated circuit.In this paper,the polishing mechanism,galvanic corrosion,surface morphology and other aspects will be studied in depth,and the law and mechanism of material removal rate will be explored.Therefore,this topic carries out the following:1..Aiming at the problems of corrosion equipment and corrosion of metal Co in acidic slurry,the effect of p H on the static corrosion rate of Co was first studied under alkaline conditions.When the p H of the slurry was 10 and the static corrosion rate of Co was 12 ?/min,which reduced the damage of the strong alkaline solution to the low-k dielectric layer.For the problem that the high abrasive concentration will cause scratches on the surface of the material,the selected abrasive concentration was 5wt% for subsequent experiments.2.Aiming at the removal rate selectivity problem of Cu/Co/TaN,the effect of slurry component abrasive on Cu/Co/TaN removal rate selectivity was studied under the condition of 10 slurry and 5wt% abrasive concentration.When the concentration of FA/O II was1ml/L,the removal rates of Cu,Co and TaN are 220?/min,602?/min and 526?/min respectively.The removal ratio of Cu:Co:TaN was close to 1:2.74:2.41.A higher removal rate selectivity was achieved.3.In order to solve the problem of poor surface quality of the above-mentioned slurry Cu/Co/TaN,the addition of nonionic surfactant to the slurry improved the surface quality of Cu/Co/TaN.At the same time,the selectivity of Cu/Co/TaN removal was less affected.A series of barrier slurry with good performance(abrasive concentration of 5wt%,FA/O II concentration of 1ml/L,BRIJ30 concentration of 10ml/L,p H of 10)were obtained by orthogonal experiment.Under the condition of slurry component,the removal rate ratio of Cu:Co:TaN is 1:2.74:2.61 and the surface quality was good..