Study On Defects In Multilayer Copper Interconnect Barrier CMP

As the continuous development of integrated circuit manufacturing technology,the wafer size is getting larger,the integration is getting higher and higher,and the feature size is getting smaller and smaller.Therefore,the requirements of defect on the barrier layer in the chemical mechanical polishing of multi-layer copper interconnect are becoming increasingly demanding.The smaller the feature size,the lower the tolerable defect size.There are several kinds of defects,including copper residue,scratch,surface contamination,and copper corrosion.Thus copper residue defect could cause short circuit in the device.Scratch defect and copper corrosion defect could induce the increase of copper wire resistance.In severe cases,it will cause open circuit.The surface contamination defect minght affect layer-to-layer adhesion and wire-to-wire connection.Therefore,each kind of defect will affect the electrical parameters and reliability,results in the device failure and lower product yield.So,in order to meet the requirements of advanced processes,the various kind of defects must be effectively controlled.Poor removal rate uniformity,severe dishing and erosion are the mainly causes of copper residue.In this paper,using swing position of the polishing head to adjust the direction of the edge of the polishing plate 1 inch,and the edge pressure of the polishing head was increased by 20%.As the same time adding FA/OII nonionic surfactant 15 ml/L,the uniformity of TEOS removal rate improved 60.9%.When 1.5 g/L cosolvent and 0.5 ml/L H₂O₂ were added to the slurry,the ratio of removal rate between TEOS and Cu was 1.96.And the dishing correction capability was 576?,as the erosion correction capability was389?,and had met the requirements of industrial production.By designing a cycling filtration system to filter out large particles in the slurry,the number of scratch defect was reduced by nearly two orders of magnitude.When the cationic surfactant was added to 10ml/L,the number of scratch defect was reduced to single digits.FA/OII non-ionic surfactants and penetrating agent JFC had better effect on reducing surface contamination defect.When on the condition of proportion of FA/OII and JFC was 1:3,the number of surface contamination defect was reduced to 0.For the copper corrosion defect,the safety interval time between the electroplating copper process and the CMP process was verified to be 48hours for this slurry.Only a few copper corrosion defect occurred at the safety interval time.Reducing the penetrant JFC would help the reducing copper corrosion defect.This study has a positive guiding significance on the defect in barrier CMP.