Study On Copper Film Efficient Planarization Materials And Process Of Multilayer Copper Interconnection

Chemical mechanical polishing(CMP)is the fundamental planarization process in the manufacture of integrated circuits(ICs)and is currently the only effective means of achieving local and global planarization.With the shrinking of IC technology nodes,the increase of wafer size,and the application of low-k dielectric materials,the polishing process is proceeding in the direction of chemical action.The polishing fluid characteristics and polishing process are key to copper CMP.Therefore,the copper film flattening performance was studied from the perspective of the polishing slurry material and the polishing process.From the material point of view,set the polishing process parameter pressure to2 psi,the flow rate to 200ml/min,the polishing head pad rotation speed to 70 and80r/min,and study the concentration of polishing slurry component of glycine-hydrogen peroxide-BTA system on the copper polishing rate.The effect,combined with the analysis of the electrochemical characteristics,shows that the polishing slurry has a good passivation effect in the alkaline range and pH<9.The anionic surfactant ammonium dodecyl sulfate(ADS)in the slurry can significantly change the passivation characteristics of the copper surface,reduce the corrosion current,and increase the removal rate of selection of the convex and concave parts of the copper material,thereby effectively reducing the height difference.Finally,1wt%silica sol,2wt% glycine,1vol% FA/OI chelating agent,20ml/L hydrogen peroxide,200 ppm BTA,and 0.5wt% ADS were determined as the optimum ratio of the polishing slurry.From the process point of view,the optimized polishing slurry was used to study the effect of polishing process parameters on the polishing rate and within-wafer non-uniformity.Both the higher material removal rate and the smaller within-wafer non-uniformity were considered to determine the optimal polishing process.The process pressure was 1.5 psi,and the polishing head and pad rotation speeds were 85 and 90 r/min,and the flow rate was 300 ml/min,4932?/min of polishing rate and4.5% within-wafer non-uniformity were obtained.According to the results of materials and processes,combined with pH-potential diagram,the effect of cooperative passivation of BTA and ADS on planarization wasanalyzed.Selecting four polishing slurries to perform contrast verification experiments on 3-inch 65-nm node wafers and 8-inch multi-size wafer lines,the results show that the wafer step height is as low as 879 ? using the optimized polishing slurry and process.Multi-size lines 100×100 ?m,50×50 ?m corresponding planarization efficiency were 73.56%,84.39%,respectively,and narrow lines 10×10?m,5×5 ?m final step height was close to zero,copper surface roughness was only0.42 nm,within-wafer non-uniformity up to 5.3%.