Stability of weakly alkaline barrier slurry with the high selectivity

•The weakly alkaline barrier slurry is free of oxidizers and inhibitors.•We studied the effect of slurry aging on stability and performance of CMP process.•The barrier slurry exhibits a stability having a shelf life of at least 30 days.•The barrier slurry can provide a good planarization performance within a month.

In order to improve the CMP performance, many methods have been devoted to the development of barrier slurry. H2O2 as an oxidizer and benzotriazole (BTA) as an inhibitor is considered to be an effective method in barrier CMP. In this paper, the high-stability weakly alkaline barrier slurry is presented. Major components include complexing agents, silica, nonionic surfactant and pH-modifier but free of oxidizers and inhibitors. We studied the stability of the slurry using the material removal rate of Cu, Ta and TEOS blanket wafers, particle size, PH-value, viscosity and zeta potential tests as a function of aging time during one month. A 300 mm copper pattern wafer was polished by the barrier slurry after one-month time to examine performance of the slurry. The results indicate that as the aging time is increased, the mean particle size, PH-value, viscosity and zeta potential of the slurries fluctuated slightly in time. The polishing results of Cu, Ta and TEOS blanket wafers show that the slurry has high selectivity of Ta and TEOS to Cu even after one-month time. The aging time has little impact on removal rate selection. The dishing values and roughness of Cu wiring after 300 mm pattern wafer polishing suggest that the slurry has an effective performance in topography modification. By experiment research, the barrier slurry exhibits a stability having a shelf life of at least 30 days.

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