We propose an alkaline barrier slurry containing guanidine hydrochloride(GH) and hydrogen peroxide.The slurry does not contain any corrosion inhibitors, such as benzotriazole(BTA). 3-inch samples of tantalum copper and oxide were polished to observe the removal rate. The effect of GH on removal rate selectivity along withhydrogenperoxidewasinvestigatedbycomparingslurrycontainingGHandH2O2withslurrycontainingonly GH. Details about the tantalum polishing mechanism in an alkaline guanidine-based slurry and the electrochemical reactions are discussed. The results show that guanidine hydrochloride can increase the tantalum polishing rate and the selectivity of copper and barrier materials. The variation of the dishing and wire line resistance with the polishing time was measured. The dishing value after a 300 mm pattern wafer polishing suggests that the slurry has an effective performance in topography modification. The result obtained from the copper wire line resistance test reveals that the wire line in the trench has a low copper loss. We propose an alkaline barrier slurry containing guanidine hydrochloride (GH) and hydrogen peroxide. The slurry does not contain any corrosion inhibitors, such as benzotriazole (BTA). 3-inch samples of tantalum copper and oxide were polished to observe the removal rate. The effect of GH on removal rate selectivity along with hydrogenperoxidewas investigated by comparingslurrycontainingGHandH2O2withslurrycontainingonly GH. Details about the tantalum polishing mechanism in an alkaline guanidine-based slurry and the electrochemical reactions are discussed. The results show that guanidine hydrochloride can increase the tantalum polishing rate and the selectivity of copper and barrier materials. The variation of the dishing and wire line resistance with the polishing time was measured. The dishing value after a 300 mm pattern wafer polishing suggests that the slurry has an effective performance in topography modification. reveals that t he wire line in the trench has a low copper loss.