No abstract

In chemical mechanical polishing (CMP) process, chemical action is generally determined by pH regulator and oxidant in the polishing slurry. In this paper, tungsten was polished by CMP, and the material removal mechanism was discussed. The in uence of pH values and H 2 O 2 concentrations on surface quality and material removal rate (MRR) were studied deeply. The oxidation and dissolution kinetics of tungsten/tungsten oxide (W/WO x ) during CMP process were investigated by electrochemical analysis and XPS. In addition, the microstructure of tungsten surface and its elemental composition and electronic state were also analyzed by SEM, white light interference and other characterization methods. Results reveal that tungsten has the best passivation effect at acidic pH, and the surface roughness increases with the increase of pH value, while the addition of H 2 O 2 will deteriorate the surface quality of tungsten and improve the MRR. Besides, the different morphologies (corrosion pits, grain boundaries, etc.) formed after W-CMP indicate that the material removal mechanism is related to the composition of slurry.(2) Under the action of alkaline slurry, WO 2 /WO 3 dual phase layer was formed on the W surface. While the WO 3 layer is continuously corroded and removed, the exposed WO 2 will be continuously oxidized, which jointly promotes the improvement of MRR.(3) The porous surface morphology allows the slurry to corrode the interior through pores, which means the material removal of the W surface under the action of OH slurry was the result of continuous etching and mechanical wear.This study shows that W-CMP using OH slurry (0.5 wt.% H 2 O 2 ) can achieve the best balance between material removal rate and surface quality, ensuring higher MRR and excellent surface quality.

In chemical mechanical polishing (CMP) process, chemical action is generally determined by pH regulator and oxidant in the polishing slurry. In this paper, tungsten was polished by CMP, and the material removal mechanism was discussed. The influence of pH values and H2O2 concentrations on surface quality and material removal rate (MRR) were studied deeply. The oxidation and dissolution kinetics of tungsten/tungsten oxide (W/WOx) during CMP process were investigated by electrochemical analysis and XPS. In addition, the microstructure of tungsten surface and its elemental composition and electronic state were also analyzed by SEM, white light interference and other characterization methods. Results reveal that tungsten has the best passivation effect at acidic pH, and the surface roughness increases with the increase of pH value, while the addition of H2O2 will deteriorate the surface quality of tungsten and improve the MRR. Besides, the different morphologies (corrosion pits, grain boundaries, etc.) formed after W-CMP indicate that the material removal mechanism is related to the composition of slurry.