Kenzo Hanawa

Mn2O3 Slurry Reuse by Circulation Achieving High Constant Removal Rate

Fumed silica is widely used in SiO2 chemical mechanical polishing (CMP). In semiconductor processes, only fresh slurry is used, and used slurry is disposed. Sustainable development demands a reduction in waste. Since reuse of slurry is effective for reducing the amount of used slurry generated, we investigated the reuse of Mn2O3 slurry and conventional fumed silica slurry. In both cases, abrasive concentration decreases as reuse time increases. The removal rate for Mn2O3 slurry maintains a value 4 times that of the conventional fumed silica slurry during slurry reuse, because the removal rate for Mn2O3 slurry is almost constant for solid concentrations between 1.0 and 10 wt %. Pad conditioning was not performed for Mn2O3 slurry. The removal rate for conventional slurry decreases as the number of times of reuse increases, even when pad conditioning is appropriately performed.

Mn2O3 Slurry Achieving Reduction of Slurry Waste

Fumed silica is widely used for SiO2 chemical mechanical polishing (CMP). In semiconductor processes, only fresh slurry is used, the used slurry being disposed of. We have demonstrated that Mn2O3 abrasive slurry polishes dielectric SiO2 film, giving 4 times the removal rate of conventional fumed silica slurry. The higher removal rate reduces the total amount of slurry used, consequently reducing the amount of used slurry waste. The removal rate of Mn2O3 slurry remains constant for solid concentrations between l and 10 wt %, and stays constant without pad conditioning. These characteristics are very useful for slurry reuse. Remanufacture of Mn2O3 slurry from used slurry has been demonstrated, and the removal rates of the remanufactured and fresh slurries are the same. Reuse and remanufacturing drastically reduce the amount of waste.

Dielectric SiO2 Planarization Using MnO2 Slurry

MnO2 slurry can polish SiO2 film faster and planarize wide feature steps (2 ×2 mm2) to a lower height than conventional silica slurry. A comparison of Gibbs free energies indicates that the MnO2 abrasive directly reacts on the SiO2 film. In post-Chemical mechanical polishing (CMP), the MnO2 abrasive can be completely removed by dipping it in mixed solutions of inorganic acids and H2O2 followed by scrubbing and dipping in HF solution. A comparison of Gibbs free energies clarifies that the MnO2 abrasive on the wafer is easily dissolved in a mixed solution of an inorganic acid and H2O2.

Dielectric SiO

MnO2 slurry can polish SiO2 film faster and planarize wide feature steps (2 ×2 mm2) to a lower height than conventional silica slurry. A comparison of Gibbs free energies indicates that the MnO2 abrasive directly reacts on the SiO2 film. In post-Chemical mechanical polishing (CMP), the MnO2 abrasive can be completely removed by dipping it in mixed solutions of inorganic acids and H2O2 followed by scrubbing and dipping in HF solution. A comparison of Gibbs free energies clarifies that the MnO2 abrasive on the wafer is easily dissolved in a mixed solution of an inorganic acid and H2O2.

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MnO2 slurry can polish SiO2 film faster and planarize wide feature steps (2 ×2 mm2) to a lower height than conventional silica slurry. A comparison of Gibbs free energies indicates that the MnO2 abrasive directly reacts on the SiO2 film. In post-Chemical mechanical polishing (CMP), the MnO2 abrasive can be completely removed by dipping it in mixed solutions of inorganic acids and H2O2 followed by scrubbing and dipping in HF solution. A comparison of Gibbs free energies clarifies that the MnO2 abrasive on the wafer is easily dissolved in a mixed solution of an inorganic acid and H2O2.