| 摘要 |
PURPOSE: An aqueous dispersion is provided which contains silica produced by pyrogenic means which exhibits a markedly reduced re-agglomeration behavior, greater stability and which, during chemical-mechanical polishing, yields high removal rates and leads to a surface which is very largely free from microscratches. CONSTITUTION: The aqueous dispersion comprises an alkali-doped silica, wherein the silica is produced pyrogenically while being doped with an alkali containing aerosol, the silica having an average particle diameter of secondary particles of less than 100 nm and a ratio dn/da of an arithmetic mean of a number distribution dn and an arithmetic mean of a surface distribution da of primary particles of at least 0.7, the alkali content of the doped silica is from 10 ppm to 10 wt.%, a BET surface of the alkali-doped silica is from 5 to 600 m¬2/g, a solids content is from 0.1 wt.% to 70 wt.%, the dispersion has a pH from 8 to 12, and the silica is doped with an aerosol comprising potassium. The process for preparing the aqueous dispersion comprises the process of dispersing the alkali doped silica in an aqueous solution, wherein the silica is dispersed in an aqueous solution by means of high energy input. The silica is dispersed in an aqueous solution with a planetary kneader/mixer, and the process further comprises pressurizing the alkali-doped silica under a pressure at up to 3500 Kg/cm¬2, pressurizing an aqueous solvent under a pressure of up to 3500 Kg/cm¬2, and depressurizing the alkali-doped silica and the aqueous solvent, wherein the depressurized alkali-doped silica and the depressurized aqueous solvent may collide with each other or a wall of a reaction device.
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