| 摘要 |
PURPOSE:To suppress generation of haze by adding the specified amount of particular anionic surface-active agent to alkali colloidal silica having mean grain size within the particular range. CONSTITUTION:The alkali colloidal silica used preferentially as pH value from 8.5 to 11.0 and also has a mean grain size, for example, of 7 to 100mmu measured by the nitrogen absorption method (BET method). As the anionic surface-active agent, the sulfonic acid salt type, sulfuric acid ester salt type, calboxylic acid salt type and phosphoric acid ester salt type agents are used. The amount of anionic surface-active agent to be added is 1ppm to 1.0wt.% in terms of the effective total component amount of a kind or several kinds of anionic surface-active agent for the solid matter of alkali colloidal silica. Thereby, haze-free silicon wafer can be obtained. |
