Effect of different reagents on stability of Alkalinity silica sol

Abstract

In recent years, the silicon sol has now entered a relatively smooth period, and plays an important role in industries. Especially the silicon sol is used in the ultra precision Machining Technique. The most application is be the composition of slurry. Its stability is very important in the process of chemical mechanical polishing. The addition of reagent can change the pH and the potential of silica sol. So the different reagents are selected to improve the stability of silica sol. The results presented here show that surfactant be selected has a strong consequence on the stability of silica dispersion. It can improve the stability of silica sol. But the organic alkali and the chelator cannot improve the stability of silica sol. Introduction Chemical mechanical polishing technology (abbreviation: CMP) was first put forward by Monsanto [1] in 1965. With the development of micro-electronics, the CMP is proved to be the only process technology. So the study about CMP is increasing. The slurry is an important factor to affect CMP effect besides equipment and process condition. The slurry classes, physics and chemistry characteristics, particle size& dispersion degree have strong relations with grinding effect. At present the slurry of CMP includes SiO2、CeO2 and Al2O3 mainly and is applied in different fields respectively. The SiO2 slurry is easy to clean because of low viscosity and weak adhesion. So the SiO2 is promising greatly. At present the slurry of CMP includes SiO2 is applied in different fields respectively. But silicon sol is not enough to meet the requirement of CMP because of its instability. In this paper the different reagent are used to study the stability of silicon sol and the experiments are as follows. Experiments and analysis The reagent can make the abrasive in the polishing slurry to keep suspension, and disperse the particles, which avoid the slurry coagulation. In addition, the polishing process is also asked to add the reagent to achieve the preference adsorption after polishing. That can get good polishing effect. Therefore, in order to explore the role of reagent on the stability of silicon sol, the different reagents are added to the silicon sol. The variation of Zeta potential and pH value are studied. The relation between the stability of silicon sol and the Zeta potential and pH value is described in the documents domestically and internationally. In general,the silica sol is stable when the pH value is more than 8. The silica sol is also stable when the absolute of the Zeta potential is above 30mv. The pH of silica sol studied is 10.23, and its Zeta potential is -40.6mv. The different reagents are added to the silicon sol in study. First, the organic alkali is added to the silica sol and the Zeta potential and pH value are measured. The organic alkali is a weak base and it can change the alkalinity of silica sol slowly. The experiment results can be seen from fig.1 to fig.2. 1487 2nd International Conference on Electronic & Mechanical Engineering and Information Technology (EMEIT-2012) Published by Atlantis Press, Paris, France. © the authors 0 2 4 6 8 10 10.45 10.50 10.55 10.60 10.65 10.70 10.75 10.80 10.85