同质异构_SSiO_2/_MSiO_2核/壳复合磨粒的合成

Preparation of Allotropic Composite Abrasives _SSiO_2/_M SiO_2 with Core/Shell Structure

以正硅酸乙酯为硅源、以氨水为催化剂、十六烷基三甲基溴化铵为结构导向模板剂,在单分散实心氧化硅(Solid-SiO2,SSiO2)内核表面包覆介孔氧化硅(Mesoporous-SiO2,MSiO2)外壳,合成了同质异构氧化硅(SSiO2/MSiO2)核/壳复合磨粒。用小角XRD、FESEM、HRTEM、FTIR、TGA和氮气吸附-脱附等手段对样品的结构进行了表征。结果表明,具有放射状介孔孔道的MSiO2均匀连续包覆在SSiO2内核(210-230nm)外表面,形成了厚度为70-80nm的外壳。壳层中的介孔孔道(孔径约2-3nm)基本垂直于内核表面,且复合磨粒样品具有较大的比表面积(558.2m2/g)。用AFM形貌分析和轮廓分析评价了所制备的复合磨粒对SiO2薄膜的抛光特性。与常规实心SiO2磨粒相比,SSiO2/MSiO2复合磨粒明显改善了抛光表面质量并提高了材料去除率。这可能归因于MSiO2壳层通过机械和/或化学方面的作用对磨粒与衬底之间真实界面接触环境的优化。

Core/shell structured composite abrasives with solid-silica （sSiO2） cores and mesoporoussilica （MSiO2） shells were synthesized using tetraethylorthosilicate as silica source, ammonia solution as catalyst and cetyltrimethylammonium bromide as sacrificial template. The prepared abrasives were characterized by small angle XRD, FESEM, HRTEM, FTIR, TGA, nitrogen adsorption-desorption isotherm and the corresponding pore size distribution. The results show that the MSiO2 shells （70-80 nm in thick- ness） with radial pores are evenly coated on the external surfaces of the sSiO2 cores （210-230 nm）.The BET surface area of the prepared abrasives is 558.2 m2/g. The mesochannels （2-3 nm in pore size） in the （MSiO2） shell are perpendicular to the surface of the sSiO2 core. The topography, roughness and profile curve of silicon wafers with a SiO2 surface film of ca 1200 nm were investigated by AFM before and after chemical-mechanical polishing in the presence of abrasives. By comparison with the conventional abrasives sSiO2, the composite abrasives are in favor of decreasing the surface roughness and increasing the material removal rate of the polished wafers. The MSiO2 shells of the prepared composite abrasives may be contribute to optimize the real interfacial contact between abrasives and wafer surface through certain mechanical and/or chemical effects.