Preparation of silica abrasives from water glass and application in silicon wafer polishing

Chemical mechanical polishing technique is more frequently adopted for planarization in integrated circuit fabrication. The silica abrasives in colloidal state are fabricated with the sodium silicate solution as raw materials through the polymerization reaction among silicic acid molecules. By continuous injection of silicic acid into the preexisting silica solution, the diameter of silica nanoparticles increases. The different sized silica nanoparticles are imaged by scanning electron microscopy, and the dried silica are characterized by X-ray diffraction and thermal analysis. The polishing test on silicon wafer with as-fabricated silica abrasives shows that the surface flatness reaches 1.1 nm roughness, however, micro scratches are still present in the surface.

Dymanic mechanical analysis of polyvinylalcohol/silica nanocomposite

Polyvinylalcohol/Silica (PVA/SiO₂) nanocomposites with different SiO₂ contents are synthesized by employing a novel self-assembly monolayer (SAM) technique. The influence of the silica on dynamic mechanical properties of the nanocomposites is investigated by conducting dynamic mechanical analysis (DMA) and quasi-thermal mechanical analysis (Q-TMA). It is found that the storage modulus (E′), loss factor (tga), glass transition temperature (T_g), and activation energy (E_a) of prepared nanocomposites all show a strong dependence on the SiO₂ content. The Q-TMA results indicate that under a constant force, the elasticity of nanocomposites decreases with SiO₂ content, and the softening temperature moves to a higher temperature when more SiO₂ is added.

One-step coating of fluoro-containing silica nanoparticles for universal generation of surface superhydrophobicity

Stable superhydrophobic surfaces with water contact angles over 170 degrees and sliding angles below 7 degrees were produced by simply coating a particulate silica sol solution of co-hydrolysed TEOS/fluorinated alkyl silane with NH₃^.H₂O on various substrates, including textile fabrics (e.g. polyester, wool and cotton), electrospun nanofibre mats, filter papers, glass slides, and silicon wafers.

Ionic liquid adsorption and nanotribology at the silica-oil interface: hundred-fold dilution in oil lubricates as effectively as the pure ionic liquid

The remarkable physical properties of ionic liquids (ILs) make them potentially excellent lubricants. One of the challenges for using ILs as lubricants is their high cost. In this article, atomic force microscopy (AFM) nanotribology measurements reveal that a 1 mol % solution of IL dissolved in an oil lubricates the silica surface as effectively as the pure IL. The adsorption isotherm shows that the IL surface excess need only be approximately half of the saturation value to prevent surface contact and effectively lubricate the sliding surfaces. Using ILs in this way makes them viable for large-scale applications.