Fabrication and characterization of nanoporous silica film

A homogeneous microporous silica films on silicon was fabricated by colloidal silica sol derived by hydrolyzing tetraethylorthosilicate (TEOS),catalyzed with NH3·H2O in a aqueous medium. glycerol combining with the hydrolyzing intermediates could avoid aggregation of SixOy(OH)z. The templated silica films with a heterostructural structure could form nanoporous silica films and avoid the films cracked during annealing. A homogeneous microporous silica films on silicon were developed during being annealed. Formation mechanism of the nanoporous silica films was elucidated. The microstructures, morphologies were characterized, some properties such as the Vecker′ hardness was 600～800(N/mm2), the thermal conductivity was 0.2W/m·K. 