We show that ellipsometric porosimetry can be used for the measurement of the pore size distribution in thin porous films deposited on top of any smooth solid substrate. In this method, in situ ellipsometry is used to determine the amount of adsorptive, which is adsorbed/condensed in the film. Changes in refractive index and film thickness are used to calculate the quantity of adsorptive present in the film. Room temperature porosimetry based on adsorption of vapor of organic solvents has been developed. In this article, a method of calculation of pore size distribution and results of measurements on mesoporous and microporous xerogel films is discussed. Examination of the validity of the Gurvitsch rule for various organic adsorptives (toluene, heptane, and carbon tetrachloride) is carried out to assess the reliability of measurements of pore size distributions by ellipsometric porosimetry.
A method to control the hydrophobicity and dielectric constant of mesoporous silica films for ultralow-k applications is described. Several surfactants have been used as sacrificial materials in (organo)silicate matrixes, prepared from tetraethoxysilane and methyltrimethoxysilane. To elucidate the relation between the composition of the films and their structure, the synthesis, chemical composition, mechanical properties, pore structure, crystallinity, and dielectric constant of the films were investigated. The high extent to which organic groups can be incorporated in these thin films opens the possibility to obtain a fully hydrophobic surface. Further, a combination of tetraethoxysilane and methyltrimethoxysilane leads to dense matrixes. The film properties were optimized for low-k applications by varying the processing conditions. Films containing 50-60% methyltrimethoxysilane in tetraethoxysilane and cetyl trimethylammonium bromide as a surfactant appear most attractive as a low-k material. These films are hydrophobic, have a dense matrix, and exhibit the smallest pore sizes (∼3 nm), which may facilitate integration issues.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.