Characterization of a Molecular Sieve Coating Using Ellipsometric Porosimetry

Abstract

Ellipsometric porosimetry was used to determine the adsorption isotherms of toluene, methanol, and water on b-oriented Silicalite-1 coatings with a thickness of less than ca. 250 nm and to obtain adsorption kinetics. The adsorption isotherms are of sufficient quality to reveal several aspects of the pore structure such as the adsorbate capacity and the adsorbate/framework affinity. The use of a combination of different molecular probes in ellipsometric porosimetry to elucidate the molecular accessibility of Silicalite-1 pores is demonstrated. It is shown that ellipsometric porosimetry is an appropriate technique for probing the influence of aging of the Silicalite-1 coating and of planarization polishing on the porosity, pore accessibility, and adsorbate/framework affinity.

Low‐kMaterials: Recent Advances

“…The k value increases from 2.7 to 3.3 after an exposure time of 30 h (k = 3.5 after several days). This observation is in good agreement with an ellipsometric porosimetry (EP) study using water as an adsorbent, reporting that the in situ crystallized film's hydrophilicity increases with aging [135].…”

Evidence of Large Voids in Pure‐Silica‐Zeolite Low‐k Dielectrics Synthesized by Spin‐on of Nanoparticle Suspensions

“…We used ellipsometric porosimetry (EP) to evaluate the on-wafer porosity and compare with the observations on the powders. [37,38] EP is equally based on the analysis of adsorption isotherms of toluene or other molecular probes but the isotherms are obtained via spectroscopic ellipsometry. [37,38] Figure 6 shows the toluene adsorption isotherms on the calcined films prepared by spinning on the Silicalite-1 suspensions on top of silicon wafers.…”

“…In parallel, the thickness and refractive index were measured by using the collected spectra of C and D in the region 350-850 nm. Further details of the ellipsometric porosimetry characterization were previously published elsewhere by some of us [37,38]. The dielectric constant in the calcined film was measured after degassing at 150 8C in nitrogen flow in a MIS-type capacitor obtained by deposition of Al dots on top of the films.…”

Nanoporous Organosilicate Films Prepared in Acidic Conditions Using Tetraalkylammonium Bromide Porogens

“…EP with water adsorbate to characterize hydrophobic films is well documented in the literature. [44][45][46][47] All films had a hydrophobic pore surface based on the small water uptake at low water vapor pressures. [26] A closer examination of the water adsorption isotherms in the low pressure region revealed some differences depending on the TAA porogen used.…”