Characterization of Porous Silicate Low-k Films by Ellipsometric Porosimetry and Variable-energy Positron Annihilation Spectroscopy

Abstract

We applied ellipsometric porosimetry and variable-energy positron annihilation spectroscopy to the pore characterization of spin-on-glass silicon-oxide-backboned porous thin films with different relative dielectric constants between 2.3 and 3.2. It was found that the relative dielectric constant decreases linearly with increasing open porosity deduced by ellipsometric porosimetry.Comparison of the open porosity with the average pore size deduced by positron annihilation lifetime spectroscopy suggested that mesopores less contribute to open porosity and are not so effective in decreasing film relative dielectric constant in comparison with micropores.

Correlation between the Doppler Broadening S Parameter and Ortho-Positronium Formation Probability in Polymers

“…We can separate the overall Doppler broadening spectrum into contributions of the e + and Ps by solving a series of simultaneous equations. The details of the procedure will be reported elsewhere [4]. As a typical example, e + and Ps profiles extracted for PFA are shown in Fig.…”

Open Porosity and Pore Size Distribution of Mesoporous Silica Films Investigated by Positron Annihilation Lifetime Spectroscopy and Ellipsometric Porosimetry

“…In this study, n f refers to the fixed refractive index of the silica film at p / p 0 = 0 and n a represents the refractive index of adsorbate ( n heptane = 1.386) [ 25 , 26 ]. Hence, the physical adsorption isotherms of heptane were measured by the changes of V filled values with p / p 0 according to Equation (1) with the measured n o .…”

Variable-Energy Positron Annihilation as Highly Sensitive Nanoporosimetry for Porous Thin Films

“…Nanoscale pores present in porous films have been successfully studied with respect to the conditions of film preparation: deposition time and gas pressure for sputtered silica film [5,9], deposition bias power for PECVD SiOCH--based film [14], film-forming particle size [11], decomposition of porogen [15], composition of precursor solution [10,20,21] and molecular weight of porogen [22] for spin-on-glass MSQ-based films, which illustrates "the great strength" [16] of PAL techniques for evaluating pore dimension.…”