Correlation between the dielectric constant and porosity of nanoporous silica thin films deposited by the gas evaporation technique

Abstract

Nanoporous silica thin films with low dielectric constants were deposited by gas evaporation of SiO2 nanoparticles in an argon atmosphere. With increasing gas pressure during the evaporation, the dielectric constant decreases, while the porosity increases. The correlation between the dielectric constant and porosity is well modeled by a serial connection of two capacitors, one with air and the other with SiO2 as the dielectric medium. This suggests that the dielectric constant of the nanoporous silica thin film using the gas evaporation technique is more effectively lowered by forming “uniformly” distributed voids of closed gaps than those of the nanoporous silica films with pores extending from the back to front surface. Therefore, the former nanoporous silica thin film requires less porosity to obtain a low dielectric constant and is regarded as an ideal low-k material.

Effects of sintering on dielectric constants of mesoporous silica

“…Ultralow dielectric constant materials represent a partial solution [1,2] and one group of promising candidates are nanoscale porous materials (NPM) [2][3][4][5][6][7]. The presence of hydroxyl, -OH groups within the material increases its dielectric constant and renders it unsuitable as an interlayer dielectric.…”

Reflectance of surfactant-templated mesoporous silica thin films: Simulations versus experiments

“…Baklanov et al [13] and Hwang et al [15] used the Lorentz-Lorenz model, Boissière et al [29] and Balkenende et al [30] used the Bruggeman model. Si et al [31] reported that the dielectric constant r (= n 2 ef f ) of nanoporous SiO 2 films deposited by gas evaporation satisfy the series model. Taylor et al [26,32,33] used the parallel model to determine the porosity of porous silica, titania, and/or zirconia and alumino-silicate thin films made by sol-gel processes.…”

A luminescence study of porous diatoms

“…Porous silica was originally investigated in an attempt to elucidate the mechanism of luminescence for porous silicon. However, porous silica has since been found to have its own unique properties and is now used in a number commercial applications [3][4][5][6]. In particular we note that porous silica has been used for novel optical fiber based photonic devices [7] and more recently as a matrix for high quantum efficiency nanoparticle luminescence devices [8,9].…”