Characterization of porosity and dielectric constant of fluorocarbon porous films synthesized by using plasma-enhanced chemical vapor deposition and solvent process

Abstract

Fluorocarbon films obtained in plasma-enhanced chemical vapor deposition with a C[4]F[8] compound were composed of a carbon cross-linked network and unlinked species encapsulated in the network [J. Appl. Phys. 89, 893 (2001)]. The unlinked species were effectively removed from the films. Then, the network probably containing the pore of the species was extracted on wafers when the films were dipped into tetrahydrofran (THF) solvent. The fact implied that fluorocarbon porous films with a low-dielectric constant might be formed by using dry and wet processes. In the present study, x-ray analyses showed that the THF-treated films actually became porous in the dipping process. The dielectric constant of the THF-treated films was consistently low (<1.9) and reduced by 10% from that of as-deposited films. The fluorocarbon network as a porous medium may be applied to interlayer dielectrics for ultralarge-scale integrated circuits.