PNNL

Abstract

There is growing interest interest in integration of low dielectric materials in microelectric devices. Highly porous silica films can potentially reduce power dissipation, cross talk, and interconnection delay in the deep submicron device regime. Recently, low k dielectric "mesoporous" silica films have been synthesized [1] using micellar surfactants to template porosity in spin-on sol-gel silica. Since then we have made significant progress in developing low k films, using both cationic and non-ionic surfactants, that could meet device performance requirements. During this development we have used high-energy ion beam techniques along with optical profilometry to characterize the porosity of these films. Rutherford backscattering spectroscopy (RBS) and 16O(d,p0)17O nuclear reaction were used to determine the total number of Si and O atoms in the films. Interaction of these films with water was characterized by the 1H(19F, alpha-gamma)16O resonant nuclear reaction. Combination of these techniques provides fast accurate, and quantitative methods for characterizing these films. However, the high-energy ion beams appear to cause significant damage in the films. X-ray photoelectron spectroscopy (XPS) measurements from the ion beam interacted region interacted region show a tail in the low binding energy side of the Si 2p core level spectrum which is characteristic to metal Si. In addition, craters as deep as 100nm were left in the films where the ion beams interacted with the material. We will dicuss the effectiveness of these techniques for these porosity measurements in nanoporous low dielectric-constant silica films.