title: Determination of copper nanoparticle size distributions with total reflection X-ray fluorescence spectroscopy.
abstract: Total reflection X-ray fluorescence (TXRF) analysis is extensively used by the semiconductor industry for measuring trace metal contamination on silicon surfaces. In addition to determining the quantity of impurities on a surface, TXRF can reveal information about the vertical distribution of contaminants by measuring the fluorescence signal as a function of the angle of incidence. In this study, two samples were intentionally contaminated with copper in non-deoxygenated and deoxygenated ultrapure water (UPW) resulting in impurity profiles that were either atomically dispersed in a thin film or particle-like, respectively. The concentration profile of the samples immersed into deoxygenated UPW was calculated using a theoretical concentration profile representative of particles, yielding a mean particle height of 16.1 nm. However, the resulting theoretical profile suggested that a distribution of particle heights exists on the surface. The fit of the angular distribution data was further refined by minimizing the residual error of a least-squares fit employing a model with a Gaussian distribution of particle heights about the mean height. The presence of a height distribution was also confirmed with atomic force microscopy measurements.
authors.affiliation: Stanford Synchrotron Radiation Laboratory, 2575 Sand Hill Road, Stanford, CA 94025, USA.
authors.forename: Andy
authors.initials: A
authors.lastname: Singh
authors.affiliation: Stanford Synchrotron Radiation Laboratory, 2575 Sand Hill Road, Stanford, CA 94025, USA.
authors.forename: Katharina
authors.initials: K
authors.lastname: Luening
authors.affiliation: Stanford Synchrotron Radiation Laboratory, 2575 Sand Hill Road, Stanford, CA 94025, USA.
authors.forename: Sean
authors.initials: S
authors.lastname: Brennan
authors.affiliation: Department of Applied Chemistry, Waseda University, Shinjuku, Tokyo 169-8555, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Homma
authors.affiliation: Department of Applied Chemistry, Waseda University, Shinjuku, Tokyo 169-8555, Japan.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Kubo
authors.affiliation: Stanford Synchrotron Radiation Laboratory, 2575 Sand Hill Road, Stanford, CA 94025, USA.
authors.forename: Stanisław H
authors.initials: SH
authors.lastname: Nowak
authors.affiliation: Stanford Synchrotron Radiation Laboratory, 2575 Sand Hill Road, Stanford, CA 94025, USA.
authors.forename: Piero
authors.initials: P
authors.lastname: Pianetta
keywords: Cu nanoparticle; grazing-incidence X-ray fluorescence; silicon wafer surface; total reflection X-ray fluorescence