In-situ determination of thin film and multilayer structure and chemical composition using x-ray fluorescence induced by grazing incidence electron beams during thin film growth
AssigneeWest Virginia University
InventorsDavid Lederman, Thomas Hubbard Myers, II, Sandeep Chandril
Life of this patent
Estimating the term…
Abstract
A method utilizing characteristic x-ray emission from a single thin film or multilayer thin film when an electron beam impinges at a grazing angle with respect to the surface of the sample to capture structural and physical properties of the layers such as layer thickness, interfacial roughness, and stoichiometry of the sample.
Claims16
A method comprising determining quantitative structural parameters of a thin film sample wherein the quantitative structural parameters are comprised of layer thickness and interfacial roughness wherein the determination comprises
- measuring x-ray fluorescence of the sample generated by irradiating the sample with an electron beam at grazing angle incidence as a function of the take-off angle;
- measuring the intensity of x-rays for each characteristic energy corresponding to each chemical element present in the sample as a function of the take-off angle;
- and
- analyzing these data to determine the electron beam's penetration, the electron beam's efficiency for x-ray fluorescence within the sample, and using the optical reciprocity theorem to make a non-linear least-squares fit to the data.
A method comprising determining the stoichiometry of a thin film sample wherein the determination comprises
- measuring the intensity of characteristic x-ray fluorescence of each element present in the sample generated by irradiating the sample with an electron beam at grazing angle incidence wherein the x-ray fluorescence is measured at a take-off angle wherein the take-off angle is large compared to the critical angle of characteristic x-rays emitted by the element with the largest critical angle and the critical angle is the angle of total external reflection for the characteristic x-ray wavelength;
- correcting the relative intensities of each element by sensitivity factors dependent on the electron emission current, time of acquisition, the atomic mass, the material's density, and the thickness of the sample;
- determining relative stoichiometries by dividing scaled intensities for each element by each other.
Dependencies are inferred from the claim text.