Thickness determination of ultra-thin films using backscattered electron spectra of a new toroidal electrostatic spectrometer

Abstract

Backscattered electron spectroscopy offers detailed information for multilayer and subsurface-layer materials with distinct Z contrast: It can be used for the validation of Monte Carlo calculations, to obtain depth selective electron microtomographic images, and to determine the thickness of ultra thin films on bulk substrates. In this paper we describe a new energy- dispersive method for thickness determination of thin films on bulk aluminum using backscattered electron (BSE) spectra obtained by a polar, toroidal, electrostatic spectrometer. After a brief recapitulation of the spectrometer's geometry, the techniques for its energy calibration and the preparation of thin double, layer films are introduced. Backscattered electron measurements and thickness calibrations for Au and Cu films with thicknesses of 0-200 nm on bulk aluminum will be presented for various primary electron energies.