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

Backscattered electron spectroscopy offers detailed information for multila yer 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 t hin films on bulk substrates. In this paper we describe a new energy-disper sive method for thickness determination of thin films on bulk aluminum usin g backscattered electron (BSE) spectra obtained by a polar, toroidal, elect rostatic spectrometer. After a brief recapitulation of the spectrometer's g eometry, the techniques for its energy calibration and the preparation of t hin 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.