High Spatial Resolution Auger Electron Spectroscopy (AES) in a Diffusion-Pumped SEM

Abstract

High spatial resolution Auger electron spectroscopy in an SEX is presented, and aspects of vacuum requirements for AES in a diffusion-pumped SEM are discussed. The vacuum system of a Cambridge Stereoscan* was rebuilt. Auger spectra recorded after 45 minutes of electron bombardment demonstrated that the carbon buildup-due to the polymerization of hydrocarbon molecules can be prevented by using the gas-jet technique. Auger data taken in an unmodified Cambridge Stereoscan, using only the gas-jet technique, is also presented. The spatial resolution of the SEM operating in the Auger mode is a function of necessary beam current, lens aberrations, and gun brightness. In the existing SEX equipped with a LaB6 electron gun, beam diameters of 0.4 ¿m containing 4 x 10¿7 A at 20 kV were obtained. This allowed the recording of greyscale Auger images with less than 0.5 ¿m spatial resolution in 400 sec.