Backscattering Correction for Auger Electron Spectroscopy

I. Development of an Improved Backscattering Correction Equation for Wide Analytical Conditions

Abstract

  This paper describes the backscattering correction for Auger quantitative surface analysis. The energy and electron incident angle dependence of backscattering coefficient for 10 elemental solids (Be, B, C, Al, Si, Cu, Zr, Ag, La, Au) were investigated using Monte Carlo (MC) simulations. In conclusions, the backscattering coefficient η_α at incident angle α could be described as

 

      η_α=(0.01η₀^−1.1+0.84)[η₀/(0.01η₀^−1.1+0.84)]^cosα

 

where η₀ is the backscattering coefficient at incident angle 0°. The Love-Scott equation [J. Phys. D 11, 106 (1978)] for η₀ was superior to the others in wide incident energy range. Using these backscattering coefficient equations, we have proposed an improved equation for backscattering correction in Auger electron spectroscopy, which can be used for wide incident energy range (3-30 keV) and incident angles (0-60°). The parameters in the equation were determined from the curve fit to the backscattering factors at normal incident angle in the 3, 5, 7.5 and 10 keV electron incident energy calculated by Ichimura-Shizimu [Surf. Sci. 112, 386 (1981)] with MC method. The root mean square (RMS) differences for backscattering factors for 10 elemental solids calculated by Monte Carlo method using continuous slowing down approximation and those from proposed equation were less 3% in the 10-30 keV (over-voltage ratio U=1.5-100 and incident angle α=0-60°). In the 3-10 keV energy range, we have also compared the proposed equation to the calculated values at incident angle 30 and 45° by Ichimura-Shimizu with MC method. We found that they coincide well each other. Then, the proposed equation for backscattering correction could be applied to the quantitative Auger analysis in wide analytical conditions.