EELS of Arsenic (As)
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Based on a non-relativistic theory, Allen and Rossouw [1] calculated the inelastic object functions for K-shell ionization. The calculated object functions for the K-shell excitations of some elements such as Te, Cd, As and Ga indicate that the localization of the object is less than 1 Å [2].

Figure 139a shows the As-L2,3 EELS spectrum, taken from a highly As-doped Si (silicon) crystal (3.7%, namely 1.85 × 2021 cm-3), before and after background extrapolation. The electron dose used for the data acquisition is 0.8 nA x 10 s at an accelerating voltage of 120 keV.

As-L2,3 EELS spectrum, taken from a highly doped As region

Figure 139a. As-L2,3 EELS spectrum, taken from a highly As-doped silicon (Si) crystal (3.7%, namely 1.85 × 2021 cm-3), before and after background extrapolation. [3]

The background extraction window can be 150 eV in energy width (from 1,173 to 1,323 eV), and the signal integration windows can be 260 eV (1,323~1,583 eV) and 150 eV for the arsenic edge and silicon edge, respectively. [3]

Figure 139b shows an As-L2,3 EELS map and a line scan of As-doped Si BiCMOS n-p-n transistors with As detection sensitivity of 1019 cm–3 at a spatial resolution of ~2 nm, measured in a STEM system with an incident beam energy of 120 keV.

As-L2,3 EELS map and a line scan of As-doped Si BiCMOS transistors

Figure 139b. As-doped Si BiCMOS transistors: (a) STEM image, (b) As-L2,3 EELS map (150 × 60 pixels at 2 nm/pixel), and (c) Line scan along the white line in (b). As segregation at a grain boundary is observed. [4]


 

 

 

 

 

 

 

 

 


[1] L.J. Allen, C.J. Rossouw, Phys. Rev. B 42 (1990) 11644–11654.
[2] N.D. Browning, S.J. Pennycook, Microbeam Anal. 2 (1993) 81–89.
[3] Alain Claverie, Transmission Electron Microscopy in Micro-nanoelectronics, 2013.
[4] Servanton, G., and Pantel, R. (2010) Arsenic dopant mapping in state-of-the-art semiconductor devices using electron energy-loss spectroscopy. Micron 41, 118–122.

 

 

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