Aluminum impurities in silicon: Investigation of x-ray Raman scattering intotal reflection x-ray fluorescence spectroscopy

Total reflection x-ray fluorescence using synchrotron radiation from the St anford Synchrotron Radiation Laboratory has been used to study Al impuritie s on Si wafer surfaces. For primary excitation energies below the Si K abso rption edge an inelastic resonance scattering due to resonant x-ray Raman s cattering is observed. This scattering dominates the background behavior of the Al K fluorescence line, and consequently limits the achievable sensiti vity for detection of Al surface contaminants. The energy and angle depende nce of the resonant x-ray Raman scattering has been investigated to determi ne the experimental conditions for which the highest sensitivity for Al can be achieved. We find that for a precise determination of the achievable se nsitivity, the specific shape of the continuous Raman background has to be taken into account. Our calculations demonstrate a minimum detection limit for Al of 6x10(9) atoms/cm(2) for a 10 000 s count time. (C) 2000 American Institute of Physics. [S0021-8979(00)04721-6].