AVS 53rd International Symposium
    Applied Surface Science Thursday Sessions
       Session AS-ThP

Paper AS-ThP33
Transient Effects during Cs/Ga Dual Beam TOF-SIMS Profiling: Experiment and Simulation

Thursday, November 16, 2006, 5:30 pm, Room 3rd Floor Lobby

Session: Aspects of Applied Surface Science Poster Session
Presenter: R.G. Vitchev, Facultes Universitaires Notre-Dame de la Paix, Belgium
Authors: R.G. Vitchev, Facultes Universitaires Notre-Dame de la Paix, Belgium
J. Brison, Facultes Universitaires Notre-Dame de la Paix, Belgium
L. Houssiau, Facultes Universitaires Notre-Dame de la Paix, Belgium
Correspondent: Click to Email
Cs@super +@ sputtering beams are widely used in TOF-SIMS dual beam depth profiling. Loading the surface with Cs increases the negative ion yields and leads to formation of MCs@super +@ secondary ions (M stands for matrix). It was shown that the MCs@super +@ ions are suitable for quantitative analysis since they are relatively insensitive to matrix effects. Secondary ion yields change dramatically in the initial stage of the Cs bombardment due to the increase of the amount of implanted Cs in the surface until a steady-state is reached. This could be a problem if ultra-thin (nm) layers are analyzed. Having a better understanding of these transient phenomena is therefore crucial for such applications. In this work the secondary ion emission from Si H-terminated surface sputtered by Cs@super +@ ions (250 eV - 1 keV, 45°) and analyzed by 15 keV Ga@super +@ ions was studied. Xe@super +@ (350 eV) sputtering was used to determine the depth profile of the implanted Cs at steady-state. The steady-state Cs surface concentration was measured by XPS. A dynamic TRIM code was used to simulate the sputtering and composition change of the Si target under Cs bombardment and obtain the energy/velocity distribution of the atoms sputtered by the analyzing Ga beam. These results, combined with the electron tunnelling model for ion formation, were used to calculate the secondary ion yield at different Cs doses. The results were compared to those obtained experimentally.