AVS 47th International Symposium
    Material Characterization Monday Sessions
       Session MC-MoM

Paper MC-MoM7
The Effect of Ion Acceleration Voltage on Interface Resolution During Depth Profiling and the Application of Advanced Data Analysis Techniques

Monday, October 2, 2000, 10:20 am, Room 207

Session: Depth Profiling
Presenter: S.J. Hutton, Kratos Analytical, UK
Authors: S.J. Hutton, Kratos Analytical, UK
N. Fairley, CASAXPS Ltd, UK
D. Surman, Kratos Analytical, UK
Correspondent: Click to Email
The effect of ion acceleration voltage on interface resolution during destructive depth profiling of a challenging multilayer sample was investigated. A compact, high speed, Kaufman ion source combined with X-ray photoelectron spectroscopy (XPS) enabled efficient concentration depth profiling through several hundred nanometer thick layers. The Kaufman source exhibits extremely high sputter rates at low ion beam acceleration potentials reducing ion induced mixing of the surface atoms. Atomic concentration profiles through inorganic oxide layers were recorded as a function of ion acceleration voltage. The improvement in interface resolution with decreasing acceleration voltage was clearly demonstrated. Chemical state information was retained with some reduction of the oxide layer observed due to preferential sputtering of oxygen from the surface during profiling. A detailed examination of the O 1s envelopes was also performed using principal component analysis (PCA) and non-linear least-square curve fitting (NLLSCF). It was shown that while four abstract factors characterised the O 1s data only two were of chemical significance with the remaining pair describing trends associated with the measurement process. Sub-sampling the periodic nature of the data matrix allowed underlaying line-shapes to be identified which were used to support the NLLSCF data reduction.