Damage formation and annealing studies of low energy ion implants ...

Chapter 4 Experimental Techniques and sample preparation
4.1 Introduction
Throughout this study several techniques have been used to characterise the
samples. The principal technique applied was medium energy ion scattering (MEIS) (1,
2), which was carried out at CCLRC Daresbury laboratory (UK) (3).
MEIS is a refinement of Rutherford Backscattering Spectrometry (RBS), which
has been in common use since the 1960s for studying a variety of applications such as
ion implantation of semiconductors, surfaces and thin films (4, 5). The underlying
principle behind RBS and MEIS is essentially the same, with modification to the
detailed experimental conditions and some differences with the equipment. MEIS is
capable of producing quantitative depth profiles of implanted heavy ions and capable of
simultaneously detecting displaced Si atoms, surface oxide atoms and any surface
contaminant. This enables the experiments to provide information on the crystal lattice
damage caused by the implantation, the regrowth of the damaged Si crystal and
movement of dopant following annealing. Occasional RBS experiments were carried
out at Salford University to confirm findings from MEIS.
Secondary ion mass spectrometry (SIMS) (2, 5, 6) was used to compliment the
MEIS analysis. SIMS was carried out at ITC-IRST, Trento, Italy and at IMEC in
Leuven, Belgium. The combination of MEIS and SIMS allows, for instance,
information regarding substitutional dopants to be obtained. SIMS is also useful for
profiling light elements such as B, for which ion scattering techniques have a very much
reduced sensitivity.
Other techniques have been used to characterise a small number of samples.
Various X-ray studies have been performed at beamline ID01 at the European
Synchrotron Radiation Facility (ESRF), France (10). Some of the findings of these
experiments are reported in this thesis and elsewhere (9, 41), where the comparison with
MEIS has been instrumental in their interpretation. Combined information has provided
further information on the segregation of As and details of the regrowth of Si. The
techniques are not explained in any detail in this thesis and further information on these
experiments and techniques can be found elsewhere (9, 10, 46, 47). Cross sectional
transmission electron microscopy (XTEM) (49) was performed at The University of
Salford to investigate damage following annealing, and the result is in Chapter 6.
Energy filtered transmission electron microscopy (EFTEM) carried out at CNR, Catania,
Italy, has been used to image specific elements and the results are used in Chapter 7.
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