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LA-WATAP
LASER-Assisted
3D Atom Probe for Semiconductors and Materials
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 The CAMECA LA-WATAP
instrument is the next generation of Tomographic (or 3D) Atom Probe,
providing quantitative atomic scale 3D elemental mapping
of chemical heterogeneities in materials.
Compared to our former OTAP Atom Probe, the new LAWATAP offers the following key advantages:
- New LASER-Assisted atom evaporation allowing the analysis of semiconductor materials,
a strong reduction of tip ruptures, and high mass resolution.
- Larger area of analysis for a better statistics on composition measurements: analysis area up to 100 nm in diameter.
- Faster acquisition rate: ~15 min. needed for collecting 1E6 atoms.
- Better quantitative results with the new Advanced Delay Line Detector (ADLD) and its benchmark multi-hit performance.
- FIM (Field Ion Microscopy) capabilities with gas introduction system available for research works.
A six-page introduction leaflet of the new LA-WATAP 3D Atom Probe can be downloaded.
The new CAMECA Wide Angle instrument (WATAP) : a larger Field of View.
Shown below is a comparison of the same metallic sample (NiCr15Al5 nickel
based alloy) analyzed with the former CAMECA TAP (left side) and the
new CAMECA WATAP instrument (right side). The advantage of the next
generation is obvious: the larger analyzed volume gives better statistics for precipitate quantitative measurements: size, shape and composition.
Note that the acquisition time is the same in both cases,
revealing a dramatic increase in the data rate with the introduction of
the new Advanced Delay Line Detector and associated electronics and
software.
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Data
obtained with a conventional TAP.
Field: 7nmx 7nm x 60nm.
Total number of atoms detected: 150 000.
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Data
obtained with the CAMECA WATAP.
Field: 40nm x 40nm x 200nm.
Total number of detected atoms: 8 000 000.
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Improvement of Atom probe mass resolving power with LASER evaporation.
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Mass
spectra of an aluminium-silicon-magnesium alloy obtained with HV pulses (green curve) and
laser pulses (blue curve). On the right, 3D image of the Mg distribution.
The
use of femto-second LASER technology and CAMECA design result in a higher mass resolving
power compared to HV pulsing (inducing an energy spread) or pico-second
conventional LASER technology (inducing thermal evaporation effect with longer heating of the tip).
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Analysis of semiconductors with the Atom Probe:
Drain silicide interface in MOS transistor structure
The concentration profiles of Ni, Si and Pt below clearly reveal the presence of both Ni2Si and NiSi phases as a consequence of the reactive diffusion between Ni and Si substrates. Furthermore, Pt enrichment at both Ni/Ni2Si and Ni2Si/NiSi interfaces is clearly evidenced.
This example illustrates the importance of quantification to understand a physical process. Two NiSi phases are assigned without ambiguity, mainly thanks to the Advanced Delay Line Detector’s superior multi-hit capabilities and optimized LASER evaporation mode. Moreover, due to the unique in-depth resolution, boundaries between phases are clearly revealed without matrix effect as observed in SIMS with this type of sample.
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