Spectroscopic techniques for characterization of high-mobility strained-Si CMOS

Schmidt, J.; Vogg, Günther; Bensch, F.; Kreuzer, Stephan; Ramm, Peter; Zollner, Stefan; Liu, Ran; Wennekers, P.

doi:10.1016/j.mssp.2004.09.095

Cited by 13 publications

(10 citation statements)

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“…Since an early study by Anastassakis et al, 3 Raman scattering has been widely used as a strain characterization technique in the semiconductor industry 4-6 and is often utilized for strain metrology in strained Si films. 7,8 Our results show that there are practical difficulties associated with the use of micro-Raman as a strain characterization technique for highly doped ultrashallow junction Si CMOS device structures.Experiments were performed on two types of tensilestrained Si wafers each grown on Si 1−x Ge x relaxed buffer layers with x = 0.2 and x = 0.17, and strained Si thicknesses of 43 and 17.5 nm, respectively. Each wafer was implanted with a 2 keV Sb ion dose of between 1 ϫ 10 14 and 1 ϫ 10 15 cm −2 creating a junction at a depth of around 10 nm.…”

mentioning

confidence: 95%

“…Since an early study by Anastassakis et al, 3 Raman scattering has been widely used as a strain characterization technique in the semiconductor industry [4][5][6] and is often utilized for strain metrology in strained Si films. 7,8 Our results show that there are practical difficulties associated with the use of micro-Raman as a strain characterization technique for highly doped ultrashallow junction Si CMOS device structures.…”

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confidence: 95%

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Constraints on micro-Raman strain metrology for highly doped strained Si materials

O'Reilly

Horan

McNally

et al. 2008

Applied Physics Letters

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Ultraviolet ͑UV͒, low penetration depth, micro-Raman spectroscopy, and high-resolution x-ray diffraction ͑HRXRD͒ are utilized as complementary, independent stress characterization tools for a range of strained Si samples doped by low energy ͑2 keV͒ Sb ion implantation. Following dopant implantation, good agreement is found between the magnitudes of strain measured by the two techniques. However, following dopant activation by annealing, strain relaxation is detected by HRXRD but not by micro-Raman. This discrepancy mainly arises from an anomalous redshift in the Si Raman peak position originating from the high levels of doping achieved in the samples. This has serious implications for the use of micro-Raman spectroscopy for strain characterization of highly doped strained Si complementary metal-oxide semiconductor devices and structures therein. We find a direct correlation between the Si Raman shift and peak carrier concentration measured by the differential Hall technique, which indicates that UV micro-Raman may become a useful tool for nondestructive dopant characterization for ultrashallow junctions in these Si-based materials. The enhancement of carrier mobilities through the introduction of strain in the channel region of metal-oxide semiconductor field effect transistors is an important option in order to maintain historical complementary metal-oxide semiconductor ͑CMOS͒ performance trends. 1 The production of ultrashallow junctions for the source/drain extension region using low energy ion implantation will be required for future CMOS devices. Biaxial tensile strain reduces the sheet resistance ͑R S ͒ of highly doped n type layers created by As or Sb implantation. The effect can be stronger for Sb, when R s lowering results not only from strain enhanced mobility, but also from an improvement in Sb metastable solubility in the presence of strain. 2 This makes Sb an interesting alternative to As for ultrashallow junctions in strain-engineered CMOS devices. Since an early study by Anastassakis et al., 3 Raman scattering has been widely used as a strain characterization technique in the semiconductor industry 4-6 and is often utilized for strain metrology in strained Si films. 7,8 Our results show that there are practical difficulties associated with the use of micro-Raman as a strain characterization technique for highly doped ultrashallow junction Si CMOS device structures.Experiments were performed on two types of tensilestrained Si wafers each grown on Si 1−x Ge x relaxed buffer layers with x = 0.2 and x = 0.17, and strained Si thicknesses of 43 and 17.5 nm, respectively. Each wafer was implanted with a 2 keV Sb ion dose of between 1 ϫ 10 14 and 1 ϫ 10 15 cm −2 creating a junction at a depth of around 10 nm.Nominally unstrained control samples were prepared using conventional p-type Si wafers for comparison. The implanted dose was confirmed by medium-energy ion scattering ͑MEIS͒. Dopant activation was achieved by rapid thermal annealing ͑RTA͒ wafer pieces for 10 s in N 2 in the range of 600-800°C. Room ...

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mentioning

confidence: 95%

mentioning

confidence: 95%

Constraints on micro-Raman strain metrology for highly doped strained Si materials

O'Reilly

Horan

McNally

et al. 2008

Applied Physics Letters

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“…This implies that the SE lacks sensitivity to parameters (such as strain in the Si) which have not yet been accounted for, as has already been observed by others who have attempted to characterize strained Si using SE alone 6,7 . However, it is also clear that the fits to the BB and, in the case of the thicker s-Si film, the BPR data have considerable scope for improvement, indicating that these technologies are sensitive to the presence of strain in the Si.…”

Section: Discussionmentioning

confidence: 96%

Strained-silicon metrology using a multi-technology optical system

et al. 2005

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A selection of thin Si layers grown epitaxially upon thick relaxed SiGe films were measured using the combination of optical metrology techniques available on the Opti-Probe ® 7341 system. The techniques used included in particular (i) angle resolved laser Beam Profile Reflectometry ® (BPR ® ) with S and P polarization, (ii) Broad-band visible-DUV spectrophotometry (BB), and (iii) spectroscopic ellipsometry (SE). The measured parameters included the Ge-content of the relaxed SiGe layer, the thickness and optical dispersion of the thin Si layer, and the thickness of the native oxide layer on the strained Si. Strain in the Si layer can be recognized by a significant downwards shift in the energy of the E1 peak and in the magnitude of the E2 peak in the ε 2 dispersion curve, which is consistent with theoretical predictions when the strain in the layer is tensile.The thickness measurements of the Si layer made by the Opti-Probe were found to be in agreement with subsequent SIMS analysis to within 5Å for the strained-Si layer. Measurement precision for thickness was <1.5Å (3σ) for the strained-Si layer. Overall, the results show that a reliable and stable measurement of Strained-Si is possible using optical metrology.

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“…Closed symbols and dashed-dotted curves represent our results [10], open circles correspond to the experimental results of Refs. [2,7,11,18,19] and solid curves are the results of the Keating-model calculations [11]. The solid straight lines with the small diamonds represent the experimental results of Ref.…”

Section: Figurementioning

confidence: 91%

Measurement of phonon pressure coefficients for a precise determination of deformation potentials in SiGe alloys

Reparaz

Goñi

Bernardi

et al. 2009

Physica Status Solidi (b)

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Stable, ultrathin micropatterns containing CdS nanoparticles (CdS‐NPs) were fabricated in a two‐step process. In the first step, a precursor film was built‐up by the layer‐by‐layer electrostatic self‐assembly of photosensitive nitro‐diazoresin and mercaptoacetic acid capped CdS nanoparticles. In the second step, the film was selectively exposed to UV light through a photomask and developed in an aqueous solution of sodium dodecylsulfate (SDS). The formation of covalently linked micropatterns was based on the different solubilities of the irradiated and non‐irradiated parts of the film in the developer. Namely, the irradiated regions were cross‐linked and insoluble, whereas the non‐irradiated regions, linked with ionic bonds, were removed by the SDS solution. The resultant patterns were systematically characterized with atomic force microscopy, field emission scanning electron microscopy, optical microscopy, and X‐ray photoelectron spectroscopy.

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Spectroscopic techniques for characterization of high-mobility strained-Si CMOS

Cited by 13 publications

References 10 publications

Constraints on micro-Raman strain metrology for highly doped strained Si materials

Constraints on micro-Raman strain metrology for highly doped strained Si materials

Strained-silicon metrology using a multi-technology optical system

Measurement of phonon pressure coefficients for a precise determination of deformation potentials in SiGe alloys

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