Raman spectroscopy of heavily doped polycrystalline silicon thin films

Nickel, N. H.; Lengsfeld, Philipp; Sieber, I.

doi:10.1103/physrevb.61.15558

Cited by 134 publications

(81 citation statements)

References 12 publications

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“…This effect has also been experimentally observed in nanocrystalline 14 and polycrystalline 15 Si films. The following expression was developed in the case of n-type bulk Si: 13…”

Section: Applied Physics Letters 92 233506 ͑2008͒supporting

confidence: 56%

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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“…This effect has also been experimentally observed in nanocrystalline 14 and polycrystalline 15 Si films. The following expression was developed in the case of n-type bulk Si: 13…”

Section: Applied Physics Letters 92 233506 ͑2008͒supporting

confidence: 56%

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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“…Comparing same free carrier concentrations, the effect is much stronger for holes than for electrons. 9 In case of the Fano distribution, the peak maximum is not exactly at k Phonon , but slightly shifted. The numerical values reported here always refer to k Phonon , likewise for the shift Dk.…”

Section: B Raman Peak Shapementioning

confidence: 99%

“…During the etch process of the semiconductor, the capacitance C versus voltage V is continuously measured. Assuming a sharp border of the sealing ring, that means a constant etch area and no undercutting among the sealing ring is observed, 17 the concentration N can be calculated with the Mott-Schottky equation (9). The depth x is the sum of the etched depth (using the Faraday equation of electrolysis) and the depletion width (10)…”

Section: Ecv Measurementsmentioning

confidence: 99%

Dopant mapping in highly p-doped silicon by micro-Raman spectroscopy at various injection levels

Kunz

Hessmann

Seren

et al. 2013

Journal of Applied Physics

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Defect engineering of the oxygen-vacancy clusters formation in electron irradiated silicon by isovalent doping: An infrared perspective J. Appl. Phys. 112, 123517 (2012) Band bending and determination of band offsets in amorphous/crystalline silicon heterostructures from planar conductance measurements J. Appl. Phys. 112, 123717 (2012) A transition of three to two dimensional Si growth on Ge (100) substrate J. Appl. Phys. 112, 126101 (2012) Fabrication of large-grained thin polycrystalline silicon films on foreign substrates by titanium-assisted metalinduced layer exchange J. Appl. Phys. 112, 123509 (2012) Additional information on J. Appl. Phys. Micro-Raman spectroscopy has been used to investigate the acceptor distribution in highly p-doped silicon. As an example, the dopant distribution in crystalline thin-film layers, as developed for solar cells, was mapped. The method is based on the analysis of the Fano-type Raman peak shape which is caused by free charge carriers. For calibration of the Raman acceptor measurements (excitation at a wavelength of 532 nm), we used mono-crystalline reference samples whose acceptor concentration was determined by electrochemical capacitance voltage. We find a significant influence of light induced free charge carriers on the peak shape which results from typical Raman excitation. Thus, the selection of a suitable intensity is important to avoid a too low signal-to-noise ratio on the one hand and systematic errors due to light induced carriers on the other hand. Different evaluation methods, i.e., peak asymmetry versus peak width analysis, are compared in respect to interference caused by random noise of the spectra or else by internal stress in the sample. While the width analysis method is more robust to a low signal-to-noise ratio, the symmetry analysis is more reliable in case of high intrinsic stress. V C 2013 American Institute of Physics. [http://dx

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“…However, by annealing the samples, the peak moves towards the single crystal silicon peak of 520 cm −1 . The broaden spectral peak compared to crystalline silicon even after annealing can be explained by the incorporation of a large concentration of dopants into the silicon host lattice that causes lattice distortion [14]. Annealing improves the quality of the film by inducing solid phase crystallisation.…”

Section: B Morphologymentioning

confidence: 99%

Junction Formation With HWCVD and TCAD Model of an Epitaxial Back-Contact Solar Cell

Rahman

Nawabjan

Tarazona³

et al. 2016

IEEE J. Photovoltaics

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Abstract-In this work we present morphological and electrical characteristics of a junction formed of Si P-type films deposited on an N-type silicon wafer using a hot wire chemical vapour deposition tool. We describe the fabrication process, and study the influence of diborane flow and post-process annealing in improving junction characteristics. Our morphological studies undertaken using atomic force microscopy show that the initial deposition suffered from voids rather than being a uniform film, however this improves significantly under our annealing treatment. The improvement in morphology was observed in the electrical characteristics, with estimated Voc doubling and rectification of the junction improving by several orders of magnitude. Fitting of the current-voltage curves to a two diode model, showed that increasing the diborane flow in the process helps reduce the saturation current and ideality factors, whilst increasing the shunt resistance. ECV and QSSPC measurements are used to characterise the deposited films further. A solar cell device with a silicon epitaxy emitter is modelled using industry standard 3D modelling tools and input parameters from experimental data, and the impact of defects is studied. A potential efficiency approaching 25% is shown to be feasible for an optimised device.

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Raman spectroscopy of heavily doped polycrystalline silicon thin films

Cited by 134 publications

References 12 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

Dopant mapping in highly p-doped silicon by micro-Raman spectroscopy at various injection levels

Junction Formation With HWCVD and TCAD Model of an Epitaxial Back-Contact Solar Cell

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