Application of IR variable angle spectroscopic ellipsometry to the determination of free carrier concentration depth profiles

Tiwald, Thomas E.; Thompson, Daniel W.; Woollam, John A.; Paulson, W. M.; Hance, R. L.

doi:10.1016/s0040-6090(97)00973-5

Cited by 123 publications

(78 citation statements)

References 8 publications

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“…8 Ellipsometry in the midinfrared ͑MIR͒ and FIR spectral range has been used for noncontact and nondestructive determination of free-charge-carrier concentration and mobility parameters and their spatial distribution in complex layered semiconductor structures. [9][10][11] In the terahertz spectral range, however, ellipsometry is still in its infancy and experimental reports are scare. [12][13][14][15] Here we report on a combined terahertz and MIR ellipsometric investigation of a p-p + silicon homojunction.…”

Section: Hole Diffusion Profile In a P-p + Silicon Homojunction Determentioning

confidence: 99%

“…The asymptotic ͑damping͒ behavior of the Fabry-Pérot interference oscillations within the MIR range provide access to the hole concentration profile on toward the p + substrate. 11 The model analysis yields the thickness of the epitaxial layer and the diffusion region of d = 16.93Ϯ 0.03 m. The diffusion region is 800 nm wide. The best-model parameters for the low-doped Si layer are = 4.6Ϯ 0.5 ⍀ cm and =98Ϯ 11 fs.…”

Section: ͑2͒mentioning

confidence: 99%

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Hole diffusion profile in a p-p+ silicon homojunction determined by terahertz and midinfrared spectroscopic ellipsometry

Hofmann

Herzinger

Tiwald

et al. 2009

Applied Physics Letters

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Noninvasive optical measurement of hole diffusion profiles in p-p+ silicon homojunction is reported by ellipsometry in the terahertz (0.2–1.5 THz) and midinfrared (9–50 THz) spectral regions. In the terahertz region a surface-guided wave resonance with transverse-electrical polarization is observed at the boundary of the p-p+ homojunction, and which is found to be extremely sensitive to the low-doped p-type carrier concentration as well as to the hole diffusion profile within the p-p+ homojunction. Effective mass approximations allow determination of homojunction hole concentrations as p=2.9×1015 cm−3, p+=5.6×1018 cm−3, and diffusion time constant Dt=7.7×10−3 μm2, in agreement with previous electrical investigations.

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Section: Hole Diffusion Profile In a P-p + Silicon Homojunction Determentioning

confidence: 99%

Section: ͑2͒mentioning

confidence: 99%

Hole diffusion profile in a p-p+ silicon homojunction determined by terahertz and midinfrared spectroscopic ellipsometry

Hofmann

Herzinger

Tiwald

et al. 2009

Applied Physics Letters

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“…We use a method based on ASTM standard 723-88, 13 which yielded good results in a previous study. 4 This method converts silicon resistivities directly into carrier densities using empirical equations that were developed from a set of carefully characterized samples. IR-VASE measurements were made on both the front and back of the pn membrane, because the highly doped region strongly absorbed infrared light.…”

Section: Experimental Setup: Ir-vasementioning

confidence: 99%

Thickness analysis of silicon membranes for stencil masks

Sossna

Kassing

Rangelow

et al. 2000

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Sossna, E.; Kassing, R.; Rangelow, I. W.; Herzinger, C. M.; Tiwald, T. E.; Woollam, John A.; and Wagner, Th., "Thickness analysis of silicon membranes for stencil masks" (2000). Stencil masks are key to charged particle projection lithography, in particular for ion projection lithography. To fulfill pattern printing requirements in the sub-70 nm regime, excellent thickness uniformity and thermal emissivity control are critical parameters for high quality stencil mask fabrication. We propose and demonstrate a technique based on infrared variable angle spectroscopic ellipsometry ͑IR-VASE͒ to measure these parameters with adequate accuracy and precision. The refractive index of the Si membrane was evaluated using a Sellmeier dispersion model combined with a Drude model. Because of its spectral range from 2 to 33 m, the IR-VASE method is sensitive to the thickness of layers as well as to the concentration and profile of Si membrane doping.

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“…[1][2][3][4] The technique has been applied to a number of materials problems, including: the transverseoptic ͑TO͒ phonon absorption and doping concentration in n-type GaAs, 5 one-and two-phonon absorption in LiF, 6,7 graded carrier concentration profiles in implanted and epitaxial silicon, 8,9 and epitaxial and bulk-doping concentrations for In x GaAs 1Ϫx Sb epilayers on GaSb. 10 IR-SE has been applied to the study of strong phonon anisotropy in bulk ␣-SiO 2 and ␣-Al 2 O 3 by Humlíček and Röseler.…”

Section: Introductionmentioning

confidence: 99%

Carrier concentration and lattice absorption in bulk and epitaxial silicon carbide determined using infrared ellipsometry

et al. 1999

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Wetteroth, T.; Wilson, S. R.; and Powell, Adrian R., "Carrier concentration and lattice absorption in bulk and epitaxial silicon carbide determined using infrared ellipsometry" (1999 Carrier concentration and lattice absorption in bulk and epitaxial silicon carbide determined using infrared ellipsometry We have measured the dielectric function of bulk nitrogen-doped 4H and 6H SiC substrates from 700 to 4000 cm Ϫ1 using Fourier-transform infrared spectroscopic ellipsometry. Photon absorption by transverse optical phonons produces a strong reststrahlen band between 797 and 1000 cm Ϫ1 with the effects of phonon anisotropy being observed in the region of the longitudinal phonon energy ͑960 to 100 cm Ϫ1 ͒. The shape of this band is influenced by plasma oscillations of free electrons, which we describe with a classical Drude equation. For the 6H-SiC samples, we modify the Drude equation to account for the strong effective mass anisotropy. Detailed numerical regression analysis yields the free-electron concentrations, which range from 7ϫ10 17 to 10 19 cm Ϫ3 , in good agreement with electrical and secondary ion mass spectrometry measurements.Finally, we observe the Berreman effect near the longitudinal optical phonon energy in nϪ/nϩ homoepitaxial 4H SiC and hydrogen implanted samples, and we are able to determine the thickness of these surface layers.

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Application of IR variable angle spectroscopic ellipsometry to the determination of free carrier concentration depth profiles

Cited by 123 publications

References 8 publications

Hole diffusion profile in a p-p+ silicon homojunction determined by terahertz and midinfrared spectroscopic ellipsometry

Hole diffusion profile in a p-p+ silicon homojunction determined by terahertz and midinfrared spectroscopic ellipsometry

Thickness analysis of silicon membranes for stencil masks

Carrier concentration and lattice absorption in bulk and epitaxial silicon carbide determined using infrared ellipsometry

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