Infrared spectroscopic analysis of the Si/SiO2 interface structure of thermally oxidized silicon

Queeney, K. T.; Weldon, M. K.; Chang, Jane P.; Chabal, Yves J.; Gurevich, Alejandra B.; Sapjeta, J.; Opila, R. L.

doi:10.1063/1.372017

Cited by 261 publications

(233 citation statements)

References 27 publications

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“…Although there is only limited knowledge regarding the electrical properties of subnanometer SiO x layers, it was previously demonstrated that even for thermally grown SiO 2 layers, the initial 6 Å of the silicon oxide layer at the Si interface is predominantly substoichiometric. 21 This is supported by theoretical predictions showing a k value of 6-7 for a 6 Å interfacial substoichiometric SiO x layer between Si͑100͒ and 17 Å of SiO 2 . Our extracted median k value for sample A is 6.3, within the range of 6-7 predicted by theory.…”

Section: Resultssupporting

confidence: 68%

“…The method of extraction first assumes that the HRTEM images give accurate thickness estimates for all three samples ͓sample A: t͑SiO x ͒ =6 Å, t͑HfO 2 ͒ = 37 Å; sample B: t͑SiO x ͒ =19 Å, t͑HfO 2 ͒ = 37 Å; sample C: t͑SiO x ͒ =29 Å, t͑HfO 2 ͒ =40 Å͔. The second assumption is that the k value for the hafnium oxide layer falls within the range of [16][17][18][19][20][21][22][23][24][25]. The third assumption is that the k value for the IL is in the range of 3.9-8.0.…”

Section: Resultsmentioning

confidence: 99%

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Electrical, structural, and chemical properties of HfO2 films formed by electron beam evaporation

Cherkaoui

Monaghan

Negara

et al. 2008

Journal of Applied Physics

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High dielectric constant hafnium oxide films were formed by electron beam ͑e-beam͒ evaporation on HF last terminated silicon ͑100͒ wafers. We report on the influence of low energy argon plasma ͑ϳ70 eV͒ and oxygen flow rate on the electrical, chemical, and structural properties of metal-insulator-silicon structures incorporating these e-beam deposited HfO 2 films. The use of the film-densifying low energy argon plasma during the deposition results in an increase in the equivalent oxide thickness ͑EOT͒ values. We employ high resolution transmission electron microscopy ͑HRTEM͒, x-ray photoelectron spectroscopy ͑XPS͒, and medium energy ion scattering experiments to investigate and understand the mechanisms leading to the EOT increase. We demonstrate very good agreement between the interfacial silicon oxide thicknesses derived independently from XPS and HRTEM measurements. We find that the e-beam evaporation technique enabled us to control the SiO x interfacial layer thickness down to ϳ6 Å. Very low leakage current density ͑Ͻ10 −4 A / cm 2 ͒ is measured at flatband voltage +1 V into accumulation for an estimated EOT of 10.9Ϯ 0.1 Å. Based on a combined HRTEM and capacitance-voltage ͑CV͒ analysis, employing a quantum-mechanical CV fitting procedure, we determine the dielectric constant ͑k͒ of HfO 2 films, and associated interfacial SiO x layers, formed under various processing conditions. The k values are found to be 21.2 for HfO 2 and 6.3 for the thinnest ͑ϳ6 Å͒ SiO x interfacial layer. The cross-wafer variations in the physical and electrical properties of the HfO 2 films are presented.

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Section: Resultssupporting

confidence: 68%

Section: Resultsmentioning

confidence: 99%

Electrical, structural, and chemical properties of HfO2 films formed by electron beam evaporation

Cherkaoui

Monaghan

Negara

et al. 2008

Journal of Applied Physics

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“…2. To the best of our knowledge, the band at $1300 cm À1 has never been observed on silica films and crystals [2,7,8,[23][24][25][26]. In addition, the band is by about 250 cm À1 higher than that of Si-O-Mo stretching vibrations on SiO 2 =Moð112Þ [2].…”

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confidence: 91%

Growth and Structure of Crystalline Silica Sheet on Ru(0001)

et al. 2010

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Thin SiO 2 films were grown on a Ru(0001) single crystal and studied by photoelectron spectroscopy, infrared spectroscopy and scanning probe microscopy. The experimental results in combination with density functional theory calculations provide compelling evidence for the formation of crystalline, double-layer sheet silica weakly bound to a metal substrate. DOI: 10.1103/PhysRevLett.105.146104 PACS numbers: 68.35.Àp, 68.47.Gh, 68.55.Àa Silicon dioxide (SiO 2 ) plays a key role in many modern technologies and applications that range from insulating layers in integrated circuits to supports for metal and oxide clusters in catalysts. For better understanding of structureproperty relationships on silica-based materials, particularly of reduced dimensions, thin silica films grown on metal single crystal substrates are suggested as suitable model systems that allow the facile application of many ''surface science'' techniques. It has recently been shown that crystalline silica films and nanowires can be grown on Mo(112) [1][2][3][4][5]. The ultrathin film consists of a monolayer honeycomblike network of corner-sharing [SiO 4 ] tetrahedra, thus resulting in a SiO 2:5 stoichiometry of the film. The Si atoms in these films can be partly substituted by Al in the course of preparing metal supported aluminosilicate films [6], which is the first step towards experimental modeling of catalytic centers in zeolitelike materials. However, attempts to grow thicker silica films on the Mo substrates resulted in amorphous structures [7][8][9], most likely due to the formation of strong Si-O-Mo bonds at the interface that govern the growth mode [9]. Recently, the preparation of crystalline silica films on other supports such as Pd(100) [10] and Ni(111) [11] has been reported. However, the atomic structure of the films, film surface termination, and the nature of the silica-metal interface were not determined.In this Letter, we report on the preparation and the atomic structure of well-defined silica films on Ru(0001). The experimental results, obtained by photoelectron and vibrational spectroscopies and high-resolution scanning probe microscopy, are complemented by density functional theory calculations which together provide compelling evidence for the formation of a double-layer sheet silicate, with a SiO 2 stoichiometric composition, weakly bound to a metal support. The results open new perspectives for employing a ''surface science'' approach to understand the reactivity of silicate surfaces consisting of hydrophobic Si-O-Si bonds, such as those of microporous all-silica zeolites [12]. Also, these films can be used as model supports for catalytically active metal and oxide clusters [4,13].The experiments were performed in an ultrahigh vacuum chamber equipped with low energy electron diffraction (LEED) and Auger electron spectroscopy, x-ray photoelectron spectroscopy (XPS), infrared reflection absorption spectroscopy (IRAS), and scanning tunneling microscopy (STM). Atomically resolved atomic force microscopy (AFM) and STM image...

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“…Reduction of the TO−LO phonon energy splitting corresponds to the stress relaxation in a silicon oxide layer [11]. The increase in the splitting of TO−LO phonons is associated with stoichiometry growth at the silicon−silicon oxide interface as the SiO 2 content in the SiO/SiO 2 mixture increases [12].…”

Section: Macroporous Silicon Structures With Sio 2 Nanocoatingsmentioning

confidence: 99%

Wannier-Stark effect and electron-phonon interaction in macroporous silicon structures with SiO2 nanocoatings

Карачевцева

Goltviansky

Kolesnyk

et al. 2014

Opto-Electronics Review

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We investigated the contribution of electron-phonon interaction to the broadening parameter Γ of the Wannier-Stark ladder levels in oxidized macroporous silicon structures with different concentration of Si-O-Si states (TO and LO phonons). The obtained value of the Wannier-Stark ladder parameter Γ is much less than the djacent level energy evaluated from giant oscillations of resonance electron scattering on the surface states. We determined the influence of broadening on the oscillation amplitude in IR absorption spectra as interaction of the surface multi-phonon polaritons with scattered electrons. This interaction transforms the resonance electron scattering in samples with low concentration of Si-O-Si states into ordinary scattering on ionized impurities for samples with high concentration of Si-O-Si states. The transformation takes place at the scattering lifetime coinciding with the period of electron oscillations in the surface electric field.

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Infrared spectroscopic analysis of the Si/SiO2 interface structure of thermally oxidized silicon

Cited by 261 publications

References 27 publications

Electrical, structural, and chemical properties of HfO2 films formed by electron beam evaporation

Electrical, structural, and chemical properties of HfO2 films formed by electron beam evaporation

Growth and Structure of Crystalline Silica Sheet on Ru(0001)

Wannier-Stark effect and electron-phonon interaction in macroporous silicon structures with SiO2 nanocoatings

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