Oxide interface studies using second harmonic generation

Tolk, N. H.; Alles, Michael L.; Pasternak, R.; Lu, Xiong; Schrimpf, R.D.; Fleetwood, D. M.; Dolan, R.; Standley, R. W.

doi:10.1016/j.mee.2007.04.101

Cited by 7 publications

(3 citation statements)

References 7 publications

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“…Surface charging processes have previously also been investigated by electric field induced second harmonic generation (EFISH), [62][63][64][65][66][67] in which the sub-surface electric field is deduced based on modeling the field-enhancement of optical second harmonic generation signal as well as photoemission. [68] We find that the field strength E ∼ 1-5 V/nm, obtained in our study of the Si/SiO 2 interface, is very similar to what was found in EFISH studies under similar excitation conditions, [65,66] but because of a lower laser repetition rate is applied here (1 kHz in UEDV, compared to 80 MHz in EFISH), cyclic residual charge accumulation from deep trap states [69][70][71][72] is avoided, allowing the transient charging behavior to be resolved directly.…”

Section: Surface Photovoltagesupporting

confidence: 75%

Ultrafast Electron Diffractive Voltammetry: General Formalism and Applications

et al. 2011

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We present a general formalism of ultrafast diffractive voltammetry approach as a contact-free tool to investigate the ultrafast surface charge dynamics in nanostructured interfaces. As case studies, the photoinduced surface charging processes in oxidized silicon surface and the hot electron dynamics in nanoparticle-decorated interface are examined based on the diffractive voltammetry framework. We identify that the charge redistribution processes appear on the surface, sub-surface, and vacuum levels when driven by intense femtosecond laser pulses. To elucidate the voltammetry contribution from different sources, we perform controlled experiments using shadow imaging techniques and N-particle simulations to aid the investigation of the photovoltage dynamics in the presence of photoemission. We show that voltammetry contribution associated with photoemission has a long decay tail and plays a more visible role in the nanosecond timescale, whereas the ultrafast voltammetry are dominated by local charge transfer, such as surface charging and molecular charge transport at nanostructured interfaces. We also discuss the general applicability of the diffractive voltammetry as an integral part of quantitative ultrafast electron diffraction methodology in researching different types of interfaces having distinctive surface diffraction and boundary conditions.

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Section: Surface Photovoltagesupporting

confidence: 75%

Ultrafast Electron Diffractive Voltammetry: General Formalism and Applications

et al. 2011

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“…Other than the wavefront sensing approach, there are a few methods of non-destructive wafer surface inspections such as: dark-field inspection [8], reflectometry [9]- [13], ellipsometry [14]- [17], interferometry [2], [18]- [20] and second-harmonic generation [21]- [23]. In terms of the topographic analysis, not much has been done to find the interface of the second or the sub-layer of the material.…”

Section: Introductionmentioning

confidence: 99%

Method for distortion correction of multi-layered surface reconstruction using time-gated wavefront sensing approach

Tan

Wang

Han³

et al. 2013

J. Eur. Opt. Soc.-Rapid Publ.

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In order to estimate the multi-layer surface profile and to detect the inter-layer surfaces defects, gated wavefront sensing approach has been proposed in the previous works [1,2]. However, the proposed methodology measures the wavefront that has been distorted by its prior surfaces (reflected wavefront) or post surfaces (transmitted wavefront). Analysis has to be performed to estimate the multi-layer wavefront sensing by taking into consideration the multi-layer surfaces condition. For reflected wavefront, the bottom layer(s) wavefront is (are) being distorted twice via separate interface points while traveling back to the lenslet arrays through our observation for the slope and phase measurement. The subsequent reconstructed surfaces are not accurate and corrected. Thus, a discrete layer correction technique for the surface reconstruction has been proposed to enhance the reconstruction accuracy by using the upper/top layer's wavefront information. This paper discusses on the case of 2-layer system, where the reflected wavefront from the bottom layer has been distorted and its surface reconstruction has been corrected. The results show that the distortion is significant and the correction is deemed necessary for industrial application such as in wafer warpage inter-layer profile estimation.

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“…A technique such as second-harmonic generation (SHG) is highly suited to investigate buried interfaces. [10][11][12] SHG is an optical technique with interface sensitivity down to the atomic level. 13 Additionally, the technique has been intensively used in the past to characterize silicon.…”

Section: Introductionmentioning

confidence: 99%

Second-harmonic generation reveals the oxidation steps in semiconductor processing

Vanbel

Valev

Vincent

et al. 2012

Journal of Applied Physics

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Monitoring oxidation steps is an important factor during the fabrication of semiconductor devices, because transistor performance can be greatly affected by defects in the passivation layer. As an example, we discuss the formation of a gate stack in metal oxide semiconductor (MOS) devices using Ge as an alternative channel material. Building an MOS gate stack on Ge requires passivation of the interface between the dielectric (typically a high-k material such as Al 2 O 3 or HfO 2 , grown by means of atomic layer deposition (ALD)) and the Ge channel. Such passivation can be obtained from a very thin Si layer, epitaxially grown on Ge. The Si surface receives an oxidizing clean (O 3 or wet chemical clean) before the ALD step. In this work, second-harmonic generation (SHG) data are presented for silicon layers with varying thickness, grown with either trisilane (Si 3 H 8 ) or silane (SiH 4 ) and with various cleaning steps. The trend in second-harmonic response upon azimuthal rotation of the samples was comparable for both silane and trisilane as a Si precursor. Our results show that upon oxidation, the SHG intensity reduces, most likely due to a reduction of the amount of crystalline Si, which is converted to SiO 2 . V

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Oxide interface studies using second harmonic generation

Cited by 7 publications

References 7 publications

Ultrafast Electron Diffractive Voltammetry: General Formalism and Applications

Ultrafast Electron Diffractive Voltammetry: General Formalism and Applications

Method for distortion correction of multi-layered surface reconstruction using time-gated wavefront sensing approach

Second-harmonic generation reveals the oxidation steps in semiconductor processing

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