The formation of hydrogen passivated silicon single-crystal surfaces using ultraviolet cleaning and HF etching

Takahagi, Takayuki; Nagai, Ichiro; Ishitani, A.; Kuroda, Haruo; Nagasawa, Y.

doi:10.1063/1.341489

Cited by 505 publications

(187 citation statements)

References 31 publications

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“…We observed that the thickness of the organic layer is directly correlated with the intensity of the dissipation peak in figure 6. The peak is also seen for the native oxide-covered device and for similar diamond and SiN devices (see [7] and supporting information), where it may be explained by a physisorbed molecular layer, possibly hydrocarbons [43]. The adventitious surface layer is small for all other devices, because they only experienced short air Figure 6.…”

Section: Temperature Dependence Of Dissipationmentioning

confidence: 94%

Permanent reduction of dissipation in nanomechanical Si resonators by chemical surface protection

et al. 2015

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We report on mechanical dissipation measurements carried out on thin (∼100 nm), single-crystal silicon cantilevers with varying chemical surface termination. We find that the 1-2 nm-thick native oxide layer of silicon contributes about 85% to the friction of the mechanical resonance. We show that the mechanical friction is proportional to the thickness of the oxide layer and that it crucially depends on oxide formation conditions. We further demonstrate that chemical surface protection by nitridation, liquid-phase hydrosilylation, or gas-phase hydrosilylation can inhibit rapid oxide formation in air and results in a permanent improvement of the mechanical quality factor between three-and five-fold. This improvement extends to cryogenic temperatures. Presented recipes can be directly integrated with standard cleanroom processes and may be especially beneficial for ultrasensitive nanomechanical force-and mass sensors, including silicon cantilevers, membranes, or nanowires.

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Section: Temperature Dependence Of Dissipationmentioning

confidence: 94%

Permanent reduction of dissipation in nanomechanical Si resonators by chemical surface protection

et al. 2015

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“…Followed by aqueous rinsing, passivation by fluoride ͑F − ͒ can be potentially removed to render the surface hydrophilic via the exchange of fluorine with OH − groups. 14,15 Researchers have been able to reduce S contamination on surfaces up to few atomic percent with controlled oxide growth. 10 The addition of a low concentration of HF into the HNO 3 solution ͑known as SE, slight etch͒ controls oxide growth by competitive oxidation and etching together.…”

mentioning

confidence: 99%

Effect of Hydrofluoric Acid in Oxidizing Acid Mixtures on the Hydroxylation of Silicon Surface

Guhathakurta

Subramanian

2007

J. Electrochem. Soc.

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Silicon ͑100͒ wafers, predipped in 1:20 ͑v/v͒ HF water, were treated separately with four different acid mixtures, viz., HNO 3 , H 2 SO 4 -H 2 O 2 , HNO 3 -HF, and H 2 SO 4 -H 2 O 2 -HF, for different time durations. Subsequent vigorous rinsing with deionized water rendered the wafer surfaces with hydroxyl termination. Synthesized surfaces were characterized by diffuse-reflectance infrared Fourier transform spectroscopy ͑DRIFTS͒, ellipsometry, contact angle and atomic force microscopy. Surfaces treated with HNO 3 and H 2 SO 4 -H 2 O 2 showed increasing hydrophilicity at room temperature due to the formation of silanol ͑−SiOH͒ terminated chemical oxides, with continuous oxide growth. An increase in hydrophilicity was observed during the first 15 min of treatment with HNO 3 -HF and H 2 SO 4 -H 2 O 2 -HF acid mixtures, causing a decrease in the hydrophilic character with longer incubation times. DRIFTS analysis confirmed the addition of HF in the oxidizing acid mixture controls chemical oxide proliferation, through creating a surface with mixed −SiOH and silicon hydride ͑−SiH x ͒ termination. Prolonged incubation in acidic mixtures containing HF resulted in a logarithmic increase of −SiH x coverage, rendering the surface hydrophobic. Incubation for 15 minutes in each of the four acid mixture systems generated surfaces with comparable hydrophilicity, controlled oxide growth and reduced surface roughness.

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“…It is important to keep in mind, that in XPS, the photoelectrons are collected from a so called escape depth, which varies with the electron energy. For our experimental conditions, the escape depth may be estimated as (15-30) A, or (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) monolayers of silicon in the (100) crystallographic direction [8]. Thus, atomic concentrations presented in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…According to this study, a silicon surface polished by colloidal silica is predominately covered by dihydride species, a significant fraction of which is backbonded to oxygen. Such a chemical structure of the silicon top layer resembles an early stage of silicon native oxidation [11,19,20].…”

Section: Thickness Of Silicon Oxide Layermentioning

confidence: 99%

Silicon surface preparation for two-dimensional dopant characterization

Ukraintsev

Potts

Wallace

et al. 1998

The 1998 International Conference on Characterization and Metrology for ULSI Technology

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Most two-dimensional (2D) dopant characterization techniques deal with near surface carrier concentration or surface potential measurements using a device cross-section. Thus, a reproducible and well-characterized surface condition is essential for accurate measurements. We report on an X-ray photoelectron spectroscopy study of surface preparation techniques commonly used in 2D dopant characterization: (i) hydrogen termination, (ii) colloidal silica polishing, (iii) low temperature silicon oxidation. Although the presented results may be applied to any other technique, in this report we concentrate on scanning capacitance microscopy (SCM). For high quality SCM a thin, uniform, and chargefree insulating film has to be formed on top of the silicon sample. Two phenomena may have a critical impact on accuracy of SCM: (i) leakage through the insulating layer and (ii) surface charging which may cause unpredictable variations in flat-band voltage. We found that samples polished by colloidal silica have about one monolayer of oxidized silicon. If the polishing is followed by baking at 200°C in the air then 1 to 2 monolayers of silicon are oxidized and an ultra-thin insulating layer of (4-6) ,~, is formed. A significant leakage through the silicon oxide layer, which may alter SCM measurements, is expected in both cases. Silicon oxidation under UV irradiation in ozone ambient improves insulating property of silicon oxide film. Interface equivalent to ca. (8-15) A of silicon dioxide is reproducibly formed by this technique. Importantly, all tested methods of silicon surface preparation are dopant independent. No noticeable surface charging has been observed for any studied method of silicon surface preparation. For silicon oxidized by UV-generated ozone the position of the Si 2p3/2 core-level relative to the Fermi level changes systematically with dopant type and concentration. The binding energy is higher for n-type silicon and lower for ptype doping. Such behavior is expected for silicon with a relatively low density of surface electronic states and hence unpinned Fermi level. We conclude that silicon oxidation by UV-generated ozone is a promising method of silicon surface preparation for high quality SCM.

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The formation of hydrogen passivated silicon single-crystal surfaces using ultraviolet cleaning and HF etching

Cited by 505 publications

References 31 publications

Permanent reduction of dissipation in nanomechanical Si resonators by chemical surface protection

Permanent reduction of dissipation in nanomechanical Si resonators by chemical surface protection

Effect of Hydrofluoric Acid in Oxidizing Acid Mixtures on the Hydroxylation of Silicon Surface

Silicon surface preparation for two-dimensional dopant characterization

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