Unexpectedly High Etching Rate of Highly Doped n-Type Crystalline Silicon in Hydrofluoric Acid

ABSTRACTThis paper reviews our works about the development of thin composite film based on aligned carbon nanotubes (CNT) forest, embedded in epoxy or PMMA polymer matrix, in order to fabricate membranes dedicated to water purification issue. Indeed, the small internal radius of nanotubes, the smoothness of their inner core and the hydrophobic properties of its interna surface induce remarkable flowing properties for water molecules. In this article, thinnin technology process is investigated to obtain composite film with opened CNT. Different etching techniques as grinding, Chemical Mechanical Polishing (CMP) and isotropic plasma O2ar investigated in term of etching rate and membrane roughness, using AFM and SEM characterizations. Results show CMP process in lapping configuration permits to obtain agreement between high etching rate and membrane roughness. Moreover, to improve water flowing through membrane, O2plasma treatment is used to remove polymer residue spread over CNT. Joint use of lapping and plasma treatment permits to obtain 35μm-thick nanoporous membrane with well-opened protruding nanotubes.

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Low Energy Focused Ion Beam Processing

MRS Proceedings ◽

10.1557/proc-279-577 ◽

1992 ◽

Vol 279 ◽

Cited By ~ 1

Author(s):

Kenji Gamo

Keyword(s):

Focused Ion Beam ◽

Ion Irradiation ◽

Ion Beam ◽

Etching Rate ◽

High Mobility ◽

Low Energy ◽

High Electron ◽

Optimization Of Process Parameters ◽

High Etching Rate

ABSTRACTFocused ion beam (FIB) techniques have many advantages which stem from being maskless and have attracted much interest for various applications includingin situprocessing. However, reduction of damage and improvement of throughput are problems awaiting solution. For reduction of damage, low energy FIB is promising and for improvement of throughput, understanding of the basic processes and optimization of process parameters based on this understanding is crucial. This paper discusses characteristics of low energy FIB system, ion beam assisted etching and ion implantation, and effect of damage with putting emphasize onin situfabrication. Low energy (0.05–25keV) FIB system being developed forms -lOOnm diameter ion beams and is connected with molecular beam epitaxy system. Many results indicate that low damage, maskless ion beam assisted etching is feasible using low energy beams. Recently it was also shown that for ion beam assisted etching of GaAs, pulse irradiation yields very high etching rate of 500/ion. This indicates that the optimization of the relative ratio of ion irradiation and reactant gas supply as important to achieve high etching rate. Low energy FIB is also important for selective doping for high electron mobility heterostructures of GaAs/GaAlAs, because high mobility is significantly degraded by a slight damage.

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Experimental investigation on anisotropic surface properties of crystalline silicon

BIBECHANA ◽

10.3126/bibechana.v8i0.4828 ◽

2012 ◽

Vol 8 ◽

pp. 59-66

Author(s):

Shobha Kanta Lamichhane

Keyword(s):

Activation Energy ◽

Potassium Hydroxide ◽

Etch Rate ◽

Crystalline Silicon ◽

Etching Rate ◽

Energy Concentration ◽

Temperature Dependent ◽

Thermal Agitation ◽

Anisotropic Surface ◽

Experimental Values

Anisotropic etching of silicon has been studied by wet potassium hydroxide (KOH) etchant with its variation of temperature and concentration. Results presented here are temperature dependent etch rate along the crystallographic orientations. The etching rate of the (111) surface family is of prime importance for microfabrication. However, the experimental values of the corresponding etch rate are often scattered and the etching mechanism of (111) remains unclear. Etching and activation energy are found to be consistently favorable with the thermal agitation for a given crystal plane. Study demonstrate that the contribution of microscopic activation energy that effectively controls the etching process. Such a strong anisotropy in KOH allows us a precious control of lateral dimensions of the silicon microstructure.Keywords: microfabrication; activation energy; concentration; anisotropy; crystal planeDOI: http://dx.doi.org/10.3126/bibechana.v8i0.4828 BIBECHANA 8 (2012) 59-66

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The Kinetics and Stoichiometry of Metal Cation Reduction on Multi-Crystalline Silicon in a Dilute Hydrofluoric Acid Matrix

Nanomaterials ◽

10.3390/nano10122545 ◽

2020 ◽

Vol 10 (12) ◽

pp. 2545

Author(s):

Stefan Schönekerl ◽

Jörg Acker

Keyword(s):

Metal Ions ◽

Valence Band ◽

Metal Cation ◽

Hydrofluoric Acid ◽

Metal Ion ◽

Crystalline Silicon ◽

Metal Deposition ◽

Equilibrium Potential ◽

Valence Bands ◽

Energetic Level

In this study, the process of metal cation reduction on multi-crystalline silicon in a dilute hydrofluoric acid (HF) matrix is described using Ag(I), Cu(II), Au(III) and Pt(IV). The experimental basis utilized batch tests with various solutions of different metal cation and HF concentrations and multi-crystalline silicon wafers. The metal deposition kinetics and the stoichiometry of metal deposition and silicon dissolution were calculated by means of consecutive sampling and analysis of the solutions. Several reaction mechanisms and reaction steps of the process were discussed by overlaying the results with theoretical considerations. It was deduced that the metal deposition was fastest if the holes formed during metal ion reduction could be transferred to the valence bands of the bulk and surface silicon with hydrogen termination. By contrast, the kinetics were lowest when the redox levels of the metal ion/metal half-cells were weak and the equilibrium potential of the H3O+/H2 half-cells was high. Further minima were identified at the thresholds where H3O+ reduction was inhibited, the valence transfer via valence band mechanism was limited by a Schottky barrier and the dissolution of oxidized silicon was restricted by the activity of the HF species F−, HF2− and H2F3−. The findings of the stoichiometric conditions provided further indications of the involvement of H3O+ and H2O as oxidizing agents in addition to metal ions, and the hydrogen of the surface silicon termination as a reducing agent in addition to the silicon. The H3O+ reduction is the predominant process in dilute metal ion solutions unless it is disabled due to the metal-dependent equilibrium potential of the H3O+/H2 half-cell and the energetic level of the valence bands of the silicon. As silicon is not oxidized up to the oxidation state +IV by the reduction of the metal ions and H3O+, water is suspected of acting as a secondary oxidant. The stoichiometric ratios increased up to a maximum with higher molalities of the metal ions, in the manner of a sigmoidal function. If, owing to the redox level of the metal half-cells and the energetic level of the valence band at the metal–silicon contact, the surface silicon can be oxidized, the hydrogen of the termination is the further reducing agent.

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Importance of the Electrolyte in Obtaining Porous Silicon and How It Modifies the Optical and Structural Proprieties: Optical and Microstructural Investigation

Journal of Nanomaterials ◽

10.1155/2015/942786 ◽

2015 ◽

Vol 2015 ◽

pp. 1-6 ◽

Cited By ~ 3

Author(s):

F. Severiano ◽

G. García ◽

L. Castañeda ◽

M. Salazar Villanueva ◽

J. Flores Méndez

Keyword(s):

Porous Silicon ◽

Raman Scattering ◽

Hydrofluoric Acid ◽

Crystalline Silicon ◽

Energy Dispersive Spectrometer ◽

Visible Range ◽

Gravimetric Analysis ◽

Sem Images ◽

Microstructural Investigation ◽

Incremental Change

The effect of using different electrolytes in the physical and optical properties of porous silicon was studied. To do this porous silicon (PS) samples photoluminescent in the visible range from (100) oriented n-type crystalline silicon prepared by anodic etching were obtained. The first electrolyte was composed of a mixture of hydrofluoric acid (HF) and ethanol (CH3-CH2-OH) in a ratio of 1 : 2, respectively. The second was composed of hydrofluoric acid (HF), ethanol (CH3-CH2-OH), and hydrogen peroxide (H2O2) in a ratio of 1 : 1 : 2, respectively. Raman scattering, photoluminescence (PL), gravimetry, scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS) measurements on the PSL were carried out. Raman scattering showed that the disorder in the samples obtained with H2O2is greater than in the samples obtained without this. The PL from PS increased in intensity with the incremental change in the anodization time and showed a blueshift. The blueshift of PL is consistent with the reduction in size of the silicon nanocrystallites. The sizes of nanocrystals were estimated to be 3.08, 2.6, and 2.28 nm. The gravimetric analysis showed that the porosity increased with the incorporation of H2O2. SEM images (morphological analysis) showed an incremental change in the quantity and in the porous size.

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4H-Silicon Carbide Wafer Surface after Chlorine Trifluoride Gas Etching

Materials Science Forum ◽

10.4028/www.scientific.net/msf.924.369 ◽

2018 ◽

Vol 924 ◽

pp. 369-372 ◽

Cited By ~ 1

Author(s):

Shogo Okuyama ◽

Keisuke Kurashima ◽

Ken Nakagomi ◽

Hitoshi Habuka ◽

Yoshinao Takahashi ◽

...

Keyword(s):

Silicon Carbide ◽

Etching Rate ◽

Concentric Circle ◽

Wafer Surface ◽

Deep Etching ◽

Gas Distributor ◽

High Etching Rate ◽

Hole Arrays ◽

Rate Profile ◽

Gas Supply

In order to develop the high etching rate reactor for silicon carbide, the 50-mm-diameter C-face 4H-silicon carbide wafer was etched using the chlorine trifluoride gas at 500 °C. By the deep etching, the concentric-circle-shaped valleys were formed at the positions corresponding to the radii of the pin-hole arrays of the gas distributor, as predicted by the calculation. The etching rate profile of 4H-silicon carbide was concluded to have a relationship with the local chlorine trifluoride gas supply . The wafer bow was small, even the wafer was very thin, about 160 μm thick.

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A New Dry Etching Method with the High Etching Rate for Patterning Cross–Linked SU–8 Thick Films

Journal of Electrical Engineering ◽

10.1515/jee-2016-0030 ◽

2016 ◽

Vol 67 (3) ◽

pp. 212-216 ◽

Cited By ~ 1

Author(s):

Jingning Han ◽

Zhifu Yin ◽

Helin Zou ◽

Wenqiang Wang ◽

Jianbo Feng

Keyword(s):

Etching Rate ◽

Chamber Pressure ◽

Gas Mixture ◽

Substrate Holder ◽

Rf Power ◽

Gas Concentration ◽

High Etching Rate ◽

Mems Device ◽

The Cross ◽

Difficult Issue

Abstract Photo sensitive polymer SU-8, owing to its excellent mechanical properties and dielectric properties on polymerization, is widely used in MEMS device fabrications. However, the removing, stripping or re-patterning of the cross-linked SU-8 is a difficult issue. In this paper, CF4/O2 gas mixture provided by a plasma asher equipment was used for the patterning of cross-linked SU-8 material. The RF power, the temperature of the substrate holder, chamber pressure and gas concentration were optimized for the cross-linked SU-8 etching process. When the CF4/O2 mixture contains about 5%CF4 by volume, the etching rate can be reached at 5.2 μm/min.

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Extremely Low Temperature Silicon Liquid Phase Epitaxy

MRS Proceedings ◽

10.1557/proc-386-339 ◽

1995 ◽

Vol 386 ◽

Cited By ~ 2

Author(s):

M. Konuma ◽

I. Silier ◽

A. Gutjahr ◽

E. Bauser ◽

F. Banhart ◽

...

Keyword(s):

Liquid Phase ◽

Liquid Phase Epitaxy ◽

Hydrofluoric Acid ◽

Crystalline Silicon ◽

Silicon Layer ◽

Extended Defects ◽

Glass Substrates ◽

Nano Crystalline ◽

Amorphous Glass ◽

Substrate Surfaces

ABSTRACTBy liquid phase epitaxy (LPE) we have grown silicon layers on silicon and partially masked silicon at temperatures below 450 °C from Ga and Ga-In solutions. Oxidation of the cleaned silicon substrate surfaces before epitaxial growth has been prevented by a buffered hydrofluoric acid treatment. The epitaxial layers reached a thickness of 7 jim and were free of extended defects.Low growth temperatures make it possible to grow silicon layers also on pre-treated glass substrates. The amorphous glass is first coated with a thin nano-crystalline silicon layer which is deposited by plasma processes from a mixture of SiH4/H2 gas. The grains in the silicon layers grown from Ga solution on glass have reached sizes up to 100 μm.

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Enhanced electrical and luminescent performance of a porous silicon/MEH-PPV nanohybrid synthesized by anodization and repeated spin coating

RSC Advances ◽

10.1039/c5ra18407j ◽

2015 ◽

Vol 5 (121) ◽

pp. 99892-99898 ◽

Cited By ~ 12

Author(s):

A. M. S. Salem ◽

F. A. Harraz ◽

S. M. El-Sheikh ◽

H. S. Hafez ◽

I. A. Ibrahim ◽

...

Keyword(s):

Porous Silicon ◽

Spin Coating ◽

Hydrofluoric Acid ◽

Crystalline Silicon ◽

Electrochemical Anodization ◽

Single Crystalline Silicon ◽

Single Crystalline ◽

Pore Sizes ◽

Wide Range

The electrochemical anodization of a single crystalline silicon in hydrofluoric acid-based solution leads to the formation of porous silicon (PSi) with tunable pore sizes and morphology for a wide range of technological applications.

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Realization of silicon nanopillar arrays with controllable sidewall profiles by holography lithography and a novel single-step deep reactive ion etching

MRS Proceedings ◽

10.1557/proc-1258-q14-02 ◽

2010 ◽

Vol 1258 ◽

Cited By ~ 3

Author(s):

Yung-Jr Hung ◽

San-Liang Lee ◽

Brian J. Thibeault ◽

Larry A. Coldren

Keyword(s):

Etching Rate ◽

Reactive Ion Etching ◽

Single Step ◽

Gas Mixture ◽

Optical Performance ◽

Ion Etching ◽

Deep Reactive Ion Etching ◽

High Etching Rate ◽

Sidewall Angle ◽

Nanopillar Arrays

AbstractA simple and efficient approach for fabricating silicon nanopillar arrays with a high aspect ratio and controllable sidewall profiles has been developed by using holographic lithography and a novel single-step deep reactive ion etching. During the etching process, scalloping of the sidewalls can be avoided while reserving the high mask selectivity and high etching rate. Besides, the sidewall angle of resultant patterns can be adjusted by tuning the composition of the gas mixture of single-step DRIE process. We further fabricate a tapered silicon nanopillar array and observe its photonic bandgap property. We believe that the good optical performance of this tapered silicon nanopillar array realized by the proposed approach shows the promising of this process for various applications.

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