Anhydrous Hf Processing as an Alternative to Hf/Water Processes

1996 ◽  
Vol 447 ◽  
Author(s):  
J. Staffa ◽  
P. Roman ◽  
K. Chang ◽  
K. Torek ◽  
J. Ruzyllo
Keyword(s):  
Water Treatment ◽  
Gas Phase ◽  
Water Consumption ◽  
Hydrofluoric Acid ◽  
Silicon Surface ◽  
Water Solution ◽  
Surface Cleaning ◽  
Silicon Surfaces ◽  
Ultrapure Water

AbstractThe HF/water treatment of silicon surfaces is among the most frequently applied steps in surface cleaning processes. It is utilized for clearing oxides from the silicon surface. Large amounts of ultrapure water are necessary to carry out this operation, both in the HF/water solution itself and the thorough rinse which must follow HF/water processes. Therefore, a gas‐phase alternative to this process would significantly reduce deionized (DI) water consumption. The focus of this paper is the anhydrous hydrofluoric acid (AHF)/alcoholic solvent process which has shown promise as an alternative to the aqueous HF process. In particular, the AHF/methanol process has been studied extensively. This paper presents a comparison between properties of silicon surfaces prepared through the dilute HF/water (dHF) process and those of surfaces prepared through AHF/alcoholic solvent processes.

STM Studies of Electrode/Electrolyte Interfaces and Silicon Surface Reactions in Controlled Atmospheres

1996 ◽  
Vol 451 ◽  
Author(s):  
Christopher P. Wade ◽  
Huihong Luo ◽  
William L. Dunbar ◽  
Matthew R. Linford ◽  
Christopher E.D. Chidsey
Keyword(s):  
Gas Phase ◽  
Scanning Tunneling Microscope ◽  
Silicon Surface ◽  
Silicon Oxide ◽  
Ammonium Fluoride ◽  
Sample Surface ◽  
Silicon Surfaces ◽  
Scanning Tunneling ◽  
Controlled Atmospheres

ABSTRACTWe have assembled a scanning tunneling microscope with an inverted sample that allows the sample surface to be contacted by fluid electrolytes in a controlled atmosphere. A hanging meniscus is formed between the sample and a small cup surrounding the tunneling tip. In-situ imaging of the electrode/electrolyte interface is conveniently achieved with clean samples under potentiostatic control. The functioning of the microscope is illustrated by the imaging of the electrodeposition of copper on gold. This microscope has been used to image hydrogen-terminated silicon surfaces and to demonstrate that islands, tentatively assigned as silicon oxide, are formed on rinsing in water but can be avoided if the surface is not rinsed on withdrawal from the ammonium fluoride etching solution. Finally, STM shows that the convenient, gas-phase photochlorination of H-Si(111) produces the simple Cl-Si(111)(1×1) structure with little or no etching of the silicon surface.

Effects of Hydrogen Coverage on Silicon Surface Reactivity

1992 ◽  
Vol 259 ◽  
Author(s):  
A.C. Dillon ◽  
M.B. Robinson ◽  
S.M. George ◽  
P. Gupta
Keyword(s):  
Porous Silicon ◽  
Silicon Surface ◽  
High Surface ◽  
Surface Cleaning ◽  
Surface Reactivity ◽  
Silicon Surfaces ◽  
Initial Surface ◽  
Hydrogen Passivation ◽  
Surface Species ◽  
Oxidation Rates

ABSTRACTHydrogen passivation of silicon surfaces plays an important role in silicon surface cleaning and preparation. To measure the effect of hydrogen passivation on silicon surface reactivity, Fourier transform infrared (FTIR) transmission spectroscopy was used to monitor the oxidation of silicon surfaces versus hydrogen coverage. Experiments were performed insitu in an ultrahigh vacuum (UHV) chamber using high surface area poroussilicon samples. Si-H stretching and bending vibrations and Si-O-Si stretching vibrations were employed to monitor the silicon surface species. Oxidation studies with O2 conducted versus various initial hydrogen coverages revealed that oxidation rates and apparent oxygen saturation levels on porous silicon decreased as a function of initial surface hydrogen coverage. Exceptional surface stability was observed when the porous silicon surface was passivated by both monohydride and dihydride surface species. In addition, new blue-shifted Si-H stretching and bending features were observed following the oxidation of partially hydrogen-passivated porous silicon which indicated the presence of Ox SiH species. Thermal annealing studies revealed that the thermal stability of these OxSiH species increased with increasing oxidation of the silicon surface. These results have important implications for silicon growth and surface cleaning because they indicate that hydrogen removal is more difficult when the silicon surface is contaminated with oxygen. These FTIR results have also been compared with earlier results of oxidation versus hydrogen coverage on Si(111) 7×7.

NOHSO4/HF – A Novel Etching System for Crystalline Silicon

2007 ◽  
Vol 62 (11) ◽  
pp. 1411-1421 ◽  
Author(s):  
Sebastian Patzig ◽  
Gerhard Roewer ◽  
Edwin Kroke ◽  
Ingo över
Keyword(s):  
Gas Phase ◽  
Chemical Etching ◽  
Silicon Surface ◽  
Crystalline Silicon ◽  
Etching Solution ◽  
Wide Range ◽  
Ft Ir ◽  
Wet Chemical ◽  
Wet Chemical Etching ◽  
Etching System

Solutions consisting of HF - NOHSO4 - H2SO4 exhibit a strong reactivity towards crystalline silicon which is controlled by the concentrations of the reactive species HF and NO+. Selective isotropic and anisotropic wet chemical etching with these solutions allows to generate a wide range of silicon surface morphology patterns. Traces of Ag+ ions stimulate the reactivity and lead to the formation of planarized (polished) silicon surfaces. Analyses of the silicon surface, the etching solution and the gas phase were performed with scanning electron microscopy (SEM), DR/FT-IR (diffusive reflection Fourier transform infra-red), FT-IR, Raman and NMR spectroscopy, respectively. It was found that the resulting silicon surface is hydrogen-terminated. The gas phase contains predominantly SiF4, NO and N2O. Furthermore, NH4+ is produced in solution. The study has confirmed the crucial role of nitrosyl ions for isotropic wet chemical etching processes. The novel etching system is proposed as an effective new way for selective surface texturing of multi- and monocrystalline silicon. A high etching bath service lifetime, besides a low contamination of the etching solution with reaction products, provides ecological and economical advantages for the semiconductor and solar industry.

Prediction ofl-Methionine VCD Spectra in the Gas Phase and Water Solution

2013 ◽  
Vol 117 (46) ◽  
pp. 14202-14214 ◽  
Author(s):  
Joanna E. Rode ◽  
Jan Cz. Dobrowolski ◽  
Joanna Sadlej
Keyword(s):  
Gas Phase ◽  
Water Solution

An Integral Heat Sink for Cooling Microelectronic Components

1993 ◽  
Vol 115 (3) ◽  
pp. 284-291 ◽  
Author(s):  
S. H. Bhavnani ◽  
C.-P. Tsai ◽  
R. C. Jaeger ◽  
D. L. Eison
Keyword(s):  
Heat Sink ◽  
Silicon Surface ◽  
Numerical Study ◽  
High Heat ◽  
Heat Fluxes ◽  
Silicon Surfaces ◽  
Source Surface ◽  
Mouth Size ◽  
Severe Constraint ◽  
Boiling Incipience

Liquid immersion cooling is rapidly becoming the mechanism of choice for the newest generation of supercomputers. Miniaturization at both the chip and module level places a severe constraint on the size of the heat sink employed to dissipate the high heat fluxes generated. A study was conducted to develop a surface that could augment boiling heat transfer from silicon surfaces under these constraints. The surface created consists of reversed pyramidal features etched directly on to the silicon surface. Experiments were conducted in a saturated pool of refrigerant-113 at atmospheric pressure. The inexpensive crystallographic etching techniques used to create the enhanced features are described in the paper. The main characteristics of interest in the present study were the incipient boiling superheat and the magnitude of the temperature overshoot at boiling incipience. Results were obtained for test sections with various cavity densities, and compared with data for the smooth untreated surface. It was found that incipient boiling superheat was reduced from a range of 27.0–53.0° C for the untreated silicon surface, to a range of 2.5–15.0° C for the enhanced surfaces. The overshoot also decreased considerably; from about 12.0–18.0° C for two classes of untreated surfaces, to a range of 1.5–5.3° C for the enhanced surfaces. The values of the incipient boiling superheat, and those of the overshoot decreased with a decrease in cavity mouth size. Two ratios of heat source surface area to the area of the enhanced surface were studied. The overshoot values obtained for these surfaces were compared with those observed for some commonly used enhanced surfaces. An elementary numerical study was conducted to estimate the magnitude of heat spreading.

Unitary Micro-Patterning Structure-Induced Hydrophobic Silicon Surface

2011 ◽  
Vol 239-242 ◽  
pp. 2524-2527
Author(s):  
Si Si Liu ◽  
Chao Hui Zhang ◽  
Han Bing Zhang
Keyword(s):  
Inductively Coupled Plasma ◽  
Silicon Surface ◽  
Scale Effects ◽  
Silicon Surfaces ◽  
Functional Surface ◽  
Inductively Coupled ◽  
Cassie State ◽  
Micro Patterning ◽  
Pillar Arrays ◽  
The Relationship

The relationship between the wettability and the roughness structure on silicon surface is studied. The unitary microscale square pillar arrays are fabricated by the way of inductively coupled plasma (ICP). The wettability of water droplets on the silicon surface is changed from hydrophilic to hydrophobic only by introducing microscale pillarlike structure. Furthermore, the scale effects of the unitary rough structure on hydrophobicity are investigated. For those silicon surfaces with a fixed pillar height, the relatively larger scale of grooves leads the droplets wettability state to unstable Cassie state and the contact angle will initially get larger and then decrease with the increase of groove width. The research could provide further insights into the design of functional surface with controllable roughness-induced hydrophobic.

Exploring chemistry features of favipiravir in octanol/water solutions

2021 ◽  
pp. 1-12
Author(s):  
Halimeh Rajabzadeh ◽  
Ayla Sharafat ◽  
Maryam Abbasi ◽  
Maryam Eslami Gharaati ◽  
Iraj Alipourfard
Keyword(s):  
Density Functional Theory ◽  
Gas Phase ◽  
Partition Coefficients ◽  
Density Functional ◽  
Water Solution ◽  
Peptide Group ◽  
Functional Theory ◽  
Water Solutions ◽  
Group Rotations ◽  
Heterocyclic Structure

Favipiravir (Fav) has become a well-known drug for medication of patients by appearance of COVID-19. Heterocyclic structure and connected peptide group could make changes for Fav yielding different features from those required features. Therefore, it is indeed a challenging task to prepare a Fav compound with specific features of desired function. In this work, existence of eight Fav structures by tautomeric formations and peptide group rotations were obtained using density functional theory (DFT) optimization calculations. Gas phase, octanol solution, and water solution were employed to show impact of solution on features of Fav besides obtaining partition coefficients (LogP) for Fav compounds. Significant impacts of solutions were seen on features of Fav with the obtained LogP order: Fav-7 >  Fav-8 >  Fav-4 >  Fav-3 >  Fav-2 >  Fav-5 >  Fav-1 >  Fav-6. As a consequence, internal changes yielded significant impacts on features of Fav affirming its carful medication of COVID-19 patients.

scholarly journals FP688OPTIMIZATION OF ULTRAPURE WATER CONSUMPTION IN THE CONTEXT OF GREEN HEMODIALYSIS

2018 ◽  
Vol 33 (suppl_1) ◽  
pp. i277-i277
Author(s):  
Jennifer Sánchez ◽  
Miguel Angel Pinedo ◽  
Sebastian Hillebrand ◽  
Francisco López ◽  
Jon Dominguez ◽  
...  
Keyword(s):  
Water Consumption ◽  
Ultrapure Water

scholarly journals Spectral properties of coumarin derivatives in various environments

2013 ◽  
Vol 11 (4) ◽  
pp. 492-501 ◽  
Author(s):  
Alzbeta Holubekova ◽  
Pavel Mach ◽  
Jan Urban
Keyword(s):  
Gas Phase ◽  
Absorption Spectra ◽  
Spectral Properties ◽  
Density Functional ◽  
Water Solution ◽  
Blue Shift ◽  
Coumarin Derivatives ◽  
Complex Environments ◽  
Td Dft ◽  
Solvent Environment

AbstractThe structural and spectral properties of coumarin derivatives in complex environments were investigated within the time-dependent density functional theory (TD DFT). Absorption spectra calculations were obtained at TD PBE0/6-31+G(d,p) level of theory for coumarin47 in the gas-phase and in various polar and non-polar organic solvents. The geometries of coumarins 6, 30, 47 and 522 in the gas phase and in inclusion complexes with the β-cyclodextrin (βCD) were determined by PM3 and DFT (HCTH/6-31G) calculations. Encapsulation of coumarin in βCD and associated changes in electronic structure produced either a red or blue shift in the absorption spectra of coumarins. A proposed cavity model for βCD-coumarin complex in water solution allowed identification of various contributions to the overall shift in the absorption spectra of coumarin upon complex formation in a solvent environment

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