Morphology of hydrofluoric acid and ammonium fluoride‐treated silicon surfaces studied by surface infrared spectroscopy

1992 ◽  
Vol 71 (11) ◽  
pp. 5646-5649 ◽  
Author(s):  
M. Niwano ◽  
Y. Takeda ◽  
Y. Ishibashi ◽  
K. Kurita ◽  
N. Miyamoto
Keyword(s):  
Infrared Spectroscopy ◽  
Hydrofluoric Acid ◽  
Ammonium Fluoride ◽  
Silicon Surfaces

Surface Chemistry of Silicon and Germanium Treated with Hydrofluoric Acid Solutions: Slow Reactions of Process Residuals

1990 ◽  
Vol 204 ◽  
Author(s):  
J. Yota ◽  
V.A. Burrows
Keyword(s):  
Thin Film ◽  
Infrared Spectroscopy ◽  
Reaction Mechanism ◽  
Surface Chemistry ◽  
Hydrofluoric Acid ◽  
Ammonium Fluoride ◽  
Ammonium Salts ◽  
Acid Solutions ◽  
Reactive Intermediate ◽  
Silicon And Germanium

ABSTRACTSolutions of hydrofluoric acid are used extensively in the processing of semiconductors, primarily in etching and in oxide stripping procedures. Such solutions are often buffered with ammonium fluoride to insure constant oxide stripping rates. Infrared spectroscopy of silicon and germanium surfaces treated with such solutions indicates that a thin film of ammonium salts will deposit on the materials unless they are immediately and very thoroughly rinsed following treatment. This thin film, comprised initially of ammonium bifluoride (NH4FHF), reacts with the semiconductor material to form ammonium fluoride (NH4F) as a reactive intermediate, and ammonium hexafluorometallate ((NH4)2 SiF6 or (NH4)2 GeF6). These reactions occur very slowly, over hours or days. They are apparently driven by favorable thermodynamics. This explanation is supported by the absence of comparable reactions using analogous chlorine-based solutions (HCI/NH4 CI). Aspects of the reaction mechanism for hexafluorometallate production is presented.

INFRARED SPECTROSCOPY OF H-TERMINATED SILICON SURFACES

1993 ◽  
Vol 07 (04) ◽  
pp. 1031-1078 ◽  
Author(s):  
Y.J. CHABAL ◽  
A.L. HARRIS ◽  
KRISHNAN RAGHAVACHARI ◽  
J.C. TULLY
Keyword(s):  
Infrared Spectroscopy ◽  
Vibrational Energy ◽  
Mass Difference ◽  
A Priori ◽  
Large Mass ◽  
Quantitative Information ◽  
Model Systems ◽  
Silicon Surfaces ◽  
Structural Description ◽  
Theoretical Understanding

In this review, the present level of infrared spectroscopy at surfaces is described by using hydrogen-terminated silicon surfaces as model systems. The electronic structure of the adsorbate, H, and the large mass difference between H and Si simplify the interpretation of the data and make it possible for the theories to give reliable quantitative information. In particular, ab initio cluster calculations provide an accurate structural description and precise vibrational frequencies for various surface configurations, and are used as the basis of a priori simulations of the line shape of H on silicon. A special emphasis is given to the recent discovery of chemical etching to prepare H-terminated silicon surfaces because it has greatly helped in understanding structural and dynamical properties of H-terminated silicon surfaces. In particular, both the energy and phase relaxation of the Si-H stretching vibration on the flat, ideally hydrogen terminated Si(111) surface have been measured directly and evidence for vibrational energy diffusion has been obtained on vicinal, H-terminated Si(111) surfaces. The data and current theoretical understanding of the chemically prepared Si(111) surfaces are presented and discussed.

scholarly journals HETEROGENEOUS CATALYTIC CONVERSIONS OF ACETYLENE

2021 ◽  
pp. 45-57
Keyword(s):  
Acetic Acid ◽  
Water Vapor ◽  
Hydrofluoric Acid ◽  
Heterogeneous Catalysts ◽  
Ammonium Fluoride ◽  
Catalyst Carrier ◽  
Heterogeneous Catalytic ◽  
Pyridine Bases ◽  
Cadmium Zinc ◽  
Selection Of

The reactions of interaction of acetylene with water vapor, acetic acid and ammonia in the presence of heterogeneous catalysts have investigated. Depending on the nature of the starting components used, acetaldehyde and acetone, vinyl acetate, pyridine bases and pyrrole synthesized. Heterogeneous catalysts selected for each studied reaction based on some scientific prerequisites for the selection of catalysts. Active catalysts for the investigated reactions were determined, which contain compounds of cadmium, zinc, bismuth, chromium, iron and copper, in general, d-group metals. γ-Al2O3, bentonite and kaolin used as a catalyst carrier. Hydrofluoric acid, acetic acid, ammonium fluoride and others used for peptization. Some hypothetical mechanisms for the formation of target products for each reaction have proposed.

In Situ Spectroscopic Approach to Atomic Layer Deposition

2002 ◽  
Vol 745 ◽  
Author(s):  
Martin M. Frank ◽  
Yves J. Chabal ◽  
Glen D. Wilk
Keyword(s):  
Infrared Spectroscopy ◽  
Atomic Layer Deposition ◽  
Aluminum Oxide ◽  
Atomic Layer ◽  
Gate Oxide ◽  
Silicon Surfaces ◽  
Oxide Growth ◽  
Layer By Layer ◽  
Layer Deposition

ABSTRACTThere is great need for a mechanistic understanding of growth chemistry during atomic layer deposition (ALD) of films for electronic applications. Since commercial ALD reactors are presently not equipped for in situ spectroscopy, we have constructed a model reactor that enables single-pass transmission infrared spectroscopy to be performed in situ on a layer-by-layer basis. We demonstrate the viability of this approach for the study of aluminum oxide growth on silicon surfaces, motivated by alternative gate oxide applications. Thanks to submonolayer dielectric and adsorbate sensitivity, we can quantify oxide thicknesses and hydroxyl areal densities on thermal and chemical SiO2/Si(100) substrates. Methyl formation and hydroxyl consumption upon initial trimethylaluminum (TMA) reaction can also be followed. We verify that in situ grown Al2O3 films are compatible in structure to films grown in a commercial ALD reactor.

scholarly journals Experiments on the Release of CMOS-Micromachined Metal Layers

2010 ◽  
Vol 2010 ◽  
pp. 1-7 ◽  
Author(s):  
Daniel Fernández ◽  
Jordi Ricart ◽  
Jordi Madrenas
Keyword(s):  
Acetic Acid ◽  
Silicon Dioxide ◽  
Hydrogen Fluoride ◽  
Hydrofluoric Acid ◽  
Ammonium Fluoride ◽  
Cmos Technology ◽  
Multilayer Structures ◽  
Structural Elements ◽  
Mems Devices ◽  
Metal Layers

We present experimental results on the release of MEMS devices manufactured using the standard CMOS interconnection metal layers as structural elements and the insulating silicon dioxide as sacrificial layers. Experiments compare the release results of four different etching agents in a CMOS technology (hydrofluoric acid, ammonium fluoride, a mixture of acetic acid and ammonium fluoride, and hydrogen fluoride), describe various phenomena found during the etching process, and show the release results of multilayer structures.

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.

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