Polymerization of C-Si Films on Metal Substrates: Potential Adhesion/Diffusion Barriers for Microelectronics

1998 ◽  
Vol 511 ◽  
Author(s):  
Li Chen ◽  
J. A. Kelber
Keyword(s):  
High Vacuum ◽  
Temperature Programmed Desorption ◽  
Diffusion Barriers ◽  
Ultra High Vacuum ◽  
Polymeric Films ◽  
Vinyl Silane ◽  
Cu Substrates ◽  
Auger Spectra ◽  
Temperature Programmed ◽  
Si Films

ABSTRACTCarbon-Silicon polymeric films have been formed by electron beam bombardment (500eV) of molecularly adsorbed vinyl silane precursors under ultra-high vacuum (UHV) conditions. Temperature programmed desorption (TPD) studies show that polymerization is occurring via the vinyl groups, while Auger spectra show that the polymerized films have compositions very similar to the starting precursors; vinyltrichlorosilane (VTCS) or vinyltrimethylsilane(VTMS). VTCSderived films ˜ 100 Å thick show no reaction with Cu substrates and no diffusion of Cu until temperatures greater than 700 K, while Cu deposited on VTMS films on Al substrates show no diffusion prior to Al reaction/decomposition at 600 K. Auger and TPD studies also show that fluorocarbon precursors, such as perfluorobenzene can be incorporated into the films by e-beaminduced reactions, a first step in the controlled growth of adherent polymer films on unreactive substrates such as Cu.

Deposition of Iron on Si(111)-(7×7): Photo- and Electron-Assisted Decomposition of Fe(CO)5

1986 ◽  
Vol 75 ◽  
Author(s):  
J. R. Swanson ◽  
C. M. Friend ◽  
Y. J. Chabal
Keyword(s):  
Auger Electron ◽  
Silicon Crystal ◽  
High Vacuum ◽  
Low Frequency ◽  
Temperature Programmed Desorption ◽  
Thermal Reaction ◽  
Ultra High Vacuum ◽  
Temperature Programmed ◽  
Ultraviolet Photons ◽  
Induced Decomposition

AbstractLaser- and electron-assisted deposition of Fe on Si(111)-(7×7) surfaces using decomposition of Fe(CO)5 has been investigated with multiple internal reflection Fourier transform infrared, Auger electron and temperature programmed desorption spectroscopies and low energy electron diffraction under ultra-high vacuum conditions. No thermal reaction was apparent in temperature programmed desorption experiments: only molecular Fe(CO)5 desorption was observed at temperatures of 150 and 170 K, corresponding to desorption energies in the range of 7–10 kcal./mole. Fe(CO)5 decomposition could be induced using either incident 1.6 keV electrons or ultraviolet photons. Significant amounts of carbon were deposited from the electron induced decomposition, consistent with earlier reports on the Si(100) surface. In contrast, ultraviolet photolysis did not result in any detectable incorporation of carbon or oxygen into the iron deposits. No partially decarbonylated Fe(CO)x, x<5, fragments were detected subsequent to exposure to photons using infrared spectroscopy. However, a new, unresolved low frequency shoulder did appear in the infrared spectrum after exposing the Fe(CO)5 covered Si(111)-(7×7) crystal to the electron beam. Iron photodeposition was evident in the Auger electron spectra obtained subsequent to photolysis and annealing of the surface to either 300 K or 1000 K in order to desorb unreacted Fe(CO)5. These data suggest that there are no surface stable Fe(CO)x, x<5, species in the photodeposition process. Instead, photolysis yields Fe atoms directly, even at low temperatures. Annealing to temperatures on the order of 1000 K subsequent to iron deposition resulted in a significant decrease in the Fe:Si ratio as measured by Auger electron spectroscopy. In addition, CO could not be readsorbed on a surface where the Fe(CO)5 had been decomposed. This is attributed to dissolution of Fe into the bulk silicon crystal.

The Surface Chemistry of CdTe Mocvd

1993 ◽  
Vol 334 ◽  
Author(s):  
Wen-Shryang Liu ◽  
Gregory B. Aupp
Keyword(s):  
Surface Chemistry ◽  
Large Fraction ◽  
High Vacuum ◽  
Temperature Programmed Desorption ◽  
Ultra High Vacuum ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Temperature Programmed ◽  
Surface Decomposition ◽  
Rate Limiting

AbstractTemperature programmed desorption (TPD) studies in ultra high vacuum revealed that diethyltellurium (DETe) and dimethylcadmium (DMCd) adsorb weakly on clean Si(100) and desorb upon heating without decomposing. These precursors adsorb both weakly and strongly on CdTe(111)A, with DMCd exhibiting the stronger interaction with the surface than DETe. Dimethylcadmium partially decomposes to produce Cd adatoms; a large fraction of the excess Cd atoms desorb upon heating. In contrast, DETe desorbs without decomposing, suggesting that the rate limiting step in CdTe MOCVD on CdTe(111)A is surface decomposition of the tellurium alkyl.

The Effect Of Surface Oxides On Cu/Ta Interfacial Interactions

1999 ◽  
Vol 564 ◽  
Author(s):  
L. Chen ◽  
B. Ekstrom ◽  
J. Kelber
Keyword(s):  
Induction Period ◽  
High Vacuum ◽  
Temperature Programmed Desorption ◽  
Ultra High Vacuum ◽  
Sublimation Temperature ◽  
Surface Oxides ◽  
Oxygen Coverage ◽  
Temperature Programmed ◽  
Kinetics Of ◽  
Effect Of Surface

AbstractWe report results of Auger electron spectroscopy (AES) and temperature programmed desorption (TPD) studies under ultra high vacuum (UHV) conditions which demonstrate that even submonolayer coverages of oxygen on Ta significantly degrade the strength of Cu/Ta chemical interactions, and affect the kinetics of Cu diffusion into bulk Ta. On clean Ta, monolayer coverages of Cu will de-wet only above 600 K. A partial monolayer of adsorbed oxygen (3L O2 at 300 K) results in a reduction of the de-wetting temperature to 500 K, while saturation oxygen coverage (10 L O2, 300 K) results in de-wetting at 400 K. Diffusion of Cu into the Ta substrate at 1100 K occurs only after a 300-second induction period at this temperature. The induction period increases to 600 sec for partially oxidized Ta and to 1200 sec for saturation oxygen coverage. TPD studies indicate no desorption of Cu for temperatures below 1300 K. The higher desorption temperature of Cu (compared to the 1150 K sublimation temperature) indicates that all the Cu originally deposited is now chemically bound to Ta.

Design of a UHV STEM for Through-The-Lens Electron Spectroscopy

1990 ◽  
Vol 48 (2) ◽  
pp. 380-381
Author(s):  
A. J. Bleeker ◽  
P. Kruit
Keyword(s):  
Secondary Electron ◽  
High Vacuum ◽  
Secondary Electron Emission ◽  
Auger Spectroscopy ◽  
Scanning Transmission Electron Microscope ◽  
Point Of View ◽  
Ultra High Vacuum ◽  
Scanning Transmission ◽  
Auger Spectra ◽  
Coincidence Measurements

Combining of the high spatial resolution of a Scanning Transmission Electron Microscope and the wealth of information from the secondary electrons and Auger spectra opens up new possibilities for materials research. In a prototype instrument at the Delft University of Technology we have shown that it is possible from the optical point of view to combine STEM and Auger spectroscopy [1]. With an Electron Energy Loss Spectrometer attached to the microscope it also became possible to perform coincidence measurements between the secondary electron signal and the EELS signal. We measured Auger spectra of carbon aluminium and Argon gas showing energy resolutions better than 1eV [2]. The coincidence measurements on carbon with a time resolution of 5 ns yielded basic insight in secondary electron emission processes [3]. However, for serious Auger spectroscopy, the specimen needs to be in Ultra High Vacuum. ( 10−10 Torr ). At this moment a new setup is in its last phase of construction.

scholarly journals Nitrile versus isonitrile adsorption at interstellar grain surfaces

2017 ◽  
Vol 608 ◽  
pp. A50 ◽  
Author(s):  
M. Bertin ◽  
M. Doronin ◽  
X. Michaut ◽  
L. Philippe ◽  
A. Markovits ◽  
...  
Keyword(s):  
Density Functional ◽  
Surface Defects ◽  
High Vacuum ◽  
Solid Support ◽  
Ultra High Vacuum ◽  
Structural Defects ◽  
Adsorption Energies ◽  
The Difference ◽  
Temperature Programmed ◽  
Open Question

Context. Almost 20% of the ~200 different species detected in the interstellar and circumstellar media present a carbon atom linked to nitrogen by a triple bond. Of these 37 molecules, 30 are nitrile R-CN compounds, the remaining 7 belonging to the isonitrile R-NC family. How these species behave in their interactions with the grain surfaces is still an open question. Aims. In a previous work, we have investigated whether the difference between nitrile and isonitrile functional groups may induce differences in the adsorption energies of the related isomers at the surfaces of interstellar grains of various nature and morphologies. This study is a follow up of this work, where we focus on the adsorption on carbonaceous aromatic surfaces. Methods. The question is addressed by means of a concerted experimental and theoretical approach of the adsorption energies of CH3CN and CH3NC on the surface of graphite (with and without surface defects). The experimental determination of the molecule and surface interaction energies is carried out using temperature-programmed desorption in an ultra-high vacuum between 70 and 160 K. Theoretically, the question is addressed using first-principle periodic density functional theory to represent the organised solid support. Results. The adsorption energy of each compound is found to be very sensitive to the structural defects of the aromatic carbonaceous surface: these defects, expected to be present in a large numbers and great diversity on a realistic surface, significantly increase the average adsorption energies to more than 50% as compared to adsorption on perfect graphene planes. The most stable isomer (CH3CN) interacts more efficiently with the carbonaceous solid support than the higher energy isomer (CH3NC), however.

Hydridization and catalysis by lanthanide films

1984 ◽  
Vol 393 (1805) ◽  
pp. 257-276 ◽  
Keyword(s):  
Activation Energy ◽  
High Vacuum ◽  
Deuterium Atom ◽  
Ultra High Vacuum ◽  
Gas Uptake ◽  
Metal Sublattice ◽  
Hydrogen Deuterium ◽  
Higher Temperature ◽  
Temperature Programmed ◽  
Interstitial Hydrogen

Hydrogen absorption to give the dihydrides MH 2+1 containing interstitial hydrogen H i has been studied for the metals Gd, Dy, Er, Yb and Lu in the form of films deposited in ultra-high vacuum on glass. Film areas were determined by Kr adsorption, and hydrogen content, in particular inter­stitial hydrogen H i , characterized by gas uptake, temperature programmed desorption, electrical conductivity and work function measurements by the diode method. The catalytic activity of the dihydride films for the H 2 + D 2 → 2HD reaction was studied at a pressure of 1.1 Torr over 175-579 K, and at 273 K over 0.19-6.2 Torr. Arrhenius plots for the rate con­stant show a low temperature low activation energy region changing over at a temperature T c to a higher temperature higher activation energy régime, with T c on average for the five metals about 50 K below the tem­perature T max at which the interstitial hydrogen H i has disappeared. The suggested mechanisms are T < T c : D 2 + H i □ s → (D 2 H i )□ s → □ s D i + HD, (1) T > T c : D 2 + H 2 + 4□ s → 2(D i □ s ) (H i □ s ) → 4□ s + 2HD, (2) where H i □ s , D i □ s , denotes a hydrogen, deuterium, atom held on a surface octahedral site in the f. c. c. metal sublattice. These mechanisms agree with the observed approximate first-order pressure dependency down to 77 K. The rate constants at both 273 K (under T c ) and 573 K (over T c ) decrease over Gd, Dy, Er, to Yb, and rise again to Lu, and this is discussed in terms of the metal-hydrogen, H i □ s or D i □ s bond strength.

High-Quality a-Si-Based Alloys : a-SiGe Films Fabricated in a Super Chamber and Superlattice Structure a-Si Films Prepared by a Photo-CVD Method

1987 ◽  
Vol 95 ◽  
Author(s):  
Shinya Tsuda ◽  
Hisao Haku ◽  
Hisaki Tarui ◽  
Takao Matsuyama ◽  
Katsunobu Sayama ◽  
...  
Keyword(s):  
Conversion Efficiency ◽  
Photovoltaic Effect ◽  
High Vacuum ◽  
Reaction Chamber ◽  
Wide Bandgap ◽  
Ultra High Vacuum ◽  
High Quality ◽  
Cvd Method ◽  
Superlattice Structure ◽  
Si Films

AbstractIn order to improve the conversion efficiency of a-Si solar cells, high-quality a-Si based alloys of both narrow handgap and wide bandgap were studied.Concerning the narrow bandgap material, we found a particular dependence of film qualities on substrate temperature. In addition, high-quality a-SiGe:H films were obtained by using a super chamber (separated ultra-high vacuum reaction chamber).As for the high-quality wide bandgap material, a-Si/a-SiC superlattice structure films fabricated by a photo-CVD method were studied for the first time. From the analysis of their properties, we found that the superlattice structure p-layer was an active layer for photovoltaic effect. A conversion efficiency of 11.2% has been obtained for a pin a-Si solar cell whose player was of the superlattice structure.

Carbon gasification catalyzed by calcium: A high vacuum temperature programmed desorption study

Carbon ◽  
1992 ◽  
Vol 30 (7) ◽  
pp. 995-1000 ◽  
Author(s):  
D. Cazorla-Amorós ◽  
A. Linares-Solano ◽  
C.Salinas-Martínez de Lecea ◽  
T. Kyotani ◽  
H. Yamashita ◽  
...  
Keyword(s):  
High Vacuum ◽  
Temperature Programmed Desorption ◽  
Carbon Gasification ◽  
Desorption Study ◽  
Temperature Programmed

Selective Oxidation of Ammonia on Ruthenium to Form p(2 x 2) Nitrogen Layer

2013 ◽  
Vol 6 (1) ◽  
Author(s):  
S. Balgooyen ◽  
I. Waluyo
Keyword(s):  
Low Temperature ◽  
High Vacuum ◽  
Hydrogenation Reaction ◽  
Ultra High Vacuum ◽  
Surface Chemical ◽  
Low Energy Electron Diffraction ◽  
Chemical Studies ◽  
Low Energy Electron ◽  
Temperature Programmed ◽  
Oxidation Of Ammonia

Oxidation of ammonia was used to prepare a p(2 x 2) nitrogen layer on the Ru(0001) surface as verified by temperature-programmed desorption (TPD) and low energy electron diffraction (LEED). The process takes place in an ultra-high vacuum (UHV) chamber. The surface is precovered with oxygen and then exposed to ammonia at low temperature. Upon heating, the ammonia is oxidized to form water, which desorbs at low temperature to leave a nitrogencovered surface. The resulting layer can be used in a variety of surface chemical studies, including a hydrogenation reaction, which is an important part in the study of the Haber-Bosch process, in which ruthenium is used as a catalyst.

scholarly journals Reactivity of formic acid (HCOOH) with H atoms on cold surfaces of interstellar interest

2020 ◽  
Vol 636 ◽  
pp. A4
Author(s):  
Henda Chaabouni ◽  
Saoud Baouche ◽  
Stephan Diana ◽  
Marco Minissale
Keyword(s):  
Formic Acid ◽  
Pyrolytic Graphite ◽  
High Vacuum ◽  
Amorphous Solid ◽  
Product Formation ◽  
Ultra High Vacuum ◽  
Star Forming ◽  
Chemical Surface ◽  
Surface Temperatures ◽  
Temperature Programmed

Context. Formic acid (HCOOH) is the simplest organic carboxylic acid in chemical synthesis and the significant species in interstellar chemistry. HCOOH has been abundantly detected in interstellar ices, dense molecular clouds and star-forming regions. Aims. Laboratory hydrogenation experiments of HCOOH molecules with H atoms were performed with two cryogenic ultra-high vacuum devices on amorphous solid water ices, and highly oriented pyrolytic graphite surfaces. The aim of this work is to study the reactivity of HCOOH molecules with H atoms at low surface temperature 10 K, low surface coverage of one monolayer to three layers, and low H-atom flux of about 3.0 × 1012 molecule cm−2 s−1. Methods. HCOOH and H beams were deposited on cold surfaces held at 10 K, and the condensed films were analyzed by in-situ Reflection Absorption InfraRed Spectroscopy and temperature programmed desorption (TPD) mass spectrometry technique by heating the sample from 10 to 200 K. Results. Using the temperature programmed during exposure desorption technique, we highlight the possible dimerization of HCOOH molecules at low surface temperatures between 10 and 100 K. In our HCOOH+H experiments, we evaluated a consumption of 20–30% of formic acid by comparing the TPD curves at m/z 46 of pure and H-exposed HCOOH ice. Conclusions. The hydrogenation HCOOH+H reaction is efficient at low surface temperatures. The main products identified experimentally are carbon dioxide (CO2) and water (H2O) molecules. CO bearing species CH3OH, and H2CO are also detected mainly on graphite surfaces. A chemical surface reaction route for the HCOOH+H system is proposed to explain the product formation.

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