Sputter-Deposited Bcc Tantalum on Steel with the Interfacial Tantalum Nitride Layer

2001 ◽  
Vol 697 ◽  
Author(s):  
Anamika Patel ◽  
Leszek Gladczuk ◽  
Charanjeet Singh Paur ◽  
Marek Sosnowski
Keyword(s):  
Corrosive Wear ◽  
Beta Phase ◽  
Nitride Layer ◽  
Alpha Phase ◽  
Tantalum Nitride ◽  
Nuclear Reaction Analysis ◽  
Sputtered Films ◽  
Bcc Structure ◽  
Two Phases ◽  
Sputter Deposited

AbstractTantalum has mainly two phases: alpha phase (bcc structure) and beta phase (tetragonal structure). The meta-stable beta phase is usually obtained in sputtered films. Alpha phase is preferred over the beta for some applications as beta phase is very brittle. One of such application is to protect steel from the erosive and the corrosive wear. It was found that with the intermediate layer of tantalum nitride the preferred alpha phase was grown on steel by DC magnetron sputtering technique. Electrical and structural properties of these films were studied by four-point probe measurement and x-ray diffraction (XRD). Stoichiometry of the interfacial tantalum nitride layer was investigated by nuclear reaction analysis (NRA). Influence of the interfacial film thickness and the ratio of argon and nitrogen gas during reactive deposition of tantalum nitride on the tantalum phase were investigated. This work also reports on the dependence of tantalum phase on the substrate temperature (100-400°C) during sputtering in Ar and Kr gases.

Quantitative X-Ray Microanalysis of Ti Alloys

1980 ◽  
Vol 38 ◽  
pp. 142-143
Author(s):  
C. G. Rhodes
Keyword(s):  
Mechanical Properties ◽  
Thin Foil ◽  
Beta Phase ◽  
Alpha Phase ◽  
Foil Thickness ◽  
X Ray ◽  
Volume Fractions ◽  
Β Phase ◽  
Two Phases ◽  
Two Parameters

This paper discusses the results of a systematic study of the effect of subtransus (below the β/α+β phase boundary) heat treatments on microstructure and mechanical properties in two α+β titanium alloys. Quantitative X-ray microanalysis was used to measure the compositions of the alpha and beta phases in order to evaluate their influence on mechanical properties. Ti-6A1-4V and Ti-4.5A1-5Mo-l.5Cr were treated to produce a microstructure consisting of equiaxed primary alpha-phase grains separated by a continuous beta phase matrix. The two parameters evaluated in this work were (1) volume fractions and (2) compositions of the alpha and beta phases. Measurement of volume fractions was straightforward; however, the measurement of the compositions of the two phases required development of a reliable comparative quantitative X-ray microanalytic technique for thin foil analysis using a conventional transmission electron microscope with STEM capability. Although our X-ray energy dispersive system included a typical thin foil computer program, it was not used because of the error introduced by estimating factors such as foil thickness and phase density.

Direct Alpha Ta Formation on TaN by Resputtering for Low Resistive Diffusion Barriers

2008 ◽  
Vol 8 (5) ◽  
pp. 2582-2587 ◽  
Author(s):  
Jung-Chih Tsao ◽  
Chuan-Pu Liu ◽  
Ying-Lang Wang ◽  
Kei-Wei Chen
Keyword(s):  
Surface Treatment ◽  
Resistivity Measurement ◽  
Beta Phase ◽  
Alpha Phase ◽  
Phase Changes ◽  
X Ray Diffraction ◽  
Body Center Cubic ◽  
Argon Ion Bombardment ◽  
Body Center ◽  
Two Phases

The Ta/TaN bilayer exhibits the best performance in the Cu metal multilevel interconnects, because it provides good coherence between Cu and dielectric layer. In the Ta/TaN bilayer, Ta has two phases: alpha-phase of body center cubic is preferred due to its lower resistivity (15–60 μΩ-cm), whereas beta-phase of tetragonal should be avoided due to high resistive (∼150–250 μΩ-cm). However, beta Ta most commonly forms on fcc TaN. Here we provide a simple scheme to bypass this high resistive phase by resputtering TaN prior to Ta deposition. We found that, with surface treatment by argon ion bombardment for enough time, alpha Ta phase can be directly formed, which is supported both by X-ray diffraction and resistivity measurement. Depth profiles of all elements from Auger electron spectroscopy reveals that the surface treatment induces a nitrogen deficient surface layer due to different sputtering yield, which causes phase changes from fcc TaN to hcp Ta2N followed by bcc Ta(N) and provide a favorable lattice constant for Ta alpha-phase formation.

The Effects of High Temperature Exposure on the Fracture of Thin Tantalum Nitride Films

1994 ◽  
Vol 343 ◽  
Author(s):  
N. R. Moody ◽  
S. K. Venkataraman ◽  
J. C Nelson ◽  
W Worobey ◽  
Andw. W. Gerberich
Keyword(s):  
Room Temperature ◽  
Tantalum Nitride ◽  
Interfacial Toughness ◽  
Sputtered Films ◽  
Sapphire Substrates ◽  
Nominal Thickness ◽  
Sputter Deposited ◽  
Temperature Exposure ◽  
Comparison Of The Results ◽  
Very High

ABSTRACTContinuous microscratch testing was used in this study to determine the effects of elevated temperature exposure on the adhesion and toughness of thin tantalum nitride films. These films were sputter-deposited at room temperature on sapphire substrates to a nominal thickness of 600 nm with some films heated to 600°C in vacuum while others were heated to 600°C in air. The films heated in vacuum exhibited no changes in composition or structure while the films heated in air completely transformed to tantalum pentoxide. Comparison of the results shows that the interfacial fracture toughness increases from 0.5 MPa-m1/2 for as-sputtered films to 0.8 MPa-m1/2 for films heated in air. However, the toughness increases to more than 3.0 MPa-m1/2 when the films are heated in vacuum. The increase in toughness values follows the reduction in deposition defect content where formation of an oxygen deficient tantalum oxide layer in air from the as-sputtered film increases interfacial toughness slightly while full densification of the tantalum nitride films in vacuum increases toughness to very high levels.

scholarly journals Structural Factors Inducing Cracking of Brass Fittings

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3255
Author(s):  
Lenka Kunčická ◽  
Michal Jambor ◽  
Adam Weiser ◽  
Jiří Dvořák
Keyword(s):  
Chemical Composition ◽  
Plastic Flow ◽  
Beta Phase ◽  
Alpha Phase ◽  
Structural Factors ◽  
Transmission Electron ◽  
Medical Gas ◽  
Hot Die Forging ◽  
Multiple Step

Cu–Zn–Pb brasses are popular materials, from which numerous industrially and commercially used components are fabricated. These alloys are typically subjected to multiple-step processing—involving casting, extrusion, hot forming, and machining—which can introduce various defects to the final product. The present study focuses on the detailed characterization of the structure of a brass fitting—i.e., a pre-shaped medical gas valve, produced by hot die forging—and attempts to assess the factors beyond local cracking occurring during processing. The analyses involved characterization of plastic flow via optical microscopy, and investigations of the phenomena in the vicinity of the crack, for which we used scanning and transmission electron microscopy. Numerical simulation was implemented not only to characterize the plastic flow more in detail, but primarily to investigate the probability of the occurrence of cracking based on the presence of stress. Last, but not least, microhardness in specific locations of the fitting were examined. The results reveal that the cracking occurring in the location with the highest probability of the occurrence of defects was most likely induced by differences in the chemical composition; the location the crack in which developed exhibited local changes not only in chemical composition—which manifested as the presence of brittle precipitates—but also in beta phase depletion. Moreover, as a result of the presence of oxidic precipitates and the hard and brittle alpha phase, the vicinity of the crack exhibited an increase in microhardness, which contributed to local brittleness.

Parameters for Nitrogen Diffusion in Ni, Ti, and Al Obtained from Implanted Bilayers

1992 ◽  
Vol 279 ◽  
Author(s):  
K. K. Bourdelle ◽  
D. O. Boerma
Keyword(s):  
Nuclear Reaction ◽  
Room Temperature ◽  
Vacuum Annealing ◽  
Nitride Layer ◽  
Nuclear Reaction Analysis ◽  
Nitrogen Diffusion ◽  
Depth Profiles ◽  
Solid Interface ◽  
Before And After ◽  
Concentration Depth Profiles

ABSTRACTNi foils and samples consisting of bilayers of Ni or Fe on Al, Ti or Si were implanted at room temperature with 15N+ ions to fluences of around 1×l017 N/cm2. The concentration depth profiles of 15N were determined with nuclear reaction analysis before and after vacuum annealing. It was found that the penetrability for N atoms of the surface and the solid/solid interface plays an important role in the N redistribution during implantation or annealing. The formation of a nitride layer or nitride clusters in Ni and Fe was deduced. Parameters for N migration determined for the metals under investigation are discussed in terms of models.

scholarly journals Phase and power modulations on the amplitude of TMS-induced motor evoked potentials

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0255815
Author(s):  
Lukas Schilberg ◽  
Sanne Ten Oever ◽  
Teresa Schuhmann ◽  
Alexander T. Sack
Keyword(s):  
Evoked Potentials ◽  
Diagnostic Tool ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Single Pulse ◽  
Beta Phase ◽  
Alpha Phase ◽  
Individual Variability ◽  
Oscillatory Activity ◽  
Alpha Power

The evaluation of transcranial magnetic stimulation (TMS)-induced motor evoked potentials (MEPs) promises valuable information about fundamental brain related mechanisms and may serve as a diagnostic tool for clinical monitoring of therapeutic progress or surgery procedures. However, reports about spontaneous fluctuations of MEP amplitudes causing high intra-individual variability have led to increased concerns about the reliability of this measure. One possible cause for high variability of MEPs could be neuronal oscillatory activity, which reflects fluctuations of membrane potentials that systematically increase and decrease the excitability of neuronal networks. Here, we investigate the dependence of MEP amplitude on oscillation power and phase by combining the application of single pulse TMS over the primary motor cortex with concurrent recordings of electromyography and electroencephalography. Our results show that MEP amplitude is correlated to alpha phase, alpha power as well as beta phase. These findings may help explain corticospinal excitability fluctuations by highlighting the modulatory effect of alpha and beta phase on MEPs. In the future, controlling for such a causal relationship may allow for the development of new protocols, improve this method as a (diagnostic) tool and increase the specificity and efficacy of general TMS applications.

Mechanical behavior of fine-grained Mg-6.5Li at elevated temperature

1994 ◽  
Vol 9 (6) ◽  
pp. 1392-1396 ◽  
Author(s):  
Eric M. Taleff ◽  
Oleg D. Sherby
Keyword(s):  
Stress Exponent ◽  
Solute Drag ◽  
Beta Phase ◽  
Alpha Phase ◽  
Dislocation Creep ◽  
Creep Process ◽  
Strain Rate Change ◽  
Fine Grained ◽  
Diffusion Controlled ◽  
Average Grain Size

A Mg-6.5 wt. % Li alloy containing 80% hep alpha phase and 20% bcc beta phase was processed to achieve an average grain size of 5.9 μm. Strain-rate-change tests were performed in the temperature range from 398 K to 573 K. Two types of creep behavior were observed. A stress exponent of five, obtained at low temperatures and high stresses, is attributed to a diffusion-controlled dislocation creep process in the alpha matrix. A stress exponent of three, obtained at high temperatures and low stresses, is attributed to a solute-drag controlled dislocation creep process in the alpha matrix.

Effect of Deposition Conditions on Intrinsic Stress, Phase Transformation and Stress Relaxation in Tantalum Thin Films

1991 ◽  
Vol 239 ◽  
Author(s):  
A. Mutscheller ◽  
L. A. Clevenger ◽  
J.M.E. Harper ◽  
C. Cabrai ◽  
K. Barmakt
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Phase Transformation ◽  
Stress Relaxation ◽  
Compressive Stress ◽  
Stress Relief ◽  
Beta Phase ◽  
Alpha Phase ◽  
Intrinsic Stress

AbstractWe demonstrate that the high temperature polymorphic tantalum phase transition from the tetragonal beta phase to the cubic alpha phase causes complete stress relaxation and a large decrease in the resistance of tantalum thin films. 100 nm beta tantalum thin films were deposited onto thermally oxidized <100> silicon wafers by dc magnetron sputtering with argon. In situ stress and resistance at temperature were measured during temperature-ramped annealing in purified He. Upon heating, films that were initially compressively stressed showed increasing compressive stress due to thermo-elastic deformation from 25 to 550°C, slight stress relief due to plastic deformation from 550 to 700°C and complete stress relief due to the beta to alpha phase transformation at approximately 700–800°C. Incomplete compressive stress relaxation was observed at high temperatures if the film was initially deposited in the alpha phase or if the beta phase did not completely transform into alpha by 800°C. This incomplete beta to alpha phase transition was most commonly observed on samples that had radio frequency substrate bias greater than -100 V. We conclude that the main stress relief mechanism for tantalum thin films is the beta to alpha phase transformation that occurs at 700 to 800°C.

Degradation behaviors and failure of magnetron sputter deposited tantalum nitride

2020 ◽  
Vol 697 ◽  
pp. 137821
Author(s):  
Ik-Soo Kim ◽  
Myung-Yeon Cho ◽  
Dong-Won Lee ◽  
Pil-Ju Ko ◽  
Weon Ho Shin ◽  
...  
Keyword(s):  
Tantalum Nitride ◽  
Degradation Behaviors ◽  
Magnetron Sputter ◽  
Sputter Deposited

The Effect of Low-Energy Nitrogen Ions on the Growth Modes of Nitrides on Polymers used in the Microelectronics Industry

1999 ◽  
Vol 585 ◽  
Author(s):  
P. Abramowitz ◽  
M. Kiene ◽  
P. Ho
Keyword(s):  
Titanium Nitride ◽  
Deposition Process ◽  
Growth Conditions ◽  
Nitride Layer ◽  
Thin Layers ◽  
Low Energy ◽  
Tantalum Nitride ◽  
Grain Structure ◽  
Nitrogen Ions ◽  
Low Energy Ions

AbstractUltra-thin titanium and tantalum nitride layers grown on three different dielectrics were studied to examine how low-energy ions change the chemical composition at and near their interface. Comparisons were made by growing titanium and tantalum nitride under similar conditions both with (ion-assisted) and without (reactive) nitrogen ions. Although the chemical reactions between the nitrides and the three dielectrics under both growth conditions depend on the type of dielectric used, a few general observations were seen. In comparison with the reactively grown samples, all of the ion-assisted growths show a significant increase in the amount of nitride in the nitride layer at and near the nitride/dielectric interface. Moreover, the amount of chemical binding between the titanium nitride and dielectric is increased when low-energy ions are used. Angle resolved x-ray photoemission determined that the enhancement in the deposition process from low-energy ions occurs without inducing significant intermixing between the nitride layer and dielectric. Although thicker layers of titanium nitride show a difference in the grain structure from ion deposition1, the ultra-thin layers grown in this work do not have any dependence with ion-assisted growth for the samples measured.

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