high power impulse magnetron sputtering

High Power Impulse Magnetron Sputtering
Author: Daniel Lundin
Publisher: Elsevier
Release Date: 2019-08-28
Pages: 398
ISBN:
Available Language: English, Spanish, And French
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High Power Impulse Magnetron Sputtering: Fundamentals, Technologies, Challenges and Applications is an in-depth introduction to HiPIMS that emphasizes how this novel sputtering technique differs from conventional magnetron processes in terms of both discharge physics and the resulting thin film characteristics. Ionization of sputtered atoms is discussed in detail for various target materials. In addition, the role of self-sputtering, secondary electron emission and the importance of controlling the process gas dynamics, both inert and reactive gases, are examined in detail with an aim to generate stable HiPIMS processes. Lastly, the book also looks at how to characterize the HiPIMS discharge, including essential diagnostic equipment. Experimental results and simulations based on industrially relevant material systems are used to illustrate mechanisms controlling nucleation kinetics, column formation and microstructure evolution. Includes a comprehensive description of the HiPIMS process from fundamental physics to applications Provides a distinctive link between the process plasma and thin film communities Discusses the industrialization of HiPIMS and its real world applications

High Power Impulse Magnetron Sputtering
Author:
Publisher:
Release Date: 2007
Pages:
ISBN:
Available Language: English, Spanish, And French
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The commonly used current-voltage characteristics are foundinadequate for describing the pulsed nature of the high power impulsemagnetron sputtering (HIPIMS) discharge, rather, the description needs tobe expanded to current-voltage-time characteristics for each initial gaspressure. Using different target materials (Cu, Ti, Nb, C, W, Al, Cr) anda pulsed constant-voltage supply it is shown that the HIPIMS dischargestypically exhibit an initial pressure dependent current peak followed bya second phase that is power and material dependent. This suggests thatthe initial phase of a HIPIMS discharge pulse is dominated by gas ionswhereas the later phase has a strong contribution from self-sputtering. For some materials the discharge switches into a mode of sustainedself-sputtering. The very large differences between materials cannot beascribed to the different sputter yields but they indicate thatgeneration and trapping ofsecondary electrons plays a major role forcurrent-voltage-time characteristics. In particular, it is argued thatthe sustained self-sputtering phase is associated with thegeneration ofmultiply charged ions because only they can cause potential emission ofsecondary electrons whereas the yield caused by singly charged metal ionsis negligibly small.

Fundamentals Of High Power Impulse Magnetron Sputtering
Author: Johan Böhlmark
Publisher:
Release Date: 2006
Pages: 64
ISBN:
Available Language: English, Spanish, And French
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Plasma Potential Mapping Of High Power Impulse Magnetron Sputtering Discharges
Author:
Publisher:
Release Date: 2011
Pages:
ISBN:
Available Language: English, Spanish, And French
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Pulsed emissive probe techniques have been used to determine the plasma potential distribution of high power impulse magnetron sputtering (HiPIMS) discharges. An unbalanced magnetron with a niobium target in argon was investigated for pulse length of 100?s at a pulse repetition rate of 100 Hz, giving a peak current of 170 A. The probe data were taken with a time resolution of 20 ns and a spatial resolution of 1 mm. It is shown that the local plasma potential varies greatly in space and time. The lowest potential was found over the target's racetrack, gradually reaching anode potential (ground) several centimeters away from the target. The magnetic pre-sheath exhibits a funnel-shaped plasma potential resulting in an electric field which accelerates ions toward the racetrack. In certain regions and times, the potential exhibits weak local maxima which allow for ion acceleration to the substrate. Knowledge of the local E and static B fields lets us derive the electrons' E×B drift velocity, which is about 105 m/s and shows structures in space and time.

Duty Cycle Control In Reactive High Power Impulse Magnetron Sputtering Of Hafnium And Niobium
Author:
Publisher:
Release Date: 2016
Pages:
ISBN:
Available Language: English, Spanish, And French
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Abstract: Instabilities in reactive sputtering have technological consequences and have been attributed to the formation of a compound layer on the target surface ('poisoning'). Here we demonstrate how the duty cycle of high power impulse magnetron sputtering (HiPIMS) can be used to control the surface conditions of Hf and Nb targets. Variations in the time resolved target current characteristics as a function of duty cycle were attributed to gas rarefaction and to the degree of poisoning of the target surface. As the operation transitions from Ar driven sputtering to metal driven sputtering, the secondary electron emission changes and reduces the target current. The target surface transitions smoothly from a poisoned state at low duty cycles to a quasi-metallic state at high duty cycles. Appropriate selection of duty cycle increases the deposition rate, eliminates the need for active regulation of oxygen flow and enables stable reactive deposition of stoichiometric metal oxide films. A model is presented for the reactive HIPIMS process in which the target operates in a partially poisoned mode with different degrees of oxide layer distribution on its surface that depends on the duty cycle. Finally, we show that by tuning the pulse characteristics, the refractive indices of the metal oxides can be controlled without increasing the absorption coefficients, a result important for the fabrication of optical multilayer stacks.

AlN Films Deposited By Dc Magnetron Sputtering And High Power Impulse Magnetron Sputtering For SAW Applications
Author:
Publisher:
Release Date: 2015
Pages:
ISBN:
Available Language: English, Spanish, And French
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Abstract In this work, aluminium nitride (AlN) films were deposited on silicon substrates buffered by an epitaxial AlN thin film for surface acoustic wave (SAW) applications. The films were deposited by dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS) deposition techniques. The structural properties of AlN films were investigated using x-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy and atomic force microscopy. In both cases of films deposited by dcMS and HiPIMS, the XRD results showed that the obtained films are oriented, with full width at half maximum rocking curves of around 1°. Raman spectroscopy revealed higher residual stress relaxation in the AlN epilayers grown by HiPIMS compared to AlN grown by dcMS, highlighted by a blue shift in the E2(high) Raman mode. The SAW measurements indicated an insertion loss of AlN-SAW devices of about 53 and 35 dB for the AlN films deposited by dcMS and HiPIMS respectively. The relation between the structural properties of AlN and the characteristics of AlN-SAW devices were correlated and discussed.

PdAg Alumina Membranes Prepared By High Power Impulse Magnetron Sputtering For Hydrogen Separation
Author:
Publisher:
Release Date: 2018
Pages:
ISBN:
Available Language: English, Spanish, And French
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Spectroscopic Imaging Of Self Organization In High Power Impulse Magnetron Sputtering Plasmas
Author:
Publisher:
Release Date: 2013
Pages:
ISBN:
Available Language: English, Spanish, And French
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Excitation and ionization conditions in traveling ionization zones of high power impulse magnetron sputtering plasmas were investigated using fast camera imaging through interference filters. The images, taken in end-on and side on views using light of selected gas and target atom and ion spectral lines, suggest that ionization zones are regions of enhanced densities of electrons, and excited atoms and ions. Excited atoms and ions of the target material (Al) are strongly concentrated near the target surface. Images from the highest excitation energies exhibit the most localized regions, suggesting localized Ohmic heating consistent with double layer formation.

DEPOSITION OF NIOBIUM AND OTHER SUPERCONDUCTING MATERIALS WITH HIGH POWER IMPULSE MAGNETRON SPUTTERING
Author:
Publisher:
Release Date: 2011
Pages:
ISBN:
Available Language: English, Spanish, And French
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Niobium coatings on copper cavities have been considered as a cost-efficient replacement of bulk niobium RF cavities, however, coatings made by magnetron sputtering have not quite lived up to high expectations due to Q-slope and other issues. High power impulse magnetron sputtering (HIPIMS) is a promising emerging coatings technology which combines magnetron sputtering with a pulsed power approach. The magnetron is turned into a metal plasma source by using very high peak power density of ̃1 kW/cm2. In this contribution, the cavity coatings concept with HIPIMS is explained. A system with two cylindrical, movable magnetrons was set up with custom magnetrons small enough to be inserted into 1.3 GHz cavities. Preliminary data on niobium HIPIMS plasma and the resulting coatings are presented. The HIPIMS approach has the potential to be extended to film systems beyond niobium, including other superconducting materials and/or multilayer systems.

Codeposition Of Amorphous Zinc Tin Oxide Using High Power Impulse Magnetron Sputtering  Characterisation And Doping
Author:
Publisher:
Release Date: 2017
Pages:
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Available Language: English, Spanish, And French
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Abstract: Thin film zinc tin oxide (ZTO) has been energetically deposited at 100 °C using high power impulse magnetron sputtering (HiPIMS). Reactive co-deposition from Zn (HiPIMS mode) and Sn (DC magnetron sputtering mode) targets yielded a gradient in the Zn:Sn ratio across a 4-inch diameter sapphire substrate. The electrical and optical properties of the film were studied as a function of composition. As-deposited, the films were amorphous, transparent and semi-insulating. Hydrogen was introduced by post-deposition annealing (1 h, 500 °C, 100 mTorr H2 ) and resulted in significantly increased conductivity with no measurable structural alterations. After annealing, Hall effect measurements revealed n-type carrier concentrations of ∼1 × 10 17 cm −3 and mobilities of up to 13 cm 2 V −1 s –1 . These characteristics are suitable for device applications and proved stable. X-ray photoelectron spectroscopy was used to explore the valence band structure and to show that downward surface band-bending resulted from OH attachment. The results suggest that HiPIMS can produce dense, high quality amorphous ZTO suitable for applications including transparent thin film transistors.

Linear Magnetron High Deposition Rate Magnet Pack For High Power Impulse Magnetron Sputtering
Author: Jake Thomas McLain
Publisher:
Release Date: 2016
Pages:
ISBN:
Available Language: English, Spanish, And French
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Analytic And Numerical Investigation Of High Power Impulse Magnetron Sputtering Discharges
Author: Sara Gallian
Publisher:
Release Date: 2015
Pages:
ISBN:
Available Language: English, Spanish, And French
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Magnetron Sputtering Of Multicomponent Refractory Thin Films
Author: Trent Mitchell Borman
Publisher:
Release Date: 2020
Pages:
ISBN:
Available Language: English, Spanish, And French
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A resurgence of interest in hypersonic flight has led to an increased demand for new refractory materials that possess a complex blend of physical, thermal, chemical, and mechanical properties. The selection of materials for use at extreme temperatures (>3000 °C) is dominated by the Group IVB and VB carbides, diborides, and nitrides. While these ultra high temperature ceramics (UHTCs) provide an excellent basis from which to start, new compositions are necessary for the envisioned applications. As complexity increases from binary carbides, diborides, and nitrides to ternary, quaternary, and high entropy compositions, the breadth of the compositional space grows exponentially. These new and vast, multi-dimensional phase diagrams pose a few important questions: what are the metal stoichiometries of interest? and how do the property-chemistry trends observed in binary systems translate to these complex compositions? Studying these new materials systems and answering these questions is not a trivial undertaking. Throughout the history of UHTC synthesis, the intrinsic properties of these ultra refractory materials have been convoluted with extrinsic factors, such as microstructure, phase purity, and defects. A valid study of the roles of metal and anion stoichiometry in these materials requires synthesis of UHTCs over broad compositional ranges while limiting the impacts of extrinsic characteristics. Physical vapor deposition has been widely used to study high entropy systems including alloys, oxides, carbides, and nitrides. This work expands on previous studies and focuses on understanding and improving the sputter deposition process for multicomponent carbides. The advantages and limitations of conventional sputtering techniques were investigated; avenues to improve the process, ranging from gas flows to pulsed power techniques, were explored; and finally, the benefits of high power impulse magnetron sputtering inspired the development of new co-sputtering techniques. (HfNbTaTiZr)C has received significant research interest in the UHTC community, as it combines 5 of the most refractory carbide systems; however, researchers had not studied the influence of carbon stoichiometry in this, or other, high entropy compositions. In this work, (HfNbTaTiZr)C films were synthesized over a broad range of carbon stoichiometries with reactive RF sputtering. These films exhibited broad crystallographic and microstructural transitions from metallic to carbide and finally nanocomposite films, simply by changing carbon content. Carbon vacancies were observed to cluster into stacking faults in substoichiometric films, despite the chemical disorder of the metal sublattice. A near-stoichiometric film with a hardness of 24 ± 3 GPa was synthesized, closely matching the rule of mixtures for the binary constituents. Additionally, ab-initio calculations validated the experimental mechanical property findings. Overall, the synthesis and property trends of (HfNbTaTiZr)C closely mirrored those of binary counterparts. Unfortunately, as with other carbides, excess carbon rapidly precipitated at methane flow rates slightly (2.5%) higher than the stoichiometric flow rate. The sudden onset of excess carbon precipitation stymied the rapid and facile synthesis of near-stoichiometric multicomponent carbides. Consequently, the deposition process needed to be improved before studying other compositions. A study of gas flows and pressures determined that operating with a modest fixed argon pressure (5-10 mT) increased deposition rate and could reduce target poisoning and carbon precipitation. Additionally, the results indicated that most of the methane was being consumed by the growing carbide film; however, partial pressure control was not feasible with the chamber's configuration. As a result, the best carbon control strategy was determined to be a combination of carefully regulated methane (flow rate) and metal (sputter rate) fluxes. Conventional temperature and pressure based microstructural development strategies were not feasible for use with reactively sputtered high entropy carbides. Fortunately, tunable high energy ion bombardment was demonstrated to be a viable alternative, influencing the microstructure, stress, and crystallography of the growing carbide films. The increased plasma densities, fixed energetics, and consistent energetics of high power impulse magnetron sputtering (HiPIMS) produced carbide films which were more microstructurally and crystallographically consistent than conventionally sputtered films. Simultaneous power and voltage regulation of the HiPIMS process resulted in more consistent deposition rates than the power regulation of conventional sputtering processes. Furthermore, films deposited with HiPIMS exhibited a much more gradual onset of excess carbon precipitation than RF sputtered counterparts. Asynchronously patterned pulsed sputtering (APPS) was developed based on the flux and energetic decoupling of HiPIMS. Conventional co-sputtering is rife with tedious calibrations and changing energetics. With conventional sputtering techniques, flux is changed by power which changes the sputtering voltage and the energetics of the deposition, resulting in inconsistent film quality. During HiPIMS, the flux is controlled by the frequency, while the energetics are dominated by the pulsing parameters (width and voltage). Asynchronously patterned pulsed sputtering consists of two HiPIMS supplies operating at the same frequency but phase shifted so the plasmas don't interact. One supply skips a fraction of the pulses, changing the time average flux and thus controlling the stoichiometry independently of energetics. APPS was demonstrated to produce linear compositional trends, consistent deposition energetics, and uniform film qualities across the entire stoichiometry range. The development of APPS and reactive APPS enabled the rapid synthesis of ternary systems, facilitating the search for properties of interest such as ductility in (NbW)C.

Investigation Of Industrially Suited Processes For Deposition Of Oxide Thin Films By High Power Impulse Magnetron Sputtering
Author: Felipe de Campos Carreri
Publisher: BoD – Books on Demand
Release Date: 2018-02-26
Pages: 218
ISBN:
Available Language: English, Spanish, And French
EBOOK SYNOPSIS:

The scope of this work is to investigate and to develop advanced HIPIMS processes for deposition of oxides, utilizing industrial-scale equipment and technology. Two classes of oxide materials were studied: insulating (aluminum oxide) and conducting oxides (indium-tin oxide and aluminum-doped zinc oxide). The electrical properties of the oxides have a significant influence on the process design, as the issues and approaches for deposition of insulating materials are fairly different from conducting materials. Different types of reactive process control were also investigated, utilizing optical emission spectroscopy to control the oxygen flow and lambda probes to control the discharge power. A non-reactive process was also studied for indium-tin oxide.

Encyclopedia Of Plasma Technology   Two Volume Set
Author: J. Leon Shohet
Publisher: CRC Press
Release Date: 2016-12-12
Pages: 1656
ISBN:
Available Language: English, Spanish, And French
EBOOK SYNOPSIS:

Technical plasmas have a wide range of industrial applications. The Encyclopedia of Plasma Technology covers all aspects of plasma technology from the fundamentals to a range of applications across a large number of industries and disciplines. Topics covered include nanotechnology, solar cell technology, biomedical and clinical applications, electronic materials, sustainability, and clean technologies. The book bridges materials science, industrial chemistry, physics, and engineering, making it a must have for researchers in industry and academia, as well as those working on application-oriented plasma technologies. Also Available Online This Taylor & Francis encyclopedia is also available through online subscription, offering a variety of extra benefits for researchers, students, and librarians, including: Citation tracking and alerts Active reference linking Saved searches and marked lists HTML and PDF format options Contact Taylor and Francis for more information or to inquire about subscription options and print/online combination packages. US: (Tel) 1.888.318.2367; (E-mail) [email protected] International: (Tel) +44 (0) 20 7017 6062; (E-mail) [email protected]

Silicon Nitride Based Coatings Grown By Reactive Magnetron Sputtering
Author: Tuomas Hänninen
Publisher: Linköping University Electronic Press
Release Date: 2018-02-13
Pages: 58
ISBN:
Available Language: English, Spanish, And French
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Silicon nitride and silicon nitride-based ceramics have several favorable material properties, such as high hardness and good wear resistance, which makes them important materials for the coating industry. This thesis focuses the synthesis of silicon nitride, silicon oxynitride, and silicon carbonitride thin films by reactive magnetron sputtering. The films were characterized based on their chemical composition, chemical bonding structure, and mechanical properties to link the growth conditions to the film properties. Silicon nitride films were synthesized by reactive high power impulse magnetron sputtering (HiPIMS) from a Si target in Ar/N2 atmospheres, whereas silicon oxynitride films were grown by using nitrous oxide as the reactive gas. Silicon carbonitride was synthesized by two different methods. The first method was using acetylene (C2H2) in addition to N2 in a Si HiPIMS process and the other was co-sputtering of Si and C, using HiPIMS for Si and direct current magnetron sputtering (DCMS) for graphite targets in an Ar/N2 atmosphere. Langmuir probe measurements were carried out for the silicon nitride and silicon oxynitride processes and positive ion mass spectrometry for the silicon nitride processes to gain further understanding on the plasma conditions during film growth. The target current and voltage waveforms of the reactive HiPIMS processes were evaluated. The main deposition parameter affecting the nitrogen concentration of silicon nitride films was found to be the nitrogen content in the plasma. Films with nitrogen contents of 50 at.% were deposited at N2/Ar flow ratios of 0.3 and above. These films showed Si-N as the dominating component in Si 2p X-ray photoelectron spectroscopy (XPS) core level spectra and Si–Si bonds were absent. The substrate temperature and target power were found to affect the nitrogen content to a lower extent. The residual stress and hardness of the films were found to increase with the film nitrogen content. Another factors influencing the coating stress were the process pressure, negative substrate bias, substrate temperature, and HiPIMS pulse energy. Silicon nitride coatings with good adhesion and low levels of compressive residual stress were grown by using a pressure of 600 mPa, a substrate temperature below 200 °C, pulse energies below 2.5 Ws, and negative bias voltages up to 100 V. The elemental composition of silicon oxynitride films was shown to depend on the target power settings as well as on the nitrous oxide flow rate. Silicon oxide-like films were synthesized under poisoned target surface conditions, whereas films deposited in the transition regime between poisoned and metallic conditions showed higher nitrogen concentrations. The nitrogen content of the films deposited in the transition region was controlled by the applied gas flow rate. The applied target power did not affect the nitrogen concentration in the transition regime, while the oxygen content increased at decreasing target powers. The chemical composition of the films was shown to range from silicon-rich to effectively stoichiometric silicon oxynitrides, where no Si–Si contributions were found in the XPS Si 2p core level spectra. The film optical properties, namely the refractive index and extinction coefficient, were shown to depend on the film chemical bonding, with the stoichiometric films displaying optical properties falling between those of silicon oxide and silicon nitride. The properties of silicon carbonitride films were greatly influenced by the synthesis method. The films deposited by HiPIMS using acetylene as the carbon source showed silicon nitride-like mechanical properties, such as a hardness of ~ 20 GPa and compressive residual stresses of 1.7 – 1.9 GPa, up to film carbon contents of 30 at.%. At larger film carbon contents the films had increasingly amorphous carbon-like properties, such as densities below 2 g/cm3 and hardnesses below 10 GPa. The films with more than 30 at.% carbon also showed columnar morphologies in cross-sectional scanning electron microscopy, whereas films with lower carbon content showed dense morphologies. Due to the use of acetylene the carbonitride films contained hydrogen, up to ~ 15 at.%. The co-sputtered silicon carbonitride films showed a layered SiNx/CNx structure. The hardness of these films increased with the film carbon content, reaching a maximum of 18 GPa at a film carbon content of 12 at.%. Comparatively hard and low stressed films were grown by co-sputtering using a C target power of 1200 W for a C content around 12 at.%, a negative substrate bias less than 100 V, and a substrate temperature up to 340 °C.

Fundamental Aspects Of HiPIMS Under Industrial Conditions
Author: Mattias Samuelsson
Publisher:
Release Date: 2012
Pages: 52
ISBN:
Available Language: English, Spanish, And French
EBOOK SYNOPSIS:

Fundamental aspects of the high power impulse magnetron sputtering (HiPIMS) process and its implication for film growth under industrial conditions have been studied. The emerging HiPIMS technique exhibits a higher plasma density and an enhanced degree of ionisation of sputtered material as compared to conventional direct current magnetron sputtering (DCMS). The increased ionisation permits control of the deposition flux and facilitates an intense ion bombardment of the growing films. The latter allows for growth of well adherent, smooth, and dense thin films. Moreover, the technique offers increased stability of reactive processes, control of film phase constitution as well as tailoring of e.g. optical and mechanical properties. In the present work, it was shown, for eight different metals (Al, Ti, Cr, Cu, Zr, Ag, Ta, and Pt), that films grown using HiPIMS exhibit a 5-15% higher density than films grown using DCMS under otherwise identical conditions. Through simulations of the fundamental ionisation processes in the plasma discharge, a correlation between high ionisation degree and film densification was established. The densification was suggested to be a consequence of increased ion irradiation of the growing films in the HiPIMS case. This knowledge was used to investigate the degree of ionisation in the deposition flux required for film modifications. Using a hybrid process, where DCMS and HiPIMS were combined on a single Cr cathode, independent control of the degree of ionisation from other experimental parameters was achieved. The results showed that the majority of the ion irradiation induced modifications of surface related film properties occurred when ~40% of the total average power was supplied by the HiPIMS generator. Under such conditions, the power normalised deposition rate was found to be ~80% of that of DCMS. This was attributed to a reduction in back-attracted ionised sputtered material, which is considered to be the main reason for the low deposition rate of HiPIMS. Thus, enhanced film properties were attainable largely without sacrificing deposition rate. ?Compound carbide and boride films were synthesised using both reactive processes and compound sources. Reactive deposition of TiC/a-C:H thin films using C2H2 as reactive gas, i.e. carbon source, was demonstrated. It was found that the high plasma density processes (i.e. HiPIMS) facilitated growth conditions for the film structure formation closer to thermodynamic equilibrium than did processes exhibiting lower plasma densities (i.e. DCMS). This was manifested in a high stoichiometry of the carbide phase, whilst excess a-C was removed by physical sputtering. Moreover, the feasibility of using HiPIMS for thin film growth from a compound source, obtaining the same composition in the films as the sputtering source, was demonstrated through synthesis of ZrB2 films.

Metallic Oxynitride Thin Films By Reactive Sputtering And Related Deposition Methods  Processes  Properties And Applications
Author: Filipe Vaz
Publisher: Bentham Science Publishers
Release Date: 2013-06-21
Pages: 362
ISBN:
Available Language: English, Spanish, And French
EBOOK SYNOPSIS:

Oxynitride thin film technology is rapidly impacting a broad spectrum of applications, ranging from decorative functions (through optoelectronics) to corrosion resistance. Developing a better understanding of the relationships between deposition processes, structure and composition of the deposited films is critical to the continued evolution of these applications. This e-book provides valuable information about the process modeling, fabrication and characterization of metallic oxynitride-based thin films produced by reactive sputtering and some related deposition processes. Its contents are spread in twelve main and concise chapters through which the book thoroughly reviews the bases of oxynitride thin film technology and deposition processes, sputtering processes and the resulting behaviors of these oxynitride thin films. More importantly, the solutions for the growth of oxynitride technology are given in detail with an emphasis on some particular compounds. This is a valuable resource for academic learners studying materials science and industrial coaters, who are concerned not only about fundamental aspects of oxynitride synthesis, but also by their innate material characteristics.

Microstructure And Properties Of Hard And Optically Transparent HfO2 Films Prepared By High Rate Reactive High Power Impulse Magnetron Sputtering
Author: Nai-Wen Pi
Publisher:
Release Date: 2016
Pages: 50
ISBN:
Available Language: English, Spanish, And French
EBOOK SYNOPSIS:

Hafnium Dioxide (HfO2) has an extraordinary high bulk modulus, high hardness, high chemical stability, high melting point and high thermal stability. This material can be used as protective coatings for application involving high temperature environments. HfO2 films were fabricated on Si using high-rate reactive high-power impulse magnetron sputtering (HiPIMS) using different deposition-averaged target power density Sd and voltage pulse durations t1. Five HfO2 films were prepared with (1) t1 = 25 microsecond, Sd = 7.6 Wcm−2 (T25S7), (2) t1 = 100 microsecond Sd =7.2 Wcm−2 (T100S7), (3) t1 = 200 microsecond, Sd =7.3 Wcm−2 (TS200S7), (4) t1 = 200 microsecond, Sd =18 Wcm−2 (T200S18) and (5) t1 = 200 microsecond, Sd =54 Wcm−2 (T200S54). Atomic force microscopy (AFM) images of the T200S54, T200S18 and T200S7 films exhibit a coarser granular structure with a similar grain size varying from 25 nm to 120 nm in diameter and an average grain size of ~70 nm. AFM images of the T25S7 and T100S7 films show smaller granular structures compared to the other three films. Transmission electron microscopy (TEM) studies show that all films are composed of an interlayer next to the Si interface followed by a nano-columnar structure layer. The interlayer structure of the films consists of a population of lower density nanoscale regions. A reduction in t1 and Sd in films T200S54, T200S18, T200S7 and T100S7 caused an increase in the interlayer thickness and a decrease in the width of the nano-columnar structures from ~46 nm to ~21 nm. This microstructural change was accompanied by a concomitant change of the grain boundary structure from tight and interlocking in films T200S54 and T200S18, to rough and thicker (~1 nm) boundaries in films T200S7 and T100S7. Film T25S7 exhibited an entirely different microstructure composed of a multilayered interlayer (~3 nm) and nano-columnar (~15 nm) structure. Films prepared with large t1 (200 microsecond) have a monoclinic HfO2 structure and that with small t1 (25 microsecond) an orthorhombic HfO2 structure. Film prepared with an intermediate t1 value (100 microsecond) exhibited a mixture of both monoclinic and orthorhombic phases. A high hardness of 17.6-17.0 GPa was shown for films with a monoclinic HfO2 structure. The films exhibited a refractive index of 2.02-2.11 and an extinction coefficient between [less than or equal to] 2x10-3 and 0.1x10-3 (both at a wavelength of 550 nm). High optical quality was achieved for films T200S54 and T200S18 owing to the presence of a dense microstructure with sharp and interlocking grain boundaries.

HiPIMS
Author:
Publisher:
Release Date: 2013
Pages:
ISBN:
Available Language: English, Spanish, And French
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Over the years, Nb/Cu technology, despite its shortcomings due to the commonly used magnetron sputtering, has positioned itself as an alternative route for the future of accelerator superconducting structures. Avenues for the production of thin films tailored for Superconducting RF (SRF) applications are showing promise with recent developments in ionized PVD coating techniques, i.e. vacuum deposition techniques using energetic ions. Among these techniques, High power impulse magnetron sputtering (HiPIMS) is a promising emerging technique which combines magnetron sputtering with a pulsed power approach. This contribution describes the benefits of energetic condensation for SRF films and the characteristics of the HiPIMS technology. It describes the on-going efforts pursued in different institutions to exploit the potential of this technology to produce bulk-like Nb films and go beyond Nb performance with the development of film systems, based on other superconducting materials and multilayer structures.