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Journal ArticleDOI

Intrinsic stress in sputter-deposited thin films

Henry Windischmann1
01 Jan 1992-Critical Reviews in Solid State and Materials Sciences (Taylor & Francis Group)-Vol. 17, Iss: 6, pp 547-596
TL;DR: A review of the sputtered film stress literature shows that the intrinsic stress can be tensile or compressive depending on the energetics of the deposition process as discussed by the authors, and extensive experimental evidence show a direct link between the particle flux and energy striking the condensing film, which determines the nature and magnitude of the stress.
Abstract: A review of the sputtered film stress literature shows that the intrinsic stress can be tensile or compressive depending on the energetics of the deposition process. Modeling studies of film growth and extensive experimental evidence show a direct link between the energetics of the deposition process and film microstructure, which in turn determines the nature and magnitude of the stress. The fundamental quantities are the particle flux and energy striking the condensing film, which are a function of many process parameters such as pressure (discharge voltage), target/sputtering gas mass ratio, cathode shape, bias voltage, and substrate orientation. Tensile stress is generally observed in zone 1-type, porous films and is explained in terms of the grain boundary relaxation model, whereas compressive stress, observed in zone T-type, dense films, is interpreted in terms of the atomic peening mechanism. Modeling of the atomic peening mechanism and experimental data indicate that the normalized moment...
Citations
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Journal ArticleDOI
TL;DR: High power pulsed magnetron sputtering (HPPMS) is an emerging technology that has gained substantial interest among academics and industrials alike as discussed by the authors, also known as HIPIMS (high power impulse...
Abstract: High power pulsed magnetron sputtering (HPPMS) is an emerging technology that has gained substantial interest among academics and industrials alike. HPPMS, also known as HIPIMS (high power impulse ...

846 citations

Book
29 Apr 2010
TL;DR: Physical vapor deposition (PVD) process technology from the characterizing and preparing the substrate material, through deposition processing and film characterization, to post-deposition processing is discussed in this paper.
Abstract: This updated version of the popular handbook further explains all aspects of physical vapor deposition (PVD) process technology from the characterizing and preparing the substrate material, through deposition processing and film characterization, to post-deposition processing. The emphasis of the new edition remains on the aspects of the process flow that are critical to economical deposition of films that can meet the required performance specifications, with additional information to support the original material. The book covers subjects seldom treated in the literature: substrate characterization, adhesion, cleaning and the processing. The book also covers the widely discussed subjects of vacuum technology and the fundamentals of individual deposition processes. However, the author uniquely relates these topics to the practical issues that arise in PVD processing, such as contamination control and film growth effects, which are also rarely discussed in the literature. In bringing these subjects together in one book, the reader can understand the interrelationship between various aspects of the film deposition processing and the resulting film properties. The author draws upon his long experience with developing PVD processes and troubleshooting the processes in the manufacturing environment, to provide useful hints for not only avoiding problems, but also for solving problems when they arise. He uses actual experiences, called 'war stories', to emphasize certain points. Special formatting of the text allows a reader who is already knowledgeable in the subject to scan through a section and find discussions that are of particular interest. The author has tried to make the subject index as useful as possible so that the reader can rapidly go to sections of particular interest. Extensive references allow the reader to pursue subjects in greater detail if desired. The book is intended to be both an introduction for those who are new to the field and a valuable resource to those already in the field. The discussion of transferring technology between R&D and manufacturing provided in Appendix 1, will be of special interest to the manager or engineer responsible for moving a PVD product and process from R&D into production. Appendix 2 has an extensive listing of periodical publications and professional societies that relate to PVD processing. The extensive Glossary of Terms and Acronyms provided in Appendix 3 will be of particular use to students and to those not fully conversant with the terminology of PVD processing or with the English language. This title is fully revised and updated to include the latest developments in PVD process technology. It includes 'War stories' drawn from the author's extensive experience emphasize important points in development and manufacturing. Appendices include listings of periodicals and professional societies, terms and acronyms, and material on transferring technology between R&D and manufacturing.

783 citations

Journal ArticleDOI
TL;DR: In this paper, the authors examined the stress associated with crystallite coalescence during the initial stages of growth in thin polycrystalline films with island growth morphology and predicted large tensile stresses in agreement with experimental results.
Abstract: We examined the stress associated with crystallite coalescence during the initial stages of growth in thin polycrystalline films with island growth morphology. As growing crystallites contacted each other at their bases, the side-walls zipped together until a balance was reached between the energy associated with eliminating surface area, creating a grain boundary and straining the film. Our estimate for the resulting strain depends only on interfacial free energies, elastic properties, and grain size and predicts large tensile stresses in agreement with experimental results. We also discuss possible stress relaxation mechanisms that can occur during film growth subsequent to the coalescence event.

554 citations

Journal ArticleDOI
TL;DR: A review of recent developments in BN film synthesis and characterization can be found in this paper, where the key experimental parameters controlling cBN film formation and synthesis techniques are discussed and the proposed mechanisms of cBN formation and the observed mechanical and electrical properties of CBN films are analyzed.
Abstract: Cubic boron nitride (cBN) has a number of highly desirable mechanical, thermal, electrical, and optical properties. Because of this, there has been an extensive worldwide effort to synthesize thin films of cBN. Film synthesis is difficult in that without significant levels of ion bombardment during growth, only sp2-bonded BN forms, not sp3-bonded cBN. Recently there has been considerable progress in improving the deposition techniques and cBN film quality. In addition, progress has been made in understanding how energetic deposition conditions can lead to cBN formation. However, unanswered questions remain and process improvements are still needed. In this paper we critically and comprehensively review recent developments in cBN film synthesis and characterization. First, the structures and stability of the BN phases and characterization techniques are described. Next, the key experimental parameters controlling cBN film formation and synthesis techniques are discussed. Following a review of microstructure, the proposed mechanisms of cBN formation and the observed mechanical and electrical properties of cBN films are analyzed. We conclude by highlighting the current impediments to the practical realization of cBN-film technology.

533 citations

Journal ArticleDOI
01 Nov 2000-Wear
TL;DR: The use of coatings to improve the tribological properties of components such as tools for metal cutting and forming, and machine elements e.g. sliding bearings, seals and valves is constantly increasing.

383 citations


Cites background from "Intrinsic stress in sputter-deposit..."

  • ...The final stress state is a combination of these components [42–45]....

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References
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Journal ArticleDOI
TL;DR: In this article, an integrodifferential equation for the sputtering yield is developed from the general Boltzmann transport equation, and solutions of the integral equation are given that are asymptotically exact in the limit of high ion energy as compared to atomic binding energies.
Abstract: Sputtering of a target by energetic ions or recoil atoms is assumed to result from cascades of atomic collisions. The sputtering yield is calculated under the assumption of random slowing down in an infinite medium. An integrodifferential equation for the yield is developed from the general Boltzmann transport equation. Input quantities are the cross sections for ion-target and target-target collisions, and atomic binding energies. Solutions of the integral equation are given that are asymptotically exact in the limit of high ion energy as compared to atomic binding energies. Two main stages of the collision cascade have to be distinguished: first, the slowing down of the primary ion and all recoiling atoms that have comparable energies---these particles determine the spatial extent of the cascade; second, the creation and slowing down of low-energy recoils that constitute the major part of all atoms set in motion. The separation between the two stages is essentially complete in the limit of high ion energy, as far as the calculation of the sputtering yield is concerned. High-energy collisions are characterized by Thomas-Fermi-type cross sections, while a Born-Mayer-type cross section is applied in the low-energy region. Electronic stopping is included when necessary. The separation of the cascade into two distinct stages has the consequence that two characteristic depths are important for the qualitative understanding of the sputtering process. First, the scattering events that eventually lead to sputtering take place within a certain layer near the surface, the thickness of which depends on ion mass and energy and on ion-target geometry. In the elastic collision region, this thickness is a sizable fraction of the ion range. Second, the majority of sputtered particles originate from a very thin surface layer (\ensuremath{\sim}5 \AA{}), because small energies dominate. The general sputtering-yield formula is applied to specific situations that are of interest for comparison with experiment. These include backsputtering of thick targets by ion beams at perpendicular and oblique incidence and ion energies above \ensuremath{\sim}100 eV, transmission sputtering of thin foils, sputtering by recoil atoms from $\ensuremath{\alpha}$-active atoms distributed homogeneously or inhomogeneously in a thick target, sputtering of fissionable specimens by fission fragments, and sputtering of specimens that are irradiated in the core of a reactor or bombarded with a neutron beam. There is good agreement with experimental results on polycrystalline targets within the estimated accuracy of the data and the input parameters entering the theory. There is no need for adjustable parameters in the usual sense, but specific experimental setups are discussed that allow independent checks or accurate determination of some input quantities.

2,552 citations

Journal ArticleDOI
TL;DR: In this paper, it is shown that very large stresses may be present in the thin films that comprise integrated circuits and magnetic disks and that these stresses can cause deformation and fracture to occur.
Abstract: The mechanical properties of thin films on substrates are described and studied. It is shown that very large stresses may be present in the thin films that comprise integrated circuits and magnetic disks and that these stresses can cause deformation and fracture to occur. It is argued that the approaches that have proven useful in the study of bulk structural materials can be used to understand the mechanical behavior of thin film materials. Understanding the mechanical properties of thin films on substrates requires an understanding of the stresses in thin film structures as well as a knowledge of the mechanisms by which thin films deform. The fundamentals of these processes are reviewed. For a crystalline film on a nondeformable substrate, a key problem involves the movement of dislocations in the film. An analysis of this problem provides insight into both the formation of misfit dislocations in epitaxial thin films and the high strengths of thin metal films on substrates. It is demonstrated that the kinetics of dislocation motion at high temperatures are expecially important to the understanding of the formation of misfit dislocations in heteroepitaxial structures. The experimental study of mechanical properties of thin films requires the development and use of nontraditional mechanical testing techniques. Some of the techniques that have been developed recently are described. The measurement of substrate curvature by laser scanning is shown to be an effective way of measuring the biaxial stresses in thin films and studying the biaxial deformation properties at elevated temperatures. Submicron indentation testing techniques, which make use of the Nanoindenter, are also reviewed. The mechanical properties that can be studied using this instrument are described, including hardness, elastic modulus, and time-dependent deformation properties. Finally, a new testing technique involving the deflection of microbeam samples of thin film materials made by integrated circuit manufacturing methods is described. It is shown that both elastic and plastic properties of thin film materials can be measured using this technique.

2,347 citations

Journal ArticleDOI
TL;DR: Two cylindrically symmetric and complementary sputtering geometries, the post and hollow cathodes, were used to deposit thick coatings of various metals (Mo, Cr, Ti, Fe, Cu, and Al-alloy) onto glass and metallic substrates at deposition rates of 1000-2000 A/min under various conditions of substrate temperature, argon pressure, and plasma bombardment as mentioned in this paper.
Abstract: Two cylindrically symmetric and complementary sputtering geometries, the post and hollow cathodes, were used to deposit thick (∼25-μ) coatings of various metals (Mo, Cr, Ti, Fe, Cu, and Al-alloy) onto glass and metallic substrates at deposition rates of 1000–2000 A/min under various conditions of substrate temperature, argon pressure, and plasma bombardment. Coating surface topographies and fracture cross sections were examined by scanning electron microscopy. Polished cross sections were examined metallographically. Crystallographic orientations were determined by x-ray diffraction. Microstructures were generally consistent with the three-zone model proposed by Movchan and Demchishin [Fiz. Metal. Metalloved. 28, 653 (1969)]. Three differences were noted: (1) at low argon pressures a broad zone 1–zone 2 transition zone consisting of densely packed fibrous grains was identified; (2) zone 2 columnar grains tended to be faceted at elevated temperatures, although facets were often replaced by smooth flat surf...

2,195 citations

Book
01 Jan 1969

2,189 citations

Journal ArticleDOI
TL;DR: In this paper, a review of the physical vapor deposition (PVD) of thin films is presented, focusing mainly on evaporation and sputtering processes and the physics of their growth and structure.
Abstract: Thick films will be defined here as those sufficiently thick to permit evolutionary selection processes during growth to influence their structures. High rates are defined as those sufficient to deposit thick films in a reasonable time. To avoid superficiality, this review is restricted to evaporation and sputtering, i.e. to physical vapor deposition (PVD). PVD is finding increased use for applications ranging from micro­ electronics to corrosion-barrier and wear-resistant coatings, and to the synthesis of free-standing shapes with unique mechanical properties. The emphasis here is on metallic deposits and on the physics of their growth and structure. Particular attention is given to sputtering, because recent developments ih sputtering tech­ nology make thick film deposition feasible, and because the subject has not been reviewed. Several reviews have concentrated on thick film deposition by evaporation (1, 2). Structure zone models (3-5) [particularly the model proposed by Movchan & Demchishin (3), which predicts three structural forms or zones as a function of T/Tm. where T is the substrate temperature and Tm is the coating-material melting point] have come into increased use in interpreting coating microstructures. There­ fore this review is organized from thc viewpoint of the zone models. After a brief survey of certain pertinent features of evaporation and sputtering, subsequent sections discuss each of the structural zones, metallurgical phase formation, and the mechanical properties of coatings. In this review the structure zones are defined in terms of dominant physical processes rather than structural forms. This generalization permits a broader correlation with experimental observations.

1,979 citations