Physical vapor deposition and thermal stability of hard oxide coatings

Physical vapor deposition and thermal stability of hard oxide coatings
Author: Ludvig Landälv
Publisher: Linköping University Electronic Press
Total Pages: 42
Release: 2019-04-26
Genre:
ISBN: 9176850889


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The state-of-the-art tools for machining metals are primarily based on a metal-ceramic composite (WC-Co) coated with different combinations of carbide, nitride, and oxide coatings. Combinations of these coating materials are optimized to withstand specific wear conditions. Oxide coatings, mainly α-Al2O3, are especially desired because of their high hot-hardness, chemical inertness with respect to the workpiece, and their low friction. The search for possible alloy elements, which may facilitate the deposition of such oxides by means of physical vapor deposition (PVD) techniques, has been the goal of this thesis. The sought alloy should form thermodynamically stable or metastable compounds, compatible with the temperature of use in metal cutting application. This thesis deals with process development and coating characterization of such new oxide alloy thin films, focusing on the Al-V-O, Al-Cr-Si-O, and Cr-Zr-O systems. Alloying aluminum oxide with iso-valent vanadium is a candidate for forming the desired alloys. Therefore, coatings of (Al1-xVx)2O3, with x ranging from 0 to 1, were deposited with reactive sputter deposition. X-ray diffraction showed three different crystal structures depending on V-metal fraction in the coating: α-V2O3 rhombohedral structure for 100 at.% V, a defect spinel structure for the intermediate region, (63 - 42 at.% V), and a gamma-alumina-like solid solution at lower V-content, (18 and 7 at.%), were observed, the later was shifted to larger d-spacing compared to the pure γ-Al2O3 sample obtained if deposited with only Al-target. Annealing the Al-rich coatings in air resulted in formation of V2O5 crystals on the surface of the coating after annealing to 500 °C for 42 at.% V and 700 °C for 18 at.% V metal fraction respectively. The highest thermal stability was shown for pure γ-Al2O3-coating which transformed to α-Al2O3 after annealing to 1100° C. Highest hardness was observed for the Al-rich oxides, ~24 GPa. The hardness then decreases with increasing V-content, larger than 7 at.% V metal fraction. Doping the Al2O3 coating with 7 at.% V resulted in a significant surface smoothening compared to the binary oxide. The measured hardness after annealing in air decreased in conjunction with the onset of further oxidation of the coatings. This work increases the understanding of this complicated material system with respect to possible phases formed with pulsed DC magnetron sputtering deposition as well as their response to annealing in air. The inherent difficulties of depositing insulating oxide films with PVD, requiring a closed electrical circuit, makes the investigation of process stability an important part of this research. In this context, I investigated the influence of adding small amount of Si in Al-Cr cathode on the coating properties in a pulsed DC industrial cathodic arc system and the plasma characteristics, process parameters, and coating properties in a lab DC cathodic arc system. Si was chosen here due to a previous study showing improved erosion behavior of Al-Cr-Si over pure Al-Cr cathode without Si incorporation in the coating. The effect of Si in the Al-Cr cathode in the industrial cathodic arc system showed slight improvements on the cathode erosion but Si was found in all coatings where Si was added in the cathode. The Si addition promoted the formation of the B1-like metastable cubic oxide phase and the incorporation led to reduced or equal hardness values compared to the corresponding Si-free processes. The DC-arc plasma study on the same material system showed only small improvements in the cathode erosion and process stability (lower pressure and cathode voltage) when introducing 5 at.% Si in the Al70Cr30-cathode. The presence of volatile SiO species could be confirmed through plasma analysis, but the loss of Si through these species was negligible, since the coating composition matched the cathode composition also under these conditions. The positive effect of added Si on the process stability at the cathode surface, should be weighed against Si incorporation in the coating. This incorporation seems to lead to a reduction in mechanical properties in the as-deposited coatings and promote the formation of a B1-like cubic metastable oxide structure for the (Al,Cr)2O3 oxide. This formation may or may not be beneficial for the final application since literature indicates a slight stabilization of the metastable phase upon Si-incorporation, contrary to the effect of Cr, which stabilizes the α-phase. The thermal stability of alloys for metal cutting application is crucial for their use. Previous studies on another alloy system, Cr-Zr-O, had shown solid solution, for Cr-rich compositions in that material system, in the sought corundum structure. The thermal stability of α-Cr0.28Zr0.10O0.61 coating deposited by reactive radio frequency (RF)-magnetron sputtering at 500 °C was therefore investigated here after annealing in vacuum up to 870 °C. The annealed samples showed transformation of α-(Cr,Zr)2O3 and amorphous ZrOx-rich areas into tetragonal ZrO2 and bcc-Cr. The instability of the α-(Cr,Zr)2O3 is surprising and possibly related to the annealing being done under vacuum, facilitating the loss of oxygen. Further in situ synchrotron XRD annealing studies on the α-Cr0.28Zr0.10O0.61 coating in air and in vacuum showed increased stability for the air annealed sample up to at least 975 °C, accompanied with a slight increase in ex-situ measured nanohardness. The onset temperature for formation of tetragonal ZrO2 was similar to that for isothermally vacuum annealing. The synchrotron-vacuum annealed coating again decomposed into bcc-Cr and t-ZrO2, with an addition of monoclinic–ZrO2 due to grain growth. The stabilization of the room temperature metastable tetragonal ZrO2 phase, due to surface energy effects present with small grains sizes, may prove to be useful for metal cutting applications. The observed phase segregation of α-(Cr,Zr)2O3 and formation of tetragonal ZrO2 with corresponding increase in hardness for this pseudobinary oxide system also opens up design routes for pseudobinary oxides with tunable microstructural and mechanical properties.

Ionized Physical Vapor Deposition

Ionized Physical Vapor Deposition
Author:
Publisher: Academic Press
Total Pages: 255
Release: 1999-10-20
Genre: Technology & Engineering
ISBN: 9780125330275


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This volume provides the first comprehensive look at a pivotal new technology in integrated circuit fabrication. For some time researchers have sought alternate processes for interconnecting the millions of transistors on each chip because conventional physical vapor deposition can no longer meet the specifications of today's complex integrated circuits. Out of this research, ionized physical vapor deposition has emerged as a premier technology for the deposition of thin metal films that form the dense interconnect wiring on state-of-the-art microprocessors and memory chips. For the first time, the most recent developments in thin film deposition using ionized physical vapor deposition (I-PVD) are presented in a single coherent source. Readers will find detailed descriptions of relevant plasma source technology, specific deposition systems, and process recipes. The tools and processes covered include DC hollow cathode magnetrons, RF inductively coupled plasmas, and microwave plasmas that are used for depositing technologically important materials such as copper, tantalum, titanium, TiN, and aluminum. In addition, this volume describes the important physical processes that occur in I-PVD in a simple and concise way. The physical descriptions are followed by experimentally-verified numerical models that provide in-depth insight into the design and operation I-PVD tools. Practicing process engineers, research and development scientists, and students will find that this book's integration of tool design, process development, and fundamental physical models make it an indispensable reference. Key Features: The first comprehensive volume on ionized physical vapor deposition Combines tool design, process development, and fundamental physical understanding to form a complete picture of I-PVD Emphasizes practical applications in the area of IC fabrication and interconnect technology Serves as a guide to select the most appropriate technology for any deposition application *This single source saves time and effort by including comprehensive information at one's finger tips *The integration of tool design, process development, and fundamental physics allows the reader to quickly understand all of the issues important to I-PVD *The numerous practical applications assist the working engineer to select and refine thin film processes

Handbook of Physical Vapor Deposition (PVD) Processing

Handbook of Physical Vapor Deposition (PVD) Processing
Author: D. M. Mattox
Publisher: Cambridge University Press
Total Pages: 947
Release: 2014-09-19
Genre: Technology & Engineering
ISBN: 0080946585


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This book covers 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 book is on the aspects of the process flow that are critical to economical deposition of films that can meet the required performance specifications. 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.

Ionized Physical Vapor Deposition

Ionized Physical Vapor Deposition
Author:
Publisher: Academic Press
Total Pages: 268
Release: 1999-10-14
Genre: Science
ISBN: 008054293X


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This volume provides the first comprehensive look at a pivotal new technology in integrated circuit fabrication. For some time researchers have sought alternate processes for interconnecting the millions of transistors on each chip because conventional physical vapor deposition can no longer meet the specifications of today's complex integrated circuits. Out of this research, ionized physical vapor deposition has emerged as a premier technology for the deposition of thin metal films that form the dense interconnect wiring on state-of-the-art microprocessors and memory chips. For the first time, the most recent developments in thin film deposition using ionized physical vapor deposition (I-PVD) are presented in a single coherent source. Readers will find detailed descriptions of relevant plasma source technology, specific deposition systems, and process recipes. The tools and processes covered include DC hollow cathode magnetrons, RF inductively coupled plasmas, and microwave plasmas that are used for depositing technologically important materials such as copper, tantalum, titanium, TiN, and aluminum. In addition, this volume describes the important physical processes that occur in I-PVD in a simple and concise way. The physical descriptions are followed by experimentally-verified numerical models that provide in-depth insight into the design and operation I-PVD tools. Practicing process engineers, research and development scientists, and students will find that this book's integration of tool design, process development, and fundamental physical models make it an indispensable reference. Key Features: The first comprehensive volume on ionized physical vapor deposition Combines tool design, process development, and fundamental physical understanding to form a complete picture of I-PVD Emphasizes practical applications in the area of IC fabrication and interconnect technology Serves as a guide to select the most appropriate technology for any deposition application *This single source saves time and effort by including comprehensive information at one's finger tips *The integration of tool design, process development, and fundamental physics allows the reader to quickly understand all of the issues important to I-PVD *The numerous practical applications assist the working engineer to select and refine thin film processes

Handbook of Deposition Technologies for Films and Coatings

Handbook of Deposition Technologies for Films and Coatings
Author: Peter M. Martin
Publisher: William Andrew
Total Pages: 932
Release: 2009-12-01
Genre: Technology & Engineering
ISBN: 0815520328


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This 3e, edited by Peter M. Martin, PNNL 2005 Inventor of the Year, is an extensive update of the many improvements in deposition technologies, mechanisms, and applications. This long-awaited revision includes updated and new chapters on atomic layer deposition, cathodic arc deposition, sculpted thin films, polymer thin films and emerging technologies. Extensive material was added throughout the book, especially in the areas concerned with plasma-assisted vapor deposition processes and metallurgical coating applications.