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Author: Ranida Wongpiya
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
As complementary metal oxide semiconductor (CMOS) transistors continue to scale down, the work function variation (WFV) of the metal gates is becoming a dominant factor of the threshold voltage variation. This is due to the different grain orientations present in polycrystalline metal gates. Replacing these with amorphous or near-amorphous metals can reduce WFV. Furthermore, amorphous materials are known to have superior diffusion barrier properties due to their lack of grain boundaries. This can help prevent work function change due to the diffusion of metals in contact with the gate. In the first part of this thesis, a CoTiN metal alloy is introduced as a potential gate material. Using TiN-based material allows for an easy integration with the current technology as polycrystalline TiN is commonly used as the gate. With the addition of cobalt, thin films of TiN become more amorphous, consisting of nanocrystals in an amorphous matrix. Reducing the nitrogen content further decreases the film's crystallinity. In addition, CoTiN films also exhibit good thermal stability, low resistivity, and low roughness. Even though these materials are not completely amorphous, their small crystal size and an amorphous matrix can potentially reduce WFV and improve the diffusion barrier behavior. The second part focuses on the barrier properties of TiN and CoTiN against the diffusion of metal in contact with the gate. The work function (WF) of the bilayer-metal gate structure (Al/CoTiN/HfO2/SiO2/Si or Al/TiN/HfO2/SiO2/Si) varies with the amount of Al that diffuses to the metal/dielectric interface and is used to measure the diffusion. The WF as a function of the bottom metal layer thicknesses is extracted using capacitance-voltage measurements. A thickness above 15 nm appears to be necessary for maintaining the WF without any effects from the top metal layer. Depending on the reactivity between different elements in different metal layers, an additional barrier may be needed to prevent unwanted diffusion and reaction. Investigating the thermodynamics of different elements within the gate stack is important and can help in choosing appropriate materials. In the last part of the thesis, the diffusion barrier properties of another amorphous metal, TaWSiC, is studied for interconnect application. Copper/barrier/Si structures are annealed at different temperatures and characterized for phase and structural changes. Unlike polycrystalline Ta, 5 nm of TaWSiC is able to prevent Cu reaction with Si up to 550C.
Author: Ranida Wongpiya
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
As complementary metal oxide semiconductor (CMOS) transistors continue to scale down, the work function variation (WFV) of the metal gates is becoming a dominant factor of the threshold voltage variation. This is due to the different grain orientations present in polycrystalline metal gates. Replacing these with amorphous or near-amorphous metals can reduce WFV. Furthermore, amorphous materials are known to have superior diffusion barrier properties due to their lack of grain boundaries. This can help prevent work function change due to the diffusion of metals in contact with the gate. In the first part of this thesis, a CoTiN metal alloy is introduced as a potential gate material. Using TiN-based material allows for an easy integration with the current technology as polycrystalline TiN is commonly used as the gate. With the addition of cobalt, thin films of TiN become more amorphous, consisting of nanocrystals in an amorphous matrix. Reducing the nitrogen content further decreases the film's crystallinity. In addition, CoTiN films also exhibit good thermal stability, low resistivity, and low roughness. Even though these materials are not completely amorphous, their small crystal size and an amorphous matrix can potentially reduce WFV and improve the diffusion barrier behavior. The second part focuses on the barrier properties of TiN and CoTiN against the diffusion of metal in contact with the gate. The work function (WF) of the bilayer-metal gate structure (Al/CoTiN/HfO2/SiO2/Si or Al/TiN/HfO2/SiO2/Si) varies with the amount of Al that diffuses to the metal/dielectric interface and is used to measure the diffusion. The WF as a function of the bottom metal layer thicknesses is extracted using capacitance-voltage measurements. A thickness above 15 nm appears to be necessary for maintaining the WF without any effects from the top metal layer. Depending on the reactivity between different elements in different metal layers, an additional barrier may be needed to prevent unwanted diffusion and reaction. Investigating the thermodynamics of different elements within the gate stack is important and can help in choosing appropriate materials. In the last part of the thesis, the diffusion barrier properties of another amorphous metal, TaWSiC, is studied for interconnect application. Copper/barrier/Si structures are annealed at different temperatures and characterized for phase and structural changes. Unlike polycrystalline Ta, 5 nm of TaWSiC is able to prevent Cu reaction with Si up to 550C.
Author: A. M. Glezer
Publisher: CRC Press
ISBN: 1351655620
Category : Science
Languages : en
Pages : 170
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Book Description
This reference is dedicated to the problem of time-temperature stability of amorphous (non-crystalline) metal alloys with strongly nonequilibrium structure and unique physical and mechanical properties that are obtained by quenching from the melt at a rate that exceeds one millions of degrees c.o.s. second. As a stability test, the behavior of the plasticity of amorphous alloys is studied. The book examines the fundamental characteristics of amorphous alloys, the basic laws of structural relaxation, generalized information about the phenomenon of the ductile-brittle transition (temper embrittlement), the development of physically justified methods of predicting the stability of the properties, and provides information about the attempts of controlling the structure for the purpose of suppressing or deceleration of the ductile-brittle transition and, as a consequence, increasing the temperature and temporal stability of the amorphous state.
Author: G. Lucovsky
Publisher:
ISBN:
Category :
Languages : en
Pages : 12
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Book Description
This paper is presented to honor Professor Radu Grigorovici at his 90th birthday celebration for his outstanding contributions to the chemical bonding and atomic structure of amorphous semiconductors, including the chalcogenides that are highlighted at this conference. A chemical bonding approach is applied in this paper to noncrystalline transition metal oxides and their silicate and aluminate alloys. Transition metal oxides and alloys are considerably more ionic than SiO2, and this increased ionicity, along with the localized electronic structure associated with transition metal atom d-states is the basis for the significant differences in their optical and electrical properties. This paper also provides new insights into the electronic structure of transition metal chalgogenide alloys.
Author: Dragica Minić
Publisher: BoD – Books on Demand
ISBN: 1789854873
Category : Technology & Engineering
Languages : en
Pages : 100
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Book Description
The term "metallic glasses" is widely used to denote the amorphous alloys obtained by rapid quenching techniques. These materials are characterized by short range atom ordering without translational periodicity of the structure. Kinetic and thermodynamic metastability is one of the main characteristics generally related to metallic glasses, while their thermally induced microstructural transformations could result in deterioration or improvement of the functional properties. Due to their favorable magnetic, electrical, mechanical, and anti-corrosion properties, metallic glasses as new and attractive materials have found application in many areas of modern industries - electronics, construction industry, aerospace industry; as well as chemistry, biomedicine, and surgery.
Author: C. Suryanarayana
Publisher: CRC Press
ISBN: 1351649523
Category : Technology & Engineering
Languages : en
Pages : 529
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Book Description
Reflecting the fast pace of research in the field, the Second Edition of Bulk Metallic Glasses has been thoroughly updated and remains essential reading on the subject. It incorporates major advances in glass forming ability, corrosion behavior, and mechanical properties. Several of the newly proposed criteria to predict the glass-forming ability of alloys have been discussed. All other areas covered in this book have been updated, with special emphasis on topics where significant advances have occurred. These include processing of hierarchical surface structures and synthesis of nanophase composites using the chemical behavior of bulk metallic glasses and the development of novel bulk metallic glasses with high-strength and high-ductility and superelastic behavior. New topics such as high-entropy bulk metallic glasses, nanoporous alloys, novel nanocrystalline alloys, and soft magnetic glassy alloys with high saturation magnetization have also been discussed. Novel applications, such as metallic glassy screw bolts, surface coatings, hyperthermia glasses, ultra-thin mirrors and pressure sensors, mobile phone casing, and degradable biomedical materials, are described. Authored by the world’s foremost experts on bulk metallic glasses, this new edition endures as an indispensable reference and continues to be a one-stop resource on all aspects of bulk metallic glasses.
Author: J. S. Dugdale
Publisher: Cambridge University Press
ISBN: 9780521268820
Category : Technology & Engineering
Languages : en
Pages : 256
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Book Description
The theory of metallic conduction has, until recently, been confined to crystalline metals with atoms in regular arrays. The discovery of solid amorphous alloys led to an explosion of measurements of their electronic properties, and the emergence of a range of interesting low temperature phenomena. The book describes in physical terms the theory of the electrical conductivity, Hall coefficient, magnetoresistance and thermopower of disordered metals and alloys. The author begins by showing how conventional Boltzmann theory can be extended and modified when the mean free path of the conduction electrons becomes comparable with their wavelength and interionic separation. Dugdale explores the consequences of this and tests the theory by applying it to experimental data on metallic glasses. Designed as a self-contained review, the book will appeal to nonspecialist physicists, metallurgists and chemists with an interest in disordered metals.
Author: S Steeb
Publisher: Elsevier
ISBN: 0444601112
Category : Technology & Engineering
Languages : en
Pages : 1163
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Book Description
Rapidly Quenched Metals, Volume I covers the proceedings of the Fifth International Conference on Rapidly Quenched Metals, held in Wurzburg, Germany on September 3-7, 1984. The book focuses on amorphous and crystalline metals formed by rapid quenching from the melt. The selection first covers the scope and trends of developments in rapid solidification technology, rapid solidification, and undercooling of liquid metals by rapid quenching. Discussions focus on experimental method, powders, strip, particulate production, consolidation, and alloys and alloy systems. The text then examines the solidification of undercooled liquid alloys entrapped in solid; crystallization kinetics in undercooled droplets; and grain refinement in bulk undercooled alloys. The manuscript tackles the undercooling of niobium-germanium alloys in a 100 meter drop tube; influence of process parameters on the cooling rate of the meltspinning process; and the mechanism of ribbon formation in melt-spun copper and copper-zirconium. The formation and structure of thick sections of rapidly-solidified material by incremental deposition and production of ultrafine dispersions of rare earth oxides in Ti alloys using rapid solidification are also mentioned. The selection is a valuable reference for physicists, chemists, physical metallurgists, and engineers.
Author: K.W. Samwer
Publisher: Elsevier
ISBN: 008098360X
Category : Technology & Engineering
Languages : en
Pages : 677
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Book Description
This volume contains most of the papers presented at symposium D, one of the four symposia that formed the 1988 Strasbourg Spring Conference. The three day programme consisted of nine oral sessions; a poster session and a plenary talk giving an overview of current topics in hard magnetic materials. Scientists involved in basic as well as applied research concentrated their discussions on the fundamental processes relevant for the formation of metastable alloys such as amorphous alloys (metallic glasses), microcrystalline, quasicrystalline and nanocrystalline alloys and their applications. These materials are proving to be of considerable interest to research workers because of their possible application in the electronics industry, e.g. as diffusion barriers in devices or as data storage media.
Author: Esther Belin-Ferre
Publisher: World Scientific
ISBN: 9812790594
Category : Science
Languages : en
Pages : 408
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Book Description
Complex metal alloys (CMAs) comprise a huge group of largely unknown alloys and compounds, where many phases are formed with crystal structures based on giant unit cells containing atom clusters, ranging from tens of to more than thousand atoms per unit cell. In these phases, for many phenomena, the physical length scales are substantially smaller than the unit-cell dimension. Hence, these materials offer unique combinations of properties which are mutually exclusive in conventional materials, such as metallic electric conductivity combined with low thermal conductivity, good light absorption with high-temperature stability, high metallic hardness with reduced wetting by liquids, etc.This book is the first of a series of books issued yearly as a deliverable to the European Community of the School established within the European Network of Excellence CMA. Written by reputed experts in the fields of metal physics, surface physics, surface chemistry, metallurgy, and process engineering, this book brings together expertise found inside as well as outside the network to provide a comprehensive overview of the current state of knowledge in CMAs.
Author: Klaus Wetzig
Publisher: John Wiley & Sons
ISBN: 3527606475
Category : Science
Languages : en
Pages : 388
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Book Description
This up-to-date handbook covers the main topics of preparation, characterization and properties of complex metal-based layer systems. The authors -- an outstanding group of researchers -- discuss advanced methods for structure, chemical and electronic state characterization with reference to the properties of thin functional layers, such as metallization and barrier layers for microelectronics, magnetoresistive layers for GMR and TMR, sensor and resistance layers. As such, the book addresses materials specialists in industry, especially in microelectronics, as well as scientists, and can also be recommended for advanced studies in materials science, analytics, surface and solid state science.
