- Home
- A-Z Publications
- Annual Review of Materials Research
- Previous Issues
- Volume 39, 2009
Annual Review of Materials Research - Volume 39, 2009
Volume 39, 2009
- Introduction
-
-
-
Molecular Electronics
Vol. 39 (2009), pp. 1–23More LessMolecular electronics describes the field in which molecules are utilized as the active (switching, sensing, etc.) or passive (current rectifiers, surface passivants) elements in electronic devices. This review focuses on experimental aspects of molecular electronics that researchers have elucidated over the past decade or so and that relate to the fabrication of molecular electronic devices in which the molecular components are readily distinguished within the electronic properties of the device. Materials, fabrication methods, and methods for characterizing electrode materials, molecular monolayers, and molecule/electrode interfaces are discussed. A particular focus is on devices in which the molecules or molecular monolayer are sandwiched between two immobile electrodes. Four specific examples of such devices, in which the electron transport characteristics reflect distinctly molecular properties, are discussed.
-
-
-
Phase Change Materials
Vol. 39 (2009), pp. 25–48More LessPhase change materials (PCMs) can exist in at least two different phases (an amorphous and one or more crystalline phases), and they can be switched repeatedly between these phases. The different phases have distinctly different physical properties such as electrical conductivity, optical reflectivity, mass density, or thermal conductivity. These differences and the repeatability of the switching give these materials the ability to store information. Rewritable compact discs, digital versatile discs, and Blu-ray™ discs store information in thin films of PCMs, using the difference in reflectivity between the phases as the storage mechanism. A novel solid-state memory technology that applies the difference in electrical resistivity is currently being developed, and possible future applications include reconfigurable logic. This article reviews the unique set of properties of PCMs and their current and future applications.
-
-
-
Porous pSiCOH Ultralow-k Dielectrics for Chip Interconnects Prepared by PECVD
Vol. 39 (2009), pp. 49–69More LessPorous pSiCOH materials with ultralow dielectric constants (ulk) have been developed with dielectric constants reaching values below 2.0. The pSiCOH films, composed of Si, C, O, and H atoms, are prepared by plasma-assisted chemical vapor deposition (PECVD), showing that PECVD can be used to prepare porous materials. The pSiCOH films are deposited as dual-phase materials, and the porosity is formed in them by curing the as-deposited films by thermal anneals, electron beams, or UV irradiation. The porous pSiCOH dielectrics are suitable for integration in the interconnects of VLSI chips of the 45-nm-and-beyond technology nodes, and films with dielectric constants of 2.4 have already been implemented in upcoming 45-nm products. This review discusses the fabrication of pSiCOH films and the characterization of their structure, porosity, and electrical and mechanical properties. The limitations of some of the characterization techniques of these amorphous thin films are also addressed.
-
-
-
Thin-Film Organic Electronic Devices
Howard E. Katz, and Jia HuangVol. 39 (2009), pp. 71–92More LessWe review recently published advancements in thin-film organic devices, ranging from the composition and properties of organic materials to be used in devices, to the applications of devices, with special emphasis on thin-film transistors, diodes, and chemical sensors. We present exemplary materials used in each kind of device, outline the physical mechanisms behind the functioning of the devices, and discuss the most advanced capabilities of the devices and device assemblies. Advantages to the selection of organic and polymeric materials, future prospects, and challenges for organic-based electronics are also considered.
-
-
-
Immersion Lithography: Photomask and Wafer-Level Materials
Vol. 39 (2009), pp. 93–126More LessOptical immersion lithography utilizes liquids with refractive indices >1 (the index of air) below the last lens element to enhance numerical aperture and resolution, enabling sub-40-nm feature patterning. This shift from conventional dry optical lithography introduces numerous challenges requiring innovations in materials at all imaging stack levels. In this article, we highlight the recent materials advances in photomasks, immersion fluids, topcoats, and photoresists. Some of the challenges encountered include the fluids' and photomask materials' UV durability, the high-index liquids' compatibility with topcoats and photoresists, and overall immersion imaging and defectivity performance. In addition, we include a section on novel materials and methods for double-patterning lithography—a technique that may further extend immersion technology by effectively doubling a less dense pattern's line density.
-
-
-
Materials for Optical Lithography Tool Application
Harry Sewell, and Jan MulkensVol. 39 (2009), pp. 127–153More LessThis review of materials development for optical lithography covers two areas: materials for optical steppers and scanners, and materials for EUV lithography. In the former, materials development for advanced immersion lenses and for high-index immersion lens is discussed, whereas in the latter, materials used in multilayer EUV mirrors and to generate EUV photons are discussed.
-
-
-
Nanoimprint Lithography Materials Development for Semiconductor Device Fabrication
Vol. 39 (2009), pp. 155–180More LessThe term nanoimprint lithography (NIL) describes a number of processes used to form nanoscale structures by molding or embossing. Step and flash imprint lithography (S-FIL, a trademark of Molecular Imprints, Inc.) is a variant of NIL that can be performed at room temperature and low pressure. In S-FIL, a low-viscosity liquid imprint material is hardened in a patterned template by exposure to UV light. S-FIL is ideally suited to integrated-circuit device fabrication. Materials development for S-FIL has progressed significantly since its introduction in 1999. We discuss the status of materials development, with specific emphasis on the imprint material and functional materials, template fabrication and release layers, and S-FIL process variations.
-
-
-
High-κ/Metal Gate Science and Technology
Vol. 39 (2009), pp. 181–202More LessHigh-κ/metal gate technology is on the verge of replacing conventional oxynitride dielectrics in state-of-the-art transistors for both high-performance and low-power applications. In this review we discuss some of the key materials issues that complicated the introduction of high-κ dielectrics, including reduced electron mobility, oxygen-based thermal instabilities, and the absence of thermally stable dual-metal electrodes. We show that through a combination of materials innovations and engineering ingenuity these issues were successfully overcome, thereby paving the way for high-κ/metal gate implementation.
-
-
-
Strain: A Solution for Higher Carrier Mobility in Nanoscale MOSFETs
Vol. 39 (2009), pp. 203–229More LessMetal-oxide-semiconductor field-effect transistors (MOSFETs) have shown impressive performance improvements over the past 10 years by incorporating strained silicon (Si) technology. This review gives an overview of the impact of strain on carrier mobility in Si n- and pMOSFETs by considering strain-induced band splitting, band warping and consequent carrier repopulation, and altered conductivity effective mass and scattering rate. Different surface orientations, channel directions, and gate electric fields are included for a fully theoretical understanding. The results are used to predict strain-enhanced silicon-on-insulator (SOI) and multigate device performance, mainly focusing on potential 22-nm and beyond device options such as double-gate and trigate fin field-effect transistor (FinFET) structures. Insights into strain-enhanced potential future channel materials (SiGe, Ge, and GaAs) are also summarized. Finally, recent technology nodes with strain engineering are reviewed, and the future developing trend is given.
-
-
-
Size-Dependent Resistivity in Nanoscale Interconnects
Vol. 39 (2009), pp. 231–254More LessAs the dimensions of conductors shrink into the nanoscale, their electrical conductivity becomes dependent on their size even at room temperature. Although the behavior varies dramatically as temperatures increase from nanokelvins to hundreds of kelvins, the effect is generally to increase the resistivity above that of bulk material. As such, the underlying size-dependent phenomena have become increasingly important as advanced technologies have shifted their focus first from macro- to microscale and more recently from micro- to nanoscale dimensions. Indeed, the size-dependent increase of electrical resistivity that results from electron scattering on external and internal surfaces of copper conductors has already become technology limiting in modern microelectronics. This article summarizes the phenomena that underlie size effects, focusing on conduction in copper lines in particular. Attention is given to describing key innovations in both theoretical and experimental assessments that have significantly modified, facilitated, or advanced understanding.
-
-
-
Carbon Nanotube Interconnects
Vol. 39 (2009), pp. 255–275More LessThe performance and power dissipation of integrated circuits (IC) are largely affected by interconnects. Carbon nanotubes, which are rolls of one-atom-thick carbon sheets, show great potential in addressing some of the major interconnect challenges in future generations of technology, when copper conductivity will degrade substantially because of size effects. Some of the fascinating properties of carbon nanotubes include very large current conduction capacity, large electron mean free paths, high mechanical strength, and stability. In this article, the physical circuit models for carbon nanotubes are reviewed, and the potential performances of both single-wall carbon nanotube (SWNT) and multiwall carbon nanotube (MWNT) interconnects are benchmarked against their copper counterparts at a realistic operating temperature (100°C). The models capture various electron phonon scattering mechanisms and the dependency of quantum conductance on temperature and diameter. A hybrid system of copper/SWNTs/MWNTs offers the highest performance enhancement for interconnects.
-
-
-
Materials for Magnetoresistive Random Access Memory
Vol. 39 (2009), pp. 277–296More LessMRAM technology is based on the storage of data in stable magnetic states using devices that have a large magnetoresistance effect, so that the data can be read by determining the resistance of the device. MRAM is inherently nonvolatile and the magnetic states can be switched extremely fast and with no wear out. In this article, we review the fundamentals of MRAM technology, explain the innovations that have overcome barriers to commercialization, and describe areas where further innovation can advance the technology most significantly. The influence of key structural and magnetic properties of materials used in magnetic tunnel junctions, and optimization of those devices for read and write performance in memory arrays, is discussed in detail. The various approaches to writing data in MRAM arrays are described and compared, with emphasis on toggle MRAM, the type that is in commercial production, and on spin-torque MRAM, which shows great promise for future improvements in power and density. In the final section, we summarize recent demonstrations of advanced MRAM technology.
-
-
-
Chameleon Coatings: Adaptive Surfaces to Reduce Friction and Wear in Extreme Environments
C. Muratore, and A.A. VoevodinVol. 39 (2009), pp. 297–324More LessAdaptive nanocomposite coating materials that automatically and reversibly adjust their surface composition and morphology via multiple mechanisms are a promising development for the reduction of friction and wear over broad ranges of ambient conditions encountered in aerospace applications, such as cycling of temperature and atmospheric composition. Materials selection for these composites is based on extensive study of interactions occurring between solid lubricants and their surroundings, especially with novel in situ surface characterization techniques used to identify adaptive behavior on size scales ranging from 10−10 to 10−4 m. Recent insights on operative solid-lubricant mechanisms and their dependency upon the ambient environment are reviewed as a basis for a discussion of the state of the art in solid-lubricant materials.
-
-
-
Doped Oxides for High-Temperature Luminescence and Lifetime Thermometry
M.D. Chambers, and D.R. ClarkeVol. 39 (2009), pp. 325–359More LessThe measurement of high temperatures in oxides and oxide-based structures in practical applications often presents challenges including steep thermal gradients, the presence of flames or chemically aggressive environments, and the transparency or translucency of most oxides. For turbine engines, oxide coatings are of great commercial importance, and the rapid motion of parts prohibits contact thermometry. Luminescence thermometry offers a number of advantages for measuring temperature in such systems and has been the subject of ongoing study for many years. Recent work on rare-earth-doped thermal barrier coatings, environmental barrier coatings, and related oxides has demonstrated the feasibility of luminescence thermometry to temperatures well in excess of 1000°C. The luminescent properties of these materials and the analytical techniques used to extract reproducible temperature measurements from the measured luminescence are reviewed.
-
-
-
Plasticity of Micrometer-Scale Single Crystals in Compression
Vol. 39 (2009), pp. 361–386More LessThis review examines the recent literature that has focused on uniaxial compression experiments of single crystals at the micrometer scale. Collectively, the studies discovered new regimes of plastic flow that are size-scale dependent and that occur in the absence of strong strain gradients. However, the quantitative comparison of the flow curves between independent studies is hampered by differences in the particular implementations of the testing methodology. Modeling of microcompression experiments using 3-D discrete dislocation simulations has provided valuable insight into the mechanisms that control plastic flow in FCC metals. These efforts identified the importance of the initial dislocation density and distribution of mobile dislocation segments, the influence of free surfaces on that distribution, as well as altered multiplication and hardening responses due to the finite source statistics. Microcrystal experiments also provide a new pathway to characterize the global system dynamics of dislocation ensembles and associated stochastic processes.
-
-
-
Recent Progress in the Study of Inorganic Nanotubes and Fullerene-Like Structures
R. Tenne, and G. SeifertVol. 39 (2009), pp. 387–413More LessThe synthesis of WS2 inorganic nanotubes (INT) and inorganic fullerene-like (IF) structures in 1992 signified the opening of a fertile and challenging field of scientific endeavor. These structures were the first of a long and ever-expanding series of INT and IF structures. Although initially much of the effort concentrated on the synthesis of INT and IF from compounds with layered structures, recently there has been a surge of efforts to synthesize crystalline and polycrystalline nanotubular structures from compounds with quasi-isotropic structures, like spinels, BaTiO3, SiO2, TiO2, and many others. The present review summarizes some of the progress in this field in recent years. Much of the progress in this field was achieved through strong interaction between theoretical and experimental work. This article has four themes: (a) new synthetic approaches leading to new kinds of IF and INT; (b) study of the molecular structure of such nanoparticles with new tools, such as aberration-corrected transmission electron microscopy (TEM) and high-angle annular dark field (HAADF); (c) recent progress in the investigation of the properties of such nanostructures; and (d) examples of applications for which clear progress has been accomplished, in particular in solid lubrication and high-strength nanocomposites.
-
-
-
Recent Progress in Theoretical Prediction, Preparation, and Characterization of Layered Ternary Transition-Metal Carbides
Vol. 39 (2009), pp. 415–443More LessLayered ternary carbides contain alternative stacking of structural slabs in the unit cells. Many mechanical and structural features are inherited with respect to their binary carbide counterparts, and some novel properties also appear because of new chemical bonds and atomic coordination at the boundaries of different slabs. In this review, we highlight important recent achievements that focus on theoretical prediction, microstructure characterization preparation, and macroscopic properties of newly developed layered ternary transition-metal carbides. These results provide insights into understanding the relationship between the structure (including crystal structure, chemical bonding, and microstructure) and the properties of these layered ternary carbides and further highlight their technological applications as high-temperature and ultrahigh-temperature structural materials.
-
-
-
Shape Memory Polymer Research
Vol. 39 (2009), pp. 445–471More LessThe past several years have witnessed significant advances in the field of shape memory polymers (SMPs) with the elucidation of new compositions for property tuning, the discovery of new mechanisms for shape fixing and recovery, and the initiation of phenomenological modeling. We critically review research findings on new shape memory polymers along these lines, emphasizing exciting progress in the areas of composites, novel recovery triggering, and new application developments.
-
-
-
Solid-Surface Characterization by Wetting
Vol. 39 (2009), pp. 473–489More LessThe current status of the theories that are required for characterization of solid surfaces by equilibrium contact angles is reviewed. Some important aspects, which are not yet completely understood, are explained and listed as future challenges. The theoretical conclusions are integrated into a methodology and technique for contact angle measurement and interpretation that avoid existing pitfalls.
-
Previous Volumes
-
Volume 54 (2024)
-
Volume 53 (2023)
-
Volume 52 (2022)
-
Volume 51 (2021)
-
Volume 50 (2020)
-
Volume 49 (2019)
-
Volume 48 (2018)
-
Volume 47 (2017)
-
Volume 46 (2016)
-
Volume 45 (2015)
-
Volume 44 (2014)
-
Volume 43 (2013)
-
Volume 42 (2012)
-
Volume 41 (2011)
-
Volume 40 (2010)
-
Volume 39 (2009)
-
Volume 38 (2008)
-
Volume 37 (2007)
-
Volume 36 (2006)
-
Volume 35 (2005)
-
Volume 34 (2004)
-
Volume 33 (2003)
-
Volume 32 (2002)
-
Volume 31 (2001)
-
Volume 30 (2000)
-
Volume 29 (1999)
-
Volume 28 (1998)
-
Volume 27 (1997)
-
Volume 26 (1996)
-
Volume 25 (1995)
-
Volume 24 (1994)
-
Volume 23 (1993)
-
Volume 22 (1992)
-
Volume 21 (1991)
-
Volume 20 (1990)
-
Volume 19 (1989)
-
Volume 18 (1988)
-
Volume 17 (1987)
-
Volume 16 (1986)
-
Volume 15 (1985)
-
Volume 14 (1984)
-
Volume 13 (1983)
-
Volume 12 (1982)
-
Volume 11 (1981)
-
Volume 10 (1980)
-
Volume 9 (1979)
-
Volume 8 (1978)
-
Volume 7 (1977)
-
Volume 6 (1976)
-
Volume 5 (1975)
-
Volume 4 (1974)
-
Volume 3 (1973)
-
Volume 2 (1972)
-
Volume 1 (1971)
-
Volume 0 (1932)