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Author: Vidyesh Parampalli Madhyastha
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
As device feature sizes shrink to single digit nanometer scale, researchers and industries are moving away from the conventional top-down approach and relying on a bottom-up approach for device fabrication. Contemporary top-down techniques involving photolithography and etching result in misalignment errors at sub-5 nm scales. Area selective deposition is a recent advanced bottom-up fabrication technique with the potential to sustain the trend as described by Moore's law. The approach involves a modified version of chemical vapor deposition (CVD) of a high dielectric constant metal oxide, Zirconia (ZrO2). High dielectric constant oxides such as Zirconia or Hafnia can replace conventional gate oxides such as silica in future generation CMOS devices. Three types of substrates namely SiO2, Cu, and Co are studied in this thesis. A procedure was identified to obtain an oxide-free surface of cobalt. Substrates are exposed to a precursor and a co-reactant, and thin film deposition was investigated using X-Ray Photoelectron Spectroscopy (XPS). A third gas phase molecule referred to as "co-adsorbate" was exploited to deposit ZrO2 thin films only on one type of surface in the presence of another. XPS was used to calculate the thickness of these thin films and to investigate their composition. Partial pressure of the co-adsorbate - 4-octyne, in the presence of N2, was measured under different flow conditions. Density Functional Theory (DFT) calculations suggest that 4-octyne binds to substrates as: Highest on Co and lowest on SiO2. Regarding Cu and SiO2, 4-octyne undergoes carbon bond rehybridization with Cu, whereas it only interacts with SiO2 by van der Waals forces. The difference in binding energies paves way to selective deposition between Cu and SiO2 at optimized substrate temperatures and vapor pressures of co-adsorbate. Preliminary AS-CVD studies were also performed between Co and Cu.
Author: Vidyesh Parampalli Madhyastha
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
As device feature sizes shrink to single digit nanometer scale, researchers and industries are moving away from the conventional top-down approach and relying on a bottom-up approach for device fabrication. Contemporary top-down techniques involving photolithography and etching result in misalignment errors at sub-5 nm scales. Area selective deposition is a recent advanced bottom-up fabrication technique with the potential to sustain the trend as described by Moore's law. The approach involves a modified version of chemical vapor deposition (CVD) of a high dielectric constant metal oxide, Zirconia (ZrO2). High dielectric constant oxides such as Zirconia or Hafnia can replace conventional gate oxides such as silica in future generation CMOS devices. Three types of substrates namely SiO2, Cu, and Co are studied in this thesis. A procedure was identified to obtain an oxide-free surface of cobalt. Substrates are exposed to a precursor and a co-reactant, and thin film deposition was investigated using X-Ray Photoelectron Spectroscopy (XPS). A third gas phase molecule referred to as "co-adsorbate" was exploited to deposit ZrO2 thin films only on one type of surface in the presence of another. XPS was used to calculate the thickness of these thin films and to investigate their composition. Partial pressure of the co-adsorbate - 4-octyne, in the presence of N2, was measured under different flow conditions. Density Functional Theory (DFT) calculations suggest that 4-octyne binds to substrates as: Highest on Co and lowest on SiO2. Regarding Cu and SiO2, 4-octyne undergoes carbon bond rehybridization with Cu, whereas it only interacts with SiO2 by van der Waals forces. The difference in binding energies paves way to selective deposition between Cu and SiO2 at optimized substrate temperatures and vapor pressures of co-adsorbate. Preliminary AS-CVD studies were also performed between Co and Cu.
Author: Pengyuan Zhao
Publisher:
ISBN:
Category :
Languages : en
Pages : 67
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Book Description
Moore's Law has been the guiding principle for semiconductor industry to scale down the device size. Consumers have been directly benefited from the ever developed technologies that lead to a faster, smaller, and more reliable performance. In order to preserve the advantages inherited from "scaling-down", researchers have invested into "bottom-up" approach which extends the "leeway" before Moore's postulation reaches saturation. Area-selective deposition (ASD) is an advanced technique to realize bottom-up fabrication as the device feature size shrinks to sub-5 nm scale. On the other hands, conventional top-down process, such as patterning of the substrate followed by selective etching process, tends to result misalignment errors. We have developed a proof-of-concept approach to address the challenge. The approach involves chemical vapor deposition (CVD) in which substrates are exposed to a precursor and a co-reactant. A third reactant termed "co-adsorbate" was utilized to direct growth only occurs on one surface in the presence of another. In this work, 4-octyne was used as co-adsorbate in the CVD of ZrO\textsubscript{2} thin films on SiO\textsubscript{2} and Cu substrates. Expected from quantum chemistry calculation, 4-octyne favors binding on Cu substrate through rehybridization, whereas it only interacts with SiO\textsubscript{2} by van der Waals force. The difference in binding energies affords selective growth.
Author: Shrikant Prabhakar Lohokare
Publisher:
ISBN:
Category :
Languages : en
Pages : 574
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Book Description
Chemical vapor deposition (CVD) is becoming an increasingly important manufacturing process for the fabrication of VLSI and ULSI devices. A major challenge in optimizing a CVD process is developing an understanding of the complex mechanistic pathways followed. The first section in this thesis reports studies on the thermal and dynamical activation of surface bound alkyl species which play a vital role in the form of intermediates in metal-organic chemical vapor deposition. The particular systems of interest are those of aluminum CVD precursors. Models of these intermediates are obtained by thermal decomposition of alkyl iodides. The results provide an insight into the complex reaction patterns involved in the thermal reactions and rate-structure sensitivities of the alkyl species in the presence of the coadsorbed halogen atom. Multiple reaction pathways including metal etching processes which bear direct implications to the synthesis of organometallics and metal etching, are identified. It is becoming apparent that chemistry at surfaces, whether it be heterogeneous catalysis, semiconductor etching, or chemical vapor deposition, is controlled by much more than the nature and structure of the surface. Also, nonthermal activation of autocatalytic reactions is often required for the nucleation and growth of thin films in devices so that the stability of the device structure is maintained. Dynamical pathways followed in these high pressure and energy processes have to be well understood. The second part of these studies describe an investigation of collision-induced reaction of alkyl intermediates using supersonic inert gas atomic beams. Selective activation of a thermodynamically favored unimolecular decomposition reaction is initiated by hyperthermal collisions. Quantitative estimations of the reaction cross sections are made using straightforward hard sphere energy transfer dynamics. This successful demonstration of collision-induced activation of large, multiatomic moieties has paved the way for proposed studies (now underway in our group) on actual CVD precursors with known barriers to nucleation and growth. In the second section, the reaction mechanisms and kinetics of competitive dissociation, disproportionation, and thin film growth processes involved in the chemical vapor deposition of metal-silicide thin films are investigated. Metal-silicides are widely used as interconnect and gate materials in devices and also as corrosion resistant materials. Reactivity of silane and disilane with copper is studied in detail using temperature programmed reaction, Auger electron, Fourier transform infrared reflection absorption spectroscopies and low energy electron diffraction. For both the precursors, the structural chemistry and product distributions of adsorbed intermediates found at low temperatures are quite rich but significantly differ at the mechanistic level. It is shown quantitatively that disilane is almost 2-3 orders of magnitude more reactive than silane due to its facile Si-Si bond dissociation. However, in both cases, kinetics of silicon deposition and silicide formation are limited by the site-blocking effect of surface bound hydrogen generated by the decomposition of the silyl fragments. An ordered silicide overlayer is readily formed at higher coverages effected above dihydrogen desorption temperatures. This bimolecular process has to compete with an associative reaction which leads to the formation of silane. The results obtained from the different spectroscopic data show that the growth process involves an intriguing set of coupled reactions in which deposition, island growth, and Si etching effectively compete in a complex manner. Understanding of these parameters and the reaction mechanisms involved, enables the application of this process for the vapor phase growth of silicide thin films.
Author: Daniel Dobkin
Publisher: Springer Science & Business Media
ISBN: 9781402012488
Category : Technology & Engineering
Languages : en
Pages : 298
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Book Description
Principles of Chemical Vapor Deposition provides a simple introduction to heat and mass transfer, surface and gas phase chemistry, and plasma discharge characteristics. In addition, the book includes discussions of practical films and reactors to help in the development of better processes and equipment. This book will assist workers new to chemical vapor deposition (CVD) to understand CVD reactors and processes and to comprehend and exploit the literature in the field. The book reviews several disparate fields with which many researchers may have only a passing acquaintance, such as heat and mass transfer, discharge physics, and surface chemistry, focusing on key issues relevant to CVD. The book also examines examples of realistic industrial reactors and processes with simplified analysis to demonstrate how to apply the principles to practical situations. The book does not attempt to exhaustively survey the literature or to intimidate the reader with irrelevant mathematical apparatus. This book is as simple as possible while still retaining the essential physics and chemistry. The book is generously illustrated to assist the reader in forming the mental images which are the basis of understanding.
Author: Nicola Pinna
Publisher: John Wiley & Sons
ISBN: 3527639926
Category : Technology & Engineering
Languages : en
Pages : 463
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Book Description
Atomic layer deposition, formerly called atomic layer epitaxy, was developed in the 1970s to meet the needs of producing high-quality, large-area fl at displays with perfect structure and process controllability. Nowadays, creating nanomaterials and producing nanostructures with structural perfection is an important goal for many applications in nanotechnology. As ALD is one of the important techniques which offers good control over the surface structures created, it is more and more in the focus of scientists. The book is structured in such a way to fi t both the need of the expert reader (due to the systematic presentation of the results at the forefront of the technique and their applications) and the ones of students and newcomers to the fi eld (through the first part detailing the basic aspects of the technique). This book is a must-have for all Materials Scientists, Surface Chemists, Physicists, and Scientists in the Semiconductor Industry.
Author: Karl E. Spear
Publisher:
ISBN:
Category : Vapor-plating
Languages : en
Pages : 762
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Book Description
Author: J. W. Elam
Publisher: The Electrochemical Society
ISBN: 1566778212
Category : Science
Languages : en
Pages : 469
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Book Description
The continuously expanding realm of Atomic Layer Deposition (ALD) Applications is the focus of this reoccurring symposium. ALD can enable the precise deposition of ultra-thin, highly conformal coatings over complex 3D topographies with controlled thickness and composition. This issue of ECS Transactions contains peer reviewed papers presented at the symposium. A broad spectrum of ALD applications is featured, including novel nano-composites and nanostructures, dielectrics for state-of-the-art transistors and capacitors, optoelectronics, and a variety of other emerging applications.
Author: Yan Yang
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
In this thesis, I will discuss four projects I participated during my Ph.D. study, with an emphasis on understanding and designing complex energy landscape between molecules and materials across nanoscale. These research projects are organized into four chapters: Chapter 1: Designer Potential Energy Surfaces via Programmable Magnetic Interactions; Chapter 2: Influence of Pore Size on the van der Waals Interaction in Two-Dimensional Molecules and Materials; Chapter 3: Non-Additivity and Finite-Size Effects in the Polarizabilities and Dispersion Coefficients of the Fullerenes; Chapter 4: Competitive Adsorption as a Route to Area-Selective Deposition. In Chapter 1, we explore how programmable magnetostatic interactions can be used in the rational design of Potential Energy Surfaces (PES) with targeted features. We first explore the PES design space that is accessible with small patterned magnetic arrays via forward and exhaustive enumeration, and characterize the resulting PES by the number, locations, and depths of the PES critical points. This is followed by a detailed investigation into the inverse problem-identification of magnetic patterns that correspond to PES with predefined features-using simulated annealing Monte Carlo (SA-MC) methods. In doing so, we demonstrate a robust theoretical and conceptual paradigm that enables forward and inverse PES engineering with precise control over the critical points and other salient surface features, thereby paving the way towards directed self-assembly using programmable magnetic interactions. As the magnetic interactions are scale-invariant, this approach can essentially scale down to the nanoscale. In Chapter 2, we investigate the influence of void space in porous twodimensional (2D) molecules and materials systems to the van der Waals (vdW) scaling landscape [1]. Analytical and numerical models presented herein demonstrate that the mere presence of a pore leads to markedly different vdW scaling across non-asymptotic distances, with certain relative pore sizes yielding effective power laws ranging from simple monotonic decay to the formation of minima, extended plateaus, and even maxima. These models are in remarkable agreement with first-principles approaches for the 2D building blocks of covalent organic frameworks (COFs), and reveal that COF macrocycle dimers and periodic bilayers exhibit unique vdW scaling behavior that is quite distinct from their non-porous analogs. These findings extend across a range of distances relevant to the nanoscale, and represent a hitherto unexplored avenue towards governing the self-assembly of complex nanostructures from porous 2D molecules and materials. In Chapter 3, we explore the nonadditivity and finite-size effect in a series of popular fullerene molecules [2]. We compute the static isotropic polarizability series (l with l = 1, 2, 3) for the C60-C84 fullerenes using finite-field derivative techniques and density functional theory (DFT), and quantitatively assess the intrinsic non-additivity in these fundamental response properties. By comparing against classical models of the fullerenes as conducting spherical shells (or solid spheres) of uniform electron density, a detailed critical analysis of the derived effective scaling laws (α1~ N^1.2, α2~N^2.0, α3~N^2.7) demonstrates that the electronic structure of finite-sized fullerenes-a unique dichotomy of electron confinement and delocalization effects due to their quasispherical cage-like structures and encapsulated void spaces-simultaneously limits and enhances their quantum mechanical response to electric field perturbations. Corresponding frequency-dependent polarizabilities are obtained by inputting the ` series into the hollow sphere model (within the modified single frequency approximation), and used to compute the molecular dispersion coefficients (Cn with n = 6, 8, 9, 10) need to describe the non-trivial vdW interactions in fullerene-based systems. Using first-order perturbation theory in conjuction with >140,000 DFT calculations, we also computed the non-negligible zero-point vibrational contributions to a1 in C60 and C70, thereby enabling a more accurate and direct comparison between theory and experiment for these quintessential nanostructures. In Chapter 4, we explore the use of competitive adsorption to facilitate area-selective deposition (ASD) [3,4]. ASD has the potential to enable next-generation manufacturing and patterning at the 5 nm node and beyond, with direct energy-related applications in solar cells, batteries, fuel cells, supercapacitors, catalysts, and sensors. Well-known for its ability to deposit atomically thin films with Angstrom scale precision along the growth direction and conformally over complex 3D substrates, ALD has already emerged as a key process in nanomanufacturing. In this regard, the range and scope of ALD-based applications and capabilities can be substantially extended by also controlling the in-plane growth, a timely and significant development that can be realized via ASD processes that depend on the chemical composition of the underlying surface. In this joint theoretical-experimental work (with the Engstrom Group at Cornell), competitive adsorption strategies will be leveraged to enable AS-ALD by blocking the dissociative chemisorption of the metal-containing precursor. In this approach, the co-adsorbate must differentiate between two competing surfaces by binding more strongly to one over the other. We computationally identified a series of co-adsorbates that can induce selectivity during chemical vapor deposition (CVD) and ALD process using dispersion-inclusive DFT, and used two of these co-adsorbates to achieve a deposition of ~30nm of a thin film on the desired growth surface using AS-CVD and 1.5nm using AS-ALD.
Author: Cheol Seong Hwang
Publisher: Springer Science & Business Media
ISBN: 146148054X
Category : Science
Languages : en
Pages : 266
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Book Description
Offering thorough coverage of atomic layer deposition (ALD), this book moves from basic chemistry of ALD and modeling of processes to examine ALD in memory, logic devices and machines. Reviews history, operating principles and ALD processes for each device.
Author: Toivo T. Kodas
Publisher: John Wiley & Sons
ISBN: 3527615849
Category : Technology & Engineering
Languages : en
Pages : 562
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Book Description
High purity, thin metal coatings have a variety of important commercial applications, for example, in the microelectronics industry, as catalysts, as protective and decorative coatings as well as in gas-diffusion barriers. This book offers detailed, up- to-date coverage of the chemistry behind the vapor deposition of different metals from organometallic precursors. In nine chapters, the CVD of metals including aluminum, tungsten, gold, silver, platinum, palladium, nickel, as well as copper from copper(I) and copper(II) compounds is covered. The synthesis and properties of the precursors, the growth process, morphology, quality and adhesion of the resulting films as well as laser- assisted, ion- assisted and plasma-assisted methods are discussed. Present applications and prospects for future developments are summarized. With ca. 1000 references and a glossary, this book is a unique source of in-depth information. It is indispensable for chemists, physicists, engineers and materials scientists working with metal- coating processes and technologies. From Reviews: 'I highly recommend this book to anyone interested in learning more about the chemistry of metal CVD.' J. Am Chem. Soc.
