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(1 - 8 of 8)
- Title
- INVESTIGATIONS ON RF SPUTTER DEPOSITED SICN THIN FILMS FOR MEMS APPLICATIONS.
- Creator
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Todi, Ravi, Coffey, Kevin, University of Central Florida
- Abstract / Description
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With the rapid increase in miniaturization of mechanical components, the need for a hard, protective coatings is of great importance. In this study we investigate some of the mechanical, chemical and physical properties of the SiCN thin films. Thin films of amorphous silicon carbide nitride (a-SiCxNy) were deposited in a RF magnetron sputtering system using a powder pressed SiC target. Films with various compositions were deposited on to silicon substrate by changing the N2/Ar gas ratios...
Show moreWith the rapid increase in miniaturization of mechanical components, the need for a hard, protective coatings is of great importance. In this study we investigate some of the mechanical, chemical and physical properties of the SiCN thin films. Thin films of amorphous silicon carbide nitride (a-SiCxNy) were deposited in a RF magnetron sputtering system using a powder pressed SiC target. Films with various compositions were deposited on to silicon substrate by changing the N2/Ar gas ratios during sputtering. Nano-indentation studies were performed to investigate the mechanical properties such as hardness and reduced modulus of the SiCN films. Surface morphology of the films was characterized by using atomic force microscopy (AFM). X-ray photoelectron spectroscopy (XPS) data indicated that the chemical status is highly sensitive to the nitrogen ratios during sputtering. Further, the films were annealed in dry oxygen ambient in the temperature range of 400 – 900°C and characterized using XPS to investigate the chemical composition and oxidation kinetics at each annealing temperature. The surface roughness of these films was studied as a function of annealing temperature and film composition with the help of a "Veeco" optical profilometer. Nano-indentation studies indicated that the hardness and the reduced modulus of the film are sensitive to the N2/Ar ratio of gas flow during sputtering. AFM studies revealed that the films become smoother as the N2/Ar ratio is increased. XPS data indicated the existence of C-N phases in the as-deposited films. The study of oxidation kinetics of RF sputter deposited SiCN thin films, using XPS, suggest that N2 co-sputtering helps to suppress the formation of a surface oxide, by allowing un-bonded Si to bond with N and C inside the vacuum chamber as opposed to bonding with O in atmosphere.
Show less - Date Issued
- 2005
- Identifier
- CFE0000839, ucf:46669
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000839
- Title
- INVESTIGATION OF REACTIVELY SPUTTERED SILICON CARBON BORON NITRIDE (SICBN) THIN FILMS FOR HIGH TEMPERATURE APPLICATIONS.
- Creator
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Vijayakumar, Arun, Sundaram, Kalpathy, University of Central Florida
- Abstract / Description
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The increasing demand for efficient energy systems in the last decade has brought about the development of advanced sensor systems that utilize advance detection methods to help in preventive maintenance of these essential systems. These usually are needed in hard to access environments where conditions are extreme and unfit for human interaction. Thin film based sensors deposited directly on the surfaces exposed to harsh environments can serve as ideal means of measuring the temperature of...
Show moreThe increasing demand for efficient energy systems in the last decade has brought about the development of advanced sensor systems that utilize advance detection methods to help in preventive maintenance of these essential systems. These usually are needed in hard to access environments where conditions are extreme and unfit for human interaction. Thin film based sensors deposited directly on the surfaces exposed to harsh environments can serve as ideal means of measuring the temperature of the component during operation. They provide the basic advantage of proximity to the surface and hence accurate measurement of the surface temperature. The low mass size ratio provides the additional advantage of least interference to system operation. The four elements consisting of Si, C, B, and N can be used to form binary, ternary and quaternary compounds like carbides, nitrides, which are chemically and thermally stable with extreme hardness, thermal conductivity and can be doped n- and p-type. Hence these compounds can be potential candidates for high temperature applications. This research is focused on studying sputtering as a candidate to obtain thin SiCBN films. The deposition and characterization of amorphous thin films of silicon boron carbon nitride (SiCBN) is reported. The SiCBN thin films were deposited in a radio frequency (rf) magnetron sputtering system using reactive co-sputtering of silicon carbide (SiC) and boron nitride (BN) targets. Films of different compositions were deposited by varying the ratios of argon and nitrogen gas in the sputtering ambient. Investigation of the oxidation kinetics of these materials was performed to study high temperature compatibility of the material. Surface characterization of the deposited films was performed using X-ray photoelectron spectroscopy and optical profilometry. Studies reveal that the chemical state of the films is highly sensitive to nitrogen flow ratios during sputtering. Surface analysis shows that smooth and uniform SiCBN films can be produced using this technique. Carbon and nitrogen content in the films seem to be sensitive to annealing temperatures. However depth profile studies reveal certain stoichiometric compositions to be stable after high temperature anneal up to 900ºC. Electrical and optical characteristics are also investigated with interesting results. Finally a metal semiconductor metal structure based optoelectronic device is demonstrated with excellent performance improvement over standard silicon based devices under higher temperature conditions.
Show less - Date Issued
- 2007
- Identifier
- CFE0001914, ucf:47490
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001914
- Title
- SURFACE CHEMISTRY OF APPLICATION SPECIFIC PADS AND COPPER CHEMICAL MECHANICAL PLANARIZATION.
- Creator
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Deshpande, Sameer Arun, Seal, Sudipta, University of Central Florida
- Abstract / Description
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Advances in the interconnection technology have played a key role in the continued improvement of the integrated circuit (IC) density, performance and cost. Copper (Cu) metallization, dual damascenes processing and integration of copper with low dielectric constant material are key issues in the IC industries. Chemical mechanical planarization of copper (Cu-CMP) has emerged as an important process for the manufacturing of ICs. Usually, Cu-CMP process consists of several steps such as the...
Show moreAdvances in the interconnection technology have played a key role in the continued improvement of the integrated circuit (IC) density, performance and cost. Copper (Cu) metallization, dual damascenes processing and integration of copper with low dielectric constant material are key issues in the IC industries. Chemical mechanical planarization of copper (Cu-CMP) has emerged as an important process for the manufacturing of ICs. Usually, Cu-CMP process consists of several steps such as the removal of surface layer by mechanical action of the pad and the abrasive particles, the dissolution of the abraded particles in the CMP solution, and the protection of the recess areas. The CMP process occurs at the atomic level at the pad/slurry/wafer interface, and hence, slurries and polishing pads play critical role in its successful implementation. The slurry for the Cu-CMP contains chemical components to facilitate the oxidation and removal of excess Cu as well as passivation of the polished surface. During the process, these slurry chemicals also react with the pad. In the present study, investigations were carried out to understand the effect of hydrogen peroxide (H2O2) as an oxidant and benzotriazole (BTA) as an inhibitor on the CMP of Cu. Interaction of these slurry components on copper has been investigated using electrochemical studies, x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). In the presence of 0.1M glycine, Cu removal rate was found to be high in the solution containing 5% H2O2 at pH 2 because of the Cu-glycine complexation reaction. The dissolution rate of the Cu was found to increase due to the formation of highly soluble Cu-glycine complex in the presence of H2O2. Addition of 0.01M BTA in the solution containing 0.1M glycine and 5% H2O2 at pH 2 exhibited a reduction in the Cu removal rate due to the formation of Cu-BTA complex on the surface of the Cu further inhibiting the dissolution. XPS and SIMS investigations revealed the formation of such Cu-glycine complex, which help understand the mechanism of the Cu-oxidant-inhibitor interaction during polishing. Along with the slurry, pads used in the Cu-CMP process have direct influence an overall process. To overcome problems associated with the current pads, new application specific pad (ASP) have been developed in collaboration with PsiloQuest Inc. Using plasma enhanced chemical vapor deposition (PECVD) process; surface of such ASP pads were modified. Plasma treatment of a polymer surface results in the formation of various functional groups and radicals. Post plasma treatment such as chemical reduction or oxidation imparts a more uniform distribution of such functional groups on the surface of the polymer resulting in unique surface properties. The mechanical properties of such coated pad have been investigated using nano-indentation technique in collaboration with Dr. Vaidyanathan's research group. The surface morphology and the chemistry of the ASP are studied using scanning electron microcopy (SEM), x-ray photoelectron spectroscopy (XPS), and fourier transform infrared spectroscopy (FTIR) to understand the formation of different chemical species on the surface. It is observed that the mechanical and the chemical properties of the pad top surface are a function of the PECVD coating time. Such PECVD treated pads are found to be hydrophilic and do not require being stored in aqueous medium during the not-in-use period. The metal removal rate using such surface modified polishing pad is found to increase linearly with the PECVD coating time. Overall, this thesis is an attempt to optimize the two most important parameters of the Cu-CMP process viz. slurry and pads for enhanced performance and ultimately reduce the cost of ownership (CoO).
Show less - Date Issued
- 2004
- Identifier
- CFE0000125, ucf:46191
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000125
- Title
- Reactive sputter deposition of lithium phosphorus oxynitride thin films, a Li battery solid state electrolyte.
- Creator
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Mani, Prabhu Doss, Coffey, Kevin, Heinrich, Helge, Hickman, James, Sundaram, Kalpathy, University of Central Florida
- Abstract / Description
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Lithium phosphorus oxy-nitride (LiPON) thin films are widely studied and used as a thin film electrolyte for lithium ion battery applications. LiPON thin films may be prepared by many techniques, but RF sputter deposition is most frequently used and was investigated in this dissertation, in spite of its low deposition rate, because of it offers more reliable and controllable processing. This dissertation includes the methodologies of sputter deposition and materials characterization of the...
Show moreLithium phosphorus oxy-nitride (LiPON) thin films are widely studied and used as a thin film electrolyte for lithium ion battery applications. LiPON thin films may be prepared by many techniques, but RF sputter deposition is most frequently used and was investigated in this dissertation, in spite of its low deposition rate, because of it offers more reliable and controllable processing. This dissertation includes the methodologies of sputter deposition and materials characterization of the LiPON thin film electrolytes.The LiPON thin films were deposited under varying conditions of process gas, substrate bias, and deposition temperature. To understand the variations in ionic conductivity observed, the films were extensively characterized to examine structural and compositional differences, including examination by x-ray photoelectron spectroscopy (XPS), inductively coupled plasma optical emission spectroscopy (ICP/OES), and spectroscopic ellipsometry. In addition, film density, and the intrinsic stress of the deposited films were also studied.The highest ionic conductivity of 9.8 x 10-6 S/cm was obtained at elevated deposition temperature and is correlated to a reduced density of defects, as indicated from the optical characterization.
Show less - Date Issued
- 2015
- Identifier
- CFE0005835, ucf:50929
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005835
- Title
- SUPPORTED MONO AND BIMETALLIC PLATINUM AND IRON NANOPARTICLES: ELECTRONIC, STRUCTURAL, CATALYTIC, AND VIBRATIONAL PROPERTIES.
- Creator
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Croy, Jason, Roldan Cuenya, Beatriz, University of Central Florida
- Abstract / Description
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Catalysis technologies are among the most important in the modern world. They are instrumental in the realization of a variety of products and processes including chemicals, polymers,foods, pharmaceuticals, fuels, and fuel cells. As such, interest in the catalysts that drive these processes is ongoing, and basic research has led to significant advances in the field, including the production of more environmentally friendly catalysts that can be tuned at the molecular/atomic level. However,...
Show moreCatalysis technologies are among the most important in the modern world. They are instrumental in the realization of a variety of products and processes including chemicals, polymers,foods, pharmaceuticals, fuels, and fuel cells. As such, interest in the catalysts that drive these processes is ongoing, and basic research has led to significant advances in the field, including the production of more environmentally friendly catalysts that can be tuned at the molecular/atomic level. However, there are many factors which influence the performance of a catalyst and many unanswered questions still remain. The first part of this work is concerned with the factors that influence the catalytic properties (activity, selectivity, and stability) of supported Pt and Pt-M nanoparticles (NPs). These factors are a synergistic combination of size, composition, support, oxidation state, and reaction environment (i.e. adsorbates, temperature, pressure, etc.). To probe the catalytic properties of complex and dynamic NP systems we have used MeOH decomposition and oxidation reactions, each of which has significant environmental and economic potential. We have given some emphasis to the state of NP oxidation, and with the aid of X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD), have followed the formation and temperature-dependent evolution of oxide species on Pt NPs. Further, we have explored how these species behave under the conditions of our probe reactions using a packed-bed mass flow reactor coupled to a quadrupole mass spectrometer (QMS). To carry out our investigations we exploit a NP synthesis method which is rather novel to nanocatalysis, micelle encapsulation. Since most available experimental techniques give information on ensemble averages, control over size distributions in NP samples is critical if unambiguous results are to be obtained. Micelle encapsulation allows us this control with several unique, inherent advantages. It is to this end that micelle encapsulation has allowed us to probe the detailed structure of small (~1 nm), supported, Pt NPs with extended X-ray absorption fine structure spectroscopy (EXAFS). Furthermore, we were able to explore experimentally, for the first time, the vibrational density of states (VDOS) of supported, isolated, monodispersed, mono and bimetallic NP systems via nuclear resonant inelastic X-ray scattering (NRIX). These synchrotron-based techniques (EXAFS, NRIXS) rely heavily on the monodispersity of the NP ensemble for reliable information.
Show less - Date Issued
- 2010
- Identifier
- CFE0003014, ucf:48349
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003014
- Title
- SYNTHESIS, STRUCTURE, AND CATALYTIC PROPERTIES OF SIZE-SELECTED PLATINUM NANOPARTICLES.
- Creator
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Mostafa, Simon, Roldan Cuenya, Beatriz, University of Central Florida
- Abstract / Description
-
The use of heterogeneous catalysis is well established in chemical synthesis, energy, and environmental engineering applications. Supported Pt nanoparticles have been widely reported to act as catalysts in a vast number of chemical reactions. In this report, the performance of Pt/ZrO2 nanocatalyst for the decomposition of methanol, ethanol, 2-propanol, and 2-butanol is investigated. The potential of each alcohol for the production of H2 and other relevant products in the presence of a...
Show moreThe use of heterogeneous catalysis is well established in chemical synthesis, energy, and environmental engineering applications. Supported Pt nanoparticles have been widely reported to act as catalysts in a vast number of chemical reactions. In this report, the performance of Pt/ZrO2 nanocatalyst for the decomposition of methanol, ethanol, 2-propanol, and 2-butanol is investigated. The potential of each alcohol for the production of H2 and other relevant products in the presence of a catalyst is studied. All the alcohols studied show some decomposition activity below 200°C which increased with increasing temperature. In all cases, high selectivity towards H2 formation is observed. With the exception of methanol, all alcohol conversion reactions lead to catalyst deactivation at high temperatures (T >250°C for 2-propanol and 2-butanol, T >325°C for ethanol) due to carbon poisoning. However, long-term catalyst deactivation can be avoided by optimizing reaction conditions such as operating temperature. In addition, the performance of Pt/γ-Al2O3 is evaluated in the oxidation of 2-propanol. Pt nanoclusters of similar size (~1 nm diameter) but different structure (shape) were found to display distinctively different catalytic properties. All the systems studied achieve high conversion (~ 90%) below 100°C. However, flatter particles display a lower reaction onset temperature, demonstrating superior catalytic performance. Acetone, CO2, and water are generated as products indicating that both partial and complete oxidation are taking place. A number of techniques including AFM, XPS, TEM, HAADF-TEM, XAFS as well as packed-bed reactor experiments were used for sample characterization and evaluation of catalytic performance.
Show less - Date Issued
- 2010
- Identifier
- CFE0003081, ucf:48319
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003081
- Title
- A theoretical and experimental investigation of the physical and chemical properties of solid nanoscale interfaces.
- Creator
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Matos, Jeronimo, Kara, Abdelkader, Heinrich, Helge, Schelling, Patrick, Masunov, Artem, University of Central Florida
- Abstract / Description
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With the emerging interest in nanoscale materials, the fascinating field of surface science is rapidly growing and presenting challenges to the design of both experimental and theoretical studies. The primary aim of this dissertation is to shed some light on the physical and chemical properties of selected nanoscale materials at the interface. Furthermore, we will discuss the effective application of cutting edge theoretical and experimental techniques that are invaluable tools for...
Show moreWith the emerging interest in nanoscale materials, the fascinating field of surface science is rapidly growing and presenting challenges to the design of both experimental and theoretical studies. The primary aim of this dissertation is to shed some light on the physical and chemical properties of selected nanoscale materials at the interface. Furthermore, we will discuss the effective application of cutting edge theoretical and experimental techniques that are invaluable tools for understanding the systems at hand. To this effect, we use density functional theory (DFT) with the inclusion of van der Waals (vdW) interactions to study the effect of long-range interactions on the adsorption characteristics of various organic molecules (i.e. benzene, olympicene radical, and sexithiophene) on transition metal surfaces. Secondly, the detailed analysis of x-ray absorption spectroscopy (XAS), scanning transmission electron microscopy (STEM), x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) measurements will be presented. These investigations will be dedicated to the study of (i) the effect of pre-treatment on the coarsening behavior of Pt nanoparticles (NPs) supported on ?-Al2O3 and (ii) deconvoluting the intrinsic (size effects) and extrinsic (ligand effects) physical and electronic properties of Au NPs encapsulated by polystyrene 2-vinylpiridine ligands.
Show less - Date Issued
- 2015
- Identifier
- CFE0005975, ucf:50783
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005975
- Title
- Deposition and characterization studies of boron carbon nitride (BCN) thin films prepared by dual target sputtering.
- Creator
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Prakash, Adithya, Sundaram, Kalpathy, Kapoor, Vikram, Yuan, Jiann-Shiun, Jin, Yier, Chow, Louis, University of Central Florida
- Abstract / Description
-
As complementary metal-oxide semiconductor (CMOS) devices shrink to smaller size, the problems related to circuit performance such as critical path signal delay are becoming a pressing issue. These delays are a result of resistance and capacitance product (RC time constant) of the interconnect circuit. A novel material with reduced dielectric constants may compromise both the thermal and mechanical properties that can lead to die cracking during package and other reliability issues. Boron...
Show moreAs complementary metal-oxide semiconductor (CMOS) devices shrink to smaller size, the problems related to circuit performance such as critical path signal delay are becoming a pressing issue. These delays are a result of resistance and capacitance product (RC time constant) of the interconnect circuit. A novel material with reduced dielectric constants may compromise both the thermal and mechanical properties that can lead to die cracking during package and other reliability issues. Boron carbon nitride (BCN) compounds have been expected to combine the excellent properties of boron carbide (B4C), boron nitride (BN) and carbon nitride (C3N4), with their properties adjustable, depending on composition and structure. BCN thin film is a good candidate for being hard, dense, pore-free, low-k dielectric with values in the range of 1.9 to 2.1. Excellent mechanical properties such as adhesion, high hardness and good wear resistance have been reported in the case of sputtered BCN thin films. Problems posed by high hardness materials such as diamonds in high cutting applications and the comparatively lower hardness of c-BN gave rise to the idea of a mixed phase that can overcome these problems with a minimum compromise in its properties. A hybrid between semi-metallic graphite and insulating h-BN may show adjusted semiconductor properties. BCN exhibits the potential to control optical bandgap (band gap engineering) by atomic composition, hence making it a good candidate for electronic and photonic devices. Due to tremendous bandgap engineering capability and refractive index variability in BCN thin film, it is feasible to develop filters and mirrors for use in ultra violet (UV) wavelength region. It is of prime importance to understand process integration challenges like deposition rates, curing, and etching, cleaning and polishing during characterization of low-k films. The sputtering technique provides unique advantages over other techniques such as freedom to choose the substrate material and a uniform deposition over relatively large area. BCN films are prepared by dual target reactive magnetron sputtering from a B4C and BN targets using DC and RF powers respectively. In this work, an investigation of mechanical, optical, chemical, surface and device characterizations is undertaken. These holistic and thorough studies, will provide the insight into the capability of BCN being a hard, chemically inert, low-k, wideband gap material, as a potential leader in semiconductor and optics industry.
Show less - Date Issued
- 2016
- Identifier
- CFE0006378, ucf:51496
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006378
