bluuebunny/crossref_metadata_2025_split huggingface dataset:
Potential-pH Diagrams of Interest to Chemical Mechanical Planarization of Copper Thin Films
Authors: Aksu Serdar 
Published: June 2019

AbstractChemical mechanical planarization (CMP), which can globally planarize both silicon dioxide (the prevalent interlayer dielectric), and copper films, has become the key process in the damascene method used for producing integrated circuit (IC) devices with multilevel copper interconnects. Cu CMP is typically carried out with slurries containing oxidizing agents, complexing agents, and corrosion inhibitors as the principal chemical components. In such slurries, complexing agents enhance the solubility of copper and increase the dissolution rate of the abraded material in Cu CMP. They also assist achieving high copper removal rates during dynamic polishing conditions. The nature of the complexing agent used, the pH and the redox potential of the slurry system are among the main factors controlling the dissolution and passivation behaviors of copper during CMP. Consequently, these factors are intimately related to the key CMP performance metrics such as removal rate and planarity. In this paper, potentialpH diagrams of copper in aqueous systems containing a number of organic complexing agents including ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), oxalic acid and malonic acid are presented. The predominance regions of copper complexes under different copper and ligand activities and their implications on copper removal during CMP are discussed.
Investigation on Abrasive Free Copper Chemical Mechanical Planarization for Cu/low k and Cu/ultra low k interconnects
Authors: Balakumar S. , Haque T. , Kumar R. , Kumar A.S. , Rahman M. 
Published: June 2019

AbstractAbrasive Free Copper Chemical Mechanical Polishing (AF-CMP) was developed for Cu/low k materials. Blanket film Cu removal rate of 6000 Å/min with very less non-uniformity of 3% achieved for polishing pressure of 1.5 psi. CMP process window and lower critical pressure were identified with pattern wafers. Material removal mechanism was studied using surface morphology of Copper blanket wafers polished using different pressure, rotation rate and slurry flow rate. Material Removal Mechanism (wear mechanism) such as Chemical wear (etching) and mechanical wear (fatigue wear, particle adhesion wear and abrasion wear) have been found. The increase of slurry flow rate and relative velocity and the decrease of pressure give the dominance of chemical wear in material removal mechanism, and vice versa. Dishing control was achieved during Cu polish using different carrier/platen speed for Cu/SiLKTM patterned wafers. The cumulative distribution of the metal line-to-line leakage current measurements of wafers shows good performance and it is comparable to abrasive process.
Feasibility of Detecting Barrier Layer to Low-k Transition in Copper Cmp Using Raman Spectroscopy
Authors: Kondoju S. , Juncker C. , Lucas P. , Raghavan S. , Fischer P. , Moinpour M. , Oehler A. 
Published: June 2019

AbstractIn copper CMP, transitions from copper to barrier as well as barrier to dielectric layer are typically sensed in situ using an optical reflectance technique. Spectroscopic techniques such as Raman, which allow monitoring the vibrational modes of silicon and low-k layers, have interesting potential for detecting these transitions. In this paper the use of Raman spectroscopy in detecting in situ removal of barrier layers from CDO materials is reported. Intensities of Raman peaks characteristic of Si-Si vibrations from Si substrate and C-H vibrations from low-k materials have been used for monitoring CDO layer thickness and detecting removal of Ta overlayer. An abrasion cell is integrated with a Raman spectrometer to demonstrate the feasibility of Raman monitoring in-situ. Capabilities and limitations of the Raman spectroscopic method are discussed.
Optimization of Psiloquest's Application Specific CMP Pads for Commercialization
Authors: Zantye Parshuram B. , Obeng Yaw , Mudhivarthi S. , Kumar Ashok 
Published: June 2019

AbstractThere is a need for metrology, characterization and optimization of CMP pad architecture before being put into service. psiloQuest, Inc. has developed a novel polishing pad which is made up of polyolefin material instead of conventional polyurethane. The surface of the pad has been modified to match the surface of the material under going CMP. In this research, we have optimized the PECVD tetraethylorthosilicate (TEOS) surface coating duration and pad thickness for optimum pad output. The pad was then extensively characterized using the several standard metrology techniques such as SEM, XPS and nanoindentation. The CMP performance evaluation of all the candidate pads was done using CETR CP-4TM bench top CMP tester. There was a correlation and interdependence of the pad coating time and surface chemical, micromechanical and tribological properties. However, their impact on the pad CMP performance was found to be indirect, if any. These findings were used to optimize the pad design and architecture before commercialization. The demonstrated methodology can also be implemented for parametric optimization of polishing pads with novel designs in the future.
Quantitative In-Situ Measurement of Asperity Compression Under the Wafer During Polishing
Authors: Gray Caprice , Apone Daniel , Rogers Chris , Manno Vincent P. , Barns Chris , Moinpour Mansour , Anjur Sriram , Philipossian Ara 
Published: June 2019

AbstractThe interaction of the wafer, slurry and pad determines the material removal rate during Chemical Mechanical Planarization (CMP). Dual emission laser induced fluorescence (DELIF) provides a means to measure the slurry layer thickness between the wafer and a Fruedenbergy FX9 pad during CMP with high spatial (4.3 μm/pixel) and temporal resolution (2 Hz). In this paper we present some preliminary measurements of pad compression using DELIF to measure the standard deviation of asperity height. Static slurry layer images were captured at high (70 kPa) and low (0 kPa) down-force applied to the wafer. In-situ, dynamic images at 10 kPa downforce applied to etched wafers were imaged. Two wafers were etched such that they contain square wells, one wafer with 27 μm and the other will 14.5 μm deep wells. In the static case, asperity compression is directly related the amount of fluid displaced. In the dynamic case, asperity compression is 35% greater under the 27 μm wells than the 14.5 μm wells.
Synergy between Chemical Dissolution and Mechanical Abrasion during Chemical Mechanical Polishing of Copper
Authors: Che Wei , Bastawros Ashraf , Chandra Abhijit 
Published: June 2019

AbstractThe synergistic roles of chemical dissolution and mechanical abrasion on the material removal mechanism during CMP process are explored. A set of nano-wear experiments are conducted on electro-plated copper surfaces with systematic exposure to active slurries. Initial results of in situ wear test in chemically active slurry showed an increased material removal rate (MRR) relative to a dry wear test. To understand the synergistic effects of chemical dissolution and mechanical abrasion, we have investigated two plausible mechanisms of material removal. Mechanism-I is based on chemical dissolution enhanced mechanical abrasion. A soft layer of chemical products is assumed to be formed on top of the polished surface due to chemical reaction with a rate much faster than the mechanical abrasion rate. It is then followed by a gentle mechanical abrasion of that soft layer. An increase in the MRR of up to 100% is identified based on the etching time and the down force. Mechanism-II is based on mechanical abrasion accelerated chemical etching. In this case, the nano-wear experiments are first performed to generate local variation of the residual stress levels, and then followed by chemical etching to investigate the variation of the wear depth and the evolution of surface topography due to etching. It is found that the residual stress caused by the mechanical wear enhances the chemical etching rate, as manifested by the increase of wear depth. The developed understanding from these experiments can be used in future studies to control the rates of chemical dissolution and mechanical abrasion as well as investigating the various process-induced defects.
Modeling of Polishing Regimes in Chemical Mechanical Polishing
Authors: Yeruva Suresh B. , Park Chang-Won , Moudgil Brij M. 
Published: June 2019

AbstractChemical mechanical polishing (CMP) is widely used for local and global planarization of microelectronic devices. It has been demonstrated experimentally in the literature that the polishing performance is a result of the synergistic effect of both the chemicals and the particles involved in CMP. However, the fundamental mechanisms of material removal and the interactions of the chemical and mechanical effects are not well understood. A comprehensive model for CMP was developed taking into account both the chemical and mechanical effects for monodisperse slurries. The chemical aspect is attributed to the chemical modification of the surface layer due to slurry chemistry, whereas the mechanical aspect is introduced by indentation of particles into the modified layer and the substrate depending on the operating conditions. In this study, the model is extended to include the particle size and pad asperity distribution effects. The refined model not only predicts the overall removal rate but also the surface roughness of the polished wafer, which is an important factor in CMP. The predictions of the model show reasonable agreement with the experimental observations.
Investigating the Effects of Diluting Solutions and Trace Metal Contamination on Aggregation Characteristics of Silica-Based ILD CMP Slurries
Authors: DeNardis D. , Choi H. , Kim A. , Moinpour M. , Oehler A. 
Published: June 2019

AbstractOne of the major drawbacks to CMP is the tendency for abrasive particles in slurries to form aggregates, which have the potential to cause defects on wafer surfaces. Therefore, it is crucial to understand the mechanisms by which aggregates are formed so appropriate metrology can be implemented that will identify defect-causing slurries before they are used in the fab. Single particle optical sensing (SPOS) techniques are commonly used to obtain large particle counts (LPC) for slurries. The SPOS technique requires slurry dilution before measuring and the instrument continues to dilute the sample during a measurement. Other techniques that can be used to characterize slurries are particle size distribution by static light scattering (SLS), mean particle size (MPS) by dynamic light scattering (DLS), and zeta potential (ZP) measurements. Like SPOS, all of these techniques require that slurry be diluted prior to measuring and the current method for doing so is with UPW. Diluted slurry demonstrates significantly different ionic strength than the undiluted slurry, and electrolyte concentration has been shown to affect aggregation and electric double layer characteristics of silica particles 2–6. An alternative diluting solution was formulated that simulates the conductivity and pH of the original slurry to mimic the conditions to which particles are actually exposed. It is crucial to identify the metrology that is compatible with high pH solutions and the impact of these solutions on measurements. A second objective of the study is to examine aluminum contamination in slurries. To date, the aluminum content of silica-based CMP slurries and effects on performance have not been well studied. Aluminum is known as a potential contaminant during abrasive and/or slurry manufacturing processes. Known defect free slurries were doped with aluminum and effects on particle aggregation were observed. Specifically, it is of interest to identify the metrology and techniques that may be useful (and those that are not) in monitoring aluminum induced aggregation.
Colloidal Silica based High Selectivity Shallow Trench Isolation (STI) Chemical Mechanical Polishing (CMP) Slurry
Authors: Bu Kyoung-Ho , Moudgil Brij M. 
Published: June 2019

AbstractAmong various properties of chemical mechanical polishing (CMP) slurry, selectivity plays a key role in global planarization of high density and small pattern size shallow trench isolation (STI) process. Lack of adequate selectivity can lead to defects such as dishing and erosion. To improve the selectivity of STI CMP process, CMP characteristics of silica and silicon nitride wafer were investigated using colloidal silica slurry as a function of slurry pH. Sodium dodecyl sulfate (SDS), an anionic surfactant, was added to increase the selectivity of the slurry. As a result, selectivity increased from 3 to 25. It was concluded that selective passivation layer formed on silicon nitride wafer surface at acidic slurry pH range was responsible for the observed selectivity increase. Adsorption characteristics of SDS on silica and silicon nitride were measured as a function of slurry pH and concentration of SDS. As indicated by zeta potential behavior under acidic pH conditions, SDS adsorption on silicon nitride was significantly higher han silica due to the electrostatic forces. Significantly higher SDS coating on silicone nitride seems to have resulted in lubrication layer leading to increased polishing selectivity.
A New Approach Using Artificial Substrates for Growth of High-Quality Precipitate-Free HTS Thin Films, Toward Electronic Device Applications
Authors: Endo K. , Badica P. , Sato H. , Akoh H. 
Published: June 2019

AbstractHigh quality thin films of HTS have been grown by MOCVD on substrates with artificial steps of predefined height and width. The surface of the films grown on the steps having width equal to the ‘double of the migration length' of the atomic species depositing on the substrate is totally free of precipitates: precipitates are gathered at the step edges where the free energy is lowest. The method has several advantages: it is simple, universal (it is independent of the materials, substrates, deposition technique or application) and allows control of precipitates segregates so that the quality and growth conditions of the films are the same as for the films grown on conventional substrates. The method is expected to result in new opportunities for the device fabrication, design and performance. As an example we present successful fabrication of a mesa structure showing intrinsic Josephson effect. We have used thin films of Bi-2212/Bi-2223 superstructure grown on (001) SrTiO3 single crystal substrates with artificial steps of 20 μm.
Pulsed-Laser Deposition of Biaxially Textured YSZ/CeO2 Films on Electrodeposited Ir/Ni-W Tapes for YBCO Superconductors
Authors: Chaudhuri Tapas , Spagnol Priscila , Bhattacharya Raghu , Phok Sovannary 
Published: June 2019

AbstractIridium film is a potential candidate as a buffer layer for yttrium barium copper oxide (YBCO) coated conductors. Pulsed laser deposition (PLD) of biaxially textured CeO2/yttrium stabilized zirconium oxide (YSZ) layers on electrodeposited Ir/Ni-W is reported. Biaxial texturing is obtained by deposition of a YSZ seed layer at 800°C in 10-6 Torr vacuum. X-ray diffraction (XRD) studies of Θ-2Θ and pole figure confirmed in-plane out-of-plane biaxial texturing with Δφ = 6.5° and Δω = 8°. Atomic force microscopy (AFM) revealed a surface with roughness of about 3 nm.
Non-Vacuum Deposition of Buffer Layer for YBCO Superconductor Oxide Films
Authors: Bhattacharya Raghu , Phok Sovannary , Spagnol Priscila , Chaudhuri Tapas 
Published: June 2019

AbstractNonvacuum electrodeposition was used to prepare biaxially textured CeO2 and Sm-doped CeO2 coatings on Ni-W substrates. The samples were characterized by X-ray diffraction (including Θ/2Θ, pole figures, omega scans, and phi scans), atomic force microscopy, and Auger electron spectroscopy (AES). Pole-figure scans show that electrodeposited CeO2 and Sm-doped CeO2 on textured Ni-W (3 at.%) is cube textured. Full-width at half-maximum values of thew scan andf scan of the electrodeposited layers were better than those of the Ni-W base substrates, indicating improved biaxial texturing of the electrodeposited layers. AES analysis of the YBCO/CeO2/YSZ/ED-CeO2/Ni-W revealed that Ni interdiffusion was completely stopped at the first electrodeposited CeO2 layer.
X-ray Photoelectron Spectroscopy Study on E-beam Co-evaporated YBCO Precursors and their Post –deposition Conversion
Authors: Zhang Yifei , Feenstra Ron , Christen David K. 
Published: June 2019

AbstractElectron beam co-evaporation is one of the ex situ techniques being developed for cost-effective fabrication of YBa2Cu3O7-δ (YBCO) coated conductors. To achieve high critical current (Ic) and fast conversion, further understanding is needed of the chemical and microstructural characteristics of the precursors and the phase evolution process towards the epitaxial c-axis oriented YBCO film during the post-deposition conversion annealing. In this study, X-ray photoelectron spectroscopy (XPS) was used to investigate the chemical and compositional profiles of the precursors. Samples quenched from the processing stage were also inspected for identifying the transient elemental chemical states during the YBCO phase formation. XPS survey and detailed spectra were recorded for the surfaces and through various depths. It is suggested that XPS spectra, especially the “Auger parameters” can be used for revealing the conversion reaction. Preliminary results indicate that the copper oxidation state might have important effect on precursor conversion behaviors.
Magnetic Field Dependence of Critical Current Density of PLD RE-Ba-Cu-O (RE=Gd, Sm, Dy, Er, Y) Film on CeO2 Capped IBAD-GZO Layers
Authors: Takahashi Kazuhiro , Konishi Masaya , Ibi Akira , Watanabe Tomonori , Muroga Takemi , Miyata Seiki , Yamada Yutaka , Shiohara Yuh , Kato Takeharu , Hirayama Tsukasa 
Published: June 2019

AbstractWe prepared REBa2Cu3O7- δ (RE= Gd, Sm, Dy, Er, Y) coated conductors on pulsed laser deposition (PLD) -CeO2/ion-beam assisted deposition (IBAD) – Gd2Zr2O7 (GZO) / metal tapes by the PLD method and measured the characteristics in magnetic fields. The GdBa2Cu3O7- σ (Gd-123) films showed superior characteristics than others in magnetic fields and showed weak anisotropy. Critical current density (Jc) value of the Gd-123 film was 3.87MA/cm2 at self-field and 0.19MA/cm2 at 3 T of perpendicular field to the tape surface in liquid nitrogen (77 K). Angular dependences in magnetic fields (Jc -Θ) of the Gd-123 and the SmBa2Cu3O7- σ (Sm-123) were superior to others and peaks in Jc -Θ were found also at 0 degree. The reduction ratios of Jc in Jc -Θ for the Gd-123 film and the Sm-123 film were smaller than other films. Transmission electron microscopy showed that the Gd-123 film had many stacking faults. It may be considered that this stacking faults naturally introduced by the PLD method contribute to improvement of anisotropy of Jc -Θ in the Gd-123 film.
AC Losses in High-TC Superconductors with Finite Thickness
Authors: Benkraouda Maamar , Mustafa M. 
Published: June 2019

AbstractThe structure and dynamics of magnetic vortices in high-Tc superconductors are studied. The model we use is applicable to highly anisotropic high-Tc superconductors, such as Bi and Th compounds, where the Josephson coupling is neglected between the superconducting layers. In this paper, we studied the ac losses occurring in a finite number of superconducting layers due to an applied ac current. It is found that the ac losses increase with the frequency and the amplitude of the applied current. By introducing random pinning centers in the layers, the effect of pinning on the reduction of ac losses is also studied.
Large-area Deposition of Amorphous Silicon Alloys Using a Roll-to-roll Operation
Authors: Guha Subhendu , Yang Jeffrey 
Published: June 2019

AbstractLarge-area deposition of thin-film amorphous silicon alloy triple-junction solar cells on lightweight and flexible stainless steel substrate is described. The proprietary roll-to-roll operation enables continuous depositions of sophisticated multi-layer structures. The deposition methods include sputtering and plasma-enhanced chemical vapor depositions. Spectrumsplitting triple-junction solar cell design, manufacturing processes, and product applications are presented.
Development Of PVDF Thick Film Interdigitated Capacitors For Pressure Measurement On Flexible Melinex Substrates
Authors: Arshak Arous , Arshak Khalil , Morris Deirdre , Korostynska Olga , Jafer Essa 
Published: June 2019

AbstractIn this work, a PVDF thick film paste was deposited onto interdigitated electrodes to form a capacitor. Two different substrates, alumina and Melinex® were used. Capacitors, fabricated on alumina substrates were tested as strain gauges, and showed a high sensitivity with low hysteresis. Capacitors on Melinex® substrates were tested as pressure sensors by adhering them to planar and cylindrical surfaces and subjecting them to pressures up to 300 kPa. Their sensitivity and hysteresis during cycling were examined and compared. It was found that sensors on cylindrical surfaces showed a higher sensitivity, however the hysteresis was also increased. It is thought that this is due to instabilities in the polymer film, accentuated by stretching of the substrate.
Nanocrystalline Silicon Thin Film Transistors on Optically Clear Polymer Foil Substrates
Authors: Kattamis Alex , Cheng I-Chun , Long Ke , Sturm James C. , Wagner Sigurd 
Published: June 2019

AbstractWe have fabricated TFTs of nanocrystalline silicon (nc-Si) at 150°C on clear polymer substrates (coefficients of thermal expansion, α∼45 to 55ppm/K), on Kapton® 200E (α=17ppm/K), and on Corning 1737 glass (α=3ppm//K) for comparison. Because thermally stable polymers, such as Kapton® 200E polyimide, have glass transition temperatures as high as 325°C, they are candidates for direct substitution of display glass. The stresses developed in the substrate and device layers, due to à, are reduced by decreasing the thickness of the active layers, by cutting the layers into islands separated by exposed substrate, and by designing stresses, via plasma conditions, into the SiNx passivating layers. By using these three techniques we have made nc-Si TFTs on high Tg, and high α, clear polymer foils with electron mobilities of up to 18cm2/Vs. When integrated with bottom-emitting organic light emitting diodes, such devices will allow for a 10x reduction in pixel TFT areas, compared to TFTs of amorphous silicon.
High Mobility Pentacene Field Effect Transistors on Plastic
Authors: Mohapatra Siddharth , Grigas Michelle , Wenz Robert , Rotzoll Robert , Olariu Viorel , Shchekin Oleg , Dimmler Klaus , Dodabalapur Ananth 
Published: June 2019

AbstractThis paper reports the electrical properties of thin-film transistors with pentacene active layers used in a bottom contact transistor geometry utilizing solution processed poly-4-vinylphenol (PVP) as the gate dielectric processed on a polyethylene napthalate (PEN) substrate. The transistors sometimes exhibit mobilities in excess of 1cm2/Vs. The effect of various surface treatments of the gate insulator, on the electrical properties of these transistors discussed. The development of photolithographically defined 2νm channel length bottom contact transistors is emphasized as the speed of circuit elements such as the rectifier scale inversely as the square of the channel length of the transistors. Surface cleaning and semiconductor deposition techniques that improve transistor characteristics and reduce hysteresis are evaluated and the variation of the ION/IOFF ratios with the different surface treatments is noted.