bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spectroscopic and Topographic Investigations of Nanoparticle Abrasive retention in Polyurethane CMP Pads for Cu CMP
Authors: Ul-hasan Iftikhar , Geer Robert 
Published: April 2011

ABSTRACTA spectroscopic and topographic investigation of abrasive nanoparticle retention in polyurethane chemical mechanical planarization (CMP) pads has been carried out as a function of ex situ pad conditioning parameters for Cu CMP. X-ray photoelectron spectroscopy (XPS) and scanning electron microscope energy dispersive spectroscopy (SEM-EDS) were utilized to quantitatively characterize the presence of alumina nanoabrasive in the pad following Cu CMP. As expected, conditioning did not modify the overall pad morphology but did increase local asperity roughness with increasing conditioner downforce. As expected, the magnitude of the conditioner downforce reduced the overall average alumina nanoabrasive retention, albeit weakly, as determined via XPS. However, local EDS analysis revealed that increased downforce does significantly reduce nanoabrasive retention at pad asperities. In contrast, increased downforce increased the amount of nanoabrasive present in the polyurethane pad surface pores. Moreover, overall conditioning time was shown to be a more dominant parameter compared to conditioner downforce regarding removal of abrasive particles from both pad asperities and pores.
Newly Developed Abrasive-free Copper CMP Slurry Based on Electrochemical Analysis
Authors: Amanokura Jin , Mabuchi Katsumi , Sakurada Takafumi , Nomura Yutaka , Habiro Masanobu , Akahoshi Haruo 
Published: April 2011

ABSTRACTIn order to reduce microscratches and obtain minimized dishing and erosion, we have developed new abrasive-free Cu CMP slurries. During the development of these slurries, some electrochemical examination was performed. The most effective knowledge was obtained through the analysis using rotary Cu disk electrode under pressure. On the basis of these studies, new abrasive-free Cu CMP slurries with a high removal rate and excellent planarity were designed and developed. The mechanism of reducing dishing and erosion was also discussed.
Experimental Investigation and Numerical Simulation of Pad Stain Formation during Copper CMP
Authors: Lee Hyosang , Zhuang Yun , Borucki Leonard , O'Moore Fergal , Joh Sooyun , Philipossian Ara 
Published: April 2011

ABSTRACTExperiments and simulations were performed to investigate the characteristics of staining on pad surface. Experiments were performed on a table-top axisymmetric polishing system, consisting of a 12-inch non-rotating platen and a 4-inch rotating wafer carrier having the same center axis. Results showed that the stain deposited on each land area was found to be darker in the direction of wafer rotation and in the radial direction, suggesting that staining agent was produced by mechanical action during polishing and was advected downstream by the slurry flow. Generally, staining increased with polishing pressure, wafer rotation rate and polishing time. The simulated slurry velocity showed shear flow on the land areas and wafer-driven circulation in the grooves. Thermal model simulation showed 12 degree temperature rise on the reaction at the surface of wafer.
Contact Model for a Pad Asperity and a Wafer Surface in the Presence of Abrasive Particles for Chemical Mechanical Polishing
Authors: Bozkaya Dincer , Muftu Sinan 
Published: April 2011

ABSTRACTA contact model for a single spherical (pad) asperity and a flat (wafer) surface, with an interface filled with spherical (abrasive) particles is introduced. Finite element method is used to determine the deformation characteristics of a single spherical abrasive indenting a hyper-elastic pad material. The asperities in Greenwood and Tripp (GT) model, which is widely used for the contact of rough spheres, are replaced with the spherical particles. Relations are developed to predict pad-to-particle-to-wafer contact in two distinct regimes, where a) pad and the wafer are separated by the particle; and b) all three bodies come in contact simultaneously. The results of the model show that the abrasive particles in the (pad) asperity-wafer interface causes the contact to be distributed over an area larger than that predicted by the Hertz model, while the maximum contact pressure becomes relatively lower. The fraction of the load carried by pad-to-wafer and pad-to-abrasive-to-wafer varies along the contact interface of the pad asperity and wafer.
Single Asperity Tribochemical Wear of Silicon by Atomic Force Microscopy
Authors: Katsuki Futoshi 
Published: April 2011

ABSTRACTWe report measurements of single asperity wear on oxidized silicon surface in aqueous KOH using atomic force microscopy (AFM), where the single crystal silicon tip was used both to tribologically load and image the surface. AFM was also operating in the lateral (frictional) force mode (LFM) to investigate the pH dependence of kinetic friction between the tip and the SiO2 surface. We found that the Si tip wear amount strongly depended on the solution pH value and was at a maximum at around pH 10. It was also found that the Si removal volume in moles was approximately equal to that of SiO2 irrespective of the solution pH value. This equality implies that the formation of the Si-O-Si bridge between one Si atom of the tip and one SiO2 molecule of the specimen at the wear interface, followed by the oxidation of the Si surface, finally the bond rupture by the tip movement, the dimeric silica (OH) 3Si-O-Si(OH) 3, including the Si-O-Si bridge is dissolved in the KOH solution. It was also found the frictional force is highly sensitive to the pH values of the solution and peaked at around pH 10. These results indicate that the interfacial reaction would be affected by the frictional force between the Si tip and the SiO2 surface, due to an increased liquid temperature and a compressive stress in Si and SiO2 networks. Strong influence is observed by the pH of the ambient solution confirming the important role of the OH- in the wear mechanism. We present a microscopic removal mechanism which is determined by an interplay of the diffusion of water in Si and SiO2.
Towards a Quantitative Description of Pattern-dependent Planarization with Ceria Slurries
Authors: Rzehak Roland , Vogel Thomas 
Published: April 2011

ABSTRACTSlurries with ceria abrasives are nowadays widely used for high-end applications like STI. Concerning the pattern dependence of planarization, such slurries exhibit a much more complex behavior than conventional silica-based slurries. The situation is complicated by the fact that depending on often unknown factors like the manufacture of the ceria abrasives and additionally present additives the observed phenomena are also quite diverse. As a consequence, quantitative models are lacking and predictions of post CMP topography that could be used e.g. to derive design rules or optimize dummy fill are not available.We here present detailed experimental results on one specific slurry system with ceria abrasives that behaves very different from conventional silica-based slurries. Possible causes for this peculiar behavior are discussed to the extent that a statement about their relevance can be made.
Ultra Thin Cu film Fabrication by Supercritical Fluid Deposition for ULSI Metallization
Authors: Momose Takeshi , Sugiyama Masakazu , Shimogaki Yukihiro 
Published: April 2011

AbstractInitial nucleation and succeeding coalescence in supercritical fluid deposition (SCFD) of Cu was studied in situ by using our devised monitoring technique, i.e. surface reflectivity measurement of visible white light. Fabrication of 10nm-thick smooth and continuous Cu film required by ULSI metallization, was succeeded. Complete filling without any seems and voids into various via patterns of 50 - 200 nm in diameter and 1 μm in depth was also achieved, which was revealed through angled polishing of patterned substrate.
Development of Simple Electrolytes for the Electrodeposition of Pb-Free, Sn-Based Alloy Solder Films
Authors: Han Chunfen , Liu Qi , Ivey Douglas G. 
Published: April 2011

AbstractA simple, cyanide-free, slightly acidic, chloride-based solution has been developed for the electrodeposition of Sn-0.7wt%Cu solder films. The solution contains only one additive (tri-ammonium citrate) other than the metal salts and is stable for more than 36 days. The optimum citrate concentration is 0.30 mol/L for 0.22 mol/L of SnCl2•2H2O. The addition of 0.003 mol/L of CuCl2•2H2O to this solution can produce near eutectic (Sn-0.7 wt% Cu) deposits, on Au, Ni or Cu substrates, at current densities of 10-12.5 mA/cm2. Plating rates are in the 20-27.5 μm/hr range at room temperature. Copper is evenly distributed (~0.7wt%Cu) through most of the thickness, with slightly higher Cu levels at the solder/Ni interface. After solder reflow at 260°C, two phases are present, Sn plus either Cu6Sn5 for Cu substrates or (Cu,Ni)6Sn5 for Ni substrates.
Hydrogen-induced Nitrogen Passivation in Dilute Nitrides: A Novel Approach to Defect Engineering
Authors: Trotta Rinaldo , Polimeni Antonio , Felici Marco , Pettinari Giorgio , Capizzi Mario , Frova Andrea , Salviati Giancarlo , Lazzarini Laura , Armani Nicola , Mariucci Luigi , Bais Giorgio , Martelli Faustino , Rubini Silvia 
Published: April 2011

AbstractThe capability of hydrogen to passivate nitrogen in dilute nitrides is exploited to in-plane engineer the electronic properties of Ga(AsN)/GaAs heterostructures. Two methods are presented: i) by deposition of hydrogen-opaque metallic masks on Ga(AsN) and subsequent hydrogen irradiation, we artificially create zones of the crystal having the band gap of untreated Ga(AsN) surrounded by GaAs-like barriers; ii) by employing an intense (∼100 nA) and narrow (∼100 nm) beam of electrons, we dissociate the complexes formed by N and H in a spatially delimited part of a hydrogenated Ga(AsN) sample. As a consequence, in the spatial regions irradiated by the electron beam, hydrogenated Ga(AsN) recovers the smaller energy gap it had before hydrogen implantation.
Formation of Hydrogen Related Defects and Nano-Voids in Plasma Hydrogenated ZnO
Authors: Job Reinhart 
Published: April 2011

AbstractUsing μ-Raman spectroscopy (μRS) and cathodoluminescence (CL) analyses, the impact of hydrogen plasma treatments on sintered zinc oxide (ZnO) samples was studied. 1 hour H-plasma treatments (150 W, 13.56 MHz) were applied at substrate temperatures between 250 °C and 500 °C. μRS and CL analyses show that plasma hydrogenation causes significant defects in ZnO samples; i) non-specified defect species are established with a maximal density upon H-plasma exposure at 350 °C substrate temperature, and ii) the formation of oxygen vacancies (VO) can be traced. Moreover, μRS reveals vibration modes of H2 molecules trapped in nano-voids. The experimental results indicate that those nano-voids are created by a coalescence of the VO defects.
The Dynamic Ultrasound Influence on the Diffusion and Drift of the Charge Carriers in Silicon p-n Structures
Authors: Burbelo Roman M. , Olikh Oleg Y. , Hinders Mark K. 
Published: April 2011

AbstractNowadays much attention is given to the ultrasound influence on electrophysical properties and defective structure of semiconductors and semiconductor structures [1,2]. In particular, a big interest is caused by the processes which take place in the material under non-equilibrium conditions, caused by the acoustic vibration [2]. This paper is devoted to the study of the ultrasonic waves dynamic influence (in situ) on the processes of the charge transport in a silicon solar sell.The silicon structures with p-n-transition received by phosphorus ions implantation in a surface layer of Si:B plate have been chosen as the research objects. Transition is located at 0,5 microns depth from surface, n-layer electron concentration is 1019 cm−3, hole concentration is 1.3×1015 cm−3. The specified structures I-V characteristics are measured under ultrasonic fluctuations excitation conditions. The researches were carried out both without external illumination as well as under external illumination. In the latter case, additional carriers photogeneration occurred both at the p-n-transition region and at the p-area depth. Longitudinal acoustic waves were excited in structures with help of LiNbO3 transducer; the ultrasound frequency is 4.1 and 13.6 MHz; the acoustic power is up to 3 W/cm2.It is revealed, that the changes of diffusion parameters take place at the non-equilibrium conditions caused by ultrasonic lading. These changes are shown in photocurrent rising. Photocurrent increase reached up to 15 %, which corresponds to 2 times diffusion length increasing approximately. Also the essential (up to 40 %) acoustostimulated decreasing of the p-n-transition saturation current is revealed. The characteristic time of the observable effects is level with tens minutes. It is established, that dependence of the dynamic changes on ultrasound power is nonlinear. It is shown, that efficiency of an acoustostimulated influences raises with an ultrasound frequency.The analysis has shown that observable effects are connected with non-equilibrium processes of defects ionization and reorientation at an acoustic field. It specifies an opportunity of a dynamic management of a charge carriers distribution processes in semiconductor structures by ultrasonic waves.
Deuterium Out-Diffusion Kinetics in Magnesium-Doped GaN
Authors: Chevallier Jacques , Jomard François , Nickel Norbert H. , de Mierry Philippe , Chenot Sébastien , Cordier Yvon , di Forte-Poisson Marie-Antoinette , Delage Sylvain 
Published: April 2011

AbstractA series of isothermal annealing experiments have been performed in the range 790–920°C under N2 flow in order to study the deuterium out-diffusion kinetics of Mg-doped GaN grown on sapphire under deuterated ammonia. The deuterium concentration was measured by SIMS analysis before and after each annealing step. The kinetics closely follow a first-order law. The activation energy related to the deuterium out-diffusion process is 3.1 eV. In addition, deuterium effusion measurements were performed measuring the molecular HD flux while the specimens were annealed in ultra high vacuum with a linear heating rate. In contrast to SIMS, this method detects the species that migrated out of the sample. Effusion peaks of the HD flux at 360 and 490°C are attributed to the fragmentation of adsorbed CHxDy complexes. The molecular HD flux starts increasing at 800°C which is the onset of the GaN decomposition and has its maximum at 920°C. This HD flux is accompanied by the desorption of H and D containing radicals and molecules desorbing above 900°C.
Modeling of Cu Surface Precipitation and Out-Diffusion from Silicon Wafers
Authors: Guo Hsiu-Wu , Dunham Scott T. 
Published: April 2011

AbstractCopper is one of the most concerned contaminants for silicon process, due to its detrimental effects on device performance if present in active regions. Gettering of Cu by changing the surface conditions at the wafer surface is commonly used. Acceleration of Cu out-diffusion and surface precipitation was observed with changes of the surface potential, which could be altered by both existing Cu precipitates and organics at the surface. In this work, physically based models are developed to describe the Cu evolution at the wafer surface including the dependence of surface potential. These models are verified by comparison to the experiment measurements from Ohkubo et al. [Jpn. J. Appl. Phys. 1 44, 3793 (2005)].
Au/n-ZnO Rectifying Contacts Fabricated with Hydrogen Peroxide Pre-treatment
Authors: Gu Qilin , Ling Chi-Chung , Cheung Chor-Keung , Luo Jiaming , Chen Xudong , Djurisic Aleksandra , Brauer Gerhard , Anwand Wolfgang , Skorupa Wolfgang , Reuther Helfried , Ong Hock-Chun 
Published: April 2011

AbstractAu contacts were fabricated on pressurized melted grown n-type ZnO single crystal samples pre-treated with boiling organic solvent and hydrogen peroxide. Contacts fabricated without any pre-treatment and with boiling organic solvent pre-treatment were found to have ohmic behavior. For the samples pre-treated with hydrogen peroxide, the Au contacts were found to have rectifying property. Systematic investigation was performed to study the dependence of the Schottky barrier height and the reverse bias leakage current on the temperature and the duration of the pre-treatment. Positron annihilation spectroscopy (PAS), X-ray photoemission (XPS) and scanning electron microscope (SEM) were also used to understand how the vacancy type defect, contamination and surface morphology would influence the electrical property of the fabricated contacts.
Interaction between Recombination Enhanced Dislocation Glide Process Activated Basal Stacking Faults and Threading Dislocations in 4H-Silicon Carbide Epitaxial Layers
Authors: Chen Yi , Dudley Michael , Liu Kendrick X , Stahlbush Robert E 
Published: April 2011

AbstractElectron-hole recombination enhanced glide of Shockley partial dislocations bounding expanding stacking faults and their interactions with threading dislocations in 4H silicon carbide epitaxial layers have been studied using synchrotron white beam X-ray topography and in situ electroluminescence. The mobile silicon-core Shockley partial dislocations bounding the stacking faults are able to cut through threading edge dislocations leaving no trailing dislocation segments in their wake. However, when the Shockley partial dislocations interact with threading screw dislocations, trailing 30o partial dislocation dipoles are initially deposited in their wake due to the pinning effect of the threading screw dislocations. These dipoles spontaneously snap into their screw orientation, regardless the normally immobile carbon-core Shockley partial dislocation components in the dipoles. They subsequently cross slip and annihilate, leaving a prismatic stacking fault in (2-1-10) plane with the displacement vector 1/3[01-10].
XPS and STM Studies on Initial Oxidation of Si(110)-16x2
Authors: Suemitsu Maki , Togashi Hideaki , Kato Atsushi , Takahashi Yuya , Konno Atsushi , Yamamoto Yoshihisa , Teraoka Yuden , Yoshigoe Akitaka , Asaoka Hidehito 
Published: April 2011

AbstractThe initial oxidation of Si(110)-16×2 clean surface has been investigated by using real-time synchrotron-radiation photoemission spectroscopy and scanning tunneling microscopy. The Si(110) initial oxidation is characterized by its unique rapid oxidation right after the introduction of oxygen molecules, which is most likely attributed to the preferential reactions at the pentagon pairs of the 16×2 reconstruction.
Structural and Electronic Properties of Oxygen Vacancies in Monoclinic HfO2
Authors: Broqvist Peter , Pasquarello Alfredo 
Published: April 2011

AbstractWe study structural and electronic properties of the oxygen vacancy in monoclinic HfO2 for five different charge states. We use a hybrid density functional to accurately reproduce the experimental band gap. To compare with measured defect levels, we determine total-energy differences appropriate to the considered experiments. Our results show that the oxygen vacancy can consistently account for the defect levels observed in optical absorption, direct electron injection, and trap-assisted conduction experiments.
Al-Oxynitride Buffer Layer Facilities for PrOX/SiC Interfaces
Authors: Henkel Karsten , Sohal Rakesh , Schwiertz Carola , Burkov Yevgen , Torche Mohamed , Schmeißer Dieter 
Published: April 2011

AbstractWe investigate the dielectric properties of Praseodymium based oxides and silicates by preparing MIS structures consisting of a metal layer (M), PrOX (praseodymium oxide) as a high-k insulating layer (I), and silicon (Si) or silicon carbide (SiC) as semiconductor substrates (S).The use of a buffer layer between PrOX and SiC is necessary as we found destructive interactions like silicate and graphite formation between these materials. Based on a higher permittivity value than SiO2 and a good lattice matching in conjunction with nearly the same thermal expansion coefficient to SiC, we focus on aluminum oxynitride (AlON) as a suitable buffer layer for this high-k/wide-bandgap system. We report on results achieved by Synchrotron Radiation Photoemission Spectroscopy (SRPES) and by electrical measurements.In our spectroscopic investigations we found a stable AlON/3C-SiC interface as well as no elemental carbon and silicate contributions in the core levels after thin PrOX deposition and annealing up to 900°C.In electrical characterizations of PrOX/AlON stacks on silicon we already found a strong improvement in the leakage current down to values of 10-7 A/cm2 at an CET of 4nm. We observed an interface state density in the range of 5x1011-1x1012/eVcm2 and 1-5x1012/eVcm2 on Si and SiC, respectively.
Investigation of Local Coordination and Electronic Structure of Dielectric Thin Films from Theoretical Energy-Loss Spectra
Authors: Singh Manish K. , Rosado Javier , Katamreddy Rajesh , Deshpande Anand , Takoudis Christos G. 
Published: April 2011

AbstractQuantum mechanical simulations were performed to calculate the valence electron energy-loss spectra (VEELS) for hafnium oxide, hafnium silicate, silicon oxide and silicon systems using the full potential Linearized Augmented Plane Wave (LAPW) formalism within the Density Functional Theory (DFT) framework. The needed energy-loss function (ELF) was derived from the calculation of the complex dielectric tensor within the random phase approximation (RPA). The calculated spectra were compared with experimental scanning transmission electron microscopy (STEM)/EELS of atomic layer deposited (ALD) HfO2 on Si(100) to evaluate their use as a “fingerprint” method that can be used to distinguish among various polymorphs of HfO2 thin films and relate the fine structure to the electronic structure and local bonding environment. Calculated low-loss spectra are found to be in satisfactory agreement with experimental data. Also, the combination of such theoretical calculations and experimental data could be of key importance in our understanding of fundamental issues of these systems. Compared to energy-loss near edge structure (ELNES) or core energy-loss spectra, the ELF calculated for low-loss spectra is computationally less expensive and can prove useful for prompt analysis.
X-Ray Reflectometry Determination of Structural Information from Atomic Layer Deposition Nanometer-scale Hafnium Oxide Thin Films
Authors: Windover Donald , Gil D. L. , Cline J. P. , Henins A , Armstrong N. , Hung P. Y. , Song S. C. , Jammy R. , Diebold A. 
Published: April 2011

AbstractThis work demonstrates the application of a Markov Chain Monte Carlo (MCMC) approach to modeling X-ray reflectometry (XRR) data taken from a sub 10 nm Hafnium oxide film. We present here a comparison of two structural models for a 6 nm HfxOy atomic layer deposition (ALD) film on Si. Using the MCMC method and two distinct structural models, we show evidence of a thin interface between the HfxOy and Si layers with a density much higher than native SiO2. Results from genetic algorithm XRR analysis and thickness measurements using cross-sectional transmission electron microscopy are included for comparison. We also demonstrate that our interpretation of HfxOy thickness differs between the two structural models (i.e., total film thicknesses may be partially additive within each model).