bluuebunny/crossref_metadata_2025_split huggingface dataset:
Formation of deuterium-related shallow donors in boron-doped diamond.
Authors: Chevallier Jacques , Teukam Zéphirin , Saguy Cécile , Kalish Rafi , Cytermann Catherine , Bailly Francis , Jomard Frančois , Kociniewski Thierry , Ballutaud Dominique , Barbé Michel , Butler James E. , Baron CÉline , Deneuville Alain 
Published: April 2011

ABSTRACTIt is well known that diffusion of deuterium in boron-doped diamond results in the passivation of boron acceptors with the formation of (B,D) complexes. In this work, we show that deuteration of boron-doped diamond can induce a p-type to n-type conversion under certain conditions. The n-type conductivity is governed by the ionization of shallow donors with a ionization energy of 0.34 eV. This is well below the lowest ionization energy of donors found up to now in diamond (0.6 eV for phosphorus donors). The electrical conductivity and the electron mobility can be as high as 6 S/cm and 430 cm2/Vs at 300 K. The reversibility of the effect under thermal annealing and the necessity of excess deuterium to trigger the n-type conductivity suggest that deuterium is involved in the formation of the shallow donors. The present status concerning the understanding of their origin is discussed. In addition, we have found that, contrary to previous conclusions, deuterium can diffuse in type Ib diamond. The conditions where this diffusion is observed are presented.
Pressure Dependence of Aluminum Doping in SiC Vapor Phase Epitaxy
Authors: Schöner Adolf , Gustafsson Malin 
Published: April 2011

AbstractThe dependence of the aluminum incorporation on the total pressure in a hot wall vapor phase reactor for SiC homoepitaxial growth has been investigated. It was found that in the doping concentration range from 1·1017 cm−3 to 1·1019 cm−3 the incorporated aluminum concentration varies by the factor 3 to 4, when the reactor pressure is changed from 150 mbar to 250 mbar. Lower reactor pressure gives lower aluminum concentration. Periodically changing reactor pressure results in aluminum concentration periodically changing with depth in the epilayer. All results were measured electrically by capacitance-voltage measurements on nickel Schottky contacts. Additional experiments have been performed for n-type nitrogen doped SiC epilayers for comparison. The nitrogen doping concentration was found to be independent of the reactor pressure within the accuracy of the applied C-V measurements and the doping profile analysis method.
4H-SiC MIS structures using oxidized Ta2Si as high-k dielectric
Authors: Pérez-Tomás A. , Godignon P. , Mestres N. , Tournier D. , Montserrat J. , Millán J. 
Published: April 2011

AbstractTa2Si silicide has been deposited by sputtering and thermally oxidized on 4H-SiC and Si substrates. A mixture of SiO2 and Ta2O5 insulator films has been obtained after oxidation in dry O2. Among the high-k dielectrics, tantalum pentoxide (Ta2O5) could be a valuable alternative due to its high dielectric constant. Atomic force microscopy (AFM), C-V measurements along with x-ray diffraction analysis have been carried out in order to study the feasibility of this material as gate dielectric for 4H-SiC MOS devices. Electrical characteristics of deposited and oxidized Ta2Si on 4H-SiC and Si samples have been obtained and compared. At the range of oxidation temperatures considered (850°C-950°C), the influence of diffusion processes between the Si substrate and Ta2Si layer during oxidation strongly influences the dielectric properties of the resulting insulator layer on Si substrates.
Aluminum-Ion Implantation into 4H-SiC (11-20) and (0001)
Authors: Negoro Y. , Kimoto T. , Matsunami H. 
Published: April 2011

AbstractHigh-dose aluminum-ion (Al+) implantation into 4H-SiC (11-20) and (0001) has been investigated. Surface morphologies of implanted (0001) samples were improved by annealing with a graphite cap. Implant-dose dependence and annealing-time dependence of electrical properties are examined by Hall-effect measurements. A low sheet resistance of 2.3 kΩ/sq. was obtained in (0001) by high-dose Al+ implantation at 500 °C with a dose of 3.0 × 1016 cm−2 and high-temperature annealing at 1800 °C for a short time of 1 min. In the case of (11-20), even room-temperature implantation brought a low sheet resistance below 2 kΩ/sq. after annealing at 1800 °C.
Characterization and Comparison of 4H-SiC(1120) and 4H-SiC(0001) 8° Off-Axis Substrates and Homoepitaxial Films
Authors: Bishop S.M. , Preble E.A. , Hallin C. , Henry A. , Sarney W. , Chang H.-R. , Storasta L. , Jacobson H. , Reitmeier Z.J. , Wagner B.P. , Janzén E. , Davis R.F. 
Published: April 2011

AbstractHomoepitaxial films of 4H-SiC(1120) and 8° off-axis 4H-SiC(0001) have been grown and characterized. The number of domains and the range of full-width half-maxima values of the x-ray rocking curves of the [1120]-oriented wafers were smaller than the analogous values acquired from the (0001) materials. Hydrogen etching of the former surface for 5 and 30 minutes reduced the RMS roughness from 0.52 nm to 0.48 nm and to 0.28 nm, respectively; the RMS roughness for a 30 μm (1120) film was 0.52 nm. Micropipes in the substrates did not thread beyond the film-substrate interface. The separation distance between stacking faults was determined to be 10 μm by transmission electron microscopy. Hall mobilities and carrier concentrations of 12,200 cm2/Vs and 3.1×1014 cm−3 and 800 cm2/Vs and 7.4×1014 cm−3 were measured at 100°K and 300°K, respectively. Photoluminescence indicated high purity. 4H-SiC(1120) PiN devices exhibited average blocking voltages to 1344 V and a minimum average forward voltage drop of 3.94 V.
Characterization of Defects Generated During Boron Diffusion in SiC
Authors: Lin Xue-feng , Smith Stephen P. , Ma Xianyun , Wang Liang , Sudarshan Tangali S. , Zhang Qingchun , Chang Hsueh-Rong 
Published: April 2011

AbstractThe defects associated with the implantation and diffusion of boron in silicon carbide have been studied using secondary ion mass spectrometry (SIMS) and photoluminescence (PL) imaging and spectroscopy. An n-type epitaxial SiC (1000) substrate was implanted with 2×1014 atoms/cm2 B and annealed to 1700°C. PL data was acquired before and after annealing, and following removal of various thicknesses of the sample by mechanical polishing. Thermal annealing generated a B diffusion profile measured by SIMS to extend to about 3 microns depth. After removing the diffused B layer, a PL spectral feature at 415nm disappeared, which is consistent with its previous identification as arising from donor-acceptor pairs (DAP). The D1 spectral features survived polishing, supporting previous suggestions that these features are intrinsic defects due to the di-interstitial (Ic-Ic or Isi-Isi) or di-vacancy (Vc-Vc or Vsi-Vsi) defects.
Mechanisms of Stacking Fault Growth in SiC PiN Diodes
Authors: Stahlbush R. E. , Twigg M. E. , Sumakeris J. J. , Irvine K. G. , Losee P. A. 
Published: April 2011

AbstractThe early development of stacking faults in SiC PiN diodes fabricated on 8° off c-axis 4H wafers has been studied. The 150μm drift region and p-n junction were epitaxially grown. The initial evolution of the stacking faults was examined by low injection electroluminescence using current-time product steps as low as 0.05 coul/cm2. The properties of the dislocations present before electrical stressing were determined based on previously observed differences of Si-core and C-core partial dislocations and the patterns of stacking fault expansion. The initial stacking fault expansion often forms a chain of equilateral triangles and at higher currents and/or longer times these triangles coalesce. All of the faulting examined in this paper originated between 10 and 40 μm below the SiC surface. The expansion rate of the bounding partial dislocations is very sensitive to the partials' line directions, their core types and the density of kinks. From these patterns it is concluded that the stacking faults originate from edge-like basal plane dislocations that have Burgers vectors either parallel or anti-parallel to the off-cut direction. Evidence for dislocation conversions between basal-plane and threading throughout the epitaxial drift region is also presented.
Challenges and Rewards of Low-Abrasive Copper CMP: Evaluation and Integration for Single-Damascene Cu/Low-k Interconnects for the 90nm Node
Authors: Borst Christopher L. , Smith Stanley M. , Eissa Mona 
Published: April 2011

AbstractLow-abrasive content slurries for copper (Cu) chemical-mechanical planarization (CMP) have been developed to achieve removal rate and removal uniformity comparable to conventional slurries. They can improve post-CMP defectivity, improve topography and allow operation at lower polish pressures that are more compatible with the low-dielectric constant (low-k) materials required for current and future high-performance interconnects. Integration of these slurries into a yielding product with 9-level Cu/low-k metallization requires fundamental learning and process characterization. This paper discusses the some of the challenges encountered during development, integration, and qualification of a low-abrasive Cu CMP process for Texas Instruments (TI) Incorporated's 90 nm technology node with copper/organosilicate interconnect. As abrasive content is reduced, the slurry chemistry must play a larger role in CMP removal. A more aggressive reactive chemical formulation requires an effective inhibitive component to keep Cu static etch rate low. As a result, wafer-scale process and consumable interactions, die-scale planarization efficiency, and feature-scale removal rates each become more sensitive to process changes. Pressure and temperature have larger effects on removal rate/profile than conventional slurries, and complete clearing of Cu puddled over underlying topography becomes more difficult. Successful integration of these slurries, however, can achieve excellent results in dishing and erosion topography, Cu thickness uniformity, and Cu loss in small features such as vias and landing pads. Low-abrasive content solutions are also more stable and easy to handle in slurry distribution vessels and lines, have lower scratch and residue defectivity, and have greatly extended margin for overpolish. As lowabrasive content Cu slurry options continue to evolve to become manufacturable solutions, their benefits far outweigh the costs and challenges encountered in their successful integration.
Adaptive Piezo-Controlled Carrier for CMP Processing
Authors: Weber Christian-Toralf , Weiser Jürgen , Zeidler Dieter , Bartha Johann W. 
Published: April 2011

AbstractThe IGAM engineering company for applied mechanics Ltd. developed an active piezocontrolled carrier for CMP. It uses several, by means of piezo-stacks individually controllable rings. The carrier is optimized regarding its stiffness and reliability by means of threedimensional finite element calculations. The high stiffness and positioning accuracy of the system allows the exact control of different surface profiles and thus the purposeful attitude of the pressure and removal profile independently of the polishing pressure. Tests show a very homogeneous pressure and removal distribution in the circumference of the wafer. The concept is transferable on further wafer diameters, whereby the width of the individual zones can be widely adapted to the requirements of the desired removal profile. Results of finite element analysis for a 12” prototype are available. The variable concept allows to upgrade existing CMP machines. The aims of current developments are the integration of in-situ-pressure determination to control the process, wireless transfer of energy and data to the carrier and the control of the local removal profile.
Measurement of Electroplated Copper Overburden for Advanced Process Development and Control
Authors: Tower Joshua , Maznev Alexei , Gostein Michael , Otsubo Koichi 
Published: April 2011

AbstractWe used a non-contact metrology system based on laser-induced surface acoustic waves to evaluate the thickness uniformity of electroplated copper. Several wafers were prepared using different plating conditions that affect the copper overburden thickness and uniformity. Measurements of overburden were made on a variety of pattern features including trench arrays of several pattern densities, solid bond pads, and the surrounding field area. In general, the overburden was found to be thicker above the arrays of narrow linewidth, as compared to the surrounding field. However, the magnitude of this “mounding” effect is dependent on the plating process, pattern density, and position on the wafer. For example, as the accelerator in the plating solution increases, the mounding on a 50% density line array varies from zero to 5000 Angstroms. Under all plating conditions used, the mounding was found to be progressively higher as the pattern density of the array increases (in the range of 20% to 50% copper). The solid pads were found to have conformal filling, in all cases. It was also found that the overburden in the field area is reduced as the adjacent mounding increases, presumably because the reactant in the plating bath becomes depleted in the vicinity of the high overburden regions above the arrays.
Effect of Abrasive in Cu-CMP Slurry on Global Planarization
Authors: Nomura Yutaka , Ono Hiroshi , Terazaki Hiroki , Kamigata Yasuo , Yoshida Masato 
Published: April 2011

AbstractWe investigated the mechanical effect of an abrasive in an abrasive-free-like (AFL) slurry using CMP evaluation and ζ potential evaluation. The amount of abrasive strongly influenced CMP performance. We found out the optimum amount of abrasive for optimal CMP performance. The ζ potential of the abrasive was positive, and those of the Cu and barrier metal were negative. We discussed a planarization model of the AFL slurry in detail based on the ζ potential results obtained.
The Application of Chemical Mechanical Polishing for Nickel Used in MEMS Devices
Authors: Vijayakumar Arun , Du Tianbao , Sundaram Kalpathy B. , Desai Vimal 
Published: April 2011

AbstractChemical mechanical planarization (CMP) has found extensive application in the fabrication of micro-electro-mechanical systems (MEMS). Nickel and Nickel based alloys are known to possess favorable properties that make them promising candidates to realize movable structures for MEMS applications. The development of CMP slurry chemistry for Ni that provides good CMP performance is the key in enabling CMP technology for Nickel based MEMS device fabrication. Unfortunately, very little work has been reported in terms of the electrochemical interaction of Ni with various CMP slurry constituents such as oxidizers, complexants and inhibitors. In this study, CMP of nickel was performed using H2O2 as oxidizer and alumina particles as abrasives. Electrochemical techniques were used to investigate the dissolution/passivation behavior of high-purity Ni under static and dynamic conditions in slurries at pH 4 with the addition of oxidizer, complexing agent and nickel salt. The affected surface layers of the statically etched Ni-disc were investigated using X-ray photoelectron spectroscopy (XPS). The Ni removal rate increased with the addition of oxidizer and further increased with the addition of complexing agent and nickel salt. The electrochemical results indicate that the surface chemistry and electrochemical characteristic of Ni play an important role in controlling the polishing behavior.
Planarization Issues in Wafer-Level Three-Dimensional (3D) Integration
Authors: Lu J.-Q. , Rajagopalan G. , Gupta M. , Cale T.S. , Gutmann R.J. 
Published: April 2011

AbstractMonolithic wafer-level three-dimensional (3D) ICs based upon bonding of processed wafers and die-to-wafer 3D ICs based upon bonding die to a host wafer require additional planarization considerations compared to conventional planar ICs and wafer-scale packaging. Various planarization issues are described, focusing on the more stringent technology requirements of monolithic wafer-level 3D ICs. The specific 3D IC technology approach considered here consists of wafer bonding with dielectric adhesives, a three-step thinning process of grinding, polishing and etching, and an inter-wafer interconnect process using copper damascene patterning. The use of a bonding adhesive to relax pre-bonding wafer planarization requirements is a key to process compatibility with standard IC processes. Minimizing edge chipping during wafer thinning requires understanding of the relationships between wafer bonding, thinning and pre-bonding IC processes. The advantage of silicon-on-insulator technology in alleviating planarization issues with wafer thinning for 3D ICs is described.
Material Removal Mechanisms of Oxide and Nitride CMP with Ceria and Silica-Based Slurries - Analysis of Slurry Particles Pre- and Post-Dielectric CMP
Authors: Chandrasekaran Naga 
Published: April 2011

AbstractThe effect of CMP process parameters (pressure and pad hardness) on the ceria and silica abrasive particle-size distribution (PSD), morphology, and surface composition when polishing oxide and nitride surfaces was investigated in detail. The PSD was observed to shift post-CMP, with ceria and silica exhibiting a decrease and increase, respectively, in the number of particles towards the tail end of the distribution. The shift in ceria PSD was observed to increase as pad hardness increased. An increase in polish pressure and work surface hardness resulted in an equivalent shift in the PSD when polished on a soft pad. The inclusion of an additive reduced the oxide removal rate, and the abrasive particles exhibited the presence of a thin organic coating on the surface. The difference in material removal mechanisms and selectivity when polishing oxide and nitride with ceria and silica-based slurries was also investigated in detail.
Compact All Pass Transmission Filter using Photonic Crystal Slabs
Authors: Suh Wonjoo , Fan Shanhui 
Published: April 2011

AbstractWe show that both the coupled photonic crystal slab and the single photonic crystal slab structure can function as an optical all-pass transmission filter for normally incident light. The filter function is synthesized by designing the spectral properties of guided resonance in the slab. We expect this compact device to be useful for optical communication systems.
Optical Study of SiO2/nanocrystalline-Si Multilayers Using Ellipsometry
Authors: Lee Kang-Joo , Kang Tae-Dong , Lee Hosun , Hong Seung Hui , Choi Suk-Ho , Kim Kyung Joong , Moon Dae Won 
Published: April 2011

AbstractUsing variable-angle spectroscopic ellipsometry, we measure the pseudo-dielectric functions of as-deposited and annealed SiO2/SiOxmultilayers (MLs). The SiO2(2nm)/SiOx(2nm) MLs have been prepared under various deposition temperature by ion beam sputtering. The annealing at temperatures ≥ 1100°C leads to the formation of Si nanocrystals (nc-Si) in the SiOxlayer of MLs. Transmission electron microscopy images clearly demonstrate the existence of nc-Si. We assume a Tauc-Lorentzian lineshape for the dielectric function of nc-Si, and use an effective medium approximation for SiO2/nc-Si MLs as a mixture of nc-Si and SiO2. We successfully estimate the dielectric function of nc-Si and its volume fraction. We find that the volume fraction of nc-Si decreases after annealing, with increasing x in as-deposited SiOxlayer. This result is compared to expected nc-Si volume fraction, which was estimated from stoichiometry of SiOx.
Solvothermal Synthesis and Characterization of Zn(NH3)CO3 Single Crystal
Authors: Wen Fushan , Chen Jiesheng , Kim Jin Hyeok , Kim Taeun , Li Wenlian 
Published: April 2011

AbstractA new 3-dimensional zinc carbonate Zn(NH3)CO3 has been synthesized from a glycol system with urea and zinc acetate as raw materials. The crystal structure and photoluminescent properties have been investigated using X-ray diffraction, smart CCD and FL. The compound had an orthorhombic system with space group of Pna21 with M = 142.41, a = 9.1449(18) Å, b = 7.5963(15) Å, c = 5.4982(11) Å, V = 381.95(13) Å3, Z = 4, R = 0.0285 and RW = 0.0745. The NH3 and CO32- were connected through the Zn-N bond and Zn-O bond in the symmetric unit. Photoluminescent property was observed in the compound at room temperature and the exited and emission peaks were located at about 350 nm and 426 nm, respectively.
Growth and patterning of strontium-titanate-oxide thin films for optical devices applications
Authors: Gaidi M. , Stafford L. , Chaker M. , Margot J. , Kulishov M. 
Published: April 2011

AbstractStrontium-titanate-oxide (STO) thin films have been deposited on silicon substrates by means of a reactive pulsed-laser-deposition technique. The influence of the oxygen deposition pressure on the microstructural properties of the films has been investigated by means of various characterization techniques. It was found that the crystalline quality of the film significantly deteriorates as the oxygen pressure increases. This is accompanied by an increase of the film microporosity. The microstructure of the film is found to directly impact the optical quality of the films. In particular, due to the higher density and crystallinity of the films deposited at lower oxygen pressure, films characterized by lower optical losses can be achieved in such conditions. These films have been used in the context of the development of optical waveguides. For this purpose, patterning of the STO films was investigated using sputter-etching with a high-density argon plasma operated in the very low pressure regime. Highly anisotropic features have been produced with high etch rate and good selectivity over resist. Preliminary results indicate the STO films can be successfully incorporated in functional waveguides.
Active Photonic Crystal Devices in Self-Assembled Electro-Optic Polymeric Materials
Authors: Li J. , Neyman P. J. , Vercellino M. , Heflin J. R. , Duncan R. , Evoy S. 
Published: April 2011

AbstractPhotonic crystals (PC) offer novel approaches for integrated photonics by allowing the manipulation of light based on the photonic bandgap effect rather than internal-reflection mechanisms employed in traditional devices. Electro-optic polymers represent interesting possibilities for the development of devices leveraging control over the phase of a confined propagating wave. We here report on the development of such active photonic crystal technology in ionically self-assembled monolayers. The simulation of active photonic devices such as Mach-Zehnder interferometers and wavelength multiplexers is first presented. We then report on the synthesis and optical characterization of electro-optic films grown through the ISAM technique. We conclude by presenting the preliminary development of a nanofabrication platform that would enable the realization of active photonic devices in such materials.
The Investigation of Erbium Complexes and Erbium Doped Materials
Authors: Lee Seunghoon , Kim Ung , Kim Juntae , Koo Sang Man 
Published: April 2011

AbstractErbium ion (Er3+) doped materials are of great interest for their optical amplification, lasing and frequency up-conversion properties. When preparing such materials, a major problem that often arises is the formation of Er-rich oxide clusters inducing optical quenching. The materials prepared at low Er3+-ion concentrations to overcome the problem have severely reduced the optical yield. Such clustering might be avoided by preparing suitable precursors. If Er is encapsulated with proper materials, clustering can be avoided and higher doping levels can be achieved. In this study, erbium phenoxide complex was obtained by metathesis reaction of erbium chloride (ErCl3) with potassium phenoxide (KOPh). And heterometallic complexes were also synthesized by encapsulation of the Er with Al or Ti derivatives. The complexes were characterized by elemental analysis, infrared and nuclear magnetic resonance spectroscopic analysis. Their crystal structures were determined by X-ray single crystal diffraction analysis. In addition, the Er-doped organic-inorganic matrices using the erbium complexes were investigated about their optical properties.