bluuebunny/crossref_metadata_2025 huggingface dataset:
Effective Work Function Modulation by As Implantation in Metal Gate Stacks.
Authors: Luna-Sánchez Rosa María , González-Martínez Ignacio
Published: November 2006

The impact of As implantation through TiN/TaN/HfO2, TiN/HfO2, TiN/TaN/SiON and TiN/SiON metal gate stacks on the effective WF was investigated. The effective WF was estimated based on the flatband voltage (VFB) shift for one dielectric thickness. The As implantation at 20 KeV influences the VFB shift for TiN/TaN/HfO2 by a maximum of 600 mV at an implanted dose of 5E15 cm-2. The shift in VFB is correlated to the As pile-up at the TaN-HfO2 interface, as evidenced by SIMS profile. The increasing dose of As ions resulted in an increase in VFB shift compared to un-implanted gate stack. This was related to the increase in As concentration at the TaN-HfO2 interface. It is suggested that As ions introduced as impurities at the interface of the gate electrode and the gate dielectric could induce interface dipole contributing to the work function of the gate stack resulting in a flat band voltage shift.
Extensive Studies for Effects of Nitrogen Incorporation into Hf-based High-k Gate Dielectrics
Authors: Luna-Sánchez Rosa María , González-Martínez Ignacio
Published: November 2006

Effects of nitrogen incorporation into Hf-based high-k gate dielectrics have been extensively studied via first-principles calculations. Particular emphasis is given to the relationship between incorporation of N atoms and oxygen vacancies (Vos). Three important aspects are outlined in this paper. The first one is the intrinsic effect of N atoms in reducing the leakage current mediated by Vo related gap states. The second one is the suppression of electron charge traps at Vo due to the strong repulsive Coulomb potential from N3- ions located around Vo. The third one is the acceleration of the Vo formation around N ions. From these analyses, we infer that the amount of N incorporation should be tuned in the fabrication of reliable gate insulators.
Metal Contamination from Process Materials Used in Wet Cleaning of Silicon Wafer.
Authors: Luna-Sánchez Rosa María , González-Martínez Ignacio
Published: November 2006

Contamination from process materials is an important consideration for the reduction of wafer contamination required for next generation of semiconductor devices. Traditionally, RCA based wafer cleaning process is employed for wet cleaning of silicon wafer. Commonly used chemicals are ammonium hydroxide (29 wt%), hydrogen peroxide (31 wt%), hydrochloric acid (37 wt%), hydrofluoric acid (49 wt%) blended with deionized water. Wetted materials widely used are 440 HP PFA Teflon, chemical resistance O-ring elastomers such as Kalrez, Teflon encapsulated viton, and regular or synthetic quartz. Elution of metal ions from interaction of these process materials with process chemicals can result into metal contamination of the wafer. In this paper, we have presented the level of metal elution from these process materials when exposed to the process chemicals used in wet cleaning of silicon wafer. Information obtained from the investigation can used to further reduce the metal contamination and to determine the suitability of these or other process materials, for wafer processing, based on contamination tolerance of the semiconductor device.
Advanced TiN Metal-Gate FinFET Technology
Authors: Luna-Sánchez Rosa María , González-Martínez Ignacio
Published: November 2006

The TiN-gate CMOS FinFET technologies for high-performance connected-double-gate 3-terminal (3T) and flexible threshold voltage (Vth) controllable independent-double-gate 4-terminal (4T) FinFETs integration have experimentally been investigated. By using the conventional reactive sputtering, the uniform TiN deposition on the sidewalls of upstanding Si- fin channels was realized by optimizing the pressure during the sputtering. Moreover, the well symmetrical Vth N- and P- channel 3T-FinFETs with the fin-height tuning and the co- integration of the TiN-gated high-performance 3T- and highly Vth-controllable 4T-FinFETs using the resist etch-back process were demonstrated. The developed technologies are very attractive for the high-performance and power-managed CMOS FinFETs circuits.
HfAlO and HfSiO Based Dielectrics for Future DRAM Applications
Authors: Luna-Sánchez Rosa María , González-Martínez Ignacio
Published: November 2006

The temperature stability of HfSiOx and HfAlOx films was investigated in the annealing temperature range of 700-1000 {degree sign}C. The main focus of this work is to compare mixed and laminate films in terms of crystallographic phase, capacitance enhancement and leakage current degradation. Single HfO2 layers in the laminate film fully crystallize into monoclinic phase. Mixed films remain nanocrystalline up to a temperature of 800- 900{degree sign}C and fully crystallize in to the cubic phase for higher temperatures. The different crystallization temperatures and crystallographic phases are reflected in the annealing temperature dependence of capacitance and leakage current. Mixed films show a significant increase of capacitance and leakage current after crystallization. For laminates the capacitance remains constant for annealing temperature up to 1000{degree sign}C and the leakage current shows a slight degradation only. Using temperature dependent leakage current measurements the formation of trap states at average levels of 0.2-0.3 eV below conduction band edge of the dielectrics is shown.
Chemical-Mechanical Polishing of SiCOH-Based Low-k Dielectrics
Authors: Luna-Sánchez Rosa María , González-Martínez Ignacio
Published: November 2006

Material and integration issues related to direct Cu/Ta CMP with low-k SiCOH are investigated. Polish rates vary significantly with the degree of post-deposition curing, and are independent upon the mechanical hardness of SiCOH but proportional to concentration of Si-O bonds with conventional oxide slurry. Soft pad yield higher polish rates than hard pad. Slurries with special proprietary chemistry and/or less amount of abrasives result in reduced polish non-uniformity, lower defectivity, and tighter resistance distribution. Decrease in breakdown strength and increase in leakage current are observed on post-CMP porous SiCOH. Such degradation in reliability can be recovered, depending on the SiCOH porosity and the slurries used. SiCOH polish mechanism is proposed and issues and challenges for SiCOH, especially porous SiCOH CMP are discussed.
The Low Leakage Current Density of MIS with SiO2 Film Made by ICP-CVD
Authors: Luna-Sánchez Rosa María , González-Martínez Ignacio
Published: November 2006

Thin Film Transistors (TFT) made from high quality semiconductor films can be used in active matrix liquid crystal displays (AMLCD). The properties of the gate oxide are very important in the operation of MIS. In this work, crystallized SiO2 films were deposited at extremely low temperature (90{degree sign}C) by inductively coupled plasma chemical vapor deposition. The results show that the deposition rate increased approximately linearly with applied r.f. power in the ICP-CVD system. Only the (1 11) X-ray diffraction peak appeared in the range of the study. At 1000 Watts, the silicon dioxide film is amorphous which may be attributed to low deposition temperature. The value of the dielectric constant of the MIS varied from 3.75 to 4.05. From the I-V curve it can be seen that the SiO2 thin film has a lower leakage current density when prepared at 1750Watt. The lowest leakage current density obtained in this study was 6.8×10-8A/cm2 @V=1V.
Charge Trapping in High-k Gate Dielectrics: A Recent Understanding
Authors: Luna-Sánchez Rosa María , González-Martínez Ignacio
Published: November 2006

Charge trapping in Hf-based high-k dielectrics, used in MOS transistor gate stacks, causes threshold voltage shift during constant voltage stress (CVS). It seemed to be very transient due to the presence of a large number of shallow traps and can be eliminated by applying a reverse direction electric field. Recent findings, however, suggest that deep traps significantly contribute to the reliability of various Hf- based high-k gate stacks. The origin of the deep traps and their dependence on O vacancy formation during dielectric deposition is discussed. Flatband shift and leakage current dependence on these deep traps is also outlined. We have experimentally observed trap levels from low temperature measurements assuring the presence of O vacancies in Hf- silicate based films. It is further shown that negative-U transition to deep defects is responsible for trap assisted tunneling under substrate injection. This has the potential to be the ultimate limiting factor for the long-term reliability of Hf-based high-k gate dielectrics.
Mobility Degradation Analysis for La2O3 nMOSFET
Authors: Luna-Sánchez Rosa María , González-Martínez Ignacio
Published: November 2006

Al/La2O3/SiO2/p-Si nMOSFET with various thicknesses of the La2O3 layer and the SiO2 interfacial layer (IL) were fabricated. We discussed mobility degradation caused by fixed charge and trapped charge at the La2O3/SiO2 interface.
Lessons Learned from the 300 mm Transition
Authors: Kramer Scott , Draina Joseph , Fandel Denis , Ferrell Jackie
Published: November 2006

The 300mm transition required unprecedented levels of industry collaboration, standardization, and investment. This paper reviews the experiences of the 300mm transition and what we have learned, and offers a strategy to comprehend those learnings and improve as we move forward into the 450 mm transition Consensus on an industry strategy for a next transition must be driven by rigorous economic and market analysis. Modeling based on supplier and device maker data must support evaluation and analysis of alternatives to validate assumptions and tradeoffs, economic and architectural attributes. The strategy should comprehend technology nodes and new or alternate substrate and process technologies. A vision for opening the architecture of next generation 300mm fab configuration before the transition to the next wafer size occurs enables more flexibility for high mix business models and allows a more cost-effective scale-up from 300mm to 450 mm.
Introductory Remarks: Process Development and Modeling
Authors: Goesele U. , Packan P.
Published: November 2006

Abstract not Available.
Oxygen Vacancies at the Si(001)/SiO2 Interface
Authors: Korkin Anatoli , Greer Jim , Hendersen T. M. , Bersuker Gennadi , Bartlett Rodney
Published: November 2006

High-k oxides deposited on silicon substrates form interfacial silicon dioxide layers. The interface layer is of importance in microelectronics, due both to charge transport at the silicon/silicon dioxide interface and to the oxide layer influencing the equivalent oxide thickness (EOT). Electrical characterization of low temperature thermal oxides grown by atomic layer deposition of hafnia dioxide indicates a dielectric constant at the interfacial region larger than for stochiometric SiO2. A proposed mechanism for the observed increase is the interface becomes oxygen deficient during the growth process. Oxygen vacancies in SiO2 are examined by ab initio computations and are found to be more stable in the vicinity of the interface, thus identifying a chemical driving force for oxygen reduction at the interface.
Defect Dynamics in the Presence of Oxygen in Growing Czochralski Silicon Crystals
Authors: Kulkarni Milind S.
Published: November 2006

Modern Czochralski (CZ) silicon crystals contain various large defects known as microdefects that affect the yield and the performance of microelectronic devices. These microdefects are primarily the agglomerates of the intrinsic point defects of silicon, vacancies and self-interstitials, and of oxygen (silicon dioxide). The distribution of microdefects in a CZ crystal is determined by the complex dynamics influenced by various reactions involving the intrinsic point defects and oxygen, and their transport. Two-dimensional oxygen influenced transient defect dynamics in growing CZ crystals is quantified and solved. The Frenkel reaction and the reactions between vacancies and oxygen are considered. The formation of all microdefects is described by the classical nucleation theory. Microdefects are assumed to be spherical clusters that grow by a diffusion-limited kinetics. The predictions of the model agree well with experimental data. Various predictions of the model and experimental results are discussed.
First Principles Calculation for Cu Gettering by Dopantor Dopant-Vacancy Complex in Silicon Crystal
Authors: Sueoka Koji , Ohara Shigehiro , Shiba Seiji , Fukutani Seishiro
Published: November 2006

For finding the effective gettering center of cupper (Cu) atom in silicon (Si) crystal, an interaction between interstitial Cu atom and dopant (B, Sb, As, P), C or O atom was studied with first principles calculation. It was found that only B could be an effective gettering center. This result indicates that heavily B doped p/p+ epitaxial wafers will show a sufficient gettering efficiency for Cu contamination. In order to design the gettering center of Cu in n/n+ epitaxial wafers, the interaction between vanancy (V)-Sb, V-As or V-P complexes and Cu was investigated. It was found that these complexes could be effective gettering centers. The mechanism of Cu gettering by oxide precipitates was also studied with further calculations. It was found that the stabilities of Cu atom in β-crystobalite or in strained Si were not superior to that in strain-free Si. The trapping at the interface or the interaction with emitted interstitial Si (I) from oxide precipitates should be the possible mechanisms for Cu gettering.
Analysis of Internal Gettering of Iron Based on the Nucleation Model of Iron Precipitation
Authors: Nakamura Kozo , Tomioka Junsuke
Published: November 2006

We propose a new simulation model to describe the behavior of the internal gettering of Fe by oxygen precipitates. The internal gettering of Fe has typically been described by the diffusion-limited model proposed by Gilles et al. While the diffusion-limited model is effective in describing the gettering behavior at low temperature (< 400oC), it fails to do so at practical gettering temperature of 600oC and above. The model proposed here accurately describes the internal gettering behavior of Fe at both low and practical temperatures by considering the nucleation of iron silicide on the oxygen precipitates. Our model also explains how the gettering behavior is influenced by the product of NRo at low temperature and by the product of NRo3 at high temperature, where N and Ro are the density and radius of the oxygen precipitates, respectively.
Silicon Self-Diffusion in Heavily B-Doped Si Using Highly Pure 30Si Epitaxial Layer
Authors: Matsumoto Satoru , Aid S. R. , Seto S. , Toyonaga K. , Nakabayashi Y. , Sakuraba M. , Shimamune Y. , Hashiba Y. , Murota J. , Wada K. , Abe T.
Published: November 2006

Si self-diffusivity in heavily B-doped Si at 867-1-67C has been determined directly using highly pure isotope 30Si as a diffusion source. Samples consist of 30Si epi-layer/B-doped natural Si epi-layer/natural Si substrates. Si self- diffusivity increases with the increase of B concentration and its enhancement degree is larger at lower diffusion temperatures. Based on the model of the Fermi level effect, energy levels of donor Si self-interstitial and acceptor vacancy are determined from the analysis of the experimental data.
Modeling Growth Behavior for Si1-xGex from SiH4 and GeH4 by CVD
Authors: Yang X. , Tao M.
Published: November 2006

A kinetic model based on the collision theory of chemical reactions, statistical physics, and the concept of competitive adsorption is proposed for Si1-xGex growth from SiH4 and GeH4 by chemical vapor deposition. It takes into account both homogeneous and heterogeneous reactions, which involve the precursors (SiH4 and GeH4) and the homogeneous decomposition product of germane, germylene (GeH2), and three types surface sites, silicon sites, hydrogen-terminated silicon sites, and germanium sites. The growth of Si1-xGex can be divided into two regimes: a heterogeneous decomposition dominated regime and a homogeneous decomposition dominated regime. Analytical equations are derived to quantitatively describe growth rate as a function of deposition conditions, including deposition temperature, silane flow rate, and germane flow rate, for the heterogeneous regime. Homogeneous decomposition of germane into germylene causes precursor depletion, and an empirical linear relation is employed to describe the growth behavior in the homogeneous regime. The model agrees well with the experimental data.
Modeling of Morphological Changes by Surface Diffusion in Silicon Trenches
Authors: Mueller Timo , Dantz Dirk , von Ammon Wilfried , Virbulis Janis , Bethers Uldis
Published: November 2006

We present a three - Dimensional model of surface diffusion which describes the time evolution and topography changes of deep trenches under low pressure hydrogen anneal and compare the results with experimental observations. A phase diagram for regular arranged cylindrical trenches was derived by using a genetic optimization algorithm. Seven different structural phases of the final bubble / layer arrangement out of the trench array anneal could be predicted. The impact of perturbations in the regular trench array is discussed too and the change in the phase diagram - shrinkage of the stable region for single top layer formation - is calculated .
Thermal Agglomeration of Ultrathin SOI and SSOI Films: A Quantitative Stability Study and Physical Model to Guide Ultrathin SOI Process Design
Authors: Danielson David T. , Michel Jurgen , Kimerling Lionel
Published: November 2006

We present the results of a controlled experimental study of the thermal agglomeration of (100)-oriented ultra-thin SOI films along with a surface-energy-driven physical model for SOI agglomeration to guide ultra-thin SOI process design. Through a UHV annealing study, the SOI agglomeration edge initiation time and edge propagation velocity were determined as a function of SOI thickness and annealing temperature for bonded and SiMOX SOI films. SiMOX SOI and strained SOI films were studied and shown to have nearly identical agglomeration behavior to bonded SOI films, clearly indicating that SOI agglomeration is not a stress-driven phenomenon. An ultra-thin SOI defect study was also performed in parallel with this agglomeration study to identify the defect responsible for bulk SOI agglomeration initiation. HF defects, dislocations, and stacking faults were ruled out and initial evidence indicates that defects at the top Si/buried SiO2 interface may be responsible.
Breakthrough of In-Line Inspection Technology in Volume Production for 65 nm Node and Beyond
Authors: Yamazaki Yuichiro
Published: November 2006

We have developed the electron beam inspection system utlizing the projection electron microcope (EBI-PEM) to improve the productivity of electron beam system for next generation semiconductor volume production use. In this paper, we will present the advantagous inpection throughput of EBI-PEM as compared with the conventional electron beam system.
Standardization of Measurement of Nitrogen Concentration in CZ Silicon Crystals
Authors: Inoue Naohisa , Karen Akiya , Yagi Hirochika , Masumoto K. , Shinomiya M. , Kashima Kazuhiko , Eifuku K. , Koizumi M. , Takahashi T. , Takenawa T. , Shingu K.
Published: November 2006

Standards for the measurement procedures of nitrogen concentration in CZ silicon crystals were established for infrared absorption spectroscopy (IR), secondary ion mass spectroscopy (SIMS) and charged particle activation analysis (CPAA) for concentration above 1x1014 atoms/cm3.Good agreement was obtained between the laboratory within the same method and between the three methods. Conversion coefficient from (weighted sum of) absorption coefficients to nitrogen concentration agreed well with the previous one.
Infrared Absorption Measurement of Carbon Concentration in Silicon Crystals
Authors: Inoue Naohisa , Nakatsu Masaomi , Akhmetov Vladimir
Published: November 2006

Sensitivity and accuracy of carbon concentration measurement by infrared (IR) absorption spectroscopy are improved. We cut unnecessary high energy light input by a low pass filter. Measurement condition of sample and reference is kept as equal as possible by using the sample changer and measure them alternately for many times. It is possible to improve the accuracy by keeping the temperature of sample and reference as close as possible. In the analytical procedure, we use a reduced phonon spectrum fitting instead of straight baseline. Standard carbon spectrum fitting to a small carbon peak make it possible to determine the carbon concentration accurately. As a result, we can measure differential carbon concentration down to about 1x1014 atomos/cm3.
X-Ray Reciprocal Space Mapping and Synchrotron Radiation Topography of Strained Si/Si1-xGex on Bonded SOI
Authors: Ma Tongda , Tu Hailing , Hu Guangyong , Shao Beiling , Liu Ansheng
Published: November 2006

In this work, X-ray triple-axis diffractometry (TAD) and synchrotron radiation double-crystal topography (SRDT) have been utilized to investigate strained-Si/Si1-xGex on bonded SOI. The structural characteristics of the Si capping layer and the underlying Si layers (the Si buffer and SOI top Si layer) have been described using high resolution reciprocal lattice mapping (HRRLM). The mosaicity in the SiGe layer leads to (004) diffraction peak broadening asymmetrically. The crosshatched contrast spatially correlated with the misfit dislocations (MDs) has been observed both in the SiGe layer and the underlying Si layers. The granular pattern due to the mosaic blocks is also shown in the topograph of the SiGe layer. It is argued that the compressive strain in the SiGe layer has been primarily released at the interface between the SiGe layer and the underlying Si layers.
Local Strain Measurement on Strained Si/SiGe Heterostructures Using Convergent Beam Electron Diffraction Analysis
Authors: Zhao Wenjun , Duscher Gerd , Rozgonyi George
Published: November 2006

Local strain variations in microelectronic device structures have been investigated with convergent beam electron diffraction (CBED). The analysis has been improved with a series of tasks: high order Laue zone (HOLZ) line detection by the Hough transform, HOLZ line position simulation with the kinematic theory, lattice parameter refinement by the examination of least square fitting, and theoretical strain state calculation with finite element (FE) modeling. The goal of this paper is to demonstrate the procedure of this strain measurement analysis. The actual strain variation in a TEM foil of a CMOS device structure was shown, followed by the FE in a strain Si/SiGe heterostructure. The strain data will not be included in this paper, but will be added later.
Frequency Changes Observed with the EQCM Resulting from Hydrophilic/Hydrophobic Transitions
Authors: Woods R. , Jeffrey Matthew I.
Published: November 2006

The processes responsible for the altered frequency response of the EQCM when the electrode surface changes from a hydrophilic to a hydrophobic condition have been investigated using silver electrodes in ethyl xanthate solution. The frequency accurately tracks the voltammetric charge when silver ethyl xanthate is formed, but moves in the opposite direction when xanthate is chemisorbed; chemisorption is known to result in the surface becoming hydrophobic. The characteristics of the EQCM in a xanthate solution that had been completely degassed was the same as that in one deaerated with nitrogen. This is inconsistent with nanobubbles being formed at a hydrophobic surface, but is in agreement with slippage occurring as a result of a change in water structure. Similar voltammograms were observed for smooth silver surfaces to those for electrodeposited ones, but the alteration in frequency response during the change in wettability was much greater. This is also explained in terms of water structure.
Gold Enhanced Observation of Surface Products in Chalcopyrite Dissolution
Authors: Hope Gregory A. , Parker Gretel , Woods R.
Published: November 2006

Gold decoration of chalcopyrite surfaces has been shown to stimulate surface enhancement of Raman scattering and this enables sulfur oxidation products to be investigated when they are undetectable by normal Raman spectroscopy. Solution cementation, sputtering and evaporative deposition of gold each facilitated SERS. The last of these techniques was selected for studies of chalcopyrite leaching since it has the least possibility of affecting the mineral surface. Similar oxidation products and electrochemical behaviour were observed on potential cycling of chalcopyrite electrodes in H2SO4 and HCl. SERS spectroscopy indicated that S-S bonding was present in the major product, indicative of sulfur in a somewhat amorphous structure. It is proposed that this species results from aging of a metal-deficient remnant sulfide lattice formed when metal atoms are dissolved. Ex situ investigations of the oxidation of chalcopyrite substantiated the conclusion that the species detected after gold deposition were oxidation products of chalcopyrite.
A Rotating Disk Electrochemical Dual Autoclave for the Study of Electrochemistry and Leaching at High Temperature and Pressure
Authors: Lazaro Isabel , Jeffrey Matthew I.
Published: November 2006

A study of the pressure acid leaching of chalcopyrite was performed using a unique rotating disc electrochemical dual autoclave. The autoclave permits electrochemical and leaching experiments to be conducted up to 200 {degree sign}C using a chalcopyrite rotating disk electrode. The paper describes in detail the design of the dual autoclave, which consists of separate pre- heater and reactor. This eliminates heat-up effects, and allows either leaching or electrochemistry to be commenced at the correct temperature. The mixed potential measurements and voltammograms of chalcopyrite at 150 {degree sign}C indicate that pressure acid leaching in a solution containing 0.1 M Fe(III) will occur quite rapidly. In comparison, when using 120 psi partial pressure of oxygen, the mixed potential is in the so- called prewave region, and hence slow leaching would be expected.
Hydrodynamic Modeling of Copper Electrodeposition at a Vertical Rotating Cylinder Electrode
Authors: Fabian Cesimiro P. , Mandin Philippe , Ridd Michael , Sheehan Madoc
Published: November 2006

The hydrodynamics of a rotating cylinder electrode were modeled to predict tertiary current distributions during electrodeposition of copper from acidic sulfate media, and to evaluate the effects of the resulting density gradients close to the electrode. Assuming no such density variations, then predictions of transport-limited current densities were in good agreement with Mizushina's empirical law and with LévÊque's theoretical description, but not with measured values. Assuming a linear density variation with copper concentration, predictions of concentration profiles agreed to within 3 % of experimentally measured limiting current densities at the rotating cylinder electrode. For solution compositions relevant to copper electrowinning, a diffusion coefficient for cupric ions of 1.2x10-9 m2/s at 45 oC, was inferred by solving the continuity, Navier-Stokes and mass balance equations with Fluent® computational fluid dynamics software.
Electrochemical Study of Copper(II) Reduction from Ammonia-Chloride Solutions
Authors: Cruz Roel , Vazquez Jorge
Published: November 2006

The mechanism of CuII reduction from CuII-NH3-Cl--H2O solutions was found to involve two steps, the kinetics of which were determined, as functions of solution composition and temperature, by voltammetry and chronoamperometry. Chronoamperometric measurements indicated that adsorption strongly affected the overall copper(II) reduction process, which involved three-dimensional nucleation and growth that was diffusion controlled at sufficiently negative overpotentials. Scanning electron micrographs of copper electrodeposits showed the effect of adsorption on their morphology.
Density, Viscosity, and Conductivity of Tetraalkyl Phosphonium Ionic Liquids
Authors: Vaughan James W. , Dreisinger David , Haggins Jana
Published: November 2006

The density, viscosity and conductivity of nine commercially available tetra-alkyl phosphonium ionic liquids (ILs) are presented. The effect of cation volume and symmetry, anion volume, and temperature are observed. The Vogel-Tamman- Fulcher (VTF) equation is used to calculate the theoretical glass transition temperature (To) and the activation energy of conductivity Ea,Λ. The conductivity of three halo-aluminate ionic liquid systems for mole fractions up to 0.7 AlCl3 is reported.
Electrochemical Preparation of Fe-Mn Alloy Film in Organic Bath
Authors: Hope Gregory A. , Liu Peng , Yang Qiqing , Li Gaoren , Tong Yexiang
Published: November 2006

Fe-Mn alloy films have been prepared by electrodeposition for the first time. The electrode process of MnII reduced in MnCl2 + DMF and the electrodeposition of Fe-Mn in FeCl2 + MnCl2 + DMF were studied by cyclic voltammetry. The MnII + 2e = Mn reaction was irreversible and the diffusion coefficient of MnII was calculated to be 1.2 x10-6 cm2 s-1 at 25{degree sign}C. An amorphous film of Fe-Mn was obtained by potentiostatic electrolysis. SEM, EDAX experiments show that the film is homogeneous, dense and adheres firmly to the copper substrate. The content of Mn varies from 4.8 at.% to 72.3 at.% with the increase of the cathodic (deposition) potential. XRD patterns of the film after heat treatment at 500{degree sign}C indicate that solid solution of Mn in g- Fe occurs. The alloying temperature of the Fe-Mn alloy film is about 740{degree sign}C, determined by DTA experiments.
PVT Growth at High Temperatures
Authors: Singh Narsingh B. , Wagner Brian , Sherwin Marc , Berghmans Andre , Thomson Darren , Kahler David , Knuteson David
Published: November 2006

Physical vapor transport (PVT) growth method was used to grow bulk crystals of AlN and thick epitaxial SiC films on on-axis Si-face 4H-SiC(0001) substrates from the powder source materials. Both bulk and thick film crystals were characterized by scanning electron microscopy (SEM), which showed a surface morphology did not have any observable growth defects or cracking. We observed nice hexagonal growth morphology a typical characteristic of diffusion-limited growth. River-patterns free from micro bubbles and micro voids were observed on the as grown surface. An XRD rocking curve measured the FWHM as 51.0 arc seconds and a reciprocal space map showed a singular intense region that is attributed to the high quality homoepitaxial SiC film. A similar value was observed for small AlN crystals also.
Influences of Gate Recess Structure on the DC Characteristics of 0.1 Micron Metamorphic HEMTs
Authors: Oh Jung-Hun , Back Yong-Hyun , Choi Seok-Gyu , Moon Sung-Woon , Lee Bok-Hyung , Rhee Jin-Koo , Kim Sam-Dong
Published: November 2006

Effects of the gate recess structures on the DC performances were investigated in 0.1-μm metamorphic high-electron-mobility transistors. Narrow gate recess structure showed significantly enhanced DC characteristics compared to wide gate recess structure in terms of drain-source saturation current increasing from 440 to 710 mA/mm and extrinsic transconductance increasing from 420 to 910 mS/mm. We propose that the observed variations in DC characteristics are due to the deep-level acceptor-type interface defects formed between the silicon-nitride passivation layer and the Schottky barrier layer. We performed hydrodynamic model simulation to verify the proposed mechanism, and the calculated result showed a good agreement with the experimental observation.
The Mechanism of Phototransistors and Its Model in OEIC Application
Authors: Tan Shih-Wei , Liao C. W. , Liu K. P. , Chen H. H. , Huang Y. S. , Chen W. C.
Published: November 2006

In this paper, we reported the fabrication, characterization and modeling of a heterojunction phototransistor using an InGaP layer for passivation (called P-HPTs) compared with similar non- passivated devices (called NP-HPTs). Effects of the base passivated by the InGaP layer on device's optical and electrical performance were investigated. In addition to improving the dc current gain in the small current regime, the photocurrent (Ip) from the p-i-n diode formed by the base, collector, and sub-collector are also enhanced in a P-HPT. The measured optical gains are 45 and 27 for a P- and a NP-HPT under 8.62-mW optical injection operated as a two-terminal (2T) device with a floating base. When the base bias is applied from a voltage source, both 3T P- and NP-HPTs exhibit degraded optical gains. Although a voltage source applied to the base can be used to push the operating point of a heterojunction bipolar transistor (HBT) to a higher collector current where the current gain is higher, only a small portion of the photocurrent generated within the base-collector region is injected across the base-emitter junction to be amplified. When the base of an HPT is biased using a current source, the Ip and enhanced dc current gain mainly determine both collector photocurrent and optical gain. Thus a P-HPT biased using a current source shows the best optical performance. Furthermore, the extended Ebers-Moll equivalent-circuit model was provided to simulate in good agreement with experiment results.
Effect of Surface Grooved Visible Light Active Carbon Modified n-TiO2 Thin Film Electrodes on Photosplitting of Water
Authors: Khan Shahed U. , Shaban Yasser
Published: November 2006

Carbon modified n-type titanium oxide (CM-n-TiO2) photoelectrodes were synthesized by thermal oxidation of grooved and non-grooved Ti metal sheet (Alfa Co. 0.25 mm thick) by heating at several temperatures for different lengths of time. The photoresponse of the CM-n-TiO2 was evaluated by measuring the photocurrent density, jp which is proportional to rate of water splitting to hydrogen and oxygen. The optimized non-grooved and grooved CM-n-TiO2 photoelectrodes showed photocurrent densities of 5.1 and 10.0 mA cm-2 at measured potential of -0.7 V/SCE respectively at illumination intensity of 50 mW cm-2 from a 150 Watt Xenon Lamp. Thus, a two fold increase in photoresponse was observed for the CM-n-TiO2 synthesized on grooved Ti metal surface compared to that on the non-grooved ones. These CM-n-TiO2 photoelectrodes were characterized using photocurrent density measurements, UV-Vis spectra, and Energy dispersive analysis by X-ray (EDAX).
Enhancement of LED Light-Extraction Efficiency by Anodic Oxidation
Authors: Wang Chien-Chun , Lu Wei-Lun , Houng Mau-Phon , Yen Te-Chi , Wang Yeong-Her , Liu Chien-Chih , Chu Chang Hsin
Published: November 2006

In this work, the enhancement of light-extraction efficiency for AlInGaP-based light-emitting diodes (LEDs) by using porous alumina is proposed. The employment of the porous alumina increases the total power by 6.35%, while the optical spectrum is unchanged. By nano-texturing the thin-film surface, it is much easier for light to escape from porous alumina light- emitting diodes (PA-LEDs). The pore distances about 25~80 nm under anodized voltage ranges of 10~30 V in the sulfuric acid. Besides, nanopores of porous alumina also can be enlarged (~0.8nm/per min) in the phosphoric acid. The diameter of the nanopores (20-60nm) and the interpore distance (25-80nm) can be modulated by anodic parameters.
The Present Status and Recent Advancements in Corona-Kelvin Non-Contact Electrical Metrology of Dielectrics for IC-Manufacturing
Authors: Wilson Marshall , Marinskiy Dmitriy , Byelyayev Anton , D'Amico John , Findlay Andrew , Jastrzebski Lubek , Lagowski Jacek
Published: November 2006

Non-contact electrical metrology offers a fast and cost saving monitoring of dielectrics in IC manufacturing process. This corona-Kelvin measuring technique has entered the maturity stage with about 400 tools installed in silicon IC-fabs. We discuss recent advancements that broaden the spectrum of monitoring parameters and enhance the precision of these measurements. We also discuss the current ongoing extension of corona-Kelvin metrology to the micro scale measurement on sites as small as 30µm x 30µm. This opens new possibilities for non-contact electrical testing of product wafers, rather than expensive process monitor wafers. Micro-measurement is illustrated using flash memory ONO structures and corona induced programming and erasing.
Capacitance-Voltage Characterization of Atomic-Layer-Deposited Al2O3/InGaAs and Al2O3/GaAs Metal-Oxide-Semiconductor Structures
Authors: Ye Peide (Peter) , Xuan Yi , Lin H.C.
Published: November 2006

Atomic layer deposition (ALD) provides a unique opportunity to integrate high-quality gate dielectrics on III-V compound semiconductors due to its low-temperature growth and low surface damage features. The investigation of bulk and interface properties of high-temperature (i.e., higher than 750{degree sign}C for activation) annealed Al2O3/In0.2Ga0.8As or Al2O3/GaAs structure is very important for self-aligned implanted III-V metal-oxide-semiconductor-field-electrical-transistor (MOSFET) devices. In this paper, ALD Al2O3/GaAs and Al2O3/In0.2Ga0.8As MOS and source-drain implanted MOSFET structure were fabricated and characterized by capacitance-voltage (C-V) and current- voltage (I-V) measurements.
Electrically Active Interface Defects in the (100)Si/SiOx/HfO2/TiN System: Origin, Instabilities and Passivation
Authors: Hurley Paul K. , Cherkaoui Karim , Groenland Alfons
Published: November 2006

An analysis of the origin and passivation of interface states in (100)Si/SiOx/HfO2/TiN capacitor structures is presented. For high-k gate/metal gate capacitors which exhibit relatively high interface state densities (> 1x1011cm-2) the dominant interfacial defects are silicon dangling bond (Pbo) centres. For (100)Si/SiOx/HfO2/TiN capacitors which experience no high temperature thermal budget following HfO2/TiN gate formation (T<600{degree sign}C), the devices exhibit instabilities, where the interface state densities are modified during electrical measurements. The origin of this instability is studied. The response of the interface state density to rapid thermal annealing (30s) in N2 over the temperature range 600-900{degree sign}C is presented. In addition, results are presented for interface state passivation in forming gas (0.5H2/0.95N2) from 350-550{degree sign}C for (100)Si/SiOx/HfO2/TiN gate stacks with no post deposition annealing following TiN gate formation and for devices following a 900{degree sign}C, 30s N2 RTA.
Correlation Between High-K Properties and Interfacial Chemical Structure of ALD HfO2 Thin Films on Si, Si1-xGex and Ge Substrates
Authors: Park Tae Joo , Hwang Cheol Seong , Kim Jeonghwan , Jang Jaehyuck , Seo Minha
Published: November 2006

The changes in the electrical and chemical properties of HfO2 films grown by atomic layer deposition on Si, Si0.8Ge0.2 and Ge substrates during the post-deposition annealing (PDA) were studied. The migration of Ge plays a key role in reducing the capacitance equivalent thickness (CET) after PDA. A high resolution x-ray photoelectron spectroscopy and extended x-ray absorption fine structure analyses confirmed that the Ge atoms which have already diffused into the HfO2 upper layer during deposition are drawn back to film/substrate interfacial layer during the PDA.
Advanced Nano-Analysis of a High-K Dielectric Stack
Authors: MacKenzie Maureen , Craven Alan , McComb David , De Gendt S. , Docherty Frances , McGilvery Catriona , McFadzean Sam
Published: November 2006

Analytical electron microscopy techniques are used to investigate elemental distributions across a high-k dielectric stack with a metal gate. Electron energy-loss spectroscopy results from a Si(100)/SiO2/HfO2/TiN/poly-Si gate stack prior to activation show evidence of interface reactions having occurred with the formation of an oxide layer at the TiN/poly- Si interface.
Metal/High-K Interface Interactions Upon High Temperature Annealing - Are They Cause of Workfunction Changes
Authors: Conard Thierry , Schram Tom , Akheyar Amal , Arstila Kai , Zschaetzsch Gerd , Vandervorst Wilfried , De Gendt Stefan , Paraschiv Vasile , Brijs Bert , Jiang Z.X. , Lerma J. , Kaushik Vidya , Ragnarsson Lars , Brunco David P.
Published: November 2006

The replacement of poly-silicon by metallic compounds in the gate stack leads to the search of metals with suitable work function. However, it is observed that thermal budget has a large influence on the effective work functions of several metals. In this paper, we investigated the possible modification of the chemical states by physical analysis techniques (XPS, ERD, SIMS) by studying investigating the chemistry of the high-k oxide/metal interface. We show that in the case of the TiN/TaN/HfO2/SiO2/Si stack, several modifications occur upon 1000{degree sign}C N2 annealing: Increase of the nitrogen content of the TaN, interdiffusion of the Ti and TaN, and formation of Ta2O5 at the TaN/HfO2 interface.
Depth Profiling of Chemical and Electronic Structures and Defects of Ultrathin HfSiON on Si(100)
Authors: Miyazaki Seiichi , Ohta Akio , Inumiya Seiji , Nara Yasuo , Yamada Keisaku
Published: November 2006

We present in-depth profiling of chemical bonding features and defect state density in ultrathin HfSiOxNy (Hf/(Hf+Si)=~43%) films with average nitrogen contents up to ~18at.% by using x- ray photoelectron spectroscopy (XPS) and total photoelectron yield spectroscopy (PYS) in combination oxide thinning in a dilute HF solution. It is found that the oxygen content becomes its minimum around ~1.2nm from the surface while the nitrogen content becomes its maximum within ~1.5nm from the surface. The result suggests that the surface re-oxidation is promoted coincidentally with the diffusion of N atoms generated by thermal decomposition of the Hf-Nx units during the N2-annealing. The depth profile of the defect states, which was derived from the change in the yield, shows that the defect state density becomes its maximum in the near-surface region where oxygen deficiency becomes significant. It is likely that the imbalance in chemical coordination between anions and cations is responsible for the defect generation.
Indium-Tin-Oxide Embedded in Zirconium-Doped Hafnium Oxide High-k Dielectric Films for Hole-Based Nonvolatile Memories
Authors: Kuo Yue , Birge Adam , Lin Chen-Han
Published: November 2006

A new nonvolatile floating gate memory based on hole trapping and detrapping is demonstrated. Metal-oxide-semiconductor capacitors were fabricated with an embedded nanolayer of crystalline indium-tin-oxide layer (ITO) in the zirconium-doped hafnium oxide high-k insulating layer. Capacitance-voltage measurements show counter-clockwise hysteresis indicating a memory effect by the ITO embedded dielectric layer. Retention measurements further confirm that the cause of the hysteresis is due to injection of holes from the substrate to the ITO layer under the accumulation condition. The injected charges display excellent long-term retention after 5000 seconds.
Mixed Oxide High-k Gate Dielectrics - Interface Layer Structure, Breakdown Mechanism, and Memories
Authors: Kuo Yue
Published: November 2006

Mixed metal oxide high-k films have many advantageous dielectric properties over conventional metal oxides. In this paper, three major subjects on the mixed oxide gate stack prepared by the sputtering method, i.e., dopant influence on interface layer structures, double-layer gate stack breakdown mechanism, and new CMOS-type nonvolatile memories based on nanocrystals embedded doped oxide high-k films, are examined and discussed.
Dielectric Properties of High-K Materials : a Theoretical View
Authors: Fiorentini Vincenzo , Delugas Pietro , Filippetti Alessio , Pourtois Geoffrety
Published: November 2006

We report recent and ongoing theoretical studies of the dielectric properties of high- dielectric-constant oxides comprising transition metal and rare earth cations Results and trends are discussed for crystal and amorphous phases derived from two main structural classes: bixbyite, typical of X2O3 sesquioxides, and perovskite-based, adopted by AXO3 compounds, with A, X trivalent metals.
Composition Control of TaSixNy Thin Films by Chemical Vapor Deposition for Future n-MOSFET Metal Gate Electrode
Authors: Sugita Yoshihiro , Aoyama Takayuki , Nara Yasuo
Published: November 2006

TaSixNy has been examined as a metal gate material for n- MOSFETs of the future. In order to control the composition of the TaSixNy film, a CVD method has been newly developed, using a commercial-based 300mm machine. The CVD film composition can be modified by stacking alternate depositions of TaN and Si. The effective workfunction of the gate electrode can be adjusted through the average composition of the TaSixNy. Excellent transistor characteristics have been confirmed, using HfSiON gate dielectric and a TaSixNy gate electrode.
A Combinatorial Study of Metal Gate/HfO2 MOSCAPS
Authors: Green Martin L. , Chang Kao-Shuo , Takeuchi Ichiro , Chikyow Toyohiro
Published: November 2006

Combinatorial methodology is a rapid technique for surveying new gate dielectrics and gate metal electrodes for the very complex advanced CMOS gate stack. Here, we report on a typical metal gate electrode alloy system, the Ni-Ti-Pt ternary. We have fabricated this metal gate thin film library on HfO2 using magnetron co-sputtering, to investigate flat- band voltage shift (DeltaVfb) and leakage current density (JL) variations. Wavelength dispersive spectroscopy (WDS) results show that over 90% pm 1% of Ni and Ti, and 75% pm 1% of Pt were attained in the library. A more negative DeltaVfb is observed close to the Ti-rich corner than close to the Ni- and Pt-rich corners, implying smaller Phi m near the Ti-rich corners and higher Phi m near Ni- and Pt-rich corners. In addition, measured JL values are consistent with the observed DeltaVfb variations.
Advanced Metal Gate Electrode Options Compatible with ALD and AVD® HfSiOx-Based Gate Dielectrics
Authors: Karim Zia , Biossiere Olivier , Lohe Christoph , Zhang Zhihong , Park Woong , Manke Christian , Baumann Peter K. , Dalton Jeremie , Ramanathan Sasangan , Lindner Johannes , Seidel Tom , Lehnen Peer
Published: November 2006

We have investigated metal gate electrodes for use with high k HfSiOx gate dielectric films using AVD® and ALD technology. First, we report on the characterization of the AVD® and ALD deposition techniques where both HfO2 and SiO2 are combined for the formation of HfSiOx. Nitrogen is then incorporated using both in-situ and ex-situ methods to form HfSiON and the resulting film properties are compared. Using an AVD process a work-function of >4.7eV for Ru and RuO2 gate electrode metals in combination with HfSiOx was obtained. A TaN-based metal gate was also characterized to target a promising pMOS solution using different compositions. Together with its high flexibility and composition control, both ALD and AVD® can become key processes for advanced high-k dielectrics as well as compatible CMOS metal electrodes.
Development of a Selective Tantalum Carbide Etchant
Authors: Starzynski John S.
Published: November 2006

A superior nonflammable selective TaC etchant has been developed. This etchant possesses a TaC etch rate of 13 Aå/minute as well as TaC to HfO2 etch selectivity of 140:1. The TaC to SiO2 etch selectivity is high enough to allow the use of this etchant with a SiO2 hard mask.
Development of 300mm MOCVD HfSiOx Process
Authors: Shi Xiaoping , Schaekers Marc , Date Lucien , Rothschild Aude , Everaert Jean-Luc , Van Elshocht Sven , Rosseel Erik , Kher Shreyas
Published: November 2006

This paper reports on the development of a 300mm MOCVD HfSiOx process. Alkylamido Hf and Si are used as precursors for HfSiOx deposition. A Design of Experiments (DOE) approach is applied to explore the effects of the precursor ratio and deposition pressure on the film composition. A wide process window from 20 to 80% Hf concentration range for deposited HfSiOx was targeted for the process optimization. Furthermore the process is optimized towards growth rate, uniformity, process stability. It is found out that the deposition rate and the process pressure have a significant impact on the HfSiOx layer within wafer uniformity. The results of a process monitoring over 50 days with a recipe of 50% Hf concentration show a very good stability for film thickness, film uniformity and Hf concentration as well.