bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dielectric breakdown Characteristics of poly-Si/HfAlOx/SiON gate stack
Authors: Torii Kazuyoshi , Ohji Hiroshi , Mutoh Akiyoshi , Kawahara Takaaki , Mitsuhashi Riichiro , Horiuchi Atsushi , Miyazaki S. , Kitajima Hiroshi 
Published: July 2011

ABSTRACTThe dielectric breakdown behavior of poly-Si gate CMOSFETs with HfAlOx/SiON gate dielectric fabricated using mass production worthy 300 mm process was investigated. If SiO2 is used as an interfacial layer (IL), the IL reduction and the intermixing between the HfAlOx layer and the IL occurred, which causes extrinsic breakdown. By using the SiON of [N]=18% as an IL and setting the maximum temperature after the HfAlOx deposition to be 1000°C, the interfacial reaction was suppressed and the extrinsic breakdown component was eliminated. In the case of the n-capacitor accumulation, an abrupt increase of gate leakage was observed, which is believed to correspond to the IL breakdown. The mean time to failure (MTTF for 0.1cm2 at 125°C) is long enough. On the other hand, gate current initially decreases and then starts to increase in the case of p-capacitor accumulation. If we define the time to breakdown at the onset of current increase, the MTTF would be only 3.7 years if it obeys the V-plot (MTTF predicted by 1/V-plot was 1.6×107 years).
Reduction of CV Hysteresis in Metal/High-k MISFETs Using Flash Lamp Post Deposition Annealing
Authors: Matsuki Takeo , Akasaka Yasushi , Hayashi Kiyoshi , Noguchi Masataka , Yamashita Koji , Syoji Hideyuki , Torii Kazuyoshi , Kasai Naoki , Arikado Tsunetoshi 
Published: July 2011

ABSTRACTA Xe flash lamp (FL) heating technique was applied to the post deposition annealing process (PDA) for HfAlOx/SiO2 gate insulator with poly-Si or W/TiN gate electrode in a gate last based process. In the case of W/TiN/HfAlOx/SiO2, CV hysteresis with less than 10mV was achieved using the FL-PDA. However, the FL-PDA increased hysteresis width up to over 100 mV when poly-Si was used as a gate electrode. That occurred also with low temperature (700 °C) rapid thermal PDA process. The lower thermal budget achieved by the flash lamp annealing and the metal gate is effective to suppress the interfacial reaction which causes the traps responsible for the hysteresis. Charge trapping in the W/TiN/HfAlOx/SiO2 was evaluated using CV hysteresis characteristics in the MISFETs and the MIS capacitors. Electron was major trapped charge of the HfAlOx.
Analysis of Ferroelectric Microcapacitors by Scanning Probe Microscope
Authors: Kin Nobuhiro , Honda Koichiro 
Published: July 2011

ABSTRACTTo develop higher density FRAM requires reducing cell size. Therefore, the size effects resulting from device processing and the material's physical properties must be measured. Therefore, analyzing the electric characteristics of a single bit cell capacitor has become important. Two known characteristics of ferroelectric material are that the Vc increases at low temperatures, and the Pr falls at high temperatures. To further evaluate the impact of temperature on ferroelectrics, we constructed a new evaluation system based on a scanning probe microscope, that can measure the electric characteristics of a single bit cell capacitor. This system can be used in the temperature range from −120 degrees to 300 degrees C. We accomplished this by circulating liquid nitrogen around a SPM stage and by using an electrical heater. We measured the electrical properties of ferroelectric microcapacitors by using a sample with IrOx/PZT/Pt structure. Our measurements revealed that 2Pr really increases at low temperatures, and Pr decreases at high temperatures. That is, we have shown that Vc increases 30% at low temperatures and Pr decreases 10% also in an actual FRAM single bit cell capacitor.
Effect of different annealing procedures on the microstructure and the electrical properties of CSD derived (Ba,Sr)TiO3 thin films.
Authors: Halder Sandip , Schneller Theodor , Waser Rainer 
Published: July 2011

ABSTRACTProcessing of BST thin films is becoming more and more important for microwave electronics and for its probable incorporation in future high density DRAM's. A co-relation between processing and final device characteristics is of utmost importance. Differences in microstructure and electrical properties were observed when chemical solution deposited thin films were annealed using a conventional diffusion furnace, rapid thermal annealing furnace with different heating ramps, and a hot plate for pyrolysis prior crystallization. The solution was made with the propionate route and then deposited on Pt coated silicon wafers. Cross-sectional SEM's were performed on the different films. It was found that the microstructure depended on the annealing method of the film. The electrical properties of the films were also found to vary considerably. Frequency dependence of the dielectric constant was studied. The leakage study on different films was performed at different temperatures.
A Study of APCVD-Deposited TiO2Characteristics in the Structure of a Tunneling Transistor
Authors: Behnam A. , Hekmatshoar B. , Mohajerzadeh S. , Arvan B. , Karbassian F. , Khakifirooz A. 
Published: July 2011

ABSTRACTTiO2 and nickel-silicide layers are consequently deposited and micro machined to compose a mesa-structured tunneling transistor. The depositions are done with the RF-sputtering method and the electrical and physical characteristics of the products are investigated. Transistors show an amplification coefficient of about 20. To improve the quality and coverage of the TiO2 layer, the oxide deposition is made by means of an APCVD reactor. The grown oxide shows a dielectric coefficient between 19 and 21 and its breakdown field is about 107 V/cm.
Investigations of Metal Gate Electrodes on HfO2 Gate Dielectrics
Authors: Schaeffer Jamie , Samavedam Sri , Fonseca Leonardo , Capasso Cristiano , Adetutu Olubunmi , Gilmer David , Hobbs Chris , Luckowski Eric , Gregory Rich , Jiang Zhi-Xiong , Liang Yong , Moore Karen , Roan Darrell , Nguyen Bich-Yen , Tobin Phil , White Bruce 
Published: July 2011

ABSTRACTAs traditional poly-silicon gated MOSFET devices scale, the additional series capacitance due to poly-silicon depletion becomes an increasingly large fraction of the total gate capacitance, excessive boron penetration causes threshold voltage shifts, and the gate resistance is elevated. To solve these problems and continue aggressive device scaling we are studying metal electrodes with suitable work-functions and sufficient physical and electrical stability. Our studies of metal gates on HfO2 indicate that excessive inter-diffusion, inadequate phase stability, and interfacial reactions are mechanisms of failure at source drain activation temperatures that must be considered during the electrode selection process. Understanding the physical properties of the metal gate – HfO2 interface is critical to understanding the electrical behavior of MOS devices. Of particular interest is Fermi level pinning, a phenomenon that occurs at metal – dielectric interfaces which causes undesirable shifts in the effective metal work function. The magnitude of Fermi level pinning on HfO2 electrodes is studied with Pt and LaB6 electrodes. In addition, the intrinsic and extrinsic contributions to Fermi level pinning of platinum electrodes on HfO2 gate dielectrics are investigated by examining the impact of oxygen and forming gas anneals on the work function of platinum-HfO2-silicon capacitors. The presence of interfacial oxygen vacancies or Pt-Hf bonds is believed to be responsible for a degree of pinning that is stronger than predicted from the MIGS model alone. Interface chemistry and defects influence the effective metal work function.
Retarded Growth of Sputtered HfO2 Films on Germanium
Authors: Kita Koji , Sasagawa Masashi , Toyama Masahiro , Kyuno Kentaro , Toriumi Akira 
Published: July 2011

ABSTRACTHfO2 films were deposited by reactive sputtering on Ge and Si substrates simultaneously, and we found not only the interface layer but the HfO2 film was thinner on Ge substrate compared with that on Si substrate. A metallic Hf layer has a crucial role for the thickness differences of both interface layer and HfO2 film, since those thickness differences were observed only when an ultrathin metallic Hf layer was predeposited before HfO2 film deposition. The role of metallic Hf is understandable by assuming a formation of volatile Hf-Ge-O ternary compounds at the early stage of film growth. These results show an advantage of HfO2/Ge over HfO2/Si systems from the viewpoint of further scaling of electrical equivalent thickness of the gate oxide films.
Electrical modeling and simulation of nanoscale MOS devices with a high-permittivity dielectric gate stack
Authors: Autran J.L. , Munteanu D. , Houssa M. , Bescond M. , Garros X. , Leroux C. 
Published: July 2011

ABSTRACTThe electrical behavior of decananometer MOS transistors with high-k dielectric gate stack has been investigated using 2D numerical simulation. Two important electrostatic limitations of high-k materials have been analyzed and discussed in this work: i) the gate-fringing field effects which compromise short-channel performance when simultaneously increasing the dielectric constant and its physical thickness and ii) the presence of discrete fixed charges in the gate stack, suspected to be at the origin of the stretch-out of C-V characteristics, that induces 2D potential fluctuations in the structure. In both cases, the resulting degradation of transistor operation and performance is evaluated with a two-dimensional quantum simulation code.
Pr4f occupancy and VB/CB band offsets of Pr2O3 at the interface to Si(001) and SiC(0001) surfaces
Authors: Schmeißer Dieter , Muessig H.J. 
Published: July 2011

AbstractResonant photoelectron spectroscopy (PES) at the Pr4d and O1s absorption edges is used to study the electronic properties at the interface of epitaxial grown Pr2O3 on Si(001).In the electronic structure of bulk Pr2O3 the valence band (VB) states are predominantly of Pr6s and O2p atomic parentage. The contribution of Pr4f states are identified from the strong increase the VB features at the Pr4d resonances. The data at the O1s edge are caused by Raman scattering and resonant Auger decay and reflect the existence of CT complexes. They are the consequence of mixed valency caused by ligand-to-Pr4f charge transfer states. The decrease of their intensity is attributed to an increase in covalent bandwidth between the Ligand (O2p, Si3p) and Pr4f states. The CT complexes originally localized now become broadened and form gap states which fill the gap towards a metallic density of states. The metallic phase may be hindered upon alloying with SiO2 or other oxides
Nitrogen Distribution and Oxidation of HfOxNy Gate Dielectrics Deposited by MOCVD using [(C2H5)2N]4Hf with NO and O2
Authors: Lee Minsoo , Landheer Dolf , Wu Xiaohua , Couillard Martin , Lu Zhenghong , Ng Wai T. , Chen Jianhao , Chao Tiensheng , Lei Tanfu 
Published: July 2011

ABSTRACTUltra-thin HfOxNy gate dielectric films were deposited by pulse-mode metalorganic chemical vapor deposition (MOCVD) with [(C2H5)2N]4Hf (TDEAH) and either NO or O2 as oxidants. Nitrogen incorporation was studied by x-ray photoelectron spectroscopy (XPS) and spatially-resolved elemental profiles were obtained by scanning transmission electron microscopy (STEM) coupled with electron energy loss spectroscopy (EELS) and energy dispersive x-ray spectroscopy (EDS). The results indicate that nitrogen is incorporated throughout the high-k film with a higher concentration in the interface layer between the deposited layer and the Si(100) substrate. The concentration of nitrogen is increased in both layers by using NO instead of O2 as the oxidant. The N in the deposited and interface layers can be replaced by oxygen during oxygen ambient annealing at temperatures above 500 °C. Films with 8 at.% nitrogen remain amorphous following vacuum annealing at temperatures up to 800 °C. By encapsulating vacuum-annealed films with amorphous Si from an e-beam evaporator prior to removal from the cluster tool, it was possible to reduce the thickness of the interface layer upon air exposure to the 0.5 nm range.
Ozone-Based Atomic Layer Deposition of HfO2 and HfxSi1-xO2 and Film Characterization
Authors: Senzaki Yoshihide , Park Seung , Tweet Douglas , Conley John F. , Ono Yoshi 
Published: July 2011

Abstract:New ALD processes for hafnium silicate films have been developed at Aviza Technology by co-injection of tetrakis(ethylmethylamino)hafnium and tetrakis(ethylmethylamino)silicon precursors. Alternating pulses of the Hf/Si precursor vapor mixture and ozone allow process temperatures below 400°C to grow HfxSi1-xO2 films. Film characterization, including film density, crystallinity, and thermal anneal effect, was performed on five 20 nm thick HfxSi1-xO2 films where x = 0.2, 0.4, 0.6, 0.8, 1.0. X-ray measurements revealed the film densities and thicknesses for the as-deposited and 1000°C annealed samples. The densification with anneals seen in the optical measurements were confirmed. The as-deposited amorphous HfO2 and Hf0.8Si0.2O2 were crystallized after a 600°C anneal. The HfO2 formed the well known monoclinic phase while the silicate formed a face-centered-cubic (fcc) structure. This fcc phase has only recently been mentioned in the literature [1].
Process Optimization and Integration of HFO2 and HF-Silicates
Authors: Takeuchi Hideki , King Tsu-Jae 
Published: July 2011

ABSTRACTWe have established in-line characterization techniques for analyzing the bulk and interface-charge properties of dielectric films, for process optimization. Surface charge analysis (SCA) is used to determine the densities of interface states, fixed charge, and near-interface traps in ultra-thin dielectrics, and is useful for tracking the influence of post-deposition processing on interface-charge properties. Spectroscopic ellipsometry (SE) is used to obtain the absorption spectra in the conduction band-tail region. The intensity of an extra absorption peak inside the bandgap of HfO2 is clearly correlated with leakage current density and near-interface trap density. Based on the observed process dependencies, defects within the HfO2 films are likely to be oxygen vacancies. The relative scalability of HfO2 and Hf-silicate films of various compositions is examined using a figure of merit based on the direct-tunneling leakage current model. Pure HfO2 is expected to be more scalable than Hf-silicates. However, it is typically accompanied by an interfacial layer which significantly increases the equivalent oxide thickness (EOT). A 20% Hf silicate with relative permittivity of 11 or higher can be more scalable than HfO2 with an interfacial layer. Alternatively, an ultra-thin interfacial Si3N4 diffusion barrier can be used with HfO2, to allow for more aggressive EOT scaling. The dependencies of interface-charge properties and surface roughness on the nitride barrier formation process are presented.
Systematic Examination of Boron Diffusion Phenomenon in HfSiON High-k Gate Insulator
Authors: Koyama Masato , Ino Tsunehiro , Kamimuta Yuuichi , Suzuki Masamichi , Nishiyama Akra , Hongo Chie 
Published: July 2011

ABSTRACTIn this paper, boron diffusivities in HfSiON high-k gate dielectric films are systematically investigated for a wide range of the film composition. Boron diffusivities in HfSiON (1000°C) change from 3X10−17cm2/sec to 3X10−15cm2/sec according to the change in the chemical composition of the films. These diffusivity values are higher than that in SiON but lower than that in HfO2. We found that higher Hf/(Hf+Si) results in great increase of diffusivities. On the other hand, higher nitrogen concentration in the film leads to the reduction in diffusivity, in the case of the same Hf/(Hf+Si). In addition, crystallization of HfSiON with the same chemical composition gives rise to an anomalous increase in diffusivities, indicating that the micro-crystallized film structure of HfSiON critically affects the microscopic mechanism of boron diffusion in this material.
Low temperature sputter deposition of Ba0.96Ca0.04Ti0.84Zr0.16O3 thin films on Ni electrodes
Authors: Cramer N. , Philofsky Elliot , Kammerdiner Lee , Kalkur T. S. 
Published: July 2011

ABSTRACTThe integration of high-K materials, such as ferroelectrics in the paraelectric state, in integrated circuits presents several challenges. If high-K materials are deposited on-chip after or between Al metalization steps, then these challenges include limits on processing gas composition, deposition temperature and electrode material. Specifically, the atmosphere present during deposition and annealing must be oxygen-free; the deposition and annealing temperatures must not exceed 450°C; and the electrode material must be etchable with chemical techniques. We studied rf magnetron sputtered Ba0.96Ca0.04Ti0.84Zr0.16O3 (BCTZ) with Ni electrodes because this system meets all the above requirements. The BCTZ deposition process uses pure Ar as the sputter gas and a substrate temperature of 450°C. Subsequent anneals may be performed in a reducing (forming gas) atmosphere with little effect on either the dielectric constant or leakage current. The Ni electrodes provide a good substrate for BCTZ films and are much easier to integrate than Pt films. Observed values for the relative dielectric constant K, exceeding 100, were not as high as for BCTZ films on Pt electrodes, however these values are sufficient to provide a clear advantage over other, non-ferroelectric materials. Overall, the device characteristics observed prove that the Ni/BCTZ/Ni capacitor is a valuable technology for on-chip capacitor applications.
Microstructure and Ferroelectric Characteristics of Ultra-Thin BaTiO3 Films
Authors: Drezner Y. , Berger S. 
Published: July 2011

AbstractMicrostructure studies of ultra-thin BaTiO3 thin films (2-10 nm thick) show nano-domains having a width as small as one unit cell. Only 180° nano-domains are formed in multi-domains structures. The domain-boundaries are formed at {001} twin boundaries. Most of the domains are oriented in parallel to the film plane but out-of-plane orientations are also observed. The films exhibit ferroelectric behavior characterized by a polarization hysteresis loop and a relatively fast switching time. A remnant polarization of about 0.5 μC/cm2 and coercive field of 2.7 V/cm were measured in parallel to the film plane. Temperature-dependent measurements show two peaks of the dielectric constant at about 60°C and 115°C. These peaks are attributed to two transition temperatures associated with the orientation of the nano-domains relative to the film plane and stress.
Properties of Pr-based high k dielectric films obtained by Metal-Organic Chemical Vapor Deposition
Authors: Nigro Raffaella Lo , Toro Roberta G. , Malandrino Graziella , Raineri Vito , Fragalà Ignazio L. 
Published: July 2011

ABSTRACTWe report the results of a recent study on the deposition of praseodymium oxides thin films on silicon substrates by Metal-Organic Chemical Vapor Deposition (MOCVD). A suited Pr(III) β-diketonate precursor has been used as the metal source and the deposition conditions have been carefully selected because of a large variety of possible PrO2−x (x= 0−0.5) phases. Pr2O3 films have been obtained in a hot-wall MOCVD reactor under non oxidising ambient at 750°C deposition temperature. The structural and morphological characteristics of Pr2O3 films have been carried out by X-ray diffraction (XRD) and high resolution transmission electron microscopy (TEM). Chemical compositional studies have been performed by X- ray photoelectron spectroscopic (XPS) analysis and a fully understanding of the MOCVD process has been achieved. Preliminary electrical measurements point to MOCVD as a reliable growth technique to obtain good quality praseodymium oxide based films.
Epitaxial Growth and Structure of Thin Single Crystal γ-Al2O3 Films on Si (111) Using e-Beam Evaporation of Sapphire in Ultra-High Vacuum
Authors: Hong M. , Kortan A. R. , Kwo J. , Mannaerts J. P. , Wu S. Y. 
Published: July 2011

ABSTRACTWe have characterized the structure of epitaxial Al2O3 films deposited on Si (111) substrate using electron beam evaporation from a high-purity single crystal sapphire source in a molecular beam epitaxy (MBE) approach. The structural studies were carried out mainly by single crystal x-ray diffraction with the initial epitaxial growth observed by in-situ reflection high energy electron diffraction. The Al2O3 films grow in the cubic γ-phase with a very uniform thickness, and a high structural perfection. The <111> axes of the film and the Si substrate are well aligned. A mosaic scan of the Al2O3 (222) peak (with no in-plane component) finds a 0.3 degree (or 18') spread. All three unit cell vectors of the film and the substrate are parallel, but the in-plane cone scans of the {004} and {044} diffraction peaks about the surface normal find a ±3 degree film in-plane rotation with respect to the substrate surface orientation.
Growth of Pr2O3 layers by pulsed injection MOCVD
Authors: Abrutis A. , Bartasyte A. , Teiserskis A. , Saltyte Z. , Baumann P.K. , Schumacher M. , Lindner J. , McEntee T. 
Published: July 2011

ABSTRACTPraseodymium oxide Pr2O3 (and Pr6O11) layers were deposited by innovative pulsed injection MOCVD technique on Si(100) in the temperature range 400-750°C. Praseodymium 2,2,6,6-tetramethyl-3,5-heptanedionate dissolved in monoglyme (1,2-dimethoxyethane) or toluene was used as precursor material. The influence of deposition conditions on film composition, growth rate, crystallization and surface roughness has been investigated. The main parameters influencing film composition and properties were substrate temperature and partial oxygen pressure during deposition. The presence of molecular oxygen in the reactor leads to the growth of Pr6O11 as the most stable phase or its mixture with PrO2, while deposition in inert atmosphere (Ar, 2 torr) allows to obtain Pr2O3 films which were amorphous or crystalline depending on the deposition temperature. Crystallized (polycrystalline) Pr2O3 films can be obtained at the growth temperatures 650°C and higher, while crystalline Pr6O11 films grow starting 400°C. Ex-situ annealing (750°C, vacuum, 2 hours) of the amorphous Pr2O3 films leads to film crystallization. Step coverage study has been performed for amorphous and crystallized Pr2O3 films. Electrical properties of thin (∼10 nm) Pr2O3 films were investigated and encouraging EOT (equivalent oxide thickness), leakage current data have been obtained.
Cover Me: Managers' Responses to Changes in Analyst Coverage in the Post-Regulation FD Period
Authors: Anantharaman Divya , Zhang Yuan 
Published: July 2011

ABSTRACT
We show that managers increase the volume of public financial guidance in response to decreases in analyst coverage of their firms, particularly to decreases that are driven by exogenous reduction in brokerage firm size. Managers do not respond to increases in analyst coverage. The managerial guidance response to decreases in coverage reflects the trade-off between the marginal benefits from analyst coverage and the marginal costs of providing guidance. Specifically, the response is concentrated within firms engaging in equity issuance activities, firms with low stock liquidity, and firms with low current guidance levels. The response is also concentrated within firms whose remaining analyst pool is smaller in number and/or has a lower percentage of analysts who are positive about the firm or who belong to a large brokerage house. Overall, our results shed insights on the interaction between managers and analysts and on how the value of analysts, as perceived by managers, varies in the cross-section with underlying firm and analyst characteristics.
Data Availability: All data used in this study are publicly available from sources identified in the text.