bluuebunny/crossref_metadata_2025_split huggingface dataset:
ALD HfO2 surface preparation study
Authors: Delabie Annelies , Caymax M. , Maes J. W. , Bajolet P. , Brijs B. , Cartier E. , Conard T. , De Gendt S. , Richard O. , Vandervorst W. , Zhao C. , Green M. , Tsai W. , Heyns M. M. 
Published: April 2011

ABSTRACTA fast screening technique is used to study the ALD HfO2 growth behavior on different types of starting surfaces (H-passivated, chemical oxide, thermal oxide). The amount of Hf deposited at the early stages of the ALD process is measured by means of RBS. The HfO2 film quality on different starting surfaces is examined with ToFSIMS. The results suggest an island growth mechanism on a H-terminated starting surface: nucleation, development of separated nuclei and flattening. It is shown that ALD growth starts faster if –OH groups are present on the surface. A remote H2 plasma surface pre-treatment at room temperature is also studied. The influence of the plasma exposure time and number of water pulses prior to HfO2 deposition was examined. The H2 plasma surface pre-treatment can be considered as a promising candidate for sub 1 nm EOT performance.
A New Approach for Metal Oxide Film Growth: Vapor-Liquid Hybrid Deposition (VALID)
Authors: Yasuda Tetsuji , Kuse Ronald 
Published: April 2011

ABSTRACTWe propose a new process for forming ultra-thin metal oxide films called vapor-liquid hybrid deposition (VALID). This process consists of two steps: i) adsorption of a metal-organic or metal-halide precursor from the gas phase, and ii) liquid-phase hydrolysis of the adsorbed precursors. Al2O3 films were grown using Al(CH3)3 and water. Growth rate was 0.18 nm per cycle at room temperature. The interface layer thickness was less than 1 nm after post-deposition annealing in vacuum at 750°C. C-V and I-V characteristics of Au/Al2O3/Si capacitors fabricated using VALID were well-behaved suggesting that this concept is a viable approach to form device-quality dielectrics.
Interface Quality and Electrical Performance of Low-Temperature Metal Organic Chemical Vapor Deposition Aluminum Oxide Thin Films for Advanced CMOS Gate Dielectric Applications
Authors: Skordas Spyridon , Papadatos Filippos , Consiglio Steven , Eisenbraun Eric , Kaloyeros Alain 
Published: April 2011

ABSTRACTIn this work, the electrical performance and interfacial characteristics of MOCVD-grown Al2O3 films are evaluated. Electrical characteristics (dielectric constant, leakage current) of as-deposited and annealed capacitor metal-oxide-semiconductor (MOS) stacks were determined using capacitance-voltage (C-V) and current-voltage (I-V) measurements. It was observed that the electrical properties were dependent upon specific annealing conditions, with an anneal in O2 followed by forming gas being superior with respect to leakage current, resulting in leakage characteristics superior to those of SiO2. All annealing conditions evaluated led to an increase in dielectric constant from 6.5 to 9.0–9.8. Also, Al2O3 growth and interfacial oxide growth characteristics on oxynitride/Si and Si substrates were evaluated and compared using spectroscopic ellipsometry. A parasitic oxide layer was observed to form on silicon during the initial stages of MOCVD Al2O3 growth, while a thin oxynitride layer deposited on Si prevented the growth of interfacial oxide.
Effect of Post-Metallization Hydrogen Annealing on C-V Characteristic of Zirconia Grown Using Atomic Layer Deposition
Authors: Chakraborty Arpan , Mane Anil U. , Shivashankar S. A. , Venkataraman V. 
Published: April 2011

ABSTRACTSubstantial amount of fixed charge present in most of the alternative gate dielectrics gives rise to large shifts in the flat-band voltage (VFB) and charge trapping and de-trapping causes hysterectic changes on voltage cycling. Both phenomena affect stable and reliable transistor operation. In this paper we have studied for the first time the effect of post-metallization hydrogen annealing on the C-V curve of MOS capacitors employing zirconia, one of the most promising gate dielectric. Samples were annealed in hydrogen ambient for up to 30 minutes at different temperatures ranging from room temperature to 400°C. C-V measurements were done after annealing at each temperature and the hysteresis width was calculated from the C-V curves. A minimum hysteresis width of ∼35 mV was observed on annealing the sample at 200°C confirming the excellent suitability of this dielectric.
MOCVD of HfO2 from Alkoxide and Alkylamide Precursors
Authors: Roberts John L. , Williams Paul A. , Jones Anthony C. , Marshall Paul , Chalker Paul R. , Bickley Jamie F. , Davies Hywel O. , Smith Lesley M. 
Published: April 2011

ABSTRACTThe alkoxide and alkylamide complexes [Hf(mmp)4] and [Hf(NMe2)4] 2 are both promising precursors for the MOCVD of HfO2. A comparison has shown that [Hf(NMe2)4] 2 deposits oxide at lower temperatures and over a wider temperature range then [Hf(mmp)4].
Advanced PECVD-Based Anti-Reflective Coating for 90nm Generation Interconnects
Authors: Ahn Sang H. , Fung Miguel , Jung Keebum , Zhu Lei , Bencher Chris , Kim B H , M'Saad Hichem 
Published: April 2011

ABSTRACTA plasma-enhanced chemical vapor deposition-based nitrogen-free dielectric anti-reflective coating was successfully developed for use in 90nm interconnects in conjunction with low κ materials. By choosing N-free precursors, it was possible to eliminate any adverse interactions between the NH2 amine group and the DUV 193nm photoresist that is directly in contact with the anti-reflective coating (ARC), thus eliminating major source of photoresist poisoning-induced footing. N-free dielectric ARC demonstrated a wide tunable range of its optical properties at 193nm in a single wafer PECVD reactor: 1.6<n<1.9 and 0< k<1.1. This range enables cost-effective and in-situ deposition of a dual-layer dielectric ARC on the low λ dielectric layers during the dual damascene process. The dual-layer coating, which consists of a phase-shift layer on an absorbing layer, can keep the substrate reflectivity below 1% across the wafer, minimizing CD swing. N-Free dielectric ARC can be easily integrated with low κ dielectrics. Its adhesion with low κ materials is excellent and it can be etched and chemically and mechanically polished together with low κ dielectrics.
Characteristics of Ultra Shallow B Implantation with Decaborane
Authors: Li Cheng , Albano Maria A. , Gladczuk Leszek , Sosnowski Marek 
Published: April 2011

ABSTRACTThe characteristics of ultra shallow B implantation with mass-analyzed decaborane cluster ions (B10Hx+) are presented. Depth profiles of B and co-implanted H were measured by SIMS, before and after annealing. Annealing results in the increase in the depth of B distribution, due to diffusion, but most of H diffuses out of Si. While the sputtering yield of Si per incoming B in a cluster was found to be comparable to the estimated sputtering yield of Si with B+ ions of the equivalent energy (∼ 1.2 keV), the surface effects of the two types of ions may be quite different. Atomic force microscopy revealed that the smoothing effect of the small decaborane cluster ions, observed previously by us on a surface of amorphous Si, is also present on crystalline Si and even on a much rougher surface of polycrystalline Ta film. The smoothing affects different parts of the power density spectra as functions of spatial frequency in the amorphous and crystalline materials. The smoothing on c-Si surfaces is in sharp contrast to roughening of these surfaces by irradiation with monomer Ar ions, which was done for reference. This indicates that different ion-surface interaction mechanisms are needed to describe impacts of cluster and of monomer ions. All other effects of Si implantation with B10Hx+ measured to date were found to be the same as those with B+ ions of equivalent energy and dose, which confirms that decaborane implantation is an alternative to the very low energy B implantation for ultra shallow p-type junctions in Si devices.
Growth Temperature Effects on Deep-Levels in Si Grown by Low Temperature Molecular Beam Epitaxy
Authors: Chung Sung-Yong , Berger Paul R. , Fang Z-Q. , Thompson Phillip E. 
Published: April 2011

ABSTRACTDeep-level transient spectroscopy (DLTS) measurements were performed on Si:Sb and Si:B n+-p step junction diodes grown by LT-MBE at various growth temperatures. The trap density dependence on growth temperature decreases with increasing temperature. However, segregation and diffusion increase with increasing temperature. Electron traps, E1 (0.42–0.45eV) and E2 (0.257eV), and hole traps, H1 (0.38–0.41eV), were found in B-doped layer grown at 370°C, 420°C, 500°C, and 600°C. These traps have been characterized by their capture cross-section, activation energy level, and trap density. The origins of the dominating electron traps are hypothesized as the association with pure divacancy defects. E1 level can be assigned for singly negatively charged divacancy V(0/-) + α and E2 level for doubly negatively charged divacancy V(-2/-).
High κ Gate Dielectrics For Si And Compound Semiconductors By Molecular Beam Epitaxy
Authors: Raynien Kwo J. , Hong Minghwei 
Published: April 2011

ABSTRACTThe ability of controlling the growth and interfaces of ultrathin dielectric films on Si and compound semiconductors by ultrahigh vacuum physical vapor deposition has led to comprehensive studies of gate stacks employing the high κ gate oxide Ga2O3(Gd2O3), and the rare earth oxides Gd2O3and Y2O3. The epitaxy and the interfaces of Gd2O3on GaAs, GaN, and Si were characterized with atomic precision, and show strong tendency to conform to the underlying substrate, thus providing insight into the fundamental mechanism for low interfacial state density and effective passivation of GaAs and GaN surfaces. These Gd2O3and Y2O3gate stacks of abrupt interfaces and controlled microstructures were employed as a model system to elucidate critical issues of materials integration in CMOS scaling.
Improvement of capacitance-voltage (C-V) characteristics of YSZ/Si(001) and ZrO2/Si thin film by Nb-doping
Authors: Wakiya Naoki , Moriya Tomohiko , Shinozaki Kazuo , Mizutani Nobuyasu 
Published: April 2011

ABSTRACTYttria stabilized zirconia (YSZ) and zirconia (ZrO2) thin films without and with Nb-doping were prepared on Si substrate by rf-magnetron sputtering. Undoped YSZ and ZrO2 thin films had (001) orientation, and the orientation was unchanged by the Nb-doping. For both undoped YSZ and ZrO2 thin films, around 2.0 V ion-drift type hysteresis was clearly observed in capacitance-voltage (C-V) characteristics. Nb-doping into YSZ brought about the increase of lattice parameter up to 20 mol% of Nb, which suggests that Nb was incorporated into YSZ lattice up to 20 mol%. By the Nb-doping, the hysteresis in C-V characteristics for YSZ thin film was considerable decreased to around 0.1 V. Drastic suppression of the hysteresis in C-V characteristics was observed for Nb-doped ZrO2 thin film. In this case, the hysteresis was completely disappeared. These facts suggest that oxygen vacancies in YSZ and ZrO2 thin films would be suppressed or disappeared by Nb-doping. This means that Nb is a excellent dopant for both YSZ and ZrO2 to suppress the ion-drift type hysteresis.
Study of interface formation of (Ba,Sr)TiO3 thin films grown by rf sputter deposition on bare Si and thermal SiO2/Si substrates.
Authors: Suvorova N. A. , Mueller A. H. , Suvorova A. A. , Saunders M. , Irene E. A. 
Published: April 2011

ABSTRACT(Ba,Sr)TiO3 (BST) thin films were deposited by ion beam sputtering on both bare and oxidized Si. Spectroscopic ellipsometry (SE) model results have shown an increase in the SiO2 layer thickness for bare substrates and those with a 1 nm initial oxide layer, and a decrease for thicker (3.5 nm) initial SiO2 films. This result was confirmed by high resolution electron microscopy (HREM) analysis of the films, and it is believed to be due to simultaneous subcutaneous oxidation of Si and reaction of the BST layer with SiO2. From high-frequency capacitance-voltage (C-V) analysis, a decrease in the interface trap density Dit of an order of magnitude was observed for oxidized Si substrates.
A study of Al2O3:C films on Si(100) grown by low pressure MOCVD
Authors: Singh M. P. , Thakur C. S. , Bhat N. , Shivashankar S. A. 
Published: April 2011

ABSTRACTWe report the characterization of carbonaceous aluminium oxide, Al2O3:C, films grown on Si(100) by metalorganic chemical vapor deposition. The focus is on the study of the effects of carbon on the dielectric properties of aluminium oxide in a qualitative manner. The carbon present in the aluminium oxide film derives from aluminium acetylacetonate used as the source of aluminium. As-grown films comprise nanometer-sized grains of alumina (∼ 20–50 nm) in an amorphous carbonaceous matrix, as examined by X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The films are shiny; they are smooth as observed by scanning electron microscopy (SEM). An attempt has been made to explore the defects (viz., oxide charge density) in the aluminium oxide films using room temperature high frequency capacitance – voltage (C-V) and current–voltage (I-V) measurements. The hysteresis and stretch-out in the high frequency C-V plots is indicative of charge trapping. The role of heteroatoms, as characterized by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy, in the transport of charge in Al2O3:C films is discussed.
Measurement of Three Dimensional Polarization Direction in Ferroelectric Thin Films Using Scanning Nonlinear Dielectric Microscopy with Rotating Electric Field
Authors: Odagawa Hiroyuki , Cho Yasuo 
Published: April 2011

ABSTRACTA scanning nonlinear dielectric microscope (SNDM) probe, called theε311 -type probe, and a system to measure the ferroelectric polarization component parallel to the surface using rotating electric field have been developed. This is achieved by measuring the ferroelectric material's nonlinear dielectric constant ε311 instead of ε333, which is measured in conventional SNDM. Experimental result shows that we can successfully determine polarization component parallel to the surface. The SNDM system can measure polarization at any angle from the surface normal which is often of interest.
Local Electromechanical Properties and Grain Size Effects in Ferroelectric Relaxors Studied by Scanning Piezoelectric Microscopy
Authors: Kholkin A. L. , Shvartsman V. V. , Woitas M. , Safari A. 
Published: April 2011

ABSTRACTThe local electromechanical properties of relaxor 0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3 (PMN-PT) films are investigated by Scanning Force Microscopy (SFM) in a piezoelectric contact mode. The domain contrast is observed only in some grains (∼20 % of the entire surface), which showed clear ferroelectric behavior. Thus on the microscopic level the material behaves as a composite with ferroelectric regions embedded in the non-polar matrix. This was attributed to the relaxor-to-ferroelectric phase transition induced by the internal bias field. The local hysteresis loops are found to depend on the size of the grains. A distinct correlation between the values of the effective piezoelectric coefficients, deffi and the size of the respective grains is observed. Small grains exhibit slim piezoelectric hysteresis loops with low remanent deff while relatively strong piezoelectric activity is characteristic of larger grains. In addition, large grains exhibit longer relaxation time after poling with an effective time constant increasing with the grain size. The nature of size effect is discussed taking in terms of dynamics of nanopolar clusters and SFM instrumentation.
Platinum-Accelerated Phase Transition in Bismuth-Based Layer-Structured Ferroelectric Thin Films
Authors: Kato Kazumi , Suzuki Kazuyuki , Fu Desheng , Nishizawa Kaori , Miki Takeshi 
Published: April 2011

ABSTRACTThe phase transition of non ferroelectric pyrochlore to ferroelectric perovskite in CaBi4Ti4O15 thin films depended on matching of the atomic arrangements in platinum bottom electrodes to the Ca-Bi-Ti-O thin films. CaBi4Ti4O15 thin films crystallized on (200)-oriented platinum at 650°C showed c-axis orientation. In contrast, thin films randomly crystallized on highly crystalline (111)-oriented platinum at the same temperature contained pyrochlore phase and showed P-V hysteresis loops. The ferroelectric properties improved with the degrees of (h00) orientation.
Ferroelectric Properties in Ca Substituted SrBi2Nb2O9 Thin Films
Authors: Das Rasmi R. , Pérez W. , Bhattacharya P. , Katiyar Ram S. 
Published: April 2011

ABSTRACTWe have studied the influence of partial substitution of Ca (0%, 5%, 10% and 15%) on the structural and electrical properties of SrBi2Nb2O9 (SBN) thin films. Pulsed laser deposition technique was used to grow thin films on platinized silicon substrates. X-ray diffraction data confirmed the polycrystalline nature of the films with preferential orientation along the polarization axis. Incorporation of Ca at Sr-site of SBN reduced the lattice parameter and was attributed to the smaller ionic radii of Ca. The soft mode frequency at 29.5 cm-1 of SBN shifted towards higher wavenumber implied increasing the transition temperature upon Ca substitution. The grain sizes of SBN thin films vary from oval to rod like structures and improving the homogeneous distribution of grains with the increase in Ca contents. The ferroelectric properties of the films enhanced with maximum remanent polarization of 35.3 mC/cm2. The increase in the coercive field with incorporation of Ca at Sr-site was attributed to the higher electronegativity of Ca. The SBN thin films with the incoporation of Ca exhibited poor leakage current behavior. The reduction of dielectric permittivity with Ca concentration was attributed to the lower dielectric permittivity of CaBi2Nb2O9.
PbZr0.53Ti0.47O3 (PZT) Thin Films on La0.5Sr0.5CoO3 (LSCO) Bottom Electrodes Prepared by Chemical Solution Deposition and Annealed at Different Temperatures
Authors: Malic Barbara , Javoric Sasa , Kosec Marija , Jiménez Ricardo , Alemany Carlos 
Published: April 2011

ABSTRACTPbZr0.53Ti0.47O3 (PZT) films on La0.5Sr0.5CoO3 (LSCO) /Pt electrodes crystallize in the perovskite phase at 550°C. Cross section SEM shows a columnar grain structure of PZT films on fine-grained LSCO. The ferroelectric response of the heterostructures depends on the annealing temperature of the LSCO layer. The remanent polarization and coercive field of the PZT annealed at 550 °C deposited on LSCO annealed at 800 °C are 25 μC/cm2 and 99 kV/cm respectively, comparable to the values obtained for PZT films on platinized silicon substrate.
Self-poling Effects in Sol-gel Derived Pb(Zr1-xTix)O3 Thin Films
Authors: Cheng Jinrong , Li Nan , Eric Cross L. , Meng Zhongyan 
Published: April 2011

ABSTRACTBased on the direct piezoelectric effect, the measurement of piezoelectric module d33 was conducted to examine the self-poling effect in sol-gel derived Pb(Zr1-xTix)O3 (PZT) thin films. It is observed that as-prepared PZT thin films have piezoelectric responses being dependent upon the film thickness and composition. The higher d33 of 26 pC/N is achieved for ∼0.4 μm thick PZT thin films with Zr/Ti ratio of 53/47. The d33 value decreases with increasing the film thickness for as-prepared PZT thin films, however, increases for the same film after external poling. The origin of the self-poling effect was briefly discussed based on the formation of an internal bias field in PZT thin films.
Contribution of Pb to Ferroelectricity in Perovskite-type Oxides
Authors: Miyazawa Hiromu , Ishii Fumiyuki , Ishida Masaya , Natori Eiji , Shimoda Tatsuya , Oguchi Tamio 
Published: April 2011

ABSTRACTWe have studied the nature of the covalent bond between Pb 6s, 6p and O 2p orbitals in perovskites based on first-principles calculations. We conclude that the Pb 6p - O 2p covalent bond, not a bond involving Pb 6s, is crucial for the large ferroelectric effect in PbTiO3. The Pb 6s states behave like a shallow core level. To examine the effect of a Pb atom at the A site in the perovskite-type structure, we compared several calculated properties of PbTiO3 and BaTiO3 - the electric polarization, piezoelectric stress tensor and Young's modulus. The piezoelectric stress tensor e33 was calculated through Berry phase theory. BaTiO3 was found to have a larger e33 value than PbTiO3. In the case of BaTiO3, the response of Ti-O(2) to c-axis distortion is larger than in PbTiO3. We found that PbTiO3 is softer than BaTiO3 because of the cooperation of both Ti-O(2) and Pb-O(1) covalent bonds. We also found that the ferroelectric state is much softer than the paraelectric state. We propose that in the structural phase transition the system with the lower symmetry avoids ion repulsion through the additional degree of freedom available from atom displacement.
Retention characteristics of Pb(Zr, Ti)O3 films deposited by various methods for high-density non-volatile memory
Authors: Shin Sangmin , Hofmann Mirko , Lee Yong Kyun , Cho Choong Rae , Lee June Key , Park Youngsoo , Lee Kyu Mann , Song Yoon Jong 
Published: April 2011

ABSTRACTRetention loss is a significant issue for an application of ferroelectric thin films to high-density non-volatile memory devices. We investigated the polarization retention characteristics of ferroelectric Pb(Zr,Ti)O3 (PZT) thin films which were fabricated on Pt/IrO2/Ir substrates by different deposition methods. In thermally-accelerated retention failure tests, Pb(Zr,Ti)O3 (PZT) films which were prepared by a chmeical solution deposition (CSD) method showed rapid decay of retained polarization charges as the films became thinner down to 1000 Å, while the films which were grown by metal organic chemical vapor deposition (MOCVD) showed relatively large nonvolatile charges at the same thickness. We concluded that in the CSD-grown films, the relatively large interfacial passive layer compared with the MOCVD-grown films had an unfavorable effect on retention behavior. We observed the existence of such interfacial layers by extrapolation of the total capacitance with thickness of the films and the capacitance of this layer was larger in MOCVD-grown films. It means that the possibility of the accumulation of space charges at the interface was reduced, so that less imprint and less retention loss could be observed in the MOCVD-grown films.
SrTiO3 Thin Film Varactors on Si for Microwave Applications
Authors: Vorobiev Andrei , Rundqvist Par , Khamchane Khaled , Gevorgian Spartak 
Published: April 2011

ABSTRACTDielectric properties of SrTiO3 (STO) thin films in Au/Pt/STO/Pt/TiO2/SiO2/Si structure are studied at microwave frequencies. STO films with thickness of 300 nm were grown by laser ablation at different temperatures on templates of Pt/TiO2/SiO2 on Si with resistivity of 5 kQ-cm. XRD measurements reveal highly textured (111)STO films with small amount of (100) and (110) domains. The full with at half maximum of the rocking curve of (11 1)STO domains is about 2 degrees. Circular Au/Pt top electrodes with diameters in the range of 10–60 μm were formed by e-beam evaporation and lift-off process. The on chip microwave impedance of devices was measured in the frequency range of 45 MHz-45 GHz as a function of DC electric field in the range of 0–800 kV/cm. The loss tangent is less than 0.06 in the whole frequency range. Application of DC bias results in resonant absorption of microwave power at frequencies of 1.3, 3.0, 4.7, 6.4, and 9.7 GHz. The relative change of the dielectric permittivity under 800 kV/cm DC field is more than 20% in the whole frequency range. The results indicate that the varactors based on these STO films are suitable for tunable microwave applications.