bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Hydrogen in Concrete by Cold Neutron Prompt Gamma-Ray Activation Analysis and Neutron Incoherent Scattering
Authors: Paul Rick L. , Chen-Mayer H. Heather , Lindstrom Richard M. , Blaauw Menno 
Published: April 2011

ABSTRACTA combination of cold neutron prompt gamma-ray activation analysis (PGAA) and neutron incoherent scattering (NIS) has been used for nondestructive characterization of hydrogen as a function of position in slabs of wet concrete of different compositions. Hydrogen was determined by PGAA by scanning each sample across a 5 mm diameter neutron beam in 10 mm increments, and measuring the 2223 keV prompt gamma ray. NIS measurements were performed by scanning the sample across a 5 mm diameter neutron beam at 5 mm increments and detecting scattered neutrons. The measurements demonstrate the feasibility of the techniques for 2D compositional mapping of hydrogen and other elements in materials, and indicate the potential of these methods for monitoring the uniformity of drying concrete.
Photoelastic Imaging of Process Induced Defects in 300mm-Silicon Wafers
Authors: Geiler H.D. , Kürner W. , Storbeck O. 
Published: April 2011

ABSTRACTProcess induced crystal defects in silicon wafers can be detected by their stress fields. The nondestructive photoelasticity based on laser polarimetry is applied to visualize the stress fields of temperture gradient induced lattice defects like sliplines or extended defect areas around boat marks. The quantitative evaluation of the defects allows their characterization by a specific danger potential for further evolution causing upstream problems in IC manufacturing.
In Situ Spectroscopic Ellipsometry for the Real Time Process Control of Plasma Etching of Silicon Nitride
Authors: Rosen I. G. , Parent T. , Fidan B. , Madhukar A. 
Published: April 2011

ABSTRACTSpectroscopic ellipsometry (SE) is a commonly used non-destructive, non-invasive in-situ sensor for dry etching. SE measures the change in the polarization state of light reflected from a surface. Sample thickness is obtained by fitting a model to the experimental ellipsometry data. In this paper we describe the design, testing and evaluation of an SE based adaptive real time feedback controller for etch rate regulation in CF4/O2 plasma etching of silicon nitride films. The feedback variable is the current etch rate as determined from the in-situ SE measurements of the film's thickness. The controller compensates for drifts in etch rate which occur during a given etch, and adaptively adjusts for the run-to-run variability inherent to plasma processing. Experimental results are presented and discussed.
In Situ Spectroscopic Ellipsometry Study of the Oxide Etching and Surface Damaging Processes on Silicon Under Hydrogen Plasma
Authors: Vargas I.M. , Manso J.Y. , Guzmán J.R. , Weiner B.R. , Morell G. 
Published: April 2011

ABSTRACTWe employed in situ ellipsometry in the monitoring of surface damage to monocrystalline silicon (Si) substrates under hydrogen plasma conditions. These measurements were complemented with spectroscopic ellipsometry and Raman spectroscopy, in order to characterize the surface conditions. It was found that heating the Si substrate to 700°C in the presence of molecular hydrogen produces etching of the native oxide layer, which is typically 10 Å thick. When the already hot and bare silicon surface is submitted to hydrogen plasma, it deteriorates very fast, becoming rough and full of voids. Modeling of the spectroscopic ellipsometry data was used to obtain a quantitative physical picture of the surface damage, in terms of roughness layer t ickness and void fraction. The results indicate that by the time a thin film starts to grow on these silicon surfaces, like in the chemical vapor deposition of diamond, the roughness produced by the hydrogen plasma has already determined to a large extent the rough nature of the film to be grown.
Electrically Based Non-Destructive Microstructural Characterization of All Classes of Materials
Authors: Gerhardt Rosario A. 
Published: April 2011

ABSTRACTThis paper gives a short summary of the background, theory and methodology needed to utilize electrical measurements as a non-destructive method for microstructural characterization. Examples are given for all classes of materials. Details are given for how to detect: (1) pore volume in thermal barrier coatings, (2) formation of surface layers due to moisture adsorption in a wide variety of materials, (3) orientation of fibers and whiskers in ceramic matrix and polymer matrix composites, (4) crack detection in metals and (5 ) stacking faults in semiconductors. Many other examples are mentioned. It needs to be emphasized that electrical measurements alone are not sufficient to identify the microstructural features of interest but must always be accompanied by complementary techniques. Proper data collection and data interpretation of properties of a specific set of materials can lead to in-line process monitoring, quality control monitoring, mechanical damage monitoring and environmental degradation monitoring of those materials.
Investigation of Quasi-Breakdown Mechanism in Ultrathin Gate Oxides
Authors: Guan Hao , He Y. D. , Li M. F. , Cho Byung Jin , Dong Zhong 
Published: April 2011

ABSTRACTThe conduction mechanism of quasi-breakdown (QB) for ultra-thin gate oxide has been studied in dual-gate CMOSFET with a 3.7 nm thick gate oxide. Systematic carrier separation experiments were conducted to investigate the evolutions of gate, source/drain, and substrate currents before and after gate oxide QB. Our experimental results clearly show that QB is due to the formation of a local physically-damaged-region (LPDR) at Si/SiO2 interface. At this region, the effective oxide thickness is reduced to the direct tunneling (DT) regime. The observed high gate leakage current is due to DT electron or hole currents through the region where the LPDR is generated. Under substrate injection stress condition, there is several orders of magnitude increase of Isub(Is/d) at the onset point of QB for n(p) - MOSFET, which mainly corresponds to valence electrons DT from the substrate to the gate. Consequently, cold holes are left in the substrate and measured as substrate current. Under gate injection stress condition, there is sudden drop and even change of sign of Isub(Is/d) at the onset point of QB for n(p)-MOSFET, which corresponds to the disappearance of impact ionization and the appearance of hole DT current from the substrate to the gate. In the LPDR region, the damaged structure may have two or multi metastable states corresponding to different effective oxide thickness. The thermal transition between two or multi metastable states leads to random telegraph switching noise (RTSN) fluctuation between two or multi levels.
Correlation Between Gate Induced Drain Leakage and Plasma Induced Interface Traps
Authors: Ma Siguang , Zhang Yaohui , Li M. F. , Li Weidan , Wang J. L. F. , Yen Andrew C. , Sheng George T. T. 
Published: April 2011

ABSTRACTIn this paper we carefully investigate the correlation between gate induced drain leakage current and plasma induced damages in the deep submicron p+ polysilicon gate pMOSFETs with gate oxide thickness of 50 Å. Low field enhancement of gate induced drain leakage current caused by plasma charging damage is a function of metal 1 antenna area/length ratio and cell location. Combined with the charge pumping measurements, it is found that gate induced drain leakage current enhancement is mainly due to the plasma induced interface traps. A linear relationship between the gate induced drain leakage and the plasma induced interface trap density is observed within the experimental error. On the other hand, the threshold voltage measurements show that oxide trapped charge has no major contribution to, and no correlation with, the gate induced drain leakage current for thin gate oxide MOSFET devices.
Characterization of Ta2O5 Thin Films With Small Current Leakage for High Density DRAMS
Authors: Kanda N. , Furukawa R. , Ishibashi M. , Kunitomo M. , Homma T. , Takahashi M. , Uemura T. , Kanai M. , Kubo M. , Ogata K. , Yoshida T. , Yamamoto H. , Ohji Y 
Published: April 2011

ABSTRACTWe have confirmed that grain boundaries are related to leakage problems in Ta2O5/SiON capacitors for high dielectric DRAMs. XRD studies using an intensity ratio of (200) to (001) showed that the crystallographic structure of Ta2O5 film was strongly dependent on preparation conditions. As the (200) oriented grains grew faster than the other grains, it became important to control its grain growth in forming uniform grain boundaries. TEM observation has shown that Ta2O5 film with a high intensity ratio of (200) to (001) was made up of large size grains and had SION interface intruding into grain boundaries. By using the current-mode AFM, we could monitor leakage current directly through grain boundaries on Ta2O5 film.
Improved Performance and Reliability in Aggressively-Scaled NMOS and PMOS FETs: i) Monolayer Interface Nitridation, and ii) Replacement of Stacked Oxide/Nitride Dielectrics With Optimized Oxide/Oxynitride Stacks
Authors: Yang Hanyang , Niimi Hiro , Lucovsky Gerry 
Published: April 2011

ABSTRACTThis paper demonstrates optimized performance and reliability in ‘second generation’ gate dielectrics which include monolayer nitrided Si-SiO2 interfaces, and deposited silicon oxynitride alloy gate dielectrics. Devices with oxynitride alloy gate dielectrics with an approximate 2:1 ratio of N:O display reduced tunneling current, improved hole mobilities and improved reliability compared to devices with Si-nitride gate dielectrics and the same nitrided interface.
Controlling the Concentration and Position of Nitrogen in Ultrathin Oxynitride Films Formed by Using Oxygen and Nitrogen Radicals
Authors: Watanabe K. , Togo M. , Tatsumi T. 
Published: April 2011

ABSTRACTThe formation of oxynitride films less than 2.0 nm by using oxygen and nitrogen radicals produced by an electron cyclotron resonance plasma in an ultrahigh-vacuum system has been studied. The nitrogen concentration of the films was evaluated by x-ray photoelectron spectroscopy, and the position of the N in the films was evaluated by secondary ion mass spectroscopy. The interface roughness was also investigated by using atomic force microscopy. We found that the N concentration can be controlled at values up to 22.5%, and that although the interface roughness tends to increase with increasing N concentration, supplying oxygen and nitrogen radicals simultaneously decreases the roughness of the film and increases its nitrogen concentration (N: 18.2%, RMS: 0.12 nm). We also found that the nitrogen profile can be controlled by using different processing sequences. Radical oxynitridation should thus be very useful for making ultrathin gate-insulator films.
Process Improvements for Reductions in Total Charge and Interface Trap Densities of Thermally-Grown Sub-3.5nm-Thick Silicon Nitrides
Authors: Dang Sanjit Singh , Takoudis Christos G. 
Published: April 2011

ABSTRACTUltra-thin silicon nitride films are being studied for use as high-dielectric constant (highk) materials in future gate dielectric applications, as Complementary Metal-Oxide-Semiconductor (CMOS) transistors are scaled down to the sub-100nm regime. In this study, process modifications are proposed to reduce the total charge and interface trap densities in sub-3.5 nm-thick silicon nitride films, grown in NH3, in a conventional furnace at 900°C and 1 atm. It is shown that by employing a short (<1 min) oxynitridation step in NO, before nitridation, and oxynitridation/Ar-annealing steps, after nitridation, silicon nitride films can be thermally grown with a total charge density as low as about 2.5E10 q/cm2 and an interface trap density of about 2.1E11/(eV-cm2). Besides, the effect of using NO as opposed to N2O for oxynitridation steps is also discussed.
Low-Temperature Oxidation of Silicon(100) Substrates Using Atomic Oxygen
Authors: Ueno T. , Chikamura S. , Sakuraba F. , Iwasaki Y 
Published: April 2011

ABSTRACTLow temperature oxidation process of Si(100) substrates using atomic oxygen has been proposed. For the generation of atomic oxygen, microwave plasma remotely attached on the oxidation chamber was used. In the microwave plasma, the large amount of rare gas and a small amount of 02 gas mixture was supplied. The existence of the large amount of rare gas controls the plasma energy to some restricted values associated with the metastable states of the rare gas. Consequently, using Kr as mixed rare gas, atomic oxygen were efficiently generated instead of excited 02 molecules with any vibrational or ionized states. The oxidation kinetics of crystalline Si using this process was shown to be diffusion limiting, even if the oxide thickness was less than several nm. The activation energy of B, which is referred to as the parabolic rate constant, was found to be as low as 0.14eV In addition, lower interface trap density of 2.6 × 1011/cm2/eV at the mid gap could be achieved for the as-grown SiO2/Si(100) interface at the processing temperature of 500C.
Theoretical and Experimental Investigation of Ultrathin Oxynitrides
Authors: Demkov A.A. , Liu R. 
Published: April 2011

ABSTRACTMicroscopic properties of thin oxynitrides are investigated using a combination of the infrared ATR and ab-initio electronic structure methods. We use a theoretical structural model based on the Si-SiO2 interface with the oxide thickness of 0.8 nm. The interfacial region amounts to about 0.4 nm (the total thickness of the oxygen containing layer is 1.2 nm). The Quantum Molecular Dynamics simulations suggest that N accumulates at the interface. We have generated samples with the nitrogen concentrations from 1.69 × 1014 cm−2 to 6.78 × 1014 cm−2. The structural analysis of nitrogen containing cells indicates a significant improvement of the oxide layer and the strain reduction at the interface. We have performed a calculation of the vibrational density of states. A N-localized mode at 809 cm-1 has been identified. The experimental ifnrared ATR data is in qualitative agreement with the calculation. The valence band offset calculations reveal a 0.3 eV increase of the offset due to nitrogen at the highest nitrogen concentration considered. The valence band offset increase comes mainly from the structural change in the oxide layer. The interfacial dipole contributes 0.12 eV to the increase, while the structural change in the oxide layer gives additional 0.2 eV.
Furnace Oxynitridation in Nitric Oxide of Thin Silicon Oxide: Atomic Transport Mechanisms and Interfacial Microstructure
Authors: Trimaille I. , Ganem J.-J. , Gosset L. G. , Bailly O. , Rigo S. , Cantin J.-L. , Bardeleben H. J. Von 
Published: April 2011

ABSTRACTOxynitridation in nitric oxide of commercial 5 nm and 13 nm oxides is investigated, as well as reoxidation steps. The results are discussed in terms of atomic transport mechanisms and modification of interfacial microstructure. Atomic transport is studied through the use of isotopic tracing and nuclear reactions analyses (NRA): we measured the atomic areal densities (14N, 15N, 16O, 18O) in the films and the concentration depth profiles of the heavy and stable isotopes (15N, 18O) with near surface subnanometric resolution. To scan the evolution of the interfacial microstructure, Pb0 centers concentrations were measured by electron paramagnetic resonance spectroscopy (EPR), after each treatment step. The previously proposed mechanisms for NO oxynitridation of silica are confirmed: i) the NO molecules diffuse via interstitial sites, without reaction with the lattice, before reacting with the dielectric/Si interface; ii) at the external surface region, oxygen exchange is observed due to a step-by-step motion of network oxygen atoms induced by the presence of network defects. During reoxidation in O2 neither loss or observable redistribution of nitrogen is evidenced. For the 13-nm thick film, in the external surface region, the oxygen exchange is seen to be more effective than in the case of silica (or silicon) oxidation: that is O2 is more reactive on NO-nitrided silica than on pure silica. The concentration of Pbo centers decreases after the NO thermal step and increases again after the further reoxidation step.
Impact of temperature and breakdown statistics on reliability predictions for ultrathin oxides
Authors: Groeseneken G. , Degraeve R. , Kaczer B. , Maes H.E. 
Published: April 2011

ABSTRACTThis paper discusses the evolution in the degradation and breakdown behaviour of ultra-thin oxides when scaling the oxide thickness into the sub-4 nm range for future CMOS technology generations. It will be shown that changes in the breakdown statistics, which can be explained by a percolation model for breakdown, lead to an increased area dependence of the time-tobreakdown. This has to be taken into account when predicting the oxide reliability. Also the impact of the test methodology, the relevance of a so-called polarity gap in the charge-tobreakdown and its consequences for reliability testing, are highlighted. Moreover, a strong increase in the temperature dependence of breakdown, especially for sub-3 nm oxides, is demonstrated and the impact of temperature on trap generation and critical trap density at breakdown is discussed. Finally it is shown that the combined effects of all these phenomena might lead to oxide reliability becoming a potential showstopper for further technology scaling.
Electrical and Physical Characterization of Ultrathin Silicon Oxynitride Gate Dielectric Films Formed by the Jet Vapor Deposition Technique
Authors: Karamcheti A. , Watt V.H.C. , Luo T.Y. , Brady D. , Shaapur F. , Vishnubhotla L. , Gale G. , Huff H.R. , Jackson M.D. , Torres K. , Diebold A. , Guan J. , Gilmer M.C. , Brown G.A. , Bersuker G. , Zeitzoff P. , Tamagawa T. , Guo X. , Wang X.W. , Ma T.P. 
Published: April 2011

ABSTRACTThis paper describes the electrical and physical characteristics of ultrathin Jet Vapor Deposited (JVD) Silicon Oxynitride films. Capacitance-Voltage measurements indicate an equivalent oxide thickness (EOT) of less than 2 nm, taking into account the quantum-mechanical correction. These films have leakage currents almost two orders of magnitude lower than thermal oxide of the same equivalent thickness. Measurements on NMOSFETs with 0.15 μm of channel length demonstrate excellent electrical properties, including high drive currents (∼0.5 mA/μm @ Vd=Vg–Vt=l.5 V), low sub-threshold swings (∼72 mV/decade), and high transconductance (∼0.36 mS/μm @ Vd=1.5 V). These films were also analyzed using a variety of physicochemical methods, including Total X-ray Fluorescence (TXRF), Atomic Force Microscopy (AFM), Nuclear Reaction Analysis (NRA), Low Energy (500 eV) Secondary Ion Mass Spectrometry (SIMS), and Transmission Electron Microscopy (TEM). Surface metal concentrations of less than 1011 atoms/cm2 were measured from the TXRF analysis. The microroughness values for these films varied between 0.15 – 0.17 nm as measured by AFM. Low energy (500 eV) SIMS and NRA indicate high [N] near the top as well as throughout the bulk of the film, and a significant amount of [O] near the top of the film. High Resolution TEM pictures show a very uniform film with a physical thickness of 2.8 ± 0.1 nM, which yields an effective dielectric constant of 5.5, consistent with these types of oxynitride films.
Detection of Interfaces States Correlated with Layer-by-Layer Oxidation on Si(100)
Authors: Hattori T. , Nohira H. , Teramoto Y , Watanabe N. 
Published: April 2011

ABSTRACTThe interface state densities near the midgap were measured with the progress of oxidation of atomically flat Si(100) surface. It was found that the interface state distribution in Si bandgap changes periodically with the progress of oxidation. Namely, the interface-state density near the midgap of Si exhibits drastic decrease at oxide film thickness where the surface roughness of oxide film takes its minimum value, while that does not exhibit decrease at the oxide film thickness where the surface roughness takes its maximum value. In order to minimize interface state densities the oxide film thickness should be precisely controlled to within an accuracy of 0.02 nm.
Quantum Confinement in Nanocrystalline Superlattices
Authors: Grom G. F. , Fauchet P. M. , Tsybeskov L. , Mccaffrey J. P. , Labbé H. J. , Lockwood D. J. 
Published: April 2011

ABSTRACTPhotoconductance spectroscopy was used to probe the effects of quantum confinement in nanocrystalline (nc)-Si/amorphous (a)-SiO2 superlattices (SLs). A Metal-Oxide-Semiconductor (MOS)-like structure with the nc-Si SL incorporated in the oxide was fabricated to study charging/discharging processes in Si nanocrystals. The fine structure observed in photoconductance spectra at low temperatures was interpreted in terms of singularities in the carrier density of states, possibly due to energy quantization. In addition, a low-resistance sample exhibited photocurrent oscillations with a frequency of several kHz, which could be a manifestation of sequential resonant carrier tunneling in the nc-Si/a-SiO2 SL.
Memory Effects of Ion-Beam Synthesized Ge and Si Nanoclusters in Thin SiO2-Layers
Authors: Gebel T. , von Borany J. , Skorupa W. , Möller W. , Thees H.-J. , Wittmaack M. , Stegemann K.-H. 
Published: April 2011

ABSTRACTNanocluster memories are promising for future non-volatile memory applications. In this work thin SiO2 films were implanted with Ge+ and Si+ and annealed subsequently. Charge storage effects of the MOS capacitors have been studied through I-V and high frequency C-V measurements. Positive voltage pulses lead to a positive flatband voltage shift of the C-V curve. Detrapping by applying negative voltage pulses leads to a negative shift. The achieved programming window using 6 V / 100 ms pulses for Ge based structures is higher than that for Si (2.0 V vs. 0.2 V). However the retention times for Si based memories are longer. For dedicated process parameters microstructural investigations (RBS, XTEM) of Ge+ implanted SiO2 layers showed two bands of clusters, one near the interface SiO2/Si and one in the center of the SiO2 layer.
Defect States Due to Silicon Dangling Bonds at the Si(100)/SiO2 Interface and the Passivation by Hydrogen Atoms
Authors: Kaneta C. , Yamasaki T. , Uchiyama T. , Uda T. , Terakura K. 
Published: April 2011

ABSTRACTThe defect states due to the Si dangling-bonds at the Si(100)/SiO2 interface is investigated by employing the first-principles method based on the density functional theory. Two prototypes of the defects at the interface are considered. One exists on one end of a Si-Si dimer. On the other hand, the other exists on an edge of a Si-O-Si bridge. The electronic structures for these systems were calculated to investigate the interface states. For the former, two defect states strongly localizing on the silicon dangling bond at the interface appear in the band gap. The latter defect also generates two defect states. But the upper level is in the conduction band, while the lower level is in the band gap. It is also shown that the interface states completely disappear by introducing a H atom into the interface and terminating the dangling bonds. Our results suggest the silicon dangling-bond on a Si-Si dimer with no adjacent O atoms as a candidate for the Pb1 center.