bluuebunny/crossref_metadata_2025_split huggingface dataset:
Permittivity and Microstructure of (Ba,Sr)TiO3 Films: Temperature and Electric Field Response
Authors: Boikov Yu.A. , Claeson T. , Ivanov Z. , Olsson E. 
Published: April 2011

AbstractEpitaxial heterostructures (001)(Y,Nd)Ba2Cu3O7-δ∥(100)SrTiO3∥(001)(Nd,Y)Ba2Cu3O7-δ,(100)SrRuO3∥(100)Ba0.8Sr0.2TiO3∥(100)SrRuO3, (100)SrRuO3∥(100)SrTiO3∥(100)SrRuO3 and (100)SrTiO3∥(001)YBa2Cu3O7-δ have been grown by laser ablation. There was only a small difference of the dielectric permittivity, in the temperature range 180-300K, between a bulk single crystal and an epitaxial (100)SrTiO3 layer inserted between either high-Tc superconducting or SrRuO3 electrodes. At T<1 50K, on the other hand, the response of the dielectric permittivity of the SrTiO3 layer on temperature or electric field depended to a large extent upon the materials used as bottom and top electrodes in the heterostructures. The temperature dependence of the dielectric permittivity for the SrTiO3 layer in (100)SrRuO3∥(100)SrTiO3∥(100)SrRuO3 was well extrapolated by a Curie-Weiss relation in the range of T=80-300K, with about the same Curie constant (C0=7.5 × 104 K) and Curie temperature (TCurie=21K) as in a bulk single crystal. At temperatures higher the phase transition point (65 K), the electric field response of the permittivity of the SrTiO3 layer between high-TC superconducting or metallic oxide electrodes was well extrapolated by the same relation used for a bulk single crystal. The smallest loss factor, tanδ, was measured for the capacitance (100)SrRuO3∥(100)SrTiO3∥(100)SrRuO3 (T ≈ 50-300K, f=100kHz). The measured conductance G for the SrTiO3 layer in the (001)(Y,Nd)Ba2Cu3O7-δ heterostructure fitted well the relation InG∼-(ED/kT), with ED=0.08-0.09 eV in a temperature range close to 300K. Pronounced hysteresis was observed in the temperature dependence of the dielectric permittivity for the (100)Ba0.8Sr0.2TiO3 layer at temperatures close to the phase transition point, like in the case of a bulk single crystal. The permittivity of the (100)Ba0.8Sr0.2TiO3 layer decreased more than 50% when an electric field of 2.5×106V/m (T ≈ 300K, f=100 kHz ) was applied.
Soft-Mode Phonons in SrTiO3 Thin Films Studied by Far-Infrared Ellipsometry and Raman Scattering
Authors: Sirenko A. A. , Bernhard C. , Golnik A. , Akimov I. A. , Clark A. M. , Hao J.-H. , Xi X. X. 
Published: April 2011

AbstractWe report the experimental studies of the vibrational spectra of SrTiO3 films with the thickness of 1 µm grown by pulsed laser deposition. Fourier-transform infrared ellipsometry between 30 and 700 cm−1 and electric field-induced Raman scattering have been utilized for investigation of the phonon behavior. These results can be used for comparison with the low-frequency measurements of the static dielectric constant. In the films, the soft mode reveals hardening compared to that in bulk crystals. This observation is in agreement with the Lyddane-Sachs-Teller formalism.
Microwave Dielectric Tuning and Losses in Epitaxial Lift-Off Thin Films of Strontium Titanate
Authors: Rogers Charles T. , Dalberth Mark J. , Price John C. 
Published: April 2011

AbstractWe report on the complex dielectric response function for SrTiO3 (STO) thin films that have been removed from the original growth substrate via an epitaxial lift-off process. We measured the dielectric response as a function of frequency (10 kHz to above 2 GHz), as a function of temperature (4 K to 300 K), and as a function of applied electric field (between +/− 10 V/µm). The dielectric properties are well described by a model based on a dilute set of thermally activated two-level dipoles in a matrix of bulk STO. Activation energies for the dipoles are found to cluster around two central values near 50 meV and 100 meV. Attempt frequencies are generally around 10 THz. Assuming that the dipole moment of a typical two-level system is equal to that of a unit cell of polarized bulk STO, we find that a volume fraction of roughly 4% of a typical film is involved in the dipole response.
Ba1−xSrxTiO3 Thin Film Sputter-Growth Processes and Electrical Property Relationships for High Frequency Devices
Authors: Im Jaemo , Auciello O. , Streiffer S.K. , Baumann P.K. , Eastman J.A. , Kaufman D.Y. , Krauss A.R. , Li Jianxing 
Published: April 2011

AbstractPrecise control of Ba1−xSrxTiO3 (BST) film composition is critical for the production of high-quality BST thin films. Specifically, it is known that nonstoichiometry greatly affects the electrical properties of BST film capacitors. We are investigating the compositionmicrostructure- electrical property relationships of polycrystalline BST films produced by magnetron sputter-deposition using a single target with a Ba/Sr ratio of 50/50 and a (Ba+Sr)/Ti ratio of 1.0. It was determined that the (Ba+Sr)/Ti ratios of these BST films could be adjusted from 0.73 to 0.98 by changing the total (Ar+O2) process pressure, while the O2/Ar ratio did not strongly affect the metal ion composition. The crystalline quality as well as the measured dielectric constant, dielectric tunability, and electrical breakdown voltage of BST films have been found to be strongly dependent on the composition of the BST films, especially the (Ba+Sr)/Ti ratio. We discuss the impact of BST film composition control, through film deposition and process parameters, on the electrical properties of BST capacitors for high frequency devices.
Boron Activation During Solid Phase Epitaxial Regrowth
Authors: Lindfors C. D. , Jones K. S. , Law M. E. , Downey D. F. , Murto R. W. 
Published: April 2011

AbstractTo continue scaling dimensions of transistors, higher dopant concentration levels are needed for ultra-shallow contacts. Therefore studies of dopant activation have been performed in preamorphized silicon wafers with various boron implant conditions to determine the maximum achievable dopant concentrations after Solid Phase Epitaxial Regrowth (SPER) alone. In the first experiment a silicon piece was preamorphized with a 30 keV, 1×1015 cm−2 and 90 keV, 1×1015 cm−2 Si+ implant followed by a 30 keV, 1×1015 cm−2 B+ implant. Solid phase epitaxial regrowth at 500 °C indicates that boron can be activated at low temperatures. Ultra Low Energy (ULE) implants were studied in the second experiment. Silicon wafers were implanted with 2.5 keV, 1×1015 cm−2 Si+ to amorphize and then B+ was implanted at 0.5 keV in the dose range of 1×1015 to 9×1015 cm−2. Samples were annealed in the temperature range of 500 to 650 °C. High concentrations of boron make it difficult to fully regrow amorphous layers and thus yield marginal electrical properties. Much of the boron remains inactive, particularly at the higher dose implants. In both experiments Variable Angle Spectroscopic Ellipsometry (VASE) is used to measure amorphous layer thickness and Hall effect measures active boron dose. For the first experiment, Secondary Ion Mass Spectrometry (SIMS) data compares chemical dose to active dose during the regrowth process. Sheet resistance data is obtained from a four point probe for the ULE implant experiment.
Effects of Nonmelt Laser Annealing on a 5keV Boron Implant in Silicon
Authors: Earles Susan , Law Mark , Jones Kevin , Brindos Rich , Talwar omit 
Published: April 2011

AbstractTo investigate the effects of ramp rate on the transient enhanced diffusion of boron in silicon, laser thermal processing (LTP) in the nonmelt regime has been investigated. A nonmelt laser anneal has been performed on a 5 keV, 1e15 boron implant. The implant energy of 5keV was chosen to simplify analysis. A rapid thermal anneal (RTA) at 1000°C and furnace anneals at 750 °C were used to show the effect of post annealing on the LTPd samples. Results show the sheet resistance drops by up to a factor of two for samples receiving the nonmelt LTP and the RTA compared with the samples just receiving the RTA. An increase in the hall mobility was also observed for the samples receiving the LTP. The nonmelt LTP was also shown to strongly affect the extended defect density. During post anneals, a higher density of smaller defects evolved in the samples receiving the LTP.
Self-Interstitial clusters in silicon
Authors: Souza M. M. De , Chichkine M. P. , Narayanan E. M. Sankara 
Published: April 2011

AbstractIn this paper we propose structural models of self-interstitial clusters in silicon using the empirical potential method. Novel, fully co-ordinated compact clusters based on the hexagonal interstitial up to size four have been proposed. The energetics of their formation indicates that energy minimisation occurs due to elimination of dangling bonds. While the conventional dangling bond model yields an exponential decrease in the formation energy with size, we observe stable defects for sizes in multiples of four. The energy barrier required for a transition from compact model to the dangling bond chain model can possibly explain the experimentally observed energy barrier for sizes greater than eight.
SSRM and SCM Observation of Enhanced Lateral As- and BF2-diffusion Induced by Nitride Spacers
Authors: Eyben P. , Duhayon N. , Stuer C. , Wolf I. De , Rooyackers R. , Clarysse T. , Vandervorst W. , Badenes G. 
Published: April 2011

AbstractState-of-the-art semiconductor devices require an accurate control of the complete twodimensional dopant distribution. The routine use of process simulators to predict the envisaged distributions and their resulting accuracy, is strongly linked to the physical models contained in these programs as well as their calibration. Whereas SIMS and SRP have been used extensively for the calibration of 1D-profiles, calibration of 2D-profiles has been very limited.In this work, we report some results obtained with the 2D-profiling techniques SSRM (Scanning Spreading Resistance Microscopy) and SCM (Scanning Capacitance Microscopy ) for the study of two-dimensional effects on diffusion. In particular, we discuss the role of the nitride spacer on the lateral diffusion of arsenic and boron. Using series of transistors with different nitride spacers with or without TEOS-liners, a strong dependence between the lateral diffusion and the nitride spacer thickness can be observed using SSRM and SCM. The process flow eliminates the possible contribution of Transient enhanced diffusion (TED) as a dominant mechanism. At the same time an enhancement of the lateral stress underneath the spacers has been observed with CBED and Raman, suggesting a correlation between the lateral diffusion and the nitride spacers. The enhanced diffusion of As and B is strongly linked to the spacer size whereby the differences in enhancement suggest that the proximity of the dopants to the stress field field region is an important parameter.
Increasing the Lateral Resolution of Scanning Spreading Resistance Microscopy
Authors: Kline R.J. , Richards J.F. , Russell P.E. 
Published: April 2011

AbstractThis paper discusses problems inherent to scanning spreading resistance microscopy (SSRM) and ways to correct them to increase the resolution of two-dimensional dopant profiling. Specifically this paper looks into issues related to the probe-silicon contact and the damaged surface layer created by the sample preparation technique. Degradation of the measured dopant profile was observed when the probe scanned over the nitride spacers. Attempts to reduce the required contact pressures to increase the lifetime and effectiveness of the probes are addressed. The force required for SSRM was successfully reduced after the damage layer was partially removed by isotropic etching.
Dopant Diffusion in Silicon Substrate during Oxynitride Process
Authors: Aoki Nobutoshi , Yaegashi Toshitake , Takeuchi Yuji , Fujiwara Makoto , Kusunoki Naoki , Sato Tsutomu , Mizushima Ichiro , Tsunashima Yoshitaka , Hazama Hiroaki , Aritome Seiichi , Shirota Riichiro , Shimizu Takashi 
Published: April 2011

AbstractWe found an anomalous behavior of dopant diffusion in Si substrate during the oxynitride process. SIMS measurements showed a notably enhanced diffusion during the NO and N2O oxynitride process. The considerably enhanced diffusion was also observed in re-oxidation of oxynitride film grown by the NO annealing or NH3 nitridation of a SiO2 film. In order to simulate the enhanced diffusion, an enhancement coefficient was introduced, showing that the simulation results are in reasonable agreement with the experimental ones. We applied the diffusion model to the simulations of MOSFETs fabricated under various conditions of the oxynitride process. The device characteristics of MOSFETs were successfully reproduced by adopting a suitable dependence of nitrogen concentration CN on the surface recombination rate of interstitial Si at the oxynitride/Si substrate interface.
Cryo-Implantation Technology for Controlling Defects and impurity out diffusion
Authors: Murakoshi Atsushi , Suguro Kyoichi , Iwase Masao , Tomita Mitsuhiro , Okumura Katsuya 
Published: April 2011

AbstractWe propose a novel process module by using cryo-implantation and rapid thermal annealing (RTA). Boron or arsenic ions were implanted into a 8 inch (100) Si substrate which was cooled by using liquid nitrogen. The substrate temperature was controlled to be below at -160°C during ion implantation. It was found that an amorphous layer was formed by boron or arsenic implantation and the amorphous layer was completely recovered to a single crystal after annealing at 900°C for 30sec. No dislocation was observed in the implanted layer. It was also found that the thermal diffusion of boron was suppressed by cryo-implantation. PN junction depth was found to be about 10-20% shallower than that of room temperature implantation. These results suggest that transient enhanced diffusion of boron can be reduced by suppressing vacancy migration toward the surface during implantation. Cryo-implantation was found to be very effective in reducing defects and PN junction leakage was successfully reduced by one order of magnitude as compared with room temperature implantation.
Quantitative Measurement of Interstitial Flux and Surface Super-saturation during Oxidation of Silicon
Authors: Carroll M. S. , Sturm J. C. 
Published: April 2011

AbstractDuring the oxidation of silicon, interstitials are generated at the oxidizing surface and diffuse into the silicon. Boron diffusion was used to map the local interstitial super-saturation, the ratio of interstitial concentration to the equilibrium concentration of interstitials I/I*, versus depth above buried Si0.795Ge0.2C0.005 layers during oxidation. The average interstitial supersaturation at the silicon surface, extrapolated from the depth profiles, is measured as, ∼24 and ∼11.5 for 750°C and 850°C respectively. Using the measured interstitial concentration at the surface, the silicon interstitial injection into the silicon is calculated for oxidation at 750°C and 850°C. Finally, it is found that the surface boundary condition remains fixed over an interstitial injection rate ranging over 4 orders of magnitude.
Understanding and Modeling Ramp Rate Effects on Shallow Junction Formation
Authors: Chakravarthi Srinvasan , Gencer Alp H. , Dunham Scott T. , Downey Daniel F. 
Published: April 2011

SummaryIn summary, we find it is possible to model the extent of diffusion during spike anneals with varying ramp rates by considering the full thermal cycle. These models allow the optimization of RTP ammealing cycles considering the trade-offs between junction depth and sheet resistance. For example, with 1050°C spike anneals, the active dose (and thus sheet conductivity) varies approximately linearly with junction depth. However, faster ramp rates allow the use of higher spike temperatures, with associated higher activation and reduced sheet resistance for the same junction depth.Work at Bosten University and the University of Washington was supported by the Semiconductor Research Corporation. We would like to thank Eric Perozziello for details and discussion regarding their experimental results.
Boron Diffusion Mechanism in Silicon Oxide Using AB Initio Methods
Authors: Zubkov V. , Senosiain J. P. , Aronowitz S. , Sukharev V. , Musgrave C. B. 
Published: April 2011

AbstractDensity functional theory was employed to explore the diffusion mechanism of boron in amorphous silicon oxide. The oxide was modeled with clusters of various sizes, and both neutral boron atoms and cations were considered. Three stable structures were found where B (or B+) was inserted into oxide: one in which B (or B+) is divalent and two in which B (or B+) is trivalent. Boron diffusion through silicon oxide proceeds as a sequence of B hops from one inserted position to another. For neutral boron the rate limiting step is B hop from one of trivalent structures to a divalent one with activation energies (Ea) in the range of 2.0-3.1 eV, depending on the model cluster. In the case of a cation the rate-limiting step is the B+ hop over the O atom in a divalent structure Si-B+-O-Si with calculated Ea of 2.4-2.8 eV. Experimental activation energies for B diffusion in silicon oxide are in the 2.3 - 4.2 eV range. Our results suggest that both neutral and cation boron can participate in B diffusion in oxide.
A Study of Boron Clustering Transients and Mechanisms in Doped Silicon
Authors: Lilak Aaron D. , Krishnamoorthy Viswanath , Vieira David , Law Mark , Jones Kevin 
Published: April 2011

AbstractThe ion implantation of boron remains the most practical means of forming shallow and ultra-shallow p+/n junctions in silicon. A high conductive junction requires both a large density of dopant atoms and electrical activation amongst these. While it is possible to simply higher doses of boron at lower energies, the potential benefits of the changes are often muted by the electrical deactivation of the boron was occurs through a clustering process. Therefore, it is important to do understanding of the kinetics and transients involved in these proces.It has been shown that ion implanted boron clusters with interst residual from the implantation process. These clusters are immobile, fractionally or totally electrically inactive, and very thermally state study a series of experiments were conducted in order to investigate processes. In addition to this, a means of utilizing X-ray Diffractio to correlate electrical activity to the rocking curve has been development
Clusters and Planar Defects in Boron Implanted Silicon an X-Ray Diffuse Scattering Study
Authors: Kegel I. , Sztucki M. , Metzger T. H. , Lubbert D. , Arthur J. , Patel J.R. 
Published: April 2011

AbstractIn a grazing incidence x-ray diffuse scattering study of defects in boron implanted and annealed silicon we have discovered narrow rods of intensity along [111] directions. These diffuse rods of intensity arise from stacking faults formed in the early stages of annealing in the range around 1000°C. From the width of the stacking fault induced rods we can estimate their size, while the integrated intensity is a measure of the total stacking fault area in the implanted layer. Surprisingly we find that these faults initially grow in size and density and after reaching a maximum begin to dissolve and ultimately are totally annihilated. The intensity rods are distinct from the point defect or point defect cluster scattering in the tails of the Bragg peaks referred to as Huang Scattering. From the nature of the q dependence of the diffuse scattering in the Bragg tails we find unequivocal evidence for the presence of clusters in our annealed samples. The average effective size seems remarkably independent of annealing temperature. These observations will be discussed in the context of the enhanced diffusion of boron over its bulk value.
The Effect of Impurities on Diffusion and Activation of ion Implanted Boron in Silicon
Authors: Robertson L. S. , Brindos R. , Jones K. S. , Law M. E. , Downey D. F. , Falk S. , Liu J. 
Published: April 2011

AbstractThe interaction between boron and silicon interstitials caused by ion implant damage is a physical process which hinders the formation of ultra-shallow, low resistivity junctions. The possibility of mitigating the effective interstitial point defect population via introduction of nonmetallic impurities in ion implanted silicon has been investigated. Amorphization of a n-type Czochralski wafer was achieved using a series of Si+ implants of 40 keV and 150 keV, each at a dose of 1×1015/cm2. The Si+ implants produced a 2800Å deep amorphous layer, which was then implanted with 8 keV 1×1014/cm2 B+. The samples were then implanted with high doses of either carbon, oxygen, sulfur, chlorine, selenium, or bromine. The implant energies of the impurities were chosen such that the damage and ion profiles of the impurity were contained within the amorphous layer. This allowed for the chemical species effect to be studied independent of the implant damage caused by the impurity implant. Post-implantation anneals were performed in a tube furnace at 750° C. Secondary ion mass spectrometry was used to monitor the dopant diffusion after annealing. Hall effect measurements were used to study the dopant activation. Transmission electron microscopy (TEM) was used to study the end-of-range defect evolution. The addition of carbon and chlorine appear to reduce the boron diffusion enhancement compared to the boron control. Carbon and chlorine also appear to prevent boron out-diffusion during annealing compared to the control, which exhibited 20% dose loss following annealing.
A Molecular Dynamics Study of Low-Energy Argon and Boron Implants on Silicon (100) Vicinal Surfaces Stepped Surface
Authors: Mazzone A.M. , Lamel C.N.R. 
Published: April 2011

AbstractThe purpose of this study is to illustrate the effects of the structure of the silicon surface on low-energy implants commonly used in current silicon technology. T o this aim Molecular Dynamics simulations with classical forces are used to study implantation of argon and boron with a kinetic energy in the range from 5eV to 30 eV into a silicon stepped surface. In addition to these calculations, the binding energy of boron atoms embedded in small clusters with a step shape hav e been studied with a quantum mechanical method of a semiempirical type. The purpose of these calculations is to compare the stable sites generated by theimplan ts with the ones attained during thermal treatments under near-equilibrium conditions.
Reaction of Excess Silicon Interstitals in the Presence of Arsenic and Germanium
Authors: Brindos R. , Keys P. H. , Griglione M. , Jones K. S. , Law M. E. , Agarwal Aditya , Andideh Ebrahim 
Published: April 2011

AbstractCVD grown boron marker layers were used to monitor the release of silicon interstitials from an arsenic doped surface region that was subsequently implanted with silicon. These structures were annealed for various times at 750°C under a nitrogen gas flow. A comparison of boron spike enhancement and defect dissolution is made. It is shown that enhancement values from the Si+ implant were reduced at short times for samples containing arsenic compared to samples implanted with Si+ alone or As+ alone. The TEM results showed that defect densities were dramatically reduced for the samples containing As. These results imply that the previously reported reduction in {311} formation observed in As doped wells is most likely not a Fermi level effect and is consistent with the formation of As interstitial clusters (AsIC's). The data shows that AsIC's form and control extended defect formation and slow the enhanced diffusion.