bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ion implantation for low-resistive source/drain contacts in FinFET devices
Authors: van Dal Mark J. H. , Duffy Ray , Pawlak Bartek J. , Collaert Nadine , Jurczak Malgorzata , Lander Robert J. P. 
Published: April 2011

ABSTRACTFinFET is one of the leading candidates to replace the classical planar MOSFET for future CMOS technologies due to the double-gate configuration of the device leading to an intrinsically superior short channel effect (SCE) control. A major challenge for FinFETs is the increase in parasitic source-drain resistance (Rsd) as the fin width is scaled. As fins must be narrow in order to control SCEs, Rsd reduction is critical. This work will deal with the challenges faced in the use of ion implantation for the low-ohmic source-drain contacts. Firstly a new technique to characterize fin sidewall doping concentration will be introduced. We will have a closer look at the Rsd dependency upon fin width for different fin implant conditions and investigate how the implant conditions affect FinFET device performance. It will be shown that the cause of the device degradation upon fin width scaling is related to the fundamental issues of silicon crystal integrity in thin-body Si after amorphizing implant and recrystallization during source-drain activation.
Pt Segregation at the NiSi/Si Interface and a Relationship with the Microstructure of NiSi
Authors: Akutsu Haruko , Itokawa Hiroshi , Nakamura Kazuhiko , Iinuma Toshihiko , Suguro Kyoichi , Uchida Hiroshi , Tada Masanori 
Published: April 2011

ABSTRACTNickel monosilicide (NiSi) is used for lowering the parasitic resistances in source/drain. However, NiSi has a disadvantage of lower thermal instability such as NiSi2 nucleation and agglomeration. We first reported Pt segregation was found at a NiSi/Si interface by Atom Probe (AP) analysis.[6] In this study, we found that the scheme of Ni silicide grain growth and the resultant NiSi crystal shape is strongly affected by the existence of Pt by utilizing AP analysis, TEM and FE-SEM. AP observations were carried on a Ni-Pt as sputterd sample and on a Ni-Pt as annealed sample. The depth profile for the sample after silicidation indicates Pt atoms are segregated at a NiSi surface and NiSi/Si interface. For the analysis of the Pt distribution in the sample after silicidation in more details, we thoroughly analyzed the 3D image as follows: a cylindrical part is extracted from the 3D image; it is divided into 5nm thick slices; and 2D images depicting density-distribution of Pt and As. From these 2D images, we found Pt atoms exist around NiSi grains. The Atom Probe result indicates that Pt atoms segregate at the NiSi surface, grain boundaries and NiSi/Si interface. Plane view TEM and FE-SEM observations were carried out on Ni(Pt) silicide and on Ni silicide without Pt to find the influence of the segregated Pt atoms on the microstructure of NiSi. The spindle shape of NiSi(w/o Pt) grains were observed on the former. On the other hand, we observed on the latter that the Pt addition affected the shape of the NiSi grains and changed NiSi grains to round polygonal shape and the average grain size became smaller. It can be said that the Pt addition suppresses a crystal growth along in a longitudinal direction of a grain. We speculate that fine round shape NiSi grains are formed as a result of the suppression of the anisotropic crystal growth by Pt segregation, and provide the improvement of the thermal stability of the NiSi film.
A Comprehensive Atomistic Kinetic Monte Carlo Model for Amorphization/Recrystallization and its Effects on Dopants
Authors: Zographos Nikolas , Martin-Bragado Ignacio 
Published: April 2011

ABSTRACTThis work shows a comprehensive atomistic model to describe amorphization and recrystallization, and its different effects on dopants in silicon. We begin by describing the physical basis of the model used, based on the transformation of ion-implanted dopants and generated point defects into amorphous pockets of different sizes. The growth and dissolution of amorphous pockets is simulated by the capture and recombination of point defects with different activation energies. In some cases, this growth leads to the formation of amorphous layers. These layers, composed of a set of amorphous elements, have an activation energy to be recrystallized. The recrystallization velocity is modeled not only depending on temperature, but also on dopant concentration. During the recrystallization, dopants move with the recrystallization front to simulate the dopant redistribution during solid phase epitaxial regrowth (SPER). At the edge of the amorphous-crystalline interface, the remaining damage forms end-of-range (EOR) defects.Once the model is explained, we discuss the calibration methodology used to reproduce several amorphous/crystalline (A/C) experiments, including the dependencies of the A/C transition temperature on dose rate and ion mass, and the A/C depth on ion implant energy.This calibrated model allows us to explore the redistribution of several dopants, including B, As, F, and In, during SPER. Experimental results for all these dopants are compared with relevant simulations.
Modelling of Sb Activation in Ultra-shallow Junction Regions in Bulk and Strained Si
Authors: Lai Yan , Cordero Nicolas , Greer James C 
Published: April 2011

ABSTRACTThe activation behaviour of dopants in ultra-shallow junctions on strained silicon is investigated from a simulation vantage point. Process models available in commercial simulation tools are typically developed for junctions formed with high implantation energies (> 50 keV) and for long anneal times. Hence the question arises as to whether these models and parameter sets can accurately predict the active profile for highly doped, ultra-shallow junctions formed thin strained silicon layers using short rapid thermal anneals (RTA, <10 seconds) at temperatures below 800 °C. By incorporating the results from experimental data, we develop modified models allowing for improved predictions of antimony activation within both bulk and strained silicon.
Modeling of Effect of Stress on C Diffusion/Clustering in Si
Authors: Guo Hsiu-Wu , Ahn Chihak , Dunham Scott T 
Published: April 2011

ABSTRACTExtensive ab-initio calculations were performed to find formation energies of stable C complex configurations in silicon as function of stress. The results indicate that substitutional C is the lowest energy state, while the <100> split interstitial is the dominant mobile species. Investigation of small carbon/interstitial clustering suggests that these clusters are only significant under a substantial interstitial supersaturation. We studied the diffusion path for neutral C including the impact of stress. Through KLMC analysis of stress effect on diffusivity, we found that tensile biaxial strain enhances the effective C diffusivity, with a stronger stress dependence for C diffusivity in the out-of-plane direction.
Atomistic Simulations of Epitaxial Regrowth of As-doped Silicon
Authors: Yoon Joo Chul , Dunham Scott 
Published: April 2011

ABSTRACTWe conducted molecular dynamics (MD) simulations of solid phase epitaxial growth of As-doped Si using a Tersoff potential characterized via comparison to DFT calculations, including energies of AsnV clusters. The Si:As systems were initialized by amorphizing the surface region of crystalline silicon via Si ion implantation and/or selective melting. The remaining crystalline region provides dual function of controlling temperature in system without perturbing regrowth and providing seed for recrystallization. After recrystallization, isolated As atoms occupy substitutional sites, with the average number of nearest neighbors for As changing from about 3.3 in amorphous Si to 4 after crystallization. We observe V incorporation associated with high As concentrations. A small fraction of isolated As atoms have associated vacancies, while vacancies are incorporated in the majority of cases in which there are sites with two As neighbors. These observations are consistent with our previous model developed to explain kinetics of As shallow junction formation which assumed V incorporation at sites with 2 or more As nearest neighbors to account for experimental data.
Efficacy of Damage Annealing in Advanced Ultra-Shallow Junction Processing
Authors: Timans Paul J , Hu Yao Zhi , Gelpey Jeff , McCoy Steve , Lerch Wilfried , Paul Silke , Bolze Detlef , Kheyrandish Hamid 
Published: April 2011

ABSTRACTLow thermal budget annealing approaches, such as millisecond annealing or solid-phase epitaxy (SPE) of amorphized silicon, electrically activate implanted dopants while minimizing diffusion. However, it is also important to anneal damage to the crystal lattice in order to minimize junction leakage. Annealing experiments were performed on low-energy B implants into both crystalline silicon and into wafers pre-amorphized by Ge implantation. Some wafers also received As implants for halo-style doping, and in some cases the halo implants were pre-annealed at 1050°C before the B-doping. The B-implants were annealed by either SPE at 650°C, spike annealing at 1050°C, or by millisecond annealing with flash-assisted RTP™ (fRTP™) at temperatures between 1250°C and 1350°C. Residual damage was characterized by photoluminescence and non-contact junction leakage current measurements, which permit rapid assessment of damage removal efficacy. Damage from the heavy ions used for the halo and pre-amorphization implants dominates the defect annealing behaviour. The halo doping is the critical factor in determining junction leakage current. Millisecond annealing at high temperatures helps to minimize residual damage while limiting diffusion.
Ab-Initio Modeling of Arsenic Pile-Up and Deactivation at the Si/SiO2 Interface
Authors: Gupta Naveen , Windl Wolfgang 
Published: April 2011

ABSTRACTTwo recent papers by Pei et al. and Steen et al. have shown that the observed pile-up of arsenic at Si/SiO2 interfaces surprisingly does not seem to involve point defects as a major factor, causes local distortions that strain the Si in the pile-up region locally, and that the segregated arsenic atoms are deep donors. In this paper, we use ab-initio modeling to study possible configurations for high As concentrations that may fulfill these criteria. We find for a simple model structure that As nearest neighbors become stable in Si in the vicinity of the interface. We also have stud-ied dopant deactivation using bulk-Si models. Even without invoking point defects explicitly and starting from a purely substitutional arrangement, we find that the energetically most favorable configurations are most stable in the neutral charge state, indicating that high enough concentra-tions of arsenic atoms make them electrically inactive and hence result in dopant dose loss.
Structural Evolution of Amorphous Ge2Sb2Te5 Thin Films in the Transition to the Crystalline Phase
Authors: De Bastiani Riccardo , Piro Alberto Maria , Grimaldi Maria Grazia , Rimini Emanuele , Baratta Giuseppe , Strazzulla Giovanni 
Published: April 2011

ABSTRACTThe crystallization kinetics of as-deposited amorphous Ge2Sb2Te5 thin films has been measured by in situ time resolved reflectivity. X-ray diffraction and Raman scattering analyses of partially transformed samples allowed to correlate the evolution of the transition to the structural modification in the long and short range configuration. The experimental results evidenced that during the early stages of crystallization there is a reduction of Ge-Te tetrahedral bonds, characteristics of the Ge coordination in amorphous Ge2Sb2Te5 films.
Photoemission Study of Energy Band Alignment of Ge2Sb2Te5 and Common CMOS Materials
Authors: Fang Lina Wei-Wei , Pan Ji-Sheng , Lim Andy Eu-Jin , Lee Rinus Tek-Po , Li Minghua , Zhao Rong , Shi Luping , Chong Tow-Chong , Yeo Yee-Chia 
Published: April 2011

ABSTRACTWe report the energy band alignment of Ge2Sb2Te5 and a variety of common complementary-metal-oxide-semiconductor (CMOS) compatible materials. These materials include silicon, silicon oxide, hafnium oxide, silicon nitride as well as nickel silicide. High-resolution X-ray photoelectron spectroscopy was employed as the main tool to obtain the core-level spectra, the valence band spectra, and the energy loss spectra. A precise determination of the valence band offsets of Ge2Sb2Te5 and the various materials were obtained. The conduction band offsets were then determined. The energy band line-ups of Ge2Sb2Te5 and these CMOS compatible materials were established.
Large Optical Transitions in Rewritable Digital Versatile Discs: An Interlayer Atomic Zipper in a SbTe Alloy
Authors: Tominaga Junji , Fons Paul , Shima Takayuki , Kuwahara Masashi , Suzuki Osamu , Kolobov Alexander 
Published: April 2011

ABSTRACTChalcogenides, in particular germanium-antimony-tellurium (GeSbTe) and antimony-rich tellurium (R-SbTe) based alloys, are the most technologically significant alloys currently being applied to recordable optical storage as typified by rewritable digital versatile discs (DVD-RW), DVD random access memory, (DVD-RAM). The same alloys are also being applied to nonvolatile random access memory electrical memory in the form of phase change random access memory (PCRAM). In 2004, the phase transition mechanism of GeSbTe was first revealed, demonstrating that the amorphous state is not a random configurational network but is locally well-ordered with the crystalline to amorphous switching process being based upon Ge atoms moving between octahedral and tetrahedral symmetry positions. The kinetic barrier between these two states gives rise to the non-volatile nature of GeSbTe as a storage medium. In contrast, no theoretical analysis has been proposed for SbTe alloys because a Ge-free system. In this paper, the Sb2Te structure has been investigated using the local density approximation (LDA) using a plane-wave basis and compared with experimental results. The effect of external stress on the structure was also investigated. It was found that Sb2Te undergoes two phase-transitions at around 18 GPa (compressive) and −3 GPa (tensile). In the case of negative stress, the c-axis was found to expanded more than the other axes, giving rise a large refractive index change. We report on coherent (uniaxial) melting induced by the breaking a sigma bond between Sb2Te3 and Sb superlattices. We believe this to be the origin of the phase transition that induces a large change in physical properties.
Crystallization Characteristics Of Phase Change Nanoparticle Arrays Fabricated By Self-Assembly Based Lithography
Authors: Zhang Yuan , Raoux Simone , Krebs Daniel , Krupp Leslie E. , Topuria Teya , Jordan-Sweet Jean , Caldwell Marissa , Rice Philip , Milliron Delia J. , Wong H.-S. Philip 
Published: April 2011

ABSTRACTPhase change nanodot arrays were fabricated using self-assembly diblock copolymer template PS-b-PMMA (polystyrene-poly (methyl-methacrylate)) and studied by time resolved X-ray diffraction. The size of the nanodots was less than 15nm in diameter with 40nm spacing. This method is quite flexible regarding the patterned materials, and can be used on different substrates. The crystallization behavior of small scale phase change nanodot arrays was studied for different materials, such as Ge15Sb85, Ge2Sb2Te5 and Ag and In doped Sb2Te. It was found that the nanodots had higher crystallization temperatures compared to their corresponding blanket films and crystallized over a broader temperature range.
Interface-charge-coupled polarization response model of Pt-BaTiO3-ZnO-Pt heterojunctions: Physical parameters variation
Authors: Voora Venkata , Hofmann Tino , Kjerstad Ann , Brandt Matthias , Lorenz Michael , Grundmann Marius , Schubert Mathias 
Published: April 2011

ABSTRACTHeterojunctions composed of wurtzite-structure (piezoelectric) ZnO and perovskite-structure (ferroelectric) BaTiO3 are very interesting because of the coupling effects between the non-switchable ionic charge of wurtzite-structure and electrically switchable lattice charge of pervoskite structure at their common interface. In this paper we report the variations in the overall electrical properties of the ZnO-BaTiO3 heterostructure as a function of different physical attributes by using our previously reported physical model approach. This numerical model analysis helps us to prepare the samples by using pulsed laser deposition with specific electrical properties. This study is also useful for the future device applications.
Oxidation of NiSi and Ni(Pt)Si: Molecular vs. Atomic Oxygen
Authors: Manandhar Sudha , Copp Brian , Vamala Chiranjeevi , Kelber Jeffry 
Published: April 2011

ABSTRACTX-ray photoelectron spectroscopy (XPS) has been used to characterize the reactivities of clean, stoichiometric NiSi and Ni(Pt)Si films on n-doped Si(100) substrates in O2, and in O+O2 environments. In the presence of O+O2, NiSi and Ni(Pt)Si form Ni silicate and Pt silicate overlayers, respectively, with oxide/silicate overlayer thicknesses of 41(4) Å (NiSi) and 28(3) Å (Ni(Pt)Si) after 4.5x104 L exposure. Exposure to O2 yields, for each material, a ∼7(1) Å thick SiO2 overlayer without transition metal oxidation. O+O2 induces rapid Si oxidation, formation of metal-rich silicides, and then the kinetically-driven oxidation of Ni or Pt to form a silicate. This may pose significant processing problems in silicate removal and unwanted Ni diffusion into other areas of the device.
Tailoring Electrical Conductivity and Mechanism of Carrier Transport in Zinc Oxide with Embedded Ag Layer
Authors: Han Hauk , Theodore N D , Alford Terry 
Published: April 2011

ABSTRACTThe effects of an embedded silver layer on the electrical properties of zinc oxide (ZnO) / silver (Ag)/ zinc oxide (ZnO) layered composite structures on polymer substrates have been investigated. We have engineered transparent conducting oxide structures with greatly improved conductivity. Electrical properties are correlated with Ag thickness. Film thicknesses were determined using Rutherford backscattering spectrometry. Hall effect, 4-point probe, and UV-Vis spectrophotometer analyses were used to characterize electrical and optical properties. The results show that carrier concentration, mobility, and conductivity increase with Ag thickness. Increasing Ag thickness from 8 to 14 nm enhances sheet resistance and resistivity by six orders of magnitude. We describe of the influence of Ag thickness on electrical properties of the ZnO/Ag/ZnO composite and propose a conduction mechanism for this system.
Humidity Sensing Property of Zinc Oxide Film Deposited by PLD
Authors: Dixit Shobhna , Dubey K. C. , Mishra K. P. , Srivastava Atul , Shukla R. K. , Srivastava Anchal 
Published: April 2011

ABSTRACTThis paper reports structural, morphological, optical and humidity sensing characteristics of pulsed laser deposited ZnO film. The XRD pattern reveals amorphous structure of the film. Scanning electron micrograph indicates formation of ZnO rods in micron size. Transmission increases gradually in the UV-VIS region. For studying the humidity sensing characteristics of the film, base of a right angled isosceles glass prism has been coated. Chopped light from a polarized He-Ne laser incident on the entry face of the prism gets reflected from the base – film – humid air interfaces and then emergent light is collected by the detector placed in front of the exit face of the prism. The least change in relative humidity which could be measured using the present configuration is 1.06RH%. Further the film is annealed at 400°C for four hours and its humidity sensing behavior is investigated in the similar manner which now shows a reversed trend. The sensitivity to humidity has decreased and the least change which could be detected now is 1.16RH%.
Emission Wavelength Control of Si-rich SiOx MOSLED by Detuning Vapor Fluence and Plasma Power During PECVD Growth
Authors: Lai Bo-Han , Pai Yi-Hao , Liu Chi-Wee , Lin Gong-Ru 
Published: April 2011

ABSTRACTPhotoluminescence (PL) intensity and wavelength control of Si-rich SiOx film and Si-rich SiOx based MOSLED achieved by detuning plasma power (RF power) during plasma-enhanced chemical vapor deposition (PECVD) growth is investigated. The peak of PL spectrum blue-shifts from 780 to 400 nm by modifying the RF power form 20 to 70 W during PECVD growth. The average sizes of Si nanocluster under RF power of 60 and 70W are 2.61 and 1.83 nm, respectively. The EL color of Si nanocrystal (nc-Si) based MOSLEDs can be tunable among orange-red, green and blue colors by growing the SiOx films with PECVD under different RF power. Under RF power from 50 to 70W, the turn-on voltage of nc-Si based MOSLEDs increases from 26 to 60 V, the optical power also increases from 1.6 W/cm2 to 9.7 W/cm2 and the power-current slope are 0.51, 3.24 and 62.92 mW/A, respectively.
Synthesis and Characterization of Monodispersed Rare-earth Ion Doped CeO2 Coated on SiO2 Spheres
Authors: Muralidharan Pandurangan , Jo Seung Hwan , Lee Hyun Wook , Kim Do Kyung 
Published: April 2011

ABSTRACTCore–shell microspheres of monodispersed SiO2 coated with rare-earth ion doped CeO2 (Eu3+ Sm3+ Dy3+) were prepared through a sol-gel method and followed by heat treatment at 800 °C for 4 h. XRD patterns revealed the crystal structures of the doped CeO2 coated on amorphous SiO2 sphere as a shell subsequent to heat treatment at 800 °C. SEM and TEM analysis indicated the microstructures of the coating and uniform size distributions of microspheres. Photoluminescence studies showed that the luminescent property had significant influence depending on different dopant ions and the thickness of the shell coated on SiO2 spheres.
Synthesis and Characterization on Fe-doped In2O3 Nanoparticles
Authors: Dussan-Devia Sandra , Singh Manoj K , Sharman G. L. , Katiyar R. S. , Rinaldi C 
Published: April 2011

ABSTRACTPure and Fe-doped In2O3 nanocrystalline powder was synthesized using a solution chemistry route based on the Sol-Gel process, which is a simple and inexpensive technique and produces long-time stable stock solutions. The X-ray diffraction patterns revealed the formation of nanocrystalline particle size with well-crystallized cubic bixbyte structure. The average crystal size was calculated from XRD patterns using Debye-Scherrer's equation for the (222) peak and found to be 8 nm. This observation agrees well with the particle size estimated from transmission electron microscopy (TEM). The observed Raman peaks in the doped materials are shifted towards the lower frequency up to 15 cm−1 and we did not observed any additional new Raman modes with Fe doping. This clearly indicates that Fe ions are indeed occupying interstitial/substitutional sites in the host In2O3, in agreement with XPS measurements. Magnetic properties were studied using superconducting quantum interface device magnetometer (Quantum design MPMS XL-7). Preliminary magnetic measurement results suggest the incorporation of the dopants in the diamagnetic In2O3-host structure.
Synthesis of Cadmium and its Oxide Nanomaterials by Pulsed Laser Ablation in Aqueous Media
Authors: Singh Subhash Chandra , Swarnkar Rajkumar , Gopal Ram 
Published: April 2011

ABSTRACTCadmium based oxide and hydroxide nanocomposites material is synthesized by pulsed laser ablation of cadmium metal in the double distilled water. A piece of cadmium metal, placed on the bottom of glass vessel containing double distilled water, was irradiated with 1064 nm of pulsed Nd:YAG laser operating at 35 mJ/pulse energy and 10 ns pulse width for 30 minutes. Colloidal solution of produced Nanoparticles is found stable for two days. Fine white colored powder is obtained after drying centrifuged solution. UV-visible absorption of colloidal solution, XRD, TGA, DTA and FTIR of the powder is used for the characterization of material. Possible mechanism of synthesis and hydroxide to oxide transition is discussed.