No. 4 (2009)
Published:
2009-12-30
ARTICLES FROM THIS ISSUE
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SOI Technology: An Opportunity for RF Designers?
Abstract
This last decade silicon-on-insulator (SOI) MOS-FET technology has demonstrated its potentialities for high frequency (reaching cutoff frequencies close to 500 GHz forn-MOSFETs) and for harsh environments (high temperature,radiation) commercial applications. For RF and system-on-chip applications, SOI also presents the major advantage of providing high resistivity substrate capabilities, leading to substantially reduced substrate losses. Substrate resistivity values higher than 1 kΩΩΩcm can easily be achieved and high resistivity silicon (HRS) is commonly foreseen as a promising substrate for radio frequency integrated circuits (RFIC) and mixed signal applications. In this paper, based on several experimenta land simulation results the interest, limitations but also possible future improvements of the SOI MOS technology are presented.
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The Impact of Externally Applied Mechanical Stress on Analog and RF Performances of SOI MOSFETs
Abstract
This paper presents a complete study of the impact of mechanical stress on the performance of SOI MOSFETs.This investigation includes dc, analog and RF characteristics.Parameters of a small-signal equivalent circuit are also extracted as a function of applied mechanical stress. Piezoresistance coefficient is shown to be a key element in describing the enhancement in the characteristics of the device due to mechanical stress.
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Prospects and Development of Vertical Normally-off JFETs in SiC
Abstract
This paper reviews the prospects of normally-off (N-off) JFET switch in SiC. The potential of selected vertical JFET concepts and all-JFET cascode solutions for N-off operation is analyzed using simulations. The performance of analyzed concepts is compared in terms of blocking voltage, specific on-state resistance, maximum output current density and switching performance in the temperature range from 25°C to 250°C. The main objective of the analysis is to ascertain consequences of different design and technology options for the total losses and high temperature performance of the devices.
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Variation Analysis of CMOS Technologies Using Surface-Potential MOSFET Model
Abstract
An analysis of the measured macroscopic withinwafer variations for threshold voltage (Vth) and on-current (Ion) over several technology generations (180 nm, 100 nm and 65 nm) is reported. It is verified that the dominant microscopic variations of the MOSFET device can be extracted quantitatively from these macroscopic variation data by applying the surface-potential compact model Hiroshima University STARC IGFET model 2 (HiSIM2), which is presently brought into industrial application. Only a small number of microscopic parameters, representing substrate doping (NSUBC), pocket-implantation doping (NSUBP), carrier-mobility degradation due to gate-interface roughness (MUESR1) and channel-length variation during the gate formation (XLD) are found sufficient to quantitatively reproduce the measured macroscopic within-wafer variations of Vth and Ion for all channel length Lg and all technology generations. Quantitative improvements from 180 nm to 65 nm are confirmed to be quite large for MUESR1 (about 70%) and Lmin(XLD) (55%) variations, related to the gate-oxide interface and the gate-stack structuring, respectively. On the other hand, doping-related technology advances, which are reflected by the variation magnitudes of NSUBC (30%) and NSUBP (25%), are found to be considerably smaller. Furthermore, specific combinations of extreme microscopic parameter-variation values are able to represent the boundaries of macroscopic fabrication inaccuracies for Vth and Ion. These combinations are found to remain identical, not only for all Lg of a given technology node, but also for all investigated technologies with minimum Lg of 180 nm, 100 nm and 65 nm.
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Analysis of the Dispersion of Electrical Parameters and Characteristics of FinFET Devices
Abstract
Extensive numerical simulations of FinFET structures have been carried out using commercial TCAD tools. A series of plasma etching steps has been simulated for different process conditions in order to evaluate the influence of plasma pressure, composition and powering on the FinFET topography. Next, the most important geometric parameters of the FinFETs have been varied and the electrical characteristics have been calculated in order to evaluate the sensitivity of the FinFET electrical parameters on possible FinFET structure variability.
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Rare Earth Silicate Formation: A Route Towards High-k for the 22 nm Node and Beyond
Abstract
Over the last decade there has been a significant amount of research dedicated to finding a suitable high-k/metal gate stack to replace conventional SiON/poly-Si electrodes. Materials innovations and dedicated engineering work has enabled the transition from research lab to 300 mm production a reality, thereby making high-k/metal gate technology a pathway for continued transistor scaling. In this paper, we will present current status and trends in rare earthbased materials innovations; in particular Gd-based, for the high-k/metal gate technology in the 22 nm node. Key issues and challenges for the 22 nm node and beyond are also highlighted.
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Technology of MISFET with SiO2/BaTiO3 System as a Gate Insulator
Abstract
The properties of barium titanate (BaTiO3, BT), such as high dielectric constant and resistivity, allow it to find numerous applications in the field of microelectronics. In this work silicon metal-insulator-semiconductor field effect transistor (MISFET) structures with BaTiO3 thin films (containing La2O3 admixture) acting as gate insulator were investigated. The films were produced by means of radio frequency plasma sputtering (RF PS) of sintered BaTiO3 + La2O3 (2% wt.) target. In the paper transfer and output I−V, transconductance and output conductance characteristics of the obtained transistors are presented and discussed. Basic parameters of these devices, such as threshold voltage (VTH) are determined and discussed.
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Modeling, Simulation and Calibration of Silicon Wet Etching
Abstract
The methods of parameter optimization in Etch3DTM simulator and the results of the comparison of simulations of silicon etching in KOH with experiments are presented. The aim of this study was to calibrate the tool to a set of process conditions that is offered by Institute of Electron Technology (ITE). The Taguchi approach was used to analyze the influence of every remove probability function (RPF) parameter on one or more output parameters. This allowed tuning the results of simulation to the results of real etching performed in ITE.
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Si-Based Electrodes for Potentiometric Measurements of Aqueous Solutions
Abstract
Three sensors for chemical and physical examination of aqueous solutions were presented in the paper. An Au potentiometric electrode, an AgCl chlorine ion sensor and a p-n junction thermometer were developed. Their layout and internal structure were explained in the light of the manufacturing process. The device characteristics were measured in conditions corresponding to normal operation of the devices. Basic electrical parameters of the developed structures, as well as their sensitivity to environmental parameter variation were estimated.
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LPT and SLPT Measurement Methods of Flat-Band Voltage (VFB) in MOS Devices
Abstract
The photoelectric techniques are often used for the measurements of metal oxide semiconductor (MOS) structure parameters. These methods, which consist in illuminating the MOS structure with a semitransparent metal gate by a UV light beam, are often competitive for typical electric measurements. The results obtained by different photoelectric methods are, in many cases, more accurate and reproducible than the results of other measurements. The flat-band voltage VFB is an important parameter of any MOS structure since its value influences the threshold voltage VT , which decides for example about power consumption of MOS transistors. One of the methods to measure the VFB value is the electric method of C(V) characteristic. This method involves certain calculations and requires the knowledge about parameters of the investigated sample. The accuracy of this method is rarely better than ±100 mV (for higher doping of the substrates the accuracy is worse). The other method of VFB value determination, outlined in this article, is the photoelectric light pulse technique (LPT) method. This method based on the idea proposed by Yun is currently being optimized and verified experimentally.
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Lateral Force Calibration Method Used for Calibration of Atomic Force Microscope
Abstract
Modern heterogeneous micro- and nanostructures usually integrate modules fabricated using various materials and technologies. Moreover, it has to be emphasized that the macro and micro nanoscale material parameters are not the same. For this reason it has become crucial to identify the nanomechanical properties of the materials commonly used in micro- and nanostructure technology. One of such tests is a nanowear test performed using the atomic force microscope (AFM). However, to obtain quantitative measurement results a precision calibration step is necessary. In this paper a novel approach to calibration of lateral force acting on the tip of an AFM cantilever is discussed. Presented method is based on application of known lateral force directly on the tip using a special test structure. Such an approach allows for measurements of nanowear parameters (force, displacement) with the uncertainty better than ±3%. The calibration structure designed specifically for this calibration method is also presented.
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The Influence of Meteorological Phenomena on Modern Satellite Systems
Abstract
The areas of attention, described in this paper, extend throughout the modern satellite systems. Future satellite systems are to be planned for the millimeter band, which has greater weather attenuation effects than until now used bands. This paper provides a brief overview of propagation factors on millimeter-band earth-satellite paths and requirements in relation to the need for specific types of propagation data.
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Trends in Use of RF Spectrum
Abstract
This paper reviews possible improvements in the use of radio waves for carrying information from an engineering viewpoint. A few new concepts are proposed, which reduce the problem to an arrangement of solids in a multidimensional space.
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Adaptive Resource Management and Flexible Radios for WiMAX
Abstract
The availability of dynamic resource management will be crucial for the deployment of future wireless systems characterized by high data rate services with rigid quality of service demands. Flexible radios appear as the technological answer required to achieve constraint goals under different channel conditions and transmission scenarios. This paper is focused on enhancing another step of flexibility within the resource management by including an efficient handling of computing resources. This concept towards flexible architectures represents a key word for a real successful implementation due to the relationship between the radio applications, which face the scarcity of resources within a heterogeneous environment, and the processing power needed to execute them.
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Mathematical Foundations of Cognitive Radios
Abstract
Recently, much interest has been directed towards software defined radios and embedded intelligence in telecommunication devices. However, no fundamental basis for cognitive radios has ever been proposed. In this paper, we introduce a fundamental vision of cognitive radios from a physical layer viewpoint. Specifically, our motivation in this work is to embed human-like intelligence in mobile wireless devices, following the three century-old work on Bayesian probability theory, the maximum entropy principle and minimal probability update. This allows us to partially answer such questions as, what are the signal detection capabilities of a wireless device, when facing a situation in which most parameters are missing, how to react and so on. As an introductory example, we will present previous works from the same authors following the cognitive framework, and especially the multi-antenna channel modeling and signal sensing.
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A Microscopic Approach for THz Intersubband Challenges
Abstract
The main candidate to be a practical and low cost high power THz source is the intersubband-based quantum cascade laser, which can have a tremendous impact in many practical applications, including last mile and indoor telecommunication systems. In this review we discuss current challenges for THz intersubband device development from a microscopic point of view. Next summarize the search for new mechanisms and structure designs that can lead to intersubband gain without population inversion. This is a very important topic of current research, since is both an extremely elegant phenomenon from the basic physics of view and crucial for effective lasing in the THz range. The reason is that scattering phenomena can lead to level broadenings of the same order of magnitude of the lasing transitions, making population inversion by carrier injection in upper lasing subbands extremely difficult. Previous work in the literature is compared and contrasted with a new scheme that may lead to high temperature lasing by engineering the nonequilibrium population inversion with a combination of band structure and many body effects mediated by a k-space filter.
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Impact of Signaling System Performance on QoE in Next Generation Networks
Abstract
The first experience of quality by multimedia applications’ users takes place during the setup phase of a new connection. If the setup phase is not accepted or “slowly accepted”, the confidence of the user decreases. The user becomes more sensitive when he/she pays the connections with assured quality of service (QoS). In this case, the process of call request should be also accomplished with QoS guarantees. This paper presents the signaling sub-system implemented within the EuQoS system. The EuQoS signaling process follows main assumptions of next generation networks (NGN) architecture and performs tasks related with codec agreement between multimedia end users, admission control and resource reservation functions. In this paper, we present analytical, simulation and experimental results showing the impact of signaling system performance on quality of experience (QoE) for the potential users of multi-layer EuQoS system. In particular, the presented approach aims at ensuring user QoE of the connection setup phase by ensuring QoS for transferring signaling messages by the network.
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Recommendations and Regulations of the European Commission Regarding the Pan-European eCall
Abstract
The paper presents the main actions conducted by the European Commission in the context of the eCall programme (the initiatives of Driving Group), the recommendations and requirements for introduction of the pan-European eCall (architecture, handling procedures, minimum set of data (MSD) content, performance criteria, etc.) as well as regulations concerning the pan-European eCall, particularly the status of the eCall project covering also the legal situation of eCall in the Member States including Poland.
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ID-Based Digital Signatures with Security Enhanced Approach
Abstract
n the paper the ID-based digital signatures with signer’s protection in case of the private key compromising is investigated. The proposed protocols have two main ingredients. First is the application of the credential system for the suitable verification key approval. Second is the application of the subliminal channel together with the interactive generation of the secret key, to obtain the increased resistance of the system against the powerful adversary. The particular interest was turned towards the significance of the deniable encryption in creation of the corresponding protocols.
