Effects of Applied Mechanical Uniaxial and Biaxial Tensile Strain on the Flatband Voltage of (001), (110), and (111) Metal–Oxide–Silicon Capacitors

The flatband-voltage shift of metal–oxide–silicon capacitors is investigated under the application of low-level stress (up to 220 MPa of biaxial stress and 380 MPa of uniaxial stress) to different substrate orientations. We propose that the flatband-voltage shift be modeled as the net effect of silicon-band-edge shifts and modulation of the separation between the band edge and the Fermi level under low levels of applied mechanical strain. For the (001) n-type substrate, a negative flatband-voltage shift is observed due mainly to the downward shift of the conduction-band edge, while a positive flatband-voltage shift is observed for the (001) p-type substrate due to the upward shift of the valence-band edge. For the uniaxial tensile strain on n-substrate capacitors for (110) and (111) substrates, the modulation of band-edge and Fermi-level separation by the conduction-band density of states exceeds the downward shift of the conduction band, which induces a positive flatband shift that is distinct from that observed in the (001) n-substrate. The shift of the band edges is determined by the proposed model and compared with theoretical calculations.      

Dynamic data retention and implied design criteria forfloating-body SOI DRAM

A physical MOSFET model in SOISPICE is used to characterize dynamic data retention in PD/SOI DRAM cells. Simulations show that transient parasitic BJT current underlies peculiar data retention, and they suggest how periodic body discharge effected by data refresh with a high flatband-voltage cell transistor can render PD/SOI technology viable and attractive for gigabit DRAM applications     

Characterization of process-induced mobile ions on the data retention in flash memory

Data retention is a major issue that significantly affects the reliability of nonvolatile memory. In this paper, data retention behaviors due to mobile ions are extensively characterized by using several test methods. The source of mobile ions during the sputtering of Ti/TiN layers for forming salicide inside array was identified by secondary ion mass spectroscopy (SIMS) analysis. Different test sequences clearly reveal the data retention caused by mobile ions. Salicide block material that includes silicon nitride effectively blocks the impact of mobile ions. Bitmapping patterns on an array indicate that the amount of charge loss spatially depends on its neighbor's high-V/sub th/ cells via the Coulomb's r-square field. The spatial effects of neighboring cells on the charge loss are then estimated. Beyond 1.98 /spl mu/m, the charge loss caused by mobile ions of a individual cell becomes unaffected by the V/sub th/ state of its neighboring cells. Plasma charging cells also attract mobile ions. A considerable charge gain, by as much as 0.8 V with a radial distribution on fresh wafer, was observed after a UV-bake test. The interaction between plasma charging effect and mobile ions movement during wafer processing explains this interesting feature.     

轮式机器人滑模轨迹跟踪控制器设计

轮式机器人是一个典型的非完整性系统。由于非线性和非完整特性,很难为移动机器人系统的轨迹跟踪建立一个合适的模型。介绍了一种轮式机器人滑模轨迹跟踪控制方法。滑模控制是一个鲁棒的控制方法,能渐近的按一条所期望的轨迹稳定移动机器人。以之为基础,描述了轮式机器人的动力学模型并在二维坐标下建立了运动学方程,根据运动学方程设计滑模控制器,该控制器使得机器人的位置误差收敛到零。     

Separation of dynamic current-voltage characteristics (DCVCs) of an oxide film from the DCVC of ionic currents in a metal/oxide/semiconductor structure: Universal quasi-static DCVCs of a film

Analytic results for a quasi-equilibrium distribution of mobile ions in an oxide film contained in a metal/oxide/semiconductor (MOS) structure, as well as formulas for the concentration of ions at the center of the film and on its boundary and formulas for the ionic centroid, are reviewed. Thresholds for the emergence of a U-shaped distribution of ions with characteristic accumulation of ions near the film’s boundary (segregation of ions) are analyzed; the case of a half-space is considered as well. A method to determine the dynamic current-voltage characteristic (DCVC) of the film’s ionic currents is proposed. This method uses an experimental DCVC of the entire structure and a quasi-equilibrium (low-frequency) electronic voltage-capacitance characteristic of the structure. The film’s DCVC has to be separated to eliminate masking effects of the semiconductor’s capacitance on the structure’s DCVC. An analytic method for calculation of the film’s quasi-static DCVC is developed for a model of a homogeneous film. When expressed in dimensionless units, such DCVCs, which are shown to depend on only the dimensionless concentration of ions in the film (per unit area), prove to be universal functions. The population of ionic traps on the film’s boundary is described using the energy Gibbs distribution of ions. The presence of traps is shown to result in the emergence of an additional “trap” peak on the film’s DCVC only if the concentration of traps is low; when this concentration is large, a single peak is observed on the DCVC.     

OLED器件寿命衰退模型的MATLAB分析计算

介绍了OLED器件寿命衰退模型的MATLAB分析计算方法.一般认为运动离子是驱动电压变化的原因之一.利用MATLAB求解了运动离子瞬态方程,得到了与时间相关的负指数形式分布函数.介绍了阳极为恒流离子源条件时模型的数值求解算法.根据模型可以计算出运动离子引入的驱动电压随时间的变化关系,其结果可用于与实验数据进行拟合比较.     

The influence of mobile ions on the Si/SiO2 interface traps

An investigation of the relation between mobile ions and interface traps was carried out, using an appropriate technique to determine the number and type of mobile ions. It was found that mobile ions do not cause interface traps in the middle 0.8 eV of the bandgap. It appears that interface traps are rather caused by some stress effect. The results are considered in light of previously reported work.     

Instability in vacuum deposited silicon oxide

The instability of vacuum deposited SiO2in field-effect transistors is described. Results for an Al-SiO2-CdSe system are accounted for by a model in which mobile ions are located predominantly in traps at the SiO2interfaces. The asymmetrical drift rate observed was accounted for by a difference in activation energy for release of ions from the two interfaces. The absorption of water vapor caused an increase in both the magnitude of the drift and the transconductance of the transistor during the drift.     

Localization of a mobile robot using the image of a moving object

This paper proposes a new approach for determining the location of a mobile robot using the image of a moving object. This scheme combines data from the observed position, using dead-reckoning sensors, and the estimated position, using images of moving objects captured by a fixed camera to determine the location of a mobile robot. Using the a priori known path of a moving object and a perspective camera model, the geometric constraint equations that represent the relation between image frame coordinates for a moving object and the estimated robot's position are derived. Since the equations are based on estimated position, measurement error may exist. However, the proposed method utilizes the error between the observed and estimated image coordinates to localize the mobile robot, and the Kalman filtering scheme is used for the estimation of the mobile robot location. The proposed approach is applied for a moving object on the wall to show the reduction of uncertainty in the determining of mobile robot location.     

Manifestations of the deneutralization of mobile charges in SiO2 in the spectroscopy of the silicon-oxide interface

The total number of mobile ions in the oxide film in a Si-based MOS structure is determined by the conventional methods of recording capacitance-voltage and dynamic current-voltage characteristics. The fraction of ions in the neutral state at the Si-SiO₂ interface is determined. Spectroscopy of the interface reveals a peak of the effective density of interface states. It is shown that the number of states in this peak corresponds to the number of neutralized particles. The mechanism for neutralization of the mobile charge of ions is discussed. Fiz. Tekh. Poluprovodn. 32, 1445–1449 (December 1998)     

Autonomous mobile target tracking system based on grey-fuzzycontrol algorithm

This paper presents a new position-based tracking system for autonomous mobile target tracking task. A grey-fuzzy controller (GFC) is developed for motion control of the tracker, in which dynamics models of the target and tracker are not required a priori. The target detection is based on the adaptive visual detector (AVD), which can online adjust the histogram model based on the change of surrounding conditions, such as light variation, in a natural environment. The AVD and GFC are integrated together for mobile target-tracking applications. There are several advantages of the integrated system, in particular: (1) it can rapidly learn the target appearance model for the detection involved with the tracking task; (2) the temporal dynamics model of the target motion can be approximated for the predictive localization of the moving target; and (3) the system can deal with the uncertain environmental conditions to ensure the tracking performance by GFC. Three mobile robots in the authors' laboratory have been used to demonstrate the success of this integrated system experimentally. They also conduct target tracking experiments, in which Chung Cheng-I tracks various moving targets. The results demonstrate the robustness and flexibility of the overall system in dealing with mobile target-tracking problems under varied natural environment conditions     

Kinetics of growth of surface amorphous layers under irradiation of silicon with low-energy light ions

The damage buildup in Si single crystals irradiated with 10-keV Ne⁺ ions was studied by a method based on measurements of anisotropy in inelastic electron scattering. It is shown that disorder buildup occurs as a result of growth of an amorphous layer starting from the boundary between the native oxide and crystalline Si. It is ascertained that the growth rate of the amorphous layer is independent of the current density of ions and that a threshold dose for the defect accumulation exists. The results are explained in terms of a model based on diffusion of generated mobile point defects to the surface with their subsequent segregation; the assumption that there are saturable sinks in the as-grown single crystals is also used. The results of calculations based on this model are in good agreement with experimental data obtained both in this study and reported in available publications.     

Comparisons of computed mobile phone induced SAR in the SAM phantom to that in anatomically correct models of the human head

The specific absorption rates (SAR) determined computationally in the specific anthropomorphic mannequin (SAM) and anatomically correct models of the human head when exposed to a mobile phone model are compared as part of a study organized by IEEE Standards Coordinating Committee 34, Sub-Committee 2, and Working Group 2, and carried out by an international task force comprising 14 government, academic, and industrial research institutions. The detailed study protocol defined the computational head and mobile phone models. The participants used different finite-difference time-domain software and independently positioned the mobile phone and head models in accordance with the protocol. The results show that when the pinna SAR is calculated separately from the head SAR, SAM produced a higher SAR in the head than the anatomically correct head models. Also the larger (adult) head produced a statistically significant higher peak SAR for both the 1- and 10-g averages than did the smaller (child) head for all conditions of frequency and position.     

Effect of ionising radiation on mobile-ion density in m.o.s. oxides

Data are presented that indicate that the density of mobile ions in m.o.s. oxides is unaffected by exposure to ionising radiation. The flat-band voltages following irradiation and anneal appear to be correlated with the density of mobile ions.     

Influence of mobile ion in organic material used in semiconductor devices

Kapton tape is often used for co-planarity of inner metal lead frame parts in the packaging of semiconductor components. It is made of organic material known as high temperature insulating tape. In this paper, the increment of leakage current in a packaged component that is caused by a Kapton tape was studied. The leakage measurement on Kapton tape was done using simple testing instruments such as source meter, micro prober and temperature controlled hot plate. The different leakage current characteristics were investigated on high temperature, test duration and length of the Kapton tape. According to the measured leakage current on various dependencies, it is suggested the leakage is due to mobile ion in Kapton tape. Various analysis techniques were able to identify the mobile ion was Sodium ions in the glue of the Kapton tape. Based on the observation, a model explaining the Sodium mobile ions failure mechanism in the Kapton tape was established. The deployment of leakage test can be applied to test incoming lead frame material. The test set up did not require expensive tester equipment and manufactured devices. It could also be transferred as new outgoing quality check mainly for lead frame suppliers.     

Kinetics of the growth of an amorphous layer at the surface of silicon bombarded with fast heavy ions at low temperatures

The accumulation of defects in the surface region of Si bombarded with 0.5-MeV Bi ions at a temperature of ?196°C is considered. It is shown that the buildup of disorder in the surface region as the ion dose increases manifests itself in the planar growth of an amorphous layer starting from the Si-SiO₂ interface, and this growth sets in after a threshold implantation dose is attained. The results obtained can be described adequately in the context of a model based on the migration of mobile point defects generated by fast ions to the surface, subsequent processes of segregation of these defects at the interphase boundary, and the presence of saturable sinks in the initial samples.     

Magnetic-Field-Induced ELF Currents in a Human Body by the Use of a GSM Phone

A finite element method (FEM) with nonuniform mesh is employed for the calculation of extremely low frequency (ELF) currents induced in a human body by a global system for mobile communications (GSM) phone. The magnetic field of the phone is measured, and an equivalent source with magnetic dipoles is constructed for the numerical simulation. A cell of variable size is used in the simulation to accurately model the most important areas of the body model, namely areas close to the source and parts of the central nervous system. Three different mobile phone positions are considered: normal operation on the side of the head, breast pocket, and the small of the back where the spinal cord is close to the phone. Obtained results are compared with the guidelines of the International Commission on Non-Ionizing Radiation Protection (ICNIRP).     

Deep trapping of implanted Na+ and Li+ ions near the Si/SiO2 interface in metal-oxide-silicon structures

Na⁺ and Li⁺ ions have been implanted in the oxide layer of MOS structures with doses ranging from 3 × 10¹¹ to 3 × 10¹³ ions/cm². Part of the implanted ions can be retraced as mobile ions: this fraction decreased with increasing dose. The trapping of the mobile ions near the Si/SiO₂ interface has been investigated by means of the thermally stimulated ionic current (TSIC) technique. The average energy depth of the ionic traps appeared to increase with increasing dose. Moreover, we found that Li⁺ ions are trapped deeper than Na⁺ ions under equivalent experimental conditions. The influence of the applied electric field on the detrapping has been studied. In the case of 3 × 10¹³ Na⁺ implantation, the barrier lowering corresponds with the Poole-Frenkel theory. We have also paid attention to the effects of bias-temperature stress treatments on the trapping kinetics. We observed a decrease of the mobile ion current after long BTS treatments.     

Multisite throughput of a mobile data radio link

In a single-site system, the uplink channel (from the mobile units to the site) has a throughput of 0.184 if pure ALOHA transmission protocol is used. The downlink channel throughput (from the site to the mobile units) for a single-site system is one because the transmissions are scheduled and no conflict occurs. To widen the service area and to increase system throughput for the single-site system without using additional frequency channels, multiple transmitter/receiver sites can be used. Throughput in both directions (uplink and downlink) and optimal site assignment in the downlink channel are calculated using an iterative method. Formulas are derived for two- and three-site systems. For systems with more than three sites, the three-site formulas can be used in an approximate method. Results produced by this method are within 1 or 2% of those generated by software simulations. For simplicity, FM capture is assumed to depend on the received signal level difference between the two strongest signals. Calculations are given assuming the message error rates are known     

Measurement of a Customer Satisfaction Index for Improvement of Mobile RFID Services in Korea

One of the ubiquitous technology fields that have received the most attention recently from technology communities worldwide is mobile radio frequency identification (RFID). Mobile handsets loaded with RFID readers enable the identification and retrieval of information on RFID tagged objects. In Korea, a variety of mobile RFID services are currently being piloted, and their commercial roll‐out looks imminent. The goal of this study is to propose, ahead of the commercial launch of mobile RFID services, a customer satisfaction index (CSI) model for this service category and to then measure the CSI to derive practical implications for their providers and pointers related to the improvement of service. A web survey was conducted on Korean mobile phone subscribers who had participated in a mobile RFID pilot program. Using the results of this survey, we tested the CSI model and its hypotheses by employing a partial least‐squares‐based structural equation model analysis and calculated the index. We further conducted an importance‐performance analysis in order to provide insights that may be useful for improving the quality of mobile RFID services.