堆叠栅介质MOS器件栅极漏电流的计算模型

采用顺序隧穿理论和传输哈密顿方法并考虑沟道表面量子化效应,建立了高介电常数堆叠栅介质MOS器件栅极漏电流的顺序隧穿模型。利用该模型数值,研究了Si3N4/SiO2、Al2O3/SiO2、HfO2/SiO2和La2O3/SiO2四种堆叠栅介质结构MOS器件的栅极漏电流随栅极电压和等效氧化层厚度变化的关系。依据计算结果,讨论了堆叠栅介质MOS器件按比例缩小的前景。     

基于氧化铪的高k栅介质纳米MOSFET栅电流模型

运用一种全量子模型研究基于氧化铪的高k栅介质纳米MOSFET栅电流,该方法特别适用于高k栅介质纳米MOS器件,还能用于多层高k栅介质纳米MOS器件。使用该方法研究了基于氧化铪高k介质氮含量等元素对栅极电流的影响。结果显示,为最大限度减少MOS器件的栅电流,需要优化介质中氮含量、铝含量。     

22nm技术节点异质栅MOSFET的特性研究

研究了22 nm栅长的异质栅MOSFET的特性,利用工艺与器件仿真软件Silvaco,模拟了异质栅MOSFET的阈值电压、亚阈值特性、沟道表面电场及表面势等特性,并与传统的同质栅MOSFET进行比较。分析结果表明,由于异质栅MOSFET的栅极由两种不同功函数的材料组成,因而在两种材料界面附近的表面沟道中增加了一个电场峰值,相应地漏端电场比同质栅MOSFET有所降低,所以在提高沟道载流子输运效率的同时也降低了小尺寸器件的热载流子效应。此外,由于该器件靠近源极的区域对于漏压的变化具有屏蔽作用,从而有效抑制了小尺寸器件的沟道长度调制效应,但是由于其亚阈值特性与同质栅MOSFET相比较差,导致漏致势垒降低效应(DIBL)没有明显改善。     

纳米级MOS器件中电子直接隧穿电流的研究

文章从分析量子力学效应对纳米级MOS器件的影响出发,采用顺序隧穿理论和巴丁传输哈密顿方法,建立了纳米级MOS器件直接隧穿栅电流的计算模型。通过和实验数据的比较,证明了该模型的有效性。计算结果表明,在纳米级MOS器件中,采用SiO2作栅介质时,1.5 nm厚度是按比例缩小的极限。该计算模型还可以用于高介电常数栅介质和多层栅介质MOS器件的直接隧穿电流的计算。     

半导体电场敏感器件和电场传感器

本文介绍了用MOS工艺制作的直接栅电场敏感FET,对其敏感特性进行了实验研究和理论分析.室温下,用此器件在空气中检测电场时,在外加电场小于空气击穿场强的范围内,器件的电流-电场跨导大于2μA/(kV/cm).用直接栅FET和普通MOSFET作差分对,利用栅绝缘层上压降正比于外电场的原理,用反馈和差分放大组合电路制作电场传感器.得到了0.2V/ (kV/cm)的线性输出.     

减少纳米MOS器件栅电流的研究分析

采用Schroedinger-Poisson方程自洽全量子求解法研究了MOS器件不同介质材料和栅结构栅电流,该模型对栅电流中的三维电流成分用行波统一地计算;对二维栅电流成分通过反型层势阱中准束缚态的隧穿率计算。模拟得出栅极电流与实验结果符合。研究结果表明,采用高愚栅介质材料、p-MOSFET或双栅结构对栅电流的减少有明显的作用,这一结果可望对器件性能作出预计并对其研制提供指导。     

表面钝化对HfTiON栅介质Ge MOS电容性能的影响

通过NO、N2O对Ge衬底进行表面钝化,生长GeOxNy界面层,然后采用反应磁控共溅射方法制备HfTiN薄膜,并利用湿N2气氛退火,将HfTiN转化为HfTiON高κ栅介质.研究了表面钝化对MOS器件性能的影响,结果表明,湿NO表面钝化能改善界面质量,有效降低MOS电容的栅极漏电流,增强器件的可靠性.     

表面钝化对Ge MOS电容可靠性的影响

通过NO、N2O对Ge衬底进行表面钝化,然后采用反应磁控共溅射方法制备HfTiN薄膜,并利用湿N2气氛退火,将HfTiN转化为HfTiON高k栅介质.研究了表面钝化对Ge MOS器件性能的影响.实验结果表明,湿NO表面钝化能生长高质量GeOxNy界面层,有效降低MOS电容的栅极漏电流,增强器件的可靠性.     

超薄HfN界面层对HfO_2栅介质Ge pMOSFET电性能的改进

通过在高k介质和Ge表面引入一层超薄HfN界面层,实验制备了HfO2/HfON叠层栅介质Ge MOS器件。与没有界面层的样品相比,HfO2/HfON叠层栅介质MOSFET表现出低的界面态密度、低的栅极漏电和高有效迁移率。因此利用HfON作为Ge MOS器件的界面钝化层对于获得小的等效氧化物厚度和高的high-k/Ge界面质量有着重要的意义。     

高压LDMOS准饱和效应研究

借助于SILVACO TCAD仿真工具,研究了高压LDMOS电流准饱和效应(Quasi-saturation effect)的形成原因。通过分析不同栅极电压下漂移区的耗尽情况以及沟道与漂移区电势、电场和载流子漂移速度的分布变化,认为当栅压较低时,LDMOS的本征MOSFET工作在饱和区,栅压对源漏电流的钳制明显,此时沟道载流子速度饱和;而在大栅压下,随着沟道导电能力的增加以及漂移区两端承载的电压的增大,本征MOSFET两端压降迅速降低,器件不能稳定地工作在饱和区而进入线性工作区,此时沟道中的载流子速度不饱和。LDMOS器件的源漏电流的增大主要受漂移区影响,栅压逐渐失去对器件电流的控制,此时增大栅压LDMOS器件的源漏电流变化很少,形成源漏电流的准饱和效应。最后,从器件工作过程对电流与栅压的关系进行了理论分析,并从理论结果对电流准饱和效应进行了深入分析。     

巨磁阻生物传感器阵列及专用锁相放大器设计

EW_GⅠ是基于GMR(巨磁阻)传感器,用于检测血样中特种病毒的正在研发的生物芯片系统。叙述了其巨磁阻传感器阵列以及后端锁相放大IC电路的设计及实现。该阵列包含32个GMR传感器单元和2个传感器参考单元,形成多路的半桥式惠斯通电桥,用于感应绑定磁球的附加磁场。每个单元(100μm×100μm)由长1mm、宽7μm的巨磁电阻蜿蜒而成,该电阻采用[Ag(2nm)/NiFe(6nm)/Cu(2.2nm)/CoFe(4nm)]20结构,采用Ag作为镜面层,其饱和磁场小于等于30mT,GMR值约6%,单个传感器电阻约为780Ω。配套的锁相放大芯片包括了信号通道、参考通道、前置低噪声放大器、带通滤波器、可控增益放大器、相敏检测电路、正交移相电路、差分直流放大电路八个部分,整个设计功耗小于50mW@Vcc=3V。     

S波段功率SiC MESFET(芯片)研制

介绍了一种S波段功率SiC MESFET芯片的研制技术。针对SiC材料的特点,对4H-SiC外延材料进行了设计和仿真,同时对Al记忆效应进行了研究,优化了4H-SiC外延生长技术。研究了栅长与沟道厚度纵横比(Lg/a)对短沟道效应和漏极势垒降低效应的影响。采用了凹槽栅结构和体标记电子束直写技术以及热氧化SiO2和SiNx复合钝化层设计等新制备工艺,实现了栅、漏泄漏电流的减小和源、漏击穿电压的提高。测试结果表明,功率SiC MESFET芯片在3.4 GHz频率下脉冲输出功率大于45 W,功率增益8.5 dB,漏极效率40%。测试条件为漏极工作电压48 V,脉宽100μs,占空比10%。     

基于DSP的光伏并网技术的研究与实现

在光伏并网发电系统中,为了避免所发电能并入电网后造成电网污染,必须使用锁相环（PLL--Phase-Locked Loop）技术,保证并网电流和电网电压严格同频同相。文中针对软件锁相环技术,提出了一种基于电网电压过零检测硬件电路的新方法,并在CCS3.3软件中编写程序,以DSP芯片TMS320F2812为控制芯片进行了实验验证。实验结果表明此锁相环方案可以快速准确地使并网电流跟踪电网电压。     

Analog VLSI Circuit Implementation of an Adaptive Neuromorphic Olfaction Chip

In this paper, we present the analog circuit design and implementation of the components of an adaptive neuromorphic olfaction chip. A chemical sensor array employing carbon black composite sensing materials with integrated signal processing circuitry forms the front end of the chip. The sensor signal processing circuitry includes a dc offset cancellation circuit to ameliorate loss of measurement range associated with chemical sensors. Drawing inspiration from biological olfactory systems, the analog circuits used to process signals from the on-chip odor sensors make use of temporal "spiking" signals to act as carriers of odor information. An on-chip spike time dependent learning circuit is integrated to dynamically adapt weights for odor detection and classification. All the component subsystems implemented on chip have been successfully tested in silicon     

Integrated multisensor chip

A multipurpose integrated-sensor chip has been fabricated for the simultaneous measurement of physical and chemical variables. The multipurpose chip which measures 8 × 9 mm²contains conventional MOS devices for signal conditioning, array accessing, and output buffering along with the following on-chip sensors: a gas-flow sensor, an infrared-sensing array, a chemical-reaction sensor, cantilever-beam accelerometers, surface-acoustic-wave (SAW) vapor sensors, a tactile sensor array, and an infrared charge-coupled device imager. The multisensing functions of this chip utilize both the pyroelectdc and piezoelectric effects in ZnO thin films. Fabrication of the chip is carried out using a conventional 3-µm Si NMOS process combined with Si micromachining techniques. Compatible fabrication technology and sensor properties are described.     

Enhanced Cu pillar design to reduce thermomechanical stress induced during flip chip assembly

In this work a Cu pillar design that combines a stiff metal pedestal with a soft polymer as buffer layer has been integrated in a dedicated test vehicle to investigate the thermo mechanical stress induced during flip chip assembly. In-situ electrical measurements of dedicated stress sensors during a Bump Assisted BEOL Stability Indentation (BABSI) test were performed to assess the strength of the bump designs. Furthermore, the package induced stress was monitored in different regions of the test chips by measuring and comparing the I_ON current of the stress sensors before and after packaging. By combining in-situ electrical measurements and finite element modeling it was possible to quantify the stress level induced in the Si die after packaging. Additionally, the package out of plane deformation has been measured after flip chip to laminate and after molding. The results show that the use of a stiff pedestal is very efficient to mitigate packaging induced stress. It has also been shown that the out of plane deformation is independent of the Cu pillar design.     

碳纳米管场效应型DMMP气敏传感器研究

基于单壁碳纳米管(SWCNT)的场效应气体传感器由于具有传感性能好、体积小、室温操作和加偏压自我解吸附等优良性能,有着广泛的应用前景。利用单壁碳纳米管自组装技术在SiO2/Si基底上制备均匀分布的SWCNT薄膜,将其作为沟道制作了具有灵敏开关特性的场效应晶体管(FET),该FET器件的开关比达到105。将此FET器件作为气体传感芯片用于甲基膦酸二甲酯(DMMP)气体分子的检测。结果显示,当通入DMMP气体时,器件的阈值电压向负栅电压方向移动。当DMMP体积分数为5×10-6,栅压为-10 V时,器件的灵敏度达到32%,响应时间为300 s。在15 V的栅压下器件能够很快地实现气体解吸附。     

分子印迹膜SPR传感器检测氯磺隆的方法

研究使用了中国科学院电子学研究所自行研制的高灵敏度单通道SPR分析仪和进样装置,仪器为棱镜耦合型SPR传感器结构,其检测角度范围是40°～70°,折射率检测范围为1.04～1.47,谐振角的精度在0.001°。适用于SPR分析仪的分子印迹芯片采用PVC-MIP共聚膜法制备,SPR角度扫描结果表明,200nm以下厚度芯片具有较好的SPR吸收特性。以氯磺隆为模板的分子印迹膜与不加氯磺隆的分子印迹膜对比实验发现前者具有特异性结合的能力。实验对浓度0.1,0.2,0.5和1μg/mL的氯磺隆进行了SPR定点检测,这四种浓度氯磺隆的折射率响应信号满足线性关系,相关系数R=0.996 4。实验中对低浓度的氯磺隆进行反复检测,检测到50ng/mL的氯磺隆,满足农残检测的要求。     

Microfabricated amperometric gas sensors

A series of Nafion-based amperometric gas sensors have been constructed using microelectronic fabrication technology. These sensors use a gold sensing-electrode in the shape of a square grid. Three different grid densities were used. To ascertain the optimal design parameters for such sensors, the response characteristics of the various microfabricated sensors were compared to each other and to a conventional `macro' amperometric sensor. The critical performance criteria considered were sensor response time, structural integrity under operating conditions, selectivity, and sensitivity to the analyte vapor. The response time of the miniaturized sensors was over an order of magnitude faster, although they had a lower sensitivity than conventional sensors. The sensitivity of these sensors was dependent on the total length of the gold-Nafion interface. A model that rationalizes this dependence is presented     

Epitaxial graphene gas sensors on SiC substrate with high sensitivity

2D material of graphene has inspired huge interest in fabricating of solid state gas sensors.In this work,epitaxial graphene,quasi-free-standing graphene,and CVD epitaxial graphene samples on SiC substrates are used to fabricate gas sensors.Defects are introduced into graphene using SF6 plasma treatment to improve the performance of the gas sensors.The epitaxial graphene shows high sensitivity to NO2 with response of 105.1%to 4 ppm NO2 and detection limit of 1 ppb.The higher sensitivity of epitaxial graphene compared to quasi-free-standing graphene,and CVD epitaxial graphene was found to be related to the different doping types of the samples.