An electrostatically suspended contactless platform

Electrostatic suspension of a silicon disk with explicit control of the lateral translational degrees-of-freedom is reported. The transduction subsystem configures electrode pairs to exert electrostatic forces on the disk and to also measure differential capacitances related to the disk position. Disk sidewall forcing electrodes are not necessary to control the disk’s lateral position because tilting the disk relative to the plane of the electrodes exerts lateral forces on the disk. Despite the fact that the disk’s lateral and angular degrees-of-freedom are strongly coupled, the system is not strongly stabilizable using only the disk’s vertical position and tilt estimates derived from electrode–disk gap measurements. Nevertheless, a stabilizing controller is proposed and lateral position measurements are added for regulating the disk’s in-plane position. Extensive experimental results corroborate the model and analysis.     

静电卡盘静电吸附力影响因素的有限元分析

As one of the core components of IC manufacturing equipment, the electrostatic chuck （ESC） has been widely applied in semiconductor processing such as etching, PVD and CVD. The clamping force of the ESC is one of the most important technical indicators. A multi-physics simulation software COMSOL is used to analyze the factors influencing the clamping force. The curves between the clamping force and the main parameters such as DC voltage, electrode thickness, electrode radius, dielectric thickness and helium gap are obtained. Moreover, the effects of these factors on the clamping force are investigated by means oforthogonal experiments. The results show that the factors can be ranked in order of voltage, electrode radius, helium gap and dielectric thickness according to their importance, which may offer certain reference for the design of ESCs.     

基于扭纵复合型超声电机动力学模型的模拟计算

基于动力学原理，利用一种新的扭纵复合型超声电动机的动力学模型，模拟计算了扭纵复合型超声电动机的转速、转矩、效率和响应时间等特性。计算结果揭示了预压力、定子两路振动振幅等输入参数对负载特性的影响。此外，转子运转的响应时间与负载力矩间的关系也可由模拟计算导出。利用该模型对所研制的复合型超声电机实验样机进行的计算结果与实际测量结果基本相符，验证了该模型及相应数值计算方法的可靠性。利用该模型首次计算出定，转子接触与分离点的不对称特性。     

磁阻式悬浮平台侧向气隙控研究

针对悬浮平台存在的侧向力干扰导致平台不能稳定悬浮的问题,设计了一种可以实现参数快速整定的模糊自适应PID侧向气隙控制系统。文中介绍了平台的悬浮结构和悬浮机理,采用有限元法分析了侧向位移对平台的影响,建立了控制系统静态、动态数学模型,并设计了模糊自适应PID控制器。通过MATLAB/Simulink软件对悬浮平台的侧向气隙控制系统进行建模仿真。结果表明,模糊自适应PID控制器响应速度快,且具有较强的鲁棒性。     

Suppression of radio frequency interference at the distributor rotor gap

Generally, for a given spark gap length, lower breakdown voltage of the gap corresponds to a lower radio frequency interference (RFI) level. Mechanisms which lead to the reduction of breakdown voltage at the spark gap by two techniques are discussed. The first technique involves the addition of a pointed electrode near the cathode, while the second technique involves the presence of bulk dielectric material on the cathode surface near the gap. Practical distributor rotor designs based on these techniques for effective RFI control are described.     

Electrostatic electrographic printing

This paper describes the empirically observed characteristics of electrographic printing in which electrostatic charge patterns are deposited onto a dielectric surface via a contacting electrode and subsequently made visible by toning. The process exhibits a threshold effect that may be used in simplifying the addressing circuitry. An equivalent circuit of the electrode and dielectric coated-paper combination that incorporates the threshold effect is presented. Typical printers using this electrographic process are described, and some requirements of the drive circuitry necessary for such printers are discussed.     

Miniature high gain slot-fed rectangular dielectric resonator antenna for IoT RF energy harvesting

Radio-frequency (RF) energy harvesting is a promising candidate for alternative power source that can reduce the dependencies on batteries. However, its power density is very low which makes it crucial to have a high gain antenna to increase the power received by the system. This study presents the design of miniature high gain dielectric resonator antenna for RF energy harvesting application with high figure of merit to increase the power received. Numerical approximation is used to assist the antenna design and modelling. The design focused on three parameters which are the width, length, and height of the dielectric resonator. The performance, electric field density, and the radiation patterns of the dielectric resonator antenna have been observed by varying the design parameters. The effect of air gap to the performance is investigated and it is found that 8.11–13% gain improvement and up to 36% improvement in impedance matching is achieved through incorporating thin air gap between the dielectric resonator. Soda-lime glass with relative permittivity 7.75 is used which allows miniaturization and transparency. Experimental results show reasonable agreement to the simulations. The work shows highest antenna gain with smallest size with high FOM at 5 GHz ISM band compared to previous works.     

Electrostatic levitator for hard disk media

This paper discusses developments in contact-less electrostatic levitators for use in ultra-high-vacuum (UHV) and clean environments. Presented is the first demonstration of an electrostatic levitation technology which can suspend disk-shaped metals and alloys. A 3.5-in diameter aluminum hard disk media has been suspended successfully by actively controlling an electrostatic attractive force acting on it. This paper describes the basic principle of electrostatic suspension, the structure of an experimental levitator, electrode design, position feedback control method, a linear system model, and operational procedures. In addition, experimental data are given to confirm the suspension. The electrostatic levitation technology will be a key technique in the developments of contactless and friction-free manipulation and transportation equipments utilized in UHV and clean environments, both of which are necessary for the manufacture of the new generation of semiconductor devices     

BP神经网络预测电极速度影响放电参数分析

文中结合小间隙放电的双过程模型,探讨电极移动引起放电场强和压强的变化对放电间隙内部相关因子的影响。文中同时利用BP神经网络预测分析电极移动速度对放电参数的影响。基于静电放电电极移动速度效应检测仪,不断改变电极移动速度,反复多次进行放电实验并统计试验数据。利用BP神经网络对已测实验数据进行训练、学习,从而预测不同速度与压强下对应的电流上升时间和峰值电流大小。实验结果表明,放电电流的上升时间与电极移动速度不存在相关性。根据新方法预测出的不同速度下的峰值电流和实际大小相比准确率更高。研究结果对探寻非接触式静电放电的规律和制定静电放电标准有一定的参考价值。     

无源电悬浮原理及其实验研究

人们在研究微电机的过程中发现：转子与基底和轴承的摩擦已构成严重影响其运转动态性能的瓶颈障碍，它的转速和寿命远未达到理论值，用电悬浮轴承替代机械轴承不适为一种可选方案，本文对无源电悬浮的稳定平衡条件进行了论证，并作了悬浮过程的动力学模拟，选择直径为３ｍｍ，厚为０．２ｍｍ的玻璃片做悬浮的宏观模拟实验，在仔细调谐电路之后，悬浮物获得六个自由度（ｘ，ｙ，ｚ，θ，ψ）上的鲁棒稳定，进而论证了电悬浮在微机械中应用的可行性。     

Electronic states of organic semiconductors vis-à-vis interactions between molecules in a submonolayer through time-restricted electrostatic assembly

We have made in-depth studies to revisit time-restricted layer-by-layer (LbL) electrostatic assembly process of a couple of organic molecules. The studies have been made in relation to electronic states of metal phthalocyanines. We show that by shortening dipping time for adsorption of the active molecules, mass adsorbed in each monolayer can be decreased and hence intermolecular spacing between the molecules can be increased. We have characterized the (sub)monolayers deposited on an electrode with scanning tunneling microscope tip to record tunneling current through the molecules. Results show that the highest occupied molecular orbitals and lowest unoccupied molecular orbitals, and also the difference between the orbitals, that is, the transport gap of the molecules in a (sub)monolayer depends on the dipping time of LbL assembly or molecule-to-molecule separation. We show that interactions between molecules in a monolayer decrease the transport gap of the metal phthalocyanines.     

DCDC—20GHz射频MEMS开关

描述了 DC— 2 0 GHz射频 MEMS开关的设计和制造工艺 .开关为一薄金属膜桥组成的桥式结构 ,形成一个单刀单掷 (SPST)并联设置的金属 -绝缘体 -金属接触 .开关通过上下电极之间的静电力进行控制 ,其插入损耗及隔离性能取决于开态和关态的电容 .测试结果如下 :射频 MEMS开关驱动电压约为 2 0 V,在“开”态下 DC— 2 0 GHz带宽的插入损耗小于 0 .6 9d B;在“关”态下在 14— 18GHz时隔离大于 13d B,在 18— 2 0 GHz时隔离大于 16 d B.本器件为国内首只研制成功的宽带射频 MEMS开关     

基于神经网络电极移动速度影响放电参数分析

结合小间隙放电的双过程模型[1],探讨电极移动引起的气体压强变化和场强变化对放电间隙内部相关因子的影响[2],进而分析电极移动速度对放电参数的影响.基于静电放电电极移动速度效应检测仪,不断改变电极移动速度,反复多次进行放电实验,统计试验数据,然后利用神经网络进行仿真分析,探究电极移动速度与放电参数之间的相关性.结果表明:电极移动速度与放电电流峰值、平均上升速度之间具有正的线性相关性,与平均下降速度间具有负的线性相关性.研究结果对于探寻非接触式静电放电的规律和静电放电标准的制定,有一定的参考价值.     

基于介质上电润湿效应的液态场效应管

用一片ITO玻璃作为场效应管的源极,在此玻璃上分别粘贴两块相同厚度塑料薄铝片作为栅极和漏极,在两块铝片之间留下很小的平行缝隙,再分别在源极、漏极、栅极的玻璃板上涂上聚四氟乙烯(Teflon)薄膜作为亲油疏水层,采用环氧树脂作为围堰材料,这样就制备了基于电润湿效应的新型液态场效应管。通过改变栅极的电压,能够调节有色油滴的位移,从而控制源极和漏极的电流变化。完成了液态场效应管的制作,并给出了初步的测试结果。     

Anisotropic transport properties of quantum dot arrays fabricated by the edge-defined nanowires

The anisotropic transport properties of quantum dot arrays fabricated by the nanoimprinted multilayer quantum wires have been investigated. The vertical transport characteristics are estimated by the carrier capture time from the electron reservoir to the low dimensional structures, which turned out to be longer than the spontaneous emission lifetime. The lateral transport characteristics are modeled after the quantum conductance between quantum dot arrays which are readily available from the miniband structures. The resulting lateral transport revealed that lateral quantum conductance can be minimized when the Fermi level is kept at the center of the miniband gap when the gap is larger than 4 kT.     

Dielectric charging induced drift in micro device reliability-a review

The movement or migration of charges in dielectric materials like silicon oxide, silicon nitride and glass, is recognized as one of the most significant causes of drift instability of MEMS devices which utilize electrostatic capacitive methods for sensing and driving. This paper reviews the current researches on the characteristics of drift phenomenon of three micro capacitive devices, micro switches, micro resonators and micro mirrors. The dielectric charging forms including polarization, ion injection and charge migration are presented in detail to explain the process and mechanism of how the charging effects gives rise to the drift of performance and influence the reliability of micro systems, and then the corresponding solutions to overcome specific drift issues are proposed based on the essential conditions needed to cause dielectric charging.     

Thermally deposited Ag-doped CdS thin film transistors with high-k rare-earth oxide Nd2O3 as gate dielectric

The performance of thermally deposited CdS thin film transistors doped with Ag has been reported. Ag-doped CdS thin films have been prepared using chemical method. High dielectric constant rare earth oxide Nd₂O₃ has been used as gate insulator. The thin film trasistors are fabricated in coplanar electrode structure on ultrasonically cleaned glass substrates with a channel length of 50 μm. The thin film transistors exhibit a high mobility of 4.3 cm² V^?1 s^?1 and low threshold voltage of 1 V. The ON-OFF ratio of the thin film transistors is found as 10⁵. The TFTs also exhibit good transconductance and gain band-width product of 1.15 × 10^?3 mho and 71 kHz respectively.     

Submicrometer polysilicon gate CMOS/SOS technology

A process is described for the fabrication of CMOS/SOS submicrometer devices and integrated circuits. The process utilizes the lateral diffusion of boron into polycrystalline silicon and a subsequent anisotropic etchant to define the narrow poly gates. Devices with channel lengths as small as 0.3 µm have been fabricated and characterized. Both avalanche and tunnel injection of carriers into the gate dielectric have been measured and both can have an impact on the limit of voltage operation. At present, these mechanisms appear to place an upper limit of about 8 V on the operating voltage of dynamic circuits containing 0.5- µm channel length devices. The propagation delay of 0.5-µm channel length CMOS/SOS inverters is about 200 ps at 5 V and dynamic binary counters will operate with a maximum input frequency of 550 MHz and 8 V while dissipating 130 mW.     

A measurement of very fast transition durations due to gapdischarge in air using distributed constant line system

Very fast transition durations (rising time in positive polarity and falling time in negative polarity) due to starting of gap discharge were investigated in time domain. The gap space was set very small for voltages below 1500 V as a simulation of the charged device model (CDM) electrostatic discharge (ESD) and the gap discharge of switch devices. The measurement system consists of a distributed constant line system with a tapered coaxial electrode, which has a matched impedance for the characteristic impedance of the distributed constant line system. The insertion loss of the tapered coaxial electrode was within -3 dB in the frequency range below 4.5 GHz. The atmosphere around the electrode is ordinary air. This experimental system enables one to measure the high-speed transients of about 100 ps due to gap discharge in time domain. As a consequence of the experiment, the relationship between the discharge voltage and transition duration was confirmed. The voltage rise time was slowed down gradually in positive polarity, while the voltage fall time was slowed down remarkably in negative polarity for the 0.1-mm needle     

Active and reactive power control for doubly-fed wound rotorinduction generator

A power control system for a doubly fed wound rotor induction generator has been developed. This power control system applies a control method using a rotating reference frame fixed on the gap flux of the generator, and can control active and reactive power independently and stably. The characteristics of the control system have been proved by experiment. Harmonic currents fed to the rotor windings are transmitted to the stator winding changing its frequency. The transmitting characteristics of the harmonic currents have been analyzed and verified by experiments