Effect of Duty Cycle on the Characteristics of Pulse-Modulated Radio-Frequency Atmospheric Pressure Dielectric Barrier Discharge

Using a one-dimensional fluid model, the pulse-modulated radio-frequency dielectric barrier discharge in atmospheric helium is described. The influences of the pulse duty cycle on the discharge characteristics are studied. The numerical results show that the dependence of discharge characteristics on the duty cycle is sensitive in the region of around 40% duty cycle under the given simulation parameters. In the case of a larger duty cycle, the plasma density is higher, the discharge becomes more intense, but the power consumption is higher. When the duty cycle is lower, one can get a weaker discharge, lower plasma density and higher electron temperature in the bulk plasma. In practical applications, in order to get a higher plasma density and a lower power consumption, it is more important to choose a suitable duty cycle to modulate the RF power supply.     

普通液压机超高压液压胀形集成装置的研制

研制出将增压器、充液器、滑动胀形模具集成于一体的超高压液压胀形装置，该装置具有快速充填液体、产生变高压、循环过滤液体、自动控制等功能,设计中采用了过盈配合密封及组合密封技术。在普通液压机上按照给定的加载路径成功胀形出汽车桥壳设计样件，经大量反复的试制及合模后的超高压试验，证明该装置实现了设计功能，性能稳定，密封可靠。该装置的研制成功，使胀形设备得到简化，有助于降低能耗，扩大液压胀形工艺的应用范围。     

超宽带无线收发机中的正交LC VCO设计

基于SMIC 0.18 μm CMOS工艺设计了一种可应用于MB-OFDM UWB无线收发机的宽带正交压控振荡器(QV-CO,Quadrature VCO).在研究VCO的相位噪声理论的基础上,采用了优化噪声的电路结构.此外,鉴于片上螺旋电感在VCO设计中的重要性,采用了一种快速选取工艺库螺旋电感的方法.仿真结果显示,QVCO的频率调谐范围为3.4～4.5 GHz,在1 MHz频率偏移处,相位噪声小于-119.6 dBc/Hz.在1.8 V电源电压下,电路总功耗为27 mw.     

感应耦合等离子体刻蚀机二维放电模拟

为研究感应耦合等离子体(ICP)刻蚀机腔室与线圈结构以及工艺参数对等离子体分布均匀性的影响,基于商业软件CFD-ACE 中等离子体与电磁场等模块建立了ICP刻蚀机二维放电模型.仿真研究了典型工艺条件(1.33Pa,200W,200sccm)下氩等离子体电子温度与电子数密度的空间分布,对比了不同气压与功率条件下等离子体参数在硅片表面的一维分布.结果表明,电子数密度随气压与功率的增加而升高;电子温度随气压的增加而降低,随功率增加在较小范围内先降低再升高.通过分析屏蔽板对等离子体参数的影响,发现其有助于提高等离子体密度.进而发现屏蔽板的孔隙率越大,电子温度越高,电子数密度则越低.     

高低频不同电压条件下腔室内CCP冷等离子体源的仿真分析

等离子体的状态的变化特征,特别是在双频情况下,是PECVD工艺设备的一项重要指标,这促使人们用不同的方法对它们进行研究。本文使用CFD-ACE 商业软件建立了二维流体模型对N2等离子体进行仿真。首先在高频13.56MHz,高频电压300V,低频电压0V的条件下描述了等离子体,特别是在鞘层部位的电势、电子数量密度、氮自由基和电子温度,分布的基本特征。在此基础上,讨论了高频电压分别是200V,300V,400V时及低频0.3MHz,低频电压分别是500V,600V,700V时对等离子体密度的影响。结论表明,在电极表面形成了约3mm厚的鞘层,在鞘层内电势和电子温度随时间和空间变化较大,而在非鞘层区域内电势跟随电极电压的变化而变化,但几乎不随空间变化,电子温度也只在很小的范围内变化。氮自由基的数量密度也受射频电压的调制,但相对变化很小。等离子体密度仅在鞘层区域内随时间发生变化,所以通过比较主等离子体区参数可以看出,等离子体的密度随着高频电压升高,随低频电压的升高略有下降,同时x方向和y方向的均匀性将会发生变化。因此,在其他条件不变的情况下需要选择合适的高低频电压来获得高密度和均匀性均合乎要求的等离子体。     

汽车桥壳液压胀形的数值模拟及其实验研究

对汽车桥壳液压胀形进行了数值模拟并进行了实验验证.分析了第1次胀形时液体压力恒定不变、液体压力按轴向压缩量线性变化、极限失稳及胀裂的情况,揭示出起皱的主要原因是液体压力过低,起皱后不利于后续胀形,而胀裂的主要原因是液体压力过高;第2次胀形时试件退火是最终成形成功的重要影响因素.得到轴向压缩量与液体胀形压力间的合理加载路径.     

Modeling Approach and Analysis of the Structural Parameters of an Inductively Coupled Plasma Etcher Based on a Regression Orthogonal Design

The geometry of an inductively coupled plasma (ICP) etcher is usually considered to be an important factor for determining both plasma and process uniformity over a large wafer. During the past few decades, these parameters were determined by the "trial and error" method, resulting in wastes of time and funds. In this paper, a new approach of regression orthogonal design with plasma simulation experiments is proposed to investigate the sensitivity of the structural parameters on the uniformity of plasma characteristics. The tool for simulating plasma is CFD-ACE+, which is commercial multi-physical modeling software that has been proven to be accurate for plasma simulation. The simulated experimental results are analyzed to get a regression equation on three structural parameters. Through this equation, engineers can compute the uni- formity of the electron number density rapidly without modeling by CFD-ACE+. An optimization performed at the end produces good results.     

基于数据挖掘的成都天府新城公交竞争力研究

以新城建设中的公交体系配套发展为契机,对成都市高新南区天府新城区域所做的区域现状调查、公交客流问卷调查。同时对当前发展迅速的机器学习研究——数据挖掘技术进行了简要介绍,然后对公交调查结果所进行了决策树数据挖掘分析,生成了公交竞争力决策树,从而以客户需求理论得到公共交通规划的目标导向,以促进区域公共交通更好更快地发展,切实做到公交优先、绿色交通的策略。     

基于回归正交设计的ICP刻蚀机工艺腔室流场特性分析

为研究感应耦合等离子体(IcP)刻蚀机工艺腔室结构对流场特性的影响,采用回归正交设计方法对腔室半径、腔室高度、进气口半径以及进气流量4个设计参数进行试验设计,利用商业软件CFD-AcE 建立IcP刻蚀机工艺腔室二维流场仿真模型.定义了静电卡盘上方气压分布均匀性评价函数,通过对试验结果的回归分析,确定了关键参数对气压分布均匀性影响程度的定量关系,并由此建立了拟合度较高的二次回归方程.结果表明腔室高度为最显著影响因素.经过验证可见,回归方程的计算结果与仿真分析结果保持了较高的一致性,可以为结构与工艺条件相近的刻蚀机、化学气相沉积(CVD)设备以及氧化/扩散系统的结构研究与设计提供参考.     

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.