微波倒装焊互连技术及特性分析

随着应用频率的提高,微波芯片与基板间的互连更多地采用了倒装焊。文中用HFSS（高频结构仿真器）有限元软件对凸点变换及倒装互连结构进行建模、仿真和优化,提取了凸点变换的等效集总电路模型,介绍了凸点制作工艺和倒装焊结构互连的微组装过程,并完成了试验样品的测试。最后,对微波倒装焊的前景进行了展望。     

热超声倒装焊在制作大功率GaN基LED中的应用

设计了适合于倒装的大功率GaN基LED芯片结构,在倒装基板硅片上制作了金凸点,采用热超声倒装焊接(FCB)技术将芯片倒装在基板上.测试结果表明获得的大面积金凸点连接的剪切力最高达53.93 g/bump,焊接后的GaN基绿光LED在350 mA工作电流下正向电压为3.0 V.将热超声倒装焊接技术用于制作大功率GaN基LED器件,能起到良好的机械互连和电气互连.     

金凸点的打球法制作与可靠性考核

本文采用打球法在芯片上制作金凸点，并将凸点倒装焊接在Ti/Ni/Au多层金属化的LTCC基板上。利用扫描电镜观察凸点形貌，X射线透射研究倒装互连状况，并通过接触电阻和剪切强度对凸点倒装焊的可靠性进行了考核。     

多金球凸点倒装片技术

文章提出了一种在IC芯片的一个I/O端制作多个金球凸点的倒装片IC焊盘设计和金球凸点芯片制作的方法。在一个I/O端制作多个金球凸点,在芯片安装时可以提高芯片安装的机械强度,进而提高芯片安装的可靠性。多焊盘芯片也可用于制作KGD。     

采用热压焊工艺实现金凸点芯片的倒装焊接

金凸点芯片的倒装焊接是一种先进的封装技术.叙述了钉头金凸点硅芯片在高密度薄膜陶瓷基板上的热压倒装焊接工艺方法,通过设定焊接参数达到所期望的最大剪切力,分析研究互连焊点的电性能和焊接缺陷,实现了热压倒装焊工艺的优化.同时,还简要介绍了芯片钉头金凸点的制作工艺.     

用于倒装芯片的晶片凸点制作工艺研究

倒装芯片在电子封装互连中占有越来越多的份额,是一种必然的发展趋势,所以对倒装芯片技术的研究变得非常重要。倒装芯片凸点的形成是其工艺过程的关键。现有的凸点制作方法主要有蒸镀焊料凸点、电镀凸点、微球装配方法、焊料转送、在没有UBM的铅焊盘上做金球凸点、使用金做晶片上的凸点、使用镍一金做晶片的凸点等。每种方法都各有其优缺点,适用于不同的工艺要求。介绍了芯片倒装焊基本的焊球类型、制作方法及各自的特点,总结了凸点制作应注意的问题。     

一种新型FC和WLP的柔性凸点技术

FC(倒装片)和WLP(圆片级封装)均要在圆片上制作各类凸点,它们与基板焊接互连后,由于各材料间的热失配可能造成凸点——基板间互连失效,从而影响了器件的可靠性和使用寿命。解决这一问题的通常做法是对芯片凸点与基板间进行下填充。本文介绍的柔性凸点技术是在焊球下面增加一层具有弹性的柔性材料,当器件工作产生热失配时,由于柔性材料的自由伸缩,将大大减小以至消除各材料间的失配应力,使芯片凸点与基板下即使不加下填充,也能达到器件稳定、长期、可靠地工作的目的。     

MCM芯片安装互连及其相关技术

本文重点介绍了MCM芯片安装技术、三种基本的芯片互连技术(WB、TAB和FCB)、三种关键支撑技术(凸点制作、KGD、下填充)和微型凸点焊、ACA互连倒装、导电环氧互连倒装、无凸点微焊接等芯片装连新型技术途径。     

倒装芯片的底部填充材料和涂布

倒装芯片是当今半导体封装领域的一大热点,它既是一种芯片互连技术,更是一种理想的芯片粘接技术。以往后级封装技术都是将芯片的有源区面朝上,背对基板粘贴后键合(如引线键合和载带自动键合TAB)。而倒装芯片则是将芯片有源区面对基板,通过芯片上呈阵列排列的焊料凸点来实现芯片与衬底的互连。显然,这种芯片互连的方式能够提供更高的I/O密度。     

倒装芯片互连凸点电迁移的研究进展

电子产品向便携化、小型化、高性能方向发展,促使集成电路的集成度不断提高,体积不断缩小,采用倒装芯片互连的凸点直径和间距进一步减小和凸点中电流密度的进一步提高,由此出现电迁移失效引起的可靠性问题.本文回顾了倒装芯片互连凸点电迁移失效的研究进展,论述了电流聚集和焊料合金成分对凸点电迁移失效的影响,指出了倒装芯片互连凸点电迁移研究亟待解决的问题.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks