电磁场与微波技术

0441 02050639点阴极电场辅助阳极连接中的紧密接触面积年吨流/周青春,陈铮,董师润(华东力助白工业学院)11电子器件一2 002,25(l)一37一40用等效电路的方法研究了点阴极情况下的电场辅助阳极连接效应,计算了连接电流、连接孕育期和紧密接触面积.文中结果表明,连接初期电流迅速衰减,随后缓慢变小,直至某一稳定值;孕育期随温度上升指数下降,连接温度高时,孕育期将难以观察到;待连接表面之间紧密接触面积随时间延长而非线性扩展,紧密接触区域增大时,其边界向外推进速度渐小,而接触面积增加渐快.图6参s(金)0441 02050640考虑曲率修正效应时粗糙…     

1．3μmDH-SLD的性能与工作电流和温度的关系

全面地测试并分析了掩埋双异质结型超辐射激光二极管模块的输出光功率、光谱和消光比与注入电流及温度的变化关系。得到：DH—SLD显示了软阈值特性，其输出光功率随注入电流的增大而增加，随管芯温度的升高而降低。温度不变时，当注入电流小于110mA(约)时，峰值波长随注入电流的增大而减小，当注入电流大于110mA(约)时，峰值波长随注入电流的增大有所增大；峰值波长随温度升高而增大。3dB带宽随注入电流的增大而减小，随温度的升高而略有增大。消光比随注入电流和温度的升高而变化。     

1. 30μm2MQW2SLD 的性能与注入电流和温度的关系

全面测试了峰值波长为1. 30μm 的InGaAsP/ InP 多量子阱型超辐射激光二极管 (MQW2SLD) 模块的输出光功率、光谱和消光比随注入电流及温度变化的关系。得到:MQW2SLD 显示了软阈值特性。温度不变时,其输出光功率随注入电流的增大而增加;MQW2SLD模块的峰值波长随注入电流的增大而减小;注入电流不变时,其输出光功率随管芯温度的升高而减小;峰值波长随温度升高而增大。SLD 模块的3dB 带宽随注入电流的增大及管芯温度的升高而变化。注入电流大于阈值电流时,MQW2SLD 模块的消光比随注入电流和管芯温度的升高而增大。     

1.30μm-MQW-SLD的性能与注入电流和温度的关系

全面测试了峰值波长为1．30μm的InGaAsP／InP多量子阱型超辐射激光二极管(MQW—SLD)模块的输出光功率、光谱和消光比随注入电流及温度变化的关系。得到：MQW—SLD显示了软阈值特性。温度不变时,其输出光功率随注入电流的增大而增加;MQW—SLD模块的峰值波长随注入电流的增大而减小;注入电流不变时,其输出光功率随管芯温度的升高而减小;峰值波长随温度升高而增大。SLD模块的3dB带宽随注入电流的增大及管芯温度的升高而变化。注入电流大于阈值电流时,MQW—SLD模块的消光比随注入电流和管芯温度的升高而增大。     

980nm半导体激光二极管的温度特性

测试并分析了980nm半导体激光二极管( SLD)模块的输出光功率、光谱和消光比与注入电流及温度的变化关系。结果反映:在测试范围内,温度不变时该模块的输出光功率随注入电流的增大而增加,经历了自发辐射和受激放大过程;电流不变时该输出光功率随管芯温度的变化基本保持稳定。温度不变的情况下,当注入电流小于阈值电流时,峰值波长、3dB带宽和消光比随注入电流的增大而较快增加,当注入电流大于阈值电流时,峰值波长、3dB带宽和消光比随注入电流的增大而缓慢增加;电流不变时峰值长、3dB带宽和消光比随温度升高而有所增大。     

有机电致发光器件中复合发光的电场和温度关系

通过分析有机电致发光器件中载流子注入、输运、激子的解离与复合过程，提出了激子解离与复合的理论模型。基于电流连续性方程和Poisson方程，给出了激子复合几率、电流密度及复合效率表达式。研究了外加电压和温度对器件中激子的复合几率及在各种接触条件下外加电压对器件电流和复合效率的影响。结果表明：(1)在一个较宽的注入势垒范围内，复合几率随电场和温度的升高而降低；(2)固定阴极势垒，而阳极势垒由小变大时，器件电流由接触限制向空间电荷限制转变；(3)复合效率随外加电压升高先增加，当电压达一临界值时而陡降，并存在一个最佳的注入势垒值。其计算值与所报道的实验结果相符合。     

微波晶体管电流增益和基极电流非理想因子的温度特性

本文研究了微波晶体管电流增益H_FE和基极电流非理想因子n随温度变化的机理,给出了电流增曾H_FE的温度模型,指出:(1)中电流时电流增益H_PE具有正温度系数,而在小电流时随温度上升迅速增大,在大电流时增大减缓,并会出现负增值,(2)基极电流非理想因子n具有负温度系数.实验结果和理论分析一致.     

双极晶体管电流增益与发射区杂质浓度关系的温度特性

本文从理论和实验两方面对积极型晶体管电流增益HFE与发射区杂质浓度NE的关系的温度特性进行了探讨。研究结果表明，HFE与NE的相关程度与温度有关，在常温下，HFE随NE的增加而增加；当温度升高时，HFE将随NE的增加而更剧烈地增加。     

变温C-V和传输线模型测量研究AlGaN/GaN HEMT温度特性

通过对异质结材料上制作的肖特基结构变温C-V测量和传输线模型变温测量,研究了蓝宝石衬底AlGaN/GaN异质结高电子迁移率晶体管的直流特性在25～200℃之间的变化,分析了载流子浓度分布、沟道方块电阻、欧姆比接触电阻和缓冲层泄漏电流随温度的变化规律.得出了器件饱和电流随温度升高而下降主要由输运特性退化造成,沟道泄漏电流随温度的变化主要由栅泄漏电流引起的结论.同时,证明了GaN缓冲层漏电不是导致器件退化的主要原因.     

变温C-V和传输线模型测量研究AlGaN/GaN HEMT温度特性

通过对异质结材料上制作的肖特基结构变温C-V测量和传输线模型变温测量,研究了蓝宝石衬底AlGaN/GaN异质结高电子迁移率晶体管的直流特性在25～200℃之间的变化,分析了载流子浓度分布、沟道方块电阻、欧姆比接触电阻和缓冲层泄漏电流随温度的变化规律.得出了器件饱和电流随温度升高而下降主要由输运特性退化造成,沟道泄漏电流随温度的变化主要由栅泄漏电流引起的结论.同时,证明了GaN缓冲层漏电不是导致器件退化的主要原因.     

Low temperature glass-to-glass wafer bonding

In this paper, results of successful anodic bonding between glass wafers at low temperature are reported. Prior to bonding, a special technique was used, i.e., an amorphous and hydrogen free silicon film was deposited on one of the glass wafers using a sputtering technique. The effects of bonding temperature and voltage were investigated. The bonding temperature and the voltage applied ranged from 200/spl deg/C to 300/spl deg/C and 200 V to 1000 V, respectively. As the bonding temperature and bonding voltage increased, both the unbonded area and the size of voids decreased. Scanning electron microscope (SEM) observations show that the two glass wafers are tightly bonded. The bond strength is higher than 10 MPa for all the bonding conditions. Furthermore, the bond strength increases with increasing bonding temperature and voltage. The study indicates that high temperature and voltage cause more Na/sup +/ ions to neutralize at the negative electrode, which leads to higher charge density inside the glass wafer. Furthermore, the transition period to the equilibrium state also becomes shorter. It is concluded that the anodic bonding mechanisms involve both oxidation of silicon film and the hydrogen bonding between hydroxyl groups.     

各向异性导电胶粘接可靠性研究进展

介绍各向异性导电胶导电机理和粘接工艺,以及影响它的粘接可靠性因素和最佳参数的研究,如粘接温度、固化时间、粘接压力、粒子含量等。对各向异性导电胶粘接可靠性中的开路、短路、接触电阻与粘接压力和温度循环的关系进行了讨论,并介绍了各向异性导电胶可靠性的理论计算模型。     

Effects of bonding force on contact pressure and frictional energy in wire bonding

A numerical study is made of the elasto-plastic deformation taking place in ultrasonic wire bonding based on the finite element method. A special focus has been placed on how the important wire bonding parameters, such as bond force and power, affect the contact pressure along the wire–bond pad interface. It is shown that the contact interface had a long elliptical shape, and the maximum contact pressure occurred always at the periphery of the contact interface, which is consistent in the current 2D and 3D finite element analyses. The normalised real contact area as well as the maximum frictional energy intensity varied in a similar manner to the contact pressure, with the maximum values occurring at the periphery of contact interface, where weld is preferentially formed in practical wire bonding. A higher bond force does not result in a higher contact pressure, or higher frictional energy intensity, suggesting that a high bond force is not directly correlated to better wire bondability.     

Spontaneous Current Oscillations during Hard Anodization of Aluminum under Potentiostatic Conditions

Nanoporous anodic aluminum oxide is prepared by hard anodization of aluminum under potentiostatic conditions using 0.3 M H₂C₂O₄. Under unstirred electrolyte condition, spontaneous current oscillations are observed. The amplitude and period of these current oscillations are observed to increase with anodization time. As a consequence of the oscillatory behavior, the resulting anodic alumina exhibits modulated pore structures, in which the diameter contrast and the length of pore modulation increase with the amplitude and the period of current oscillations, respectively, and the current peak profile determines the internal geometry of oxide nanopores. The mechanism responsible for the oscillatory behavior is suggested to be a diffusion‐controlled anodic oxidation of aluminum.     

表面活化处理在激光局部键合中的应用

为了研究低热应力键合工艺,提出了一种将表面活化直接键合与激光局部键合相结合的键合技术。首先采用RCA溶液对键合片进行表面亲水活化处理,并在室温下成功地完成了预键合。然后在不使用任何夹具施加外力辅助的情况下,利用波长1064nm、光斑直径500μm、功率70W的Nd:YAG连续式激光器,实现了激光局部键合,并取得了6.3MPa~6.8MPa的键合强度。结果表明,这种以表面活化预键合代替加压的激光局部键合技术克服了传统激光键合存在的激光对焦困难,以及压力不匀易损害键合片和玻璃盖板等缺点,同时缩短了表面活化直接键合的退火时间,提高了键合效率。     

Electromigration in Al/Si contacts—Induced open-circuit failure

Open-circuit failures caused by electromigration in Al/Si contacts are studied. This failure mode is associated with Al depletion or vacancy condensation over the entire position contact area. The contacts exhibiting this failure are those closest to bonding pads. This location preference is attributed to vacancy supplies associated with the large bonding pad. The current acceleration factor for electromigration open failure is found to be 2.5 ± 0.5 and the activation energy is 0.5 ± 0.1 eV. Our empirical data suggests that, for operating temperatures below about 100°C, open-circuit failure will be dominant over junction leakage failure.     

Localized bonding processes for assembly and packaging of polymeric MEMS

Localized bonding schemes for the assembly and packaging of polymer-based microelectromechanical systems (MEMS) devices have been successfully demonstrated. These include three bonding systems of plastics-to-silicon, plastics-to-glass, and plastics-to-plastics combinations based on two bonding processes of localized resistive heating: 1) built-in resistive heaters and 2) reusable resistive heaters. In the prototype demonstrations, aluminum thin films are deposited and patterned as resistive heaters and plastic materials are locally melted and solidified for bonding. A typical contact pressure of 0.4 MPa is applied to assure intimate contact of the two bonding substrates and the localized bonding process is completed within less than 0.25 s of heating. It is estimated that the local temperature at the bonding interface can reach above 150/spl deg/C while the substrate temperature away from the heaters can be controlled to be under 40/spl deg/C during the bonding process. The approach of localized heating for bonding of plastic materials while maintaining low temperature globally enables direct sealing of polymer-based MEMS without dispensing additional adhesives or damaging preexisting, temperature-sensitive substances. Furthermore, water encapsulation by plastics-to-plastics bonding is successfully performed to demonstrate the capability of low temperature processing. As such, this technique can be applied broadly in plastic assembly, packaging, and liquid encapsulation for microsystems, including microfluidic devices.     

单片集成MEMS中的阳极键合工艺

分析了阳极键合工艺的原理及其工艺条件对CMOS电路的影响，并通过理论分析和实验研究了单片集成MEMS中的两种阳极键合方法：对于玻璃在硅片上方的键合方式，通过在电路部分上方玻璃上腐蚀一定深度的腔及用氮化硅层保护电路可以在很大程度上减轻阳极键合工艺的影响；而玻璃在硅片下方的键合方式，硅片上的电路几乎不受阳极键合工艺的影响，两种方法各有优缺点。     

Facilitating intermetallic formation in wire bonding by applying a pre-ultrasonic energy

It is conventionally believed that wire bonding initiates at the periphery of the contact area and no bonding occurs in the central area. However, this paper demonstrated that two bonding patterns exist, and are determined by bonding processes. If a selected pre-ultrasonic energy is applied, intermetallic compounds initiate in both peripheral and central area of bonds. However, if a pre-ultrasonic energy is absent, intermetallic compounds are only present at the peripheral area as conventionally reported. The application of the pre-ultrasonic energy significantly improves bonding strength, from 66.8 to 94.5 MPa for 20 μm Au wire bonds, due to the intermetallic compounds of greater structured integrity. Two different mechanisms are respectively proposed to account for the intermetallic formation in the center and periphery of the bond interface.     

阳极连接中碱金属双离子迁移模型􀀂

在假设玻璃中仅有两种可动碱金属离子的情况下，提出了一个金属－玻璃电场辅助阳极连接模型。根据该模型，玻璃中的Na和K耗尽层厚度在演化过程中成比例，它们的演化规律决定于耗尽层边上的负电荷层。数据拟合结果表明，文献[4]中的Na、K耗尽层厚度与连接时间的关系可用时间的对数函数很好地描述。K富集层起因于K^ 离子的中和，Na耗尽导上的负电荷产生的电场引起了实验中测得K^ 离子跃迁激活能与Na^ 离子的激活能几乎相等。阳极连接过程中不存在稳态，总可观测到微小电流，该电流仍源于离子电导。