Electromigration in fine-line conductors (0.45–2 μm)

The electromigration behaviour of various metallization systems has been tested on Si, GaAs and GaInAs substrates. Lifetime dependence on temperature and current density has been measured by accelerated lifetime tests. Linewidth was between 0.45 μm and 2 μm. The best electromigration resistance was found for electroplated gold lines, however also the system Al on Ti showed a as much as 40 times better performance than standard Al metallization. For linewidths of 0.45 μm a steep increase in stability has been found.     

多场耦合作用下重金属离子在粘土中的迁移性状试验研究

粘土由于截污能力强、渗透系数小及价格经济等优势,被广泛应用于填埋场衬垫系统中。在渗流场和浓度场综合作用下,粘土衬垫不能完全隔绝污染物的向下扩散。当在土中施加直流电场时,污染物在电渗透和电迁移作用下向相反方向运动。本文根据水和离子在电场、渗流场和浓度场作用下的迁移原理研制了室内动电模拟试验装置,试验研究了多场耦合作用下锌离子在粘土中的迁移性状,并对试验结束后的土样进行了浓度,含水率及pH等测定。结果表明,动电作用可以有效地阻滞锌离子在粘土中的迁移。     

互连铝通孔电迁移特征及其可靠性研究

研究了超大规模集成电路铝互连系统中铝通孔的电迁移失效机理及其可靠性寿命评价技术.试验采用CMOS和BiCMOS两种工艺各3组的铝通孔样品,分别在三个温度、恒定电流的加速条件下试验,以通孔开路为电迁移失效判据,最后得到了在加速条件下互连铝通孔的电迁移寿命,其结果符合标准的威布尔分布,试验准确可行.通过电迁移模型对试验数据进行了拟合,得到了激活能、电流加速因子和温度加速因子,计算出了正常工作条件下通孔电迁移的寿命,完成了对铝通孔电迁移的研究和寿命评价.     

栅极导电层Au迁移导致放大器失效原因分析

针对限幅低噪声放大器使用过程中出现输出不稳定现象,利用扫描电镜和能谱仪对场效应管栅极表面的金属缺失层和栅源之间的金属堆积物进行微观分析,寻找放大器工作不正常的原因。结果表明:场效应管栅极Au层的电迁移,使导线局部电阻增大,温度升高,导致Au的热迁移加重,引起导线出现孔洞和栅源中间堆积金属颗粒,使栅极导线出现开路和栅源极间产生不稳定接触,最终导致场效应管的工作参数漂移和放大器工作不正常。     

Sn-3.0Ag-0.5Cu-XCo钎焊接头金属间化合物层电迁移现象的研究

研究了以Co颗粒为增强相的Sn3.0Ag0.5Cu钎料合金接头的电迁移特性。结果表明,50℃、104A/cm2条件下直至16d,Sn3.0Ag0.5Cu-0.2Co钎料接头无明显电迁移现象产生。将温度提高至150℃后,接头正、负极处金属间化合物(IMC)层的厚度产生明显差异,即电子风力引发的‘极化效应’。Sn3.0Ag0.5Cu钎料接头在通电1d和3d后,正、负极处IMC层的结构发生了相反的变化。而Sn3.0Ag0.5Cu-0.05Co接头在通电3d后,负极处产生明显裂纹。此外,Co的引入有效地缓解了IMC层的生长趋势,提高了接头显微组织的稳定性。     

Effect of electromigration and isothermal aging on interfacial microstructure and tensile fracture behavior of SAC305/Cu solder joint

The Cu/Sn-3.OAg-0.5Cu/Cu butting solder joints were fabricated to investigate the evolution of the interfacial intermetallic compound(IMC) and the degradation of the tensile strength of solder joints under the effect of electromigration(EM) and aging processes.Scanning electron microscopy(SEM) results indicated that the Cu_6Sn_5 interfacial IMC presented obvious asymmetrical growth with the increase of EM time under current density of 1.78×10~4 A/cm~2 at 100℃,and the growth of anodic IMC presented a parabolic relationship with time while the cathodic IMC got thinner gradually.However,as for aging samples at 100℃ without current stressing,the Cu_6Sn_5 IMC presented a symmetrical growth with a slower rate than the anodic IMC of EM samples.The tensile results indicated that the tensile strength of the solder joints under current stress declined more drastic with time than the aging samples,and the fracture mode transformed from ductile fracture to brittle fracture quickly while the fracture mode of aging samples transformed from cup-cone shaped fracture to microporous gathering fracture in a slow way.     

微连接技术在3D-WLP中可靠性的研究现状

为了研究新型技术对微连接可靠性的影响,阐述了微连接技术在倒装焊、热压力焊、硅通孔技术中的应用情况。对微连接技术在晶圆级封装(3D-WLP)中影响其可靠性的常见问题及主要因素进行了综述。分析表明,在常见的Sn基无铅焊料与Cu基板的反应过程中,金属间化合物层主要由Cu6Sn5和少量Cu3Sn组成。柯肯达尔孔洞、电迁移、金属间化合物的机械性能、锡须及尺寸效应是影响微连接可靠性的常见问题。在此基础上,归纳并探讨了焊料成分、微量合金、稀土元素、镀层及粉末精度等影响微连接可靠性主要因素的研究情况和发展趋势。     

Electrical Properties of Uranium Carbonitride

Rapid separation using NTA in paper electromigration was applied to the study of the γ-decay of ¹⁴⁸Pr and ¹⁴⁹Pr produced in the fission of ²³⁵U. The γ-ray spectrum was measured with a high-resolution Ge(Li) detector. The γ-transitions found to decay with half-lives shorter than 3 min were: 135, 162, 256, 300, 511, 614, 696, 868, 1,022 and 1,248 keV. Of these, the values of 300 keV, and of 135 and 162 keV were in fair agreement with those reported for ¹⁴⁸Pr and ¹⁴⁹Pr. The decay plot of the strong photopeak of 300 keV presented good linearity and the accurate half-life of ¹⁴⁸Pr could be determined as 2.30±0.03 min, which is longer than the 1.98 min reported for ¹⁴⁸Pr. Similar decay plots of both photopeaks at 135 and 162 keV gave a half-life of 2.9±0.1 min for ¹⁴⁹Pr, which again is longer than the reported value of 2.3 min. Other low intensity photopeaks at 256, 696, 868 and 1,022 keV decaying with half-lives of 2.1～2.4 min can possibly be attributed to ¹⁴⁸Pr. The γ-transitions of 110, 578 and 742 keV reported for ¹⁴⁹Pr could not be observed in this experiment.     

无铅焊点在热疲劳和电迁移作用下的组织演变

研究了Cu/Sn-58Bi/Cu焊点接头在室温和55℃下通电过程中阴极和阳极界面处微观组织的演变,电流密度均采用104A/cm2。结果表明,室温条件下通电达到25 d,Bi原子由阴极向阳极发生了扩散迁移,在阳极界面处形成了厚度约22.4μm的均匀Bi层,而阴极出现了Sn的聚集。加载55℃通电2 d后,焊点发生了熔融,阴极界面处形成了厚度为34.3μm的扇贝状IMC,而阳极界面IMC的厚度仅为9.7μm。在IMC层和钎料基体之间形成了厚度约7.5μm的Bi层,它的形成阻碍了Sn原子向阳极界面的扩散迁移,进而阻碍了阳极界面IMC的生长,导致了异常极化效应的出现。     

尺寸效应下的无铅微焊点研究进展

为了研究无铅微焊点在尺寸效应下的可靠性,综述了微焊点的界面反应机制,常用添加元素对微连接金属间化合物(IMC)的作用及微焊点在尺寸效应下的主要问题.分析表明,IMC层主要由两种铜锡化合物Cu6 Sn5和Cu3 Sn组成.微焊点的连接形式有焊盘小尺寸微焊点和微通孔焊盘无铅微焊点两种,柯肯达尔(Kirkendall)孔洞、电迁移及焊料尺寸都会对接头的力学性能、拉伸强度和剪切强度造成较大的影响.同时,压力钎焊等新工艺可以促进焊料中元素的扩散,从而对抑制接头组织中脆性相和提高钎焊接头强度有显著效果.