半导体器件金铝键合的寿命研究

金铝键合失效是MOSFET器件常见的失效模式之一,主要是由于金属间化合物的生成,影响了金铝键合的接触电性能,从而导致键合强度下降,接触电阻升高。针对这种失效模式,进行了三种不同高温条件下的加速寿命试验,并对这三种试验的器件进行金铝键合现象观察,对目前工艺水平下的金铝键合寿命进行了评估。     

基于薄膜HIC金铝键合失效的工艺研究

介绍了薄膜混合集成电路(HIC)中金铝键合失效机理,提出了一种解决金铝键合失效的新工艺.分析失效机理发现,铝丝和薄膜金导带形成的金铝界面因原子扩散而形成内部空洞,出现键合根部的键合丝断裂的现象.通过改变键合区金属层结构,实现了单一金属化系统,有效避免了金属间化合物的形成.该项研究结果对陶瓷基薄膜HIC的工艺应用范围的拓...     

在管壳柯伐柱上敷铝以铝-铝系统代替金-铝系统

文中对管柱上金-铝键合的相连方法,在高温下因生成有害的金属间化合物而失效的机理进行了初步分析,其主要原因是称为“白斑”的物质所引起;而管柱上金-铝键合的互连,在煮盐水中所引起的失效是电化学腐蚀。 在金属圆管壳的柯伐柱端面,进行机械研磨、抛光后,分别“用甲苯、丙酮、乙醇清洗,用选择性蒸发法敷铝,最后于真空炉中进行一定时间的热处理而成。 以铝-铝键合的互连系统和金-铝键合的互连系统进行了对比加速试验,300℃高温贮存224小时后,用测克计检查其键合点的抗拉强度,金-铝键合的互联,绝大部分脱键,其拉力值为零;而铝-铝键合的互联,大部分在铝丝中间拉断,其拉力值0.5～1克。 煮盐水的对比试验明显可以看出,敷铝管壳的铝丝与柯伐柱敷铝处的键合点,大部分是完好的;而镀金管壳的铝丝与柯伐柱镀金处的键合点,绝大部分被腐蚀断。 实验结果明显表明,铝-铝互连系统优越于金-铝互联系统。 文中对加速试验的结果有实验数据,并列有表格和样品照片。     

基于温冲应力环境的Au-Al键合可靠性

为了适应半导体器件的高可靠要求,对Au-Al键合抗温变应力性能进行了考核。试验结果表明,Au—Al键合具有较好的抗热疲劳性能,键合界面处无裂纹产生,且机械性能良好。然而试验中的高温应力导致金铝间形成了电阻率较高的化合物Au5Al2,引起键合失效。并对目前工艺水平下的Au-Al键台可靠性进行了评价,预测了键合寿命。     

电子元器件金铝键合失效分析研究

金铝键合失效是电子元器件常见的失效模式之一。对某型号射频芯片和检波器两例产品开展了失效分析研究。结果表明,一例失效产品出现了键合丝脱落的情况,一例失效产品出现了键合拉力几乎为零的情况,这是由于铝焊盘与金键合丝之间形成了金铝间化合物,金铝间化合物电阻率较高,使得键合强度降低或键合脱开,最终导致产品失效。研究了金铝化合物的失效机理,借助扫描电子显微镜对金铝化合物形貌及元素进行了分析,最后对金铝化合物所导致的失效提出了预防和改进措施,对于提高电子元器件的可靠性具有一定的借鉴意义。     

Ni-Co合金+Au镀覆陶瓷外壳的引线键合可靠性研究

为了提高陶瓷外壳镀层耐高温变色、耐腐蚀以及长期贮存的能力,带金属零件的陶瓷外壳需采用Co含量在20%~40%的Ni-Co+Au镀覆结构,镀层经退火处理。研究分析了Ni+Au镀覆和NiCo+Au镀覆结构对铝丝楔焊和金丝球焊可靠性的影响,通过常温、300℃高温贮存1 h、300℃高温贮存24 h后引线键合强度变化、键合面的元素面分布进行量化比较。试验表明Ni+Au和Ni-Co+Au镀覆结构对引线键合强度和可靠性无明显影响;两种镀覆结构的外壳在键合时,键合工艺参数也不需要进行较大的调整;铝丝在Ni-Co+Au镀覆结构与Ni+Au镀覆结构上键合,在键合界面均会生成金铝金属间化合物,但只要金层厚度受控,均不会产生"Kirkendall"失效,相对来讲Ni-Co+Au镀覆结构的缺陷密度较低,生成金铝金属间化合物进程会慢些。     

高温对金-铝系统电阻和强度的影响研究

在讨论金-铝键合系统失效机理的基础上,对高温条件下金-铝键合系统接触电阻和键合强度衰变情况进行研究.给出了金-铝系统接触电阻高温衰减曲线和破坏性键合拉力强度高温衰减曲线.通过对实验结果的分析,提出在设计中通过评估键合点工作温度来避免金-铝键合系统的可靠性隐患.     

Kirkendall空洞引起的铝丝—金层之间键合强度的退化

研究了铝丝-镀金层系统的健合强度的退化。这种健合系统在高温贮存时,健合强度的退化为下列三种退化模式之一:(ⅰ)A模式—随热退火时间的增加,键合强度下降,直到某一确定值,(ⅱ)B模式—在一确定的退火时间以后,键合强度开始分成两个值,(ⅲ)C模式—键合强度迅速降到零。在铝-金界面之间富金金属间化合物相处生成的Kirkendall空洞可圆满地解释这三种退化模式的物理机理,此时,富金金属间化合物相的生长速率对决定退化模式起着非常重要的作用。当金层含有大量的铅或铊时,这个生长速率减慢,退化是C模式或者是B模式。有时在金层中掺入银,能使键合强度的退化减弱。     

键合参数对金铝键合可靠性的影响

金-铝（Au-Al）两种金属在焊接界面上产生不对称扩散,导致焊缝空洞形成与生长,最终形成脱键,是引线键合工艺中备受关注的失效模式之一。本文以超声时间和超声电流为变量,研究了键合参数对金铝键合可靠性的影响。采用金丝球焊,与带有铝焊盘的芯片作为键合试验样品,在300℃高温条件下进行2h（小时）到24h的烘烤试验。结果表明,在较短键合时间下键合完成的样品,与在较长键合时间下键合完成的样品相比较,发生键合脱键的时间更晚,键合强度衰减的更慢。     

金丝球焊复合键合工艺可靠性研究

对芯片铝焊盘上不同重叠面积的金丝球焊复合键合的可靠性进行研究,并与非复合键合进行对比.结果 表明,随着复合键合重叠面积的减少,键合拉力和界面生成的合金化合物面积均无明显变化,而剪切强度呈下降趋势.高温储存结果表明,复合键合拉力值满足国军标要求.复合键合有掉铝和弹坑缺陷隐患.经分析,原因是复合键合时施加的超声能量破坏了硅...     

Investigations of strength of copper-bonded wafers with several quantitative and qualitative tests

The strengths of Cu-bonded wafers with respect to different bonding temperatures and bonding durations by quantitative and qualitative approaches were reviewed and investigated. These investigations include the mechanical dicing test, the tape test, the pull test, and the push test. For all test results, the strength of Cu-bonded wafers increases with increases in bonding duration or bonding temperature. Thermal anneal after bonding improved the bonding strength only at the high bonding temperature and not at the low temperature.     

用高低温循环加速试验评估光源模块长期贮存寿命的研究

Light source modules are the most crucial and fragile devices that affect the life and reliability of the interferometric fiber optic gyroscope （IFOG）. While the light emitting chips were stable in most cases, the module packaging proved to be less satisfactory. In long-term storage or the working environment, the ambient temperature changes constantly and thus the packaging and coupling performance of light source modules are more likely to degrade slowly due to different materials with different coefficients of thermal expansion in the bonding interface. A constant temperature accelerated life test cannot evaluate the impact of temperature variation on the performance of a module package, so the temperature cycling accelerated life test was studied. The main failure mechanism affecting light source modules is package failure due to solder fatigue failure including a fiber coupling shift, loss of cooling efficiency and thermal resistor degradation, so the Norris-Landzberg model was used to model solder fatigue life and determine the activation energy related to solder fatigue failure mechanism. By analyzing the test data, activation energy was determined and then the mean life of light source modules in different storage environments with a continuously changing temperature was simulated, which has provided direct reference data for the storage life prediction of IFOG.     

Reliability of Au bump––Cu direct interconnections fabricated by means of surface activated bonding method

As a room temperature bonding method, surface activated bonding (SAB) method has been introduced to be one of the most appropriate interconnection methods for the next generation of electronic packaging. Thus it is important to study the reliability of SAB interconnection in long term life test.In this paper, interconnections of Au bump and Cu film bonded by SAB method were performed in high temperature thermal aging test. Degradation of properties such as electrical resistance, shear strength of bump and interface microstructure during aging process were studied to investigate the failure mechanism of the interconnection. Intermetallic compound Cu₃Au was found formed at the interface during thermal aging, and it causes evolvement of the properties and failure mode of the interconnection changing in shear test. Results reveal that SAB is suitable for the interconnection between Au bump and Cu film and it is reliable in thermal reliability test.     

导电胶粘接可伐载板工艺的仿真与优化

导电胶是一种很有潜力的互连材料,其粘接可靠性是制约其应用的主要因素。基于对某混频模块粘接失效的分析,探索温度试验条件及载板尺寸对可伐载板粘接可靠性的影响。通过仿真和试验设计,研究不同温度试验条件下不同尺寸载板在粘接界面处的应力分布情况,并优化了可伐载板粘接工艺。结果表明,温度试验条件越严苛,载板尺寸越大,可伐载板粘接可靠性越差,可采取环氧绝缘胶加固或柔性导电胶粘接的方式对其粘接工艺进行优化。     

Ultra-high-density interconnection technology of three-dimensional packaging

The study of 20-μm-pitch interconnection technology of three-dimensional (3D) packaging focused on reliability, ultrasonic flip–chip bonding and Cu bump bonding is described. The interconnection life under a temperature cycling test (TCT) was at an acceptable level for semiconductor packages. Failure analysis and finite element analysis revealed the effect of material properties. Basic studies on ultrasonic flip–chip bonding and very small Cu bump formation were investigated for low-stress bonding methods. The accuracy of ultrasonic flip–chip bonding was almost the same level as that of thermocompression bonding and the electrical connection was also confirmed. Atomic-level bonding was established at the interface of Au bumps. For Cu bump bonding, a dry process was applied for under bump metallurgy (UBM) removal. Electroless Sn diffusion in Cu was investigated and the results clarified that the intermetallic layer was formed just after plating. Finally, we succeeded in building a stacked chip sample with 20-μm-pitch interconnections.     

石英玻璃低温键合界面的环境适应性试验

石英玻璃的低温键合技术作为一种可靠的固体连接方式,受到了欧美发达国家的广泛重视,并在航天、基础科研、强激光等诸多领域得到了广泛应用。该技术基于氢氧化物催化玻璃表面的水解/脱水过程,通过在键合界面之间形成硅酸盐三维网状结构实现键合,是一种高强度、高精确性、可靠的室温键合方法。对石英玻璃低温键合技术的工作原理和基本工艺过程进行了阐述,并实现了石英玻璃的低温键合。对键合界面进行了多项环境适应性试验,结果表明:相对传统的光胶方法,低温键合技术在键合强度、温度冲击环境及水环境的适应性方面表现出显著优势,在键合均匀性、精确度、透明度、密封性、常规温度及振动环境方面与传统方法表现相当。     

各向异性导电胶粘结工艺技术研究

分析了影响各向异性导电胶粘结可靠性的各因素,通过正交实验优化工艺参数,并在150℃高温贮存以及-65℃～150℃温度循环后对导电胶的剪切强度和接触电阻进行了可靠性实验。结果表明:影响ACA可靠性的主要因素导电粒子体积比例为15%,粘结温度200℃,时间10s,粘结压力为39.2N时,导电胶的剪切强度为286.2N,凸点的接触电阻为35mΩ。在可靠性试验后,导电胶的剪切强度满足GJB548B-2005的要求,接触电阻变化率小于5%。     

一种基于Ag-Sn等温凝固的圆片键合技术

研究了用Ag-Sn作为键合中间层的圆片健合。相对于成熟的Au-Sn键合系统(典型键合温度是280℃),该系统可以提供更低成本、更高键合后分离(De-Bonding)温度的圆片级键合方案。使用直径为100mm硅片,盖板硅片上溅射多层金属Ti/Ni/Sn/Au,利用Lift-off工艺来形成图形。基板硅片上溅射Ti/Ni/Au/Ag。硅片制备好后,将盖板和基板叠放在一起送入键合机进行键合。键合过程在N2气氛中进行,键合过程中不需要使用助焊剂。研究了不同键合参数,如键合压力、温度等对键合结果的影响。剪切强度测试表明样品的剪切强度平均在55.17MPa。TMA测试表明键合后分离温度可以控制在500℃左右。He泄漏测试证明封接的气密性极好。