阳极键合工艺进展及其在微传感器中的应用

分析了阳极键合技术的原理和当前阳极键合技术的研究进展，综述了微传感器对阳极键合的新需求，展望了阳极键合技术在传感器领域的应用前景。     

阳极键合强度及其评价方法

阳极键合作为一种在微机电系统(MEMS)中运用的关键技术,具有工艺简单、键合强度高、密封性好等优点。经过几十年的发展,该技术在键合机理和提高与评价键合强度等诸多方面都得到了很大的发展,并应用于越来越多的领域。对阳极键合技术的机理、键合基片材料的发展以及键合强度的评价方法等方面进行了综述和评价,并对阳极键合技术在MEMS中的发展趋势作出展望。     

采用线阴极的快速阳极键合方法

在平板阴极和点阴极方式做阳极键合时,时间-电流特性、键合速度、结合界面质量等都有所不同。通过建立力学和电学模型,分析了不同阴极形状对阳极键合的时间、强度以及结合界面特性的影响。根据模型分析,采取了线阴极工作方式做阳极键合,样品的键合区扩散时间只需要84s。结合界面无空洞,键合强度为16.7MPa。     

低温阳极键合技术研究

通过键合温度220~250℃、键合电压400~600 V的硅玻璃低温阳极键合实验,分析了温度和电场分别对键合强度和键合效率的影响,并讨论了键合机理。     

复合量程加速度计阳极键合残余应力研究

复合量程加速度计阳极键合过程中产生的残余热应力会引起加速度计的零位失调,也是导致加速度计失效的原因之一。对键合过程中产生的残余热应力进行了研究,仿真并分析了残余热应力与键合温度、玻璃基底厚度和框架键合宽度的影响,确定了适合复合量程加速度计的最佳键合宽度和玻璃基底厚度。     

硅牌键合技术的研究进展

硅片键合技术是指通过化学和物理作用将硅片与硅片、硅片与玻璃或其它材料紧密地结合起来的方法.硅片键合往往与表面硅加工和体硅加工相结合,用在MEMS的加工工艺中.常见的硅片键合技术包括金硅共熔键合、硅/玻璃静电键合、硅/硅直接键合以及玻璃焊料烧结等.文中将讨论这些键合技术的原理、工艺及优缺点.     

硅片键合技术的研究进展

硅片键合技术是指通过化学和物理作用将硅片与硅片，硅片与玻璃或其它材料紧密地结合起来的方法，硅片键合往往与表面硅加工和体硅加工相结合，用在MEMS的加工工艺中，常见的硅片键合技术包括金硅共熔键合，硅／玻璃静电键合，硅／硅直接键合以及玻璃焊料烧结等，文中将讨论这些键合技术的原理，工艺及优缺点。     

MEMS硅玻璃阳极键合工艺评价方法

为了得到微机电系统(MEMS)加速度计硅-玻璃阳极键合的键合强度,进行了剪切破坏测试,并结合材料力学相关理论,得到键合强度表征方法.通过对实验数据的分析,制定键合强度的失效判据,提出了一种评价硅玻璃键合工艺质量的有效方法,在工程实际中具有一定的参考价值.     

两电极多层阳极键合实验研究

介绍了用2个电极通过一次电极反接的方式实现多层样片之间阳极键合的操作工艺和键合机理,并以玻璃-硅-玻璃三层结构为例对其进行了实验研究。结果显示：多余的玻璃对第一次键合过程的电流特性影响不大,而第一次键合的玻璃对第二次键合电流产生显著的影响,电流出现不规则的突变。而且,在第二次键合过程中,第一次键合的玻璃在键合面上会出现由于钠元素积聚而产生的黄褐色斑点。拉伸强度实验的结果表明：第二次键合过程中在第一次键合面形成的反向电压会减弱键合的强度;通过合理选择键合参数可以得到满足MEMS封装要求的键合强度。     

表面有微结构的硅片键合技术

针对表面带有微结构硅晶圆的封装展开研究,以采用Ti/Au作为金属过渡层的硅—硅共晶键合为对象,提出一种表面带有微结构的硅—硅共晶键合工艺,以亲水湿法表面活化处理降低硅片表面杂质含量,以微装配平台与键合机控制键合环境及温度来保证键合精度与键合强度,使用恒温炉进行低温退火,解决键合对硅晶圆表面平整度和洁净度要求极高,环境要求苛刻的问题。高低温循环测试试验与既定拉力破坏性试验结果表明:提出的工艺在保证了封装组件封装强度的同时,具有工艺温度低、容易实现图形化、应力匹配度高等优点。     

基于正交试验的光纤传感器金属化连接工艺优化

为了克服光纤传感器有机胶封装带来的可靠性差、应变传递效率低的问题,采用粒子扩散系统对光纤传感器进行金属化连接以实现光纤传感器的无胶封装;为提高金属粘接层与基体的结合强度,设计了以工作距离、驱动电压、进给速度、粒子场气压为试验素的4水平正交试验方案,并用划痕法对金属粘接层的结合强度结果进行评估。通过统计分析,获得了影响金属粘接层与基体结合强度的主要因素和次要因素,优化了光纤传感器金属化连接工艺。     

The effects of helping,self-expression,and enjoyment on social capital in social media: the moderating effect of avoidance attachment in the tourism context

ABSTRACT

A majority of senior Internet users maintains persistent social connections with others through social media (SM), such as Facebook and Twitter. This research explores the impacts of helping, self-expression, and enjoyment on bonding social capital and bridging social capital which in turn influence SM involvement; it also explores the moderating effect of avoidance attachment among senior SM users. The results show that helping, self-expression, and enjoyment have significant impacts on bonding social capital and bridging social capital. Also, bonding social capital and bridging social capital have significant effects on SM involvement. Furthermore, relationships between helping and bonding social capital, between self-expression and bonding social capital, and between self-expression and bridging social capital are stronger for seniors with high avoidance attachment. Conversely, the relationships between enjoyment and bonding social capital as well as between enjoyment and bridging social capital are stronger for seniors with low avoidance attachment. Accordingly, the results of this study provide theoretical contributions to the literature of behaviour and information technology. In addition, some implications of the research and various strategies for practitioners and marketers that can be used to better increase users’ involvement in SM for tourism-related activities are discussed.     

圆片级封装铝锗键合后残余应力的测量和分析

以圆片级铝锗键合后的残余应力为研究对象,在键合环下方和周围制作了一系列形状相同的力敏电阻条,通过比较键合前后力敏电阻条的阻值变化,分析电阻条处残余应力的大小及与工艺相关性。结果表明：键合环内外的压阻变化约为键合环下方压阻变化的3倍。这种方法可以作为晶圆级键合质量的有效在线表征手段之一。     

Single-wafer die-level fusion bonding process for multi-layer devices

Single-wafer die-level fusion bonding (SDFB) process is proposed, which can reduce the mask number and fabrication time in the prototype research of multi-layer fusion bonding devices. The conception and scheme are illustrated using micro gas turbine of MIT as an example. The techniques to etch different mask and depth in a single-wafer are listed and analyzed. The alignment compensation mechanism in the SDFB is also discussed which can avoid the photolithography misalignment and improve the precision between key layers. The advantages and disadvantages of SDFB are analyzed in detail. The feasibility of the scheme is verified by the experiment. Besides micro gas turbine of MIT, the SDFB process can also be used in other multi-layer fusion bonding devices such as ultra thick proof mass inertial sensors, multi-layer fluidic devices, etc.     

Virtual communities in schools as tools to promote social capital with high schools students

The general aim of this study was to test the hypothesis that students belonging to a school online community would show higher levels of both offline bridging and bonding social capital than a control group of students, not using the online community. We further hypothesized that the more students used the online community the higher their level of their offline bonding and bridging social capital. Participants were 264 high school boys and girls, 126, (62 males and 64 females) who had joined the community online Spallanzani shout and 138, (62 males and 76 females) who did not. ANOVAs analysis showed that levels of bridging and bonding social capitals were significantly higher for members. Instead intensity of use was significantly related only to bridging but not to bonding social capital. Implications of the findings and directions for future research are discussed.     

Bonding of thermoplastic polymer microfluidics

Thermoplastics are highly attractive substrate materials for microfluidic systems, with important benefits in the development of low cost disposable devices for a host of bioanalytical applications. While significant research activity has been directed towards the formation of microfluidic components in a wide range of thermoplastics, sealing of these components is required for the formation of enclosed microchannels and other microfluidic elements, and thus bonding remains a critical step in any thermoplastic microfabrication process. Unlike silicon and glass, the diverse material properties of thermoplastics opens the door to an extensive array of substrate bonding options, together with a set of unique challenges which must be addressed to achieve optimal sealing results. In this paper we review the range of techniques developed for sealing thermoplastic microfluidics and discuss a number of practical issues surrounding these various bonding methods.     

金丝键合短尾问题分析及解决

金丝键合通常由金丝球超声键合完成。短尾是金丝球键合过程中一个典型的失效模式,详细分析了金丝球键合过程中第二点键合的四个关键步骤,分析了第二点键合形貌形成过程,分别研究了键合第二点各个区域与键合劈刀的位置关系,在此基础上详细分析了造成第二点键合金丝短尾的主要因素和机理,提出劈刀上升前后两种主要的短尾模式,得出键合参数是影响键合质量和键合强度的关键因素,给出了优化改进措施,提出通过降低超声功率和压力,或者通过优化原材料、劈刀,以便使用较低的工艺参数就可以完成键合,解决第二点键合短尾问题。     

Localized silicon fusion and eutectic bonding for MEMS fabricationand packaging

Silicon fusion and eutectic bonding processes based on the technique of localized heating have been successfully demonstrated. Phosphorus-doped polysilicon and gold films are applied separately in the silicon-to-glass fusion bonding and silicon-to-gold eutectic bonding experiments. These films are patterned as line-shape resistive heaters with widths of 5 or 7 μm for the purpose of heating and bonding. In the experiments, silicon-to-glass fusion bonding and silicon to gold eutectic bonding are successfully achieved at temperatures above 1000°C and 800°C, respectively, by applying 1-MPa contact pressure. Both bonding processes can achieve bonding strength comparable to the fracture toughness of bulk silicon in less than 5 min. Without using global heating furnaces, localized bonding process is conducted in the common environment of room temperature and atmospheric pressure. Although these processes are accomplished within a confined bonding region and under high temperature, the substrate temperature remains low. This new class of bonding scheme has potential applications for microelectromechanical systems fabrication and packaging that require low-temperature processing at the wafer level, excellent bonding strength, and hermetic sealing characteristics     

Bench scale glass-to-glass bonding for microfluidic prototyping

Microfluidics, an increasingly ubiquitous technology platform, has been extensively utilized in assorted research areas. Commonly, microfluidic devices are fabricated using cheap and convenient elastomers such as poly(dimethylsiloxane) (PDMS). However, despite the popularity of these materials, their disadvantages such like deformation under moderate pressure, chemical incompatibility, and surface heterogeneity have been widely recognized as impediments to expanding the utility of microfluidics. Glass-based microfluidic devices, on the other hand, exhibit desirable properties including rigidity, chemically inertness, and surface chemistry homogeneity. That the universal adoption of glass-based microfluidics has not yet been achieved is largely attributable to the difficulties in device fabrication and bonding, which usually require large capital investment. Therefore, in this work, we have developed a bench-scale glass-to-glass bonding protocol that allows the automated bonding of glass microfluidic devices within 6 h via a commercially available furnace. The quality of the bonds was inspected comprehensively in terms of bonding strength, channel deformation and reliability. Additionally, femtosecond pulsed laser micromachining was employed to rapidly engrave channels on a glass substrate with arbitrary-triangular in this case-cross-section. Bonded glass microfluidic devices with machined channels have been used to verify calculated capillary entry pressures. This combination of fast laser micromachining that produces arbitrary cross-sectioned microstructures and convenient bench-scale glass bonding protocol will facilitate a broad range of micro-scale applications.