一种真空度可调的圆片级封装技术

提出了一种MEMS器件的圆片级封装技术。通过金硅键合和DRIE通孔制备等关键工艺技术,可以实现真空度从102 Pa到2个大气压可调的圆片级封装。作为工艺验证,成功实现了圆片级真空封装MEMS陀螺仪的样品制备。对封装后的陀螺仪样品进行了剪切力和品质因数Q值测试,剪切力测试结果证明封装样品键合强度达到5 kg以上,圆片级真空封装后陀螺的品质因数Q值约为75 000,对该陀螺的品质因数进行了历时1年的跟踪测试,在此期间品质因数Q的最大变化量小于7‰,品质因数测试结果表明封装具有较好的真空特性。     

MEMS圆片级真空封装金硅键合工艺研究

提出一种适用于微机电系统(MEMS)圆片级真空封装的键合结构,通过比较分析各种键合工艺的优缺点后,选择符合本试验要求的金硅键合工艺.根据所提出键合结构和金硅键合的特点设计键合工艺流程,在多次试验后优化工艺条件.在此工艺条件下,选用三组不同结构参数完成键合试验.之后对比不同的结构参数分别测试其键合质量(包括键合腔体泄漏率...     

一种硅四层键合的高对称电容式加速度传感器

提出了一种利用体微机械加工技术制作的硅四层键合高对称电容式加速度传感器.采用硅/硅直接键合技术实现中间对称梁质量块结构的制作,然后采用硼硅玻璃软化键合方法完成上、下电极的键合.在完成整体结构圆片级真空封装的同时,通过引线腔结构方便地实现了中间电极的引线.传感器芯片大小为6.8mm×5.6mm×1.68mm,其中敏感质量块尺寸为3.2mm×3.2mm×0.84mm.对封装的传感器性能进行了初步测试,结果表明制作的传感器漏率小于0.1×10-9cm3/s,灵敏度约为6pF/g,品质因子为35,谐振频率为489Hz.     

一种硅四层键合的高对称电容式加速度传感器

提出了一种利用体微机械加工技术制作的硅四层键合高对称电容式加速度传感器.采用硅/硅直接键合技术实现中间对称梁质量块结构的制作,然后采用硼硅玻璃软化键合方法完成上、下电极的键合.在完成整体结构圆片级真空封装的同时,通过引线腔结构方便地实现了中间电极的引线.传感器芯片大小为6.8mm×5.6mm×1.68mm,其中敏感质量块尺寸为3.2mm×3.2mm×0.84mm.对封装的传感器性能进行了初步测试,结果表明制作的传感器漏率小于0.1×10-9cm3/s,灵敏度约为6pF/g,品质因子为35,谐振频率为489Hz.     

高g微机械加速度传感器芯片盖帽封装设计北大核心

为了提高高g微机械加速度传感器在极端恶劣环境中应用的可靠性,根据自制的高g微机械加速度传感器芯片,研究设计了一种新型＂台阶式＂传感器芯片的盖帽封装结构。利用圆片级键合工艺和有限元分析（FEA）方法确定了盖帽封装结构材料与尺寸的设计方案。优化微电子机械系统（MEMS）加工工艺流程完成对盖帽封装结构的加工,并通过数字电子拉力机对实现圆片级盖帽封装的传感器芯片进行键合强度测试。测试结果表明,键合强度为35 000 kPa,远大于抗过载封装设计要求下的键合强度值（401.2 kPa）,证明了盖帽封装结构设计的可行性和可靠性。     

一种MEMS陀螺晶圆级真空封装工艺

为了提高MEMS陀螺的品质因数(Q值),提出了一种晶圆级真空封装工艺。先在陀螺盖帽晶圆上刻蚀出浅腔,然后在浅腔结构上制备钨(W)金属引线,再通过PECVD工艺淀积介质层,在介质层上制备钛/金(Ti/Au)键合环,最后将盖帽晶圆与制备好的结构晶圆完成金硅共晶键合,并利用吸气剂实现晶圆的长久真空封装。经测试,采用本方案的封装的气密性与金属层厚度紧密相关,调整合适的金属层厚度后可使真空泄漏速率小于2.0×10-12 Pa·m~3·s-1。此外,设计了一种特殊的浅腔阵列结构,该结构将金硅键合强度从小于20 MPa提升至大于26 MPa,同时可防止键合时液相合金向外溢流。对陀螺芯片的性能测试表明,该真空封装工艺简单有效,封装气密性良好,Q值高达168 540,满足设计指标要求。     

微机电系统封装技术

首先提出了MEMS封装技术的一些基本要求,包括低应力、高真空、高气密性、高隔离度等,随后简要介绍了MEMS封装技术的分类.在此基础上,综述了三个微机电系统封装的关键技术:微盖封装、圆片级芯片尺寸封装和近气密封装,并介绍了其封装结构和工艺流程.     

MEMS器件封装的低温玻璃浆料键合工艺研究

玻璃浆料是一种常用于MEMS器件封装的密封材料.系统研究了MEMS器件在低温下使用玻璃浆料键合硅和玻璃的过程.与大多数MEMS器件采用的玻璃浆料相比(烧结温度400℃以上),此工艺(烧结温度350℃)在键合完成后所形成的封装结构同样具有较高的剪切强度(封装器件剪切强度大于360 kPa),同时具有较好的气密性(合格率达到93.3%),漏率测试结果符合相关标准.结果表明,在保证MEMS器件封装剪切强度和气密性的同时,降低键合温度条件是可以实现的.     

一种硅微机械陀螺制造方法研究

给出了一种硅微机械陀螺制造方法,该方法可适用于各种不同的微机电系统(MEMS)器件,包括加速度计、剪切应力传感器及MEMS光开关等。利用该方法制备了硅微机械陀螺,并给出了该陀螺的性能测试结果。同时分析了利用该方法制备各种不同器件时,工艺流程对器件性能的影响,重点讨论了硅-玻璃阳极键合、减薄工艺及深刻蚀所形成的侧壁质量,包括侧壁垂直度、侧壁杂质等因素对器件性能的影响。     

应用BCB材料进行硅-玻璃气密性封装的实验与理论研究

应用苯并环丁烯(BCB)材料对硅片和玻璃片进行了250℃下的圆片级低温键合实验,同时进行了300℃下的硅片与玻璃片阳极键合实验,并对其气密性和剪切力特性进行了对比研究.测试结果表明:在250℃的低温键合条件下,经过500kPa He气保压2h,BCB封装后样品的气密性达到(5.5±0.5)×10-4Pa cc/s He;剪切力在9.0～13.4 MPa之间,达到了封装工艺要求;封装成品率达到100%.这表明应用BCB材料键合是一种有效的圆片级低温气密性封装方法.还根据渗流模型理论,讨论了简易模型下气密性(即渗流率)和器件腔体边缘到划片边缘的间距的关系.     

A Novel Wafer-Level Hermetic Packaging for MEMS Devices

Some emerging microelectromechanical systems (MEMS) devices such as high-performance inertial sensors and high-speed actuators must be operated in a high vacuum and in order to create this vacuum environment, specific packaging is required. To satisfy this demand, this paper presents a novel method for hermetic and near-vacuum packaging of MEMS devices. We use wafer-level bonding technology to combine with vacuum packaging, simultaneously. For this packaging solution, the wafers with air-guided micro-through-holes were placed on a custom-built design housed in a vacuum chamber maintained at a low-pressure environment of sub-10 mtorr. Packaging structure is then sealed by solder ball reflow process with the lower heating temperature of 300degC to fill up micro-through-hole. Experimental results shown the hermetical packaging technique using solder sealing is adapted to the wafer-level microfabrication process for MEMS devices and can achieve better yield and performance. Thus, this technique is very useful for many applications with high performance and low packaging cost can be obtained due to wafer-level processing.     

用于MEMS器件的键合工艺研究进展

随着MEMS器件的广泛研究和快速进步,非硅基材料被广泛用于MEMS器件中.键合技术成为MEMS器件制作、组装和封装的关键性技术之一,它不仅可以降低工艺的复杂性,而且使许多新技术和新应用在MEMS器件中得以实现.目前主要的键合技术包括直接键合、阳极键合、粘结剂键合和共晶键合.     

基于混合电极两步键合工艺的阳极键合研究

提出了一种基于新型混合电极的两步键合工艺。阳极键合工艺是在自行设计的多功能键合系统中完成,分析了不同电极配置对键合时间,键合强度以及键合界面的影响,并详细分析了键合界面和键合强度。借助于新型混合电极结构,能够在15-20min内实现无气泡晶圆级阳极键合,其键合强度高于10MPa。 以上结果表明,该种键合方法有非常好的应用价值,能应用于绝大多数晶圆级MEMS封装。     

Wafer-level packaging of silicon to glass with a BCB intermediate layer using localised laser heating

Adhesive wafer-level bonding is an excellent solution to meet the stringent requirements in micro-electro-mechanical systems (MEMS) packaging, one of the challenges in MEMS manufacturing, in a steadily growing micro-systems market. A range of bonding processes for commercially available substrate bonders have been developed, which apply global heating during the bonding procedure. This article, however, describes an approach where heating is kept to a minimum by combining the merits of laser joining, a truly localised heating technique, and adhesive wafer-level bonding. This unique bonding technique, which enables the use of temperature-sensitive materials within the package, is demonstrated for bonding of silicon to glass - materials commonly used in MEMS fabrication - with a benzocyclobutene (BCB) intermediate bonding layer. As a proof of concept for wafer-level packaging, bonding of two simplified patterns is demonstrated, one with five individual samples on the same wafer, and the other with nine samples. To verify the influence of this innovative bonding technique on the quality of the seal the devices are shear force tested and the results are compared with those of devices packaged at chip-level.     

Wafer-level hermetic MEMS packaging by anodic bonding and its reliability issues

This paper reviews wafer-level hermetic packaging technology using anodic bonding from several reliability points of view. First, reliability risk factors of high temperature, high voltage and electrochemical O₂ generation during anodic bonding are discussed. Next, electrical interconnections through a hermetic package, i.e. electrical feedthrough, is discussed. The reliability of both hermetic sealing and electrical feedthrough must be simultaneously satisfied. In the last part of this paper, a new wafer-level MEMS packaging material, anodically-bondable low temperature cofired ceramic (LTCC) wafer, is introduced, and its reliability data on hermetic sealing, electrical interconnection and flip-chip mounting on a printed circuit board (PCB) are described.     

Selective bonding and encapsulation for wafer-level vacuum packaging of MEMS and related micro systems

A laser-assisted bonding technique is demonstrated for low temperature region selective processing. A continuous wave carbon dioxide (CO₂) laser (λ=10.6 μm) is used for solder (Pb37/Sn63) bonding of metallized silicon substrates (chips or wafers) for MEMS applications. Laser-assisted selective heating of silicon led to the reflow of an electroplated, or screen-printed, intermediate solder layer which produced silicon–solder–silicon joints. The bonding process was performed on fixtures in a vacuum chamber at an air pressure of 10⁻³ Torr to achieve fluxless soldering and vacuum encapsulation. The bonding temperature at the sealing ring was controlled to be close to the reflow temperature of the solder. Pull test results showed that the joint was sufficiently strong. Helium leak testing showed that the leak rate of the package met the requirements of MIL-STD-883E under optimized bonding conditions and bonded packages survived thermal shock testing. The testing, based on a design of experiments method, indicated that both laser incident power and scribe velocity significantly influenced bonding results. This novel method is especially suitable for encapsulation and vacuum packaging of chips or wafers containing MEMS and other micro devices with low temperature budgets, where managing stress distribution is important. Further, released and encapsulated devices on the sealed wafers can be diced without damaging the MEMS devices at wafer level.     

基于BCB键合的MEMS加速度计圆片级封装工艺

对基于BCB的圆片级封装工艺进行了研究,该工艺代表了MEMS加速度计传感器封装的发展趋势,是MEMS加速度计产业化的关键。选用3000系列BCB材料进行MENS传感器的粘结键合工艺试验,解决了圆片级封装问题,在低温250℃和适当压力辅助下≤2．5bar（1bar=100kPa）实现了加速度计的圆片级封装,并对相关的旋涂、键合、气氛、压力等诸多工艺参数进行了优化。     

基于阳极键合的硅微圆盘多环谐振陀螺的设计与制作

提出了一种新型的基于阳极键合的硅微圆盘多环谐振陀螺的结构设计及其制作方法.该种陀螺采用MEMS工艺制作而成,基底材料为肖特BF33玻璃,电极和谐振器均由单晶硅片加工而成,肖特BF33玻璃与单晶硅片通过阳极键合工艺键合在一起.介绍了该种陀螺的基本结构、工作原理,并进行了仿真分析,得出该种陀螺具有较小的频率分裂,表现出陀螺效应.最后,通过MEMS工艺进行了实际加工,得到了该种陀螺的实验样品.     

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。