3D封装与硅通孔(TSV)工艺技术

在IC制造技术受到物理极限挑战的今天,3D封装技术越来越成为了微电子行业关注的热点。对3D封装技术结构特点、主流多层基板技术分类及其常见键合技术的发展作了论述,对过去几年国际上硅通孔（TSV）技术发展动态给与了重点的关注。尤其就硅通孔关键工艺技术如硅片减薄技术、通孔制造技术和键合技术等做了较详细介绍。同时展望了在强大需求牵引下2015年前后国际硅通孔技术进步的蓝图。     

新型的3D堆叠封装制备工艺及其实验测试

为了满足超大规模集成电路(VLSI)芯片高性能、多功能、小尺寸和低功耗的需求,采用了一种基于贯穿硅通孔(TSV)技术的3D堆叠式封装模型.先用深反应离子刻蚀法(DRIE)形成通孔,然后利用离子化金属电浆(IMP)溅镀法填充通孔,最后用Cu/Sn混合凸点互连芯片和基板,从而形成了3D堆叠式封装的制备工艺样本.对该样本的接触电阻进行了实验测试,结果表明,100 μm2Cu/Sn混合凸点接触电阻约为6.7 mΩ高90 μm的斜通孔电阻在20～30mΩ该模型在高达10 GHz的频率下具有良好的机械和电气性能.     

用于3D WLP和3D SIC的穿透硅通孔技术

数家研究小组和公司已经展示了通过芯片叠层和穿透硅通孔（TSV）互连来实现复杂3D芯片的可行性。     

射频系统2.5D/3D封装结构的研究进展

射频系统封装已经成为无线通信系统重要的集成技术,对于不断向高速率、小型化、多功能方向发展的无线通信系统,先进射频系统封装结构为其提供了坚实的基础.介绍了2.5D/3D射频系统封装结构的研究进程,重点分析了中介层结构、埋入结构、堆叠结构中的关键工艺,并从信号传输、电磁干扰、结构集成度等多角度出发,对不同封装结构做了深入剖...     

深硅刻蚀实现3D集成封装——贯穿硅的通孔技术正被用于MEMS制造、功率器件和3D结构中。

Sematech在2004年提出，光靠改变互连的工艺和材料还不足以满足下一代IC的性能要求，同时预测所需的推动力可能来自于不同种类器件的混合集成。目前，各大器件制造商和封装厂都在积极研发晶圆级封装技术，以满足未来器件小型化和更多功能的要求。     

叠层式3D封装技术发展现状

随着电子产品朝小型化、高密度化、高可靠性、低功耗方向发展,将多种芯片、器件集成于同一封装体的3D封装成为满足技术发展的新方向,其中叠层3D封装因具有集成度高、质量轻、封装尺寸小、制造成本低等特点而具有广阔的应用前景。综述了叠层式3D封装的主要类型、性能特点、技术优势以及应用现状。     

先进的叠层式3D封装技术及其应用前景

采用叠层3D封装技术将使芯片所包含晶体管数目成倍的增加,它不但具有体积小、性能高、功耗低等优点,而且拥有无可比拟的封装效率.对其叠层3D封装的发展趋势、技术特点、技术优势、散热问题以及应用前景等几个方面进行了探讨.     

3D封装的发展动态与前景

3D封装是手机等便携式电子产品小型化和多功能化的必然产物。3D封装有两种形式,芯片堆叠和封装堆叠。文章介绍了芯片堆叠和封装堆叠的优缺点、关键技术、最新动态和发展前景。     

基于TSV的三维集成螺旋电感等效电路模型

基于硅通孔(TSV)技术,可以实现微米级三维无源电感的片上集成,可应用于微波/射频电路及系统的微型化、一体化三维集成。考虑到三维集成电路及系统中复杂、高密度的电磁环境,在TSV电感的设计和使用中,必须对其电路性能及各项参数指标进行精确评估及建模。采用解析方法对电感进行等效电路构建和寄生参数建模,并通过流片测试对模型进行了验证。结果表明,模型的S参数结果与三维仿真结果吻合良好,证实了等效电路构建的精确性。采用所建立的等效电路模型可以提高TSV电感的设计精度和仿真效率,解决微波电路设计及三维电磁场仿真过程中硬件配置要求高、仿真速度慢等问题。     

An investigation into warpages,stresses and keep-out zone in 3D through-silicon-via DRAM packages

This paper aims to measure and simulate the warpages of 3D through-silicon via (TSV) die-stacked dynamic-random-access-memory (DRAM) packages during the manufacturing process. The related die stresses and keep-out zone (KOZ) for the stacked dies in the packages at room temperature are further calculated with the validated simulation model. The out-of-plane deformations (or warpages) of the packages from the full-field shadow moiré are documented under temperature loading and found consistent with those from finite-element method (FEM). The results of the stresses and KOZs at the proximity of a single TSV for each die in the package at room temperature are presented. It is found that the sizes of KOZs in four-die stacked DRAM packages with and without epoxy molding compound (EMC) at room temperature are dominated by the horizontal pMOS transistors and more than double the size in wafer-level die. The sizes of KOZs at each die are similar in this four-die stacked DRAM package, even though the stresses at each die are apparently different.     

3DIC集成与硅通孔(TSV)互连

介绍了3维封装及其互连技术的研究与开发现状,重点讨论了垂直互连的硅通孔（TSV）互连工艺的关键技术及其加工设备面临的挑战．提出了工艺和设备开发商的应对措施并探讨了3DTSV封装技术的应用前景。     

用于3D封装的带TSV的超薄芯片新型制作方法

提出了一种应用于3D封装的带有硅通孔(TSV)的超薄芯片的制作方法。具体方法为通过刻蚀对硅晶圆打孔和局部减薄,然后进行表面微加工,最后从硅晶圆上分离出超薄芯片。利用两种不同的工艺实现了TSV的制作和硅晶圆局部减薄,一种是利用深反应离子刻蚀(DRIE)依次打孔和背面减薄,另一种是先利用KOH溶液湿法腐蚀局部减薄,再利用DRIE刻蚀打孔。通过实验优化了KOH和异丙醇(IPA)的质量分数分别为40%和10%。这种方法的优点在于制作出的超薄芯片翘曲度相较于CMP减薄的小,而且两个表面都可以进行表面微加工,使集成度提高。利用这种方法已经在实验室制作出了厚50μm的带TSV的超薄芯片,表面粗糙度达到0.02μm,并无孔洞地电镀填满TSV,然后在两面都制作了凸点,在表面进行了光刻、溅射和剥离等表面微加工工艺。实验结果证实了该方法的可行性。     

Clock Mesh Network Design with Through‐Silicon Vias in 3D Integrated Circuits

Many methodologies for clock mesh networks have been introduced for two‐dimensional integrated circuit clock distribution networks, such as methods to reduce the total wirelength for power consumption and to reduce the clock skew variation through consideration of buffer placement and sizing. In this paper, we present a methodology for clock mesh to reduce both the clock skew and the total wirelength in three‐dimensional integrated circuits. To reduce the total wirelength, we construct a smaller mesh size on a die where the clock source is not directly connected. We also insert through‐silicon vias (TSVs) to distribute the clock signal using an effective clock TSV insertion algorithm, which can reduce the total wirelength on each die. The results of our proposed methods show that the total wirelength was reduced by 12.2%, the clock skew by 16.11%, and the clock skew variation by 11.74%, on average. These advantages are possible through increasing the buffer area by 2.49% on the benchmark circuits.     

一种对三维芯片中硅通孔进行完整建模与寄生参数提取的有效方法

针对三维芯片中硅通孔（through-silicon via, TSV）的准确电学建模问题,本文提出了一种电阻电容（RC）电路模型以及相应的有效参数提取技术。该电路模型同时考虑了半导体效应与静电场影响,适合于低频与中频的电路信号范围。该方法采用一种基于悬浮随机行走（floating random walk, FRW）算法的静电场电容提取技术,然后将它与刻画半导体效应的MOS电容结合,形成等效电路模型。与Synopsys公司软件Sdevice所采用的对静电场/半导体效应进行完整仿真的方法相比,本文方法计算效率更高,并且也能处理一般的TSV电路版图。对多个含TSV的结构进行了计算实验,结果验证了本文方法在从10KHz到1GHz频率范围内的建模准确性,也显示出它相比Sdevice方法最多有47倍的加速比。     

叠层封装技术

首先介绍叠层封装技术的发展现状及最新发展趋势,然后采用最传统的两层叠层封装结构进行分析,包括描述两层叠层封装的基本结构和细化两层叠层封装技术的SMT组装工艺流程。最后重点介绍了目前国际上存在并投入使用的六类主要的叠层封装方式范例,同时进一步分析了叠层封装中出现的翘曲现象以及温度对翘曲现象的影响。分析结果表明:由于材料属性不同会引起正负两种翘曲现象;从室温升高到150℃左右的时候易发生正变形的翘曲现象,在150℃升高至260℃的回流焊温度过程中多发生负变形的翘曲现象。     

堆叠封装技术进展

目前电子产品正朝着高集成化、多功能及微型化方向不断发展。堆叠封装(PoP)作为一种新型3D封装技术,在兼容现有的标准表面贴装技术(SMT)的基础上能够实现不同集成电路在垂直方向上堆叠,从而能够提升封装密度,节省PCB板组装空间,缩短互连线路长度。该技术已从初期的低密度双层堆叠发展至当前的高密度多层堆叠,并在互连方式与塑封形式等封装结构及工艺上不断改进,以适应高性能电子产品的发展需求。通过对PoP上层与下层封装体结构及其封装工艺的近期研究成果进行综述,对比分析它们的各自特点与优势,并展望PoP未来发展趋势。     

Novel Bumping and Underfill Technologies for 3D IC Integration

In previous work, novel maskless bumping and no‐flow underfill technologies for three‐dimensional (3D) integrated circuit (IC) integration were developed. The bumping material, solder bump maker (SBM) composed of resin and solder powder, is designed to form low‐volume solder bumps on a through silicon via (TSV) chip for the 3D IC integration through the conventional reflow process. To obtain the optimized volume of solder bumps using the SBM, the effect of the volumetric mixing ratio of resin and solder powder is studied in this paper. A no‐flow underfill material named “fluxing underfill” is proposed for a simplified stacking process for the 3D IC integration. It can remove the oxide layer on solder bumps like flux and play a role of an underfill after the stacking process. The bumping process and the stacking process using the SBM and the fluxing underfill, respectively, for the TSV chips are carefully designed so that two‐tier stacked TSV chips are sucessfully stacked.     

Experimental characterization of coaxial through silicon vias for 3D integration

Coaxial through silicon via (TSV) technology is gaining considerable interest as a 3D packaging solution due to its superior performance compared to the current existing TSV technology. By confining signal propagation within the coaxial TSV shield, signal attenuation from the lossy silicon substrate is eliminated, and unintentional signal coupling is avoided. In this paper, we propose and demonstrate a coaxial TSV 3D fabrication process. Next, the fabricated coaxial TSVs are characterized using s-parameters for high frequency analysis. The s-parameter data indicates the coaxial TSVs confine electromagnetic propagation by extracting the inductance and capacitance of the device. Lastly, we demonstrate the coaxial TSVs reduce signal attenuation and time delay by 35% and 25% respectively compared to the shield-less standard TSV technology. In addition, the coaxial interconnect significantly decreases electromagnetic coupling compared to traditional TSV architectures. The improved signal attenuation and high isolation of the coaxial TSV make it an excellent option for 3D packaging applications expanding into the millimeter wave regime.