Silicon on sapphire CMOS for optoelectronic microsystems

we report on a hybrid integration approach that represents a paradigm shift from traditional optoelectronic integration and packaging methods. A recent metamorphosis and wider availability of silicon on sapphire CMOS VLSI technology is generating a great deal of excitement in the optoelectronic systems community as it offers simple and elegant solutions to the many system integration and packaging challenges that one faces when employing bulk silicon CMOS technologies. In the bulk silicon CMOS processes that are used for high-speed interface electronics the substrate is absorbing at both 850 nm and 980 nm wavelengths, necessitating complex and expensive integration procedures such as VCSEL substrate removal to enable the implementation of optical vias through the substrate. Working together, the optical transparency of the sapphire substrate, its superb thermal conductivity and the excellent high speed device characteristics of silicon-on-sapphire CMOS circuits make this technology an excellent choice for cost effective optoelectronic Die-AS-Package (DASP) systems and for implementing optical interconnects for high performance computer architectures. What is perhaps even more important, packaging and input/output interface issues can now be addressed at the CMOS wafer fabrication level where input/output structures can be accurately defined, optimized and processed using lithographic techniques, eliminating problematic die post-processing and packaging-related optical alignment issues     

晶圆级多层堆叠技术

随着5G和人工智能等新型基础设施建设的不断推进,单纯通过缩小工艺尺寸、增加单芯片面积等方式带来的系统功能和性能提升已难以适应未来发展的需求。晶圆级多层堆叠技术作为能够突破单层芯片限制的先进集成技术成为实现系统性能、带宽和功耗等方面指标提升的重要备选方案之一。对目前已有的晶圆级多层堆叠技术及其封装过程进行了详细介绍;并对封装过程中的两项关键工艺,硅通孔工艺和晶圆键合与解键合工艺进行了分析;结合实际封装工艺对晶圆级多层堆叠过程中的可靠性管理进行了论述。在集成电路由二维展开至三维的发展过程中,晶圆级多层堆叠技术将起到至关重要的作用。     

Laser-patterned interconnect for thin-film hybrid wafer-scale circuits

High-performance electronic systems are often constrained by conventional packaging and interconnection technologies. A new technique is described for electrically connecting integrated circuit chips to a silicon wafer interconnection substrate, enabling future fabrication of hybrid wafer-scale circuits to be performed exclusively with thin-film interconnection technology. Thin-film wiring is fabricated down beveled edges of the chips and patterned using discretionary laser etching techniques. Interconnections on a 25-µm pitch (1600 wires around a 1-cm square chip) were achieved with this approach. Functioning hybrid memory modules have been fabricated to demonstrate feasibility of the technology.     

3D集成的发展现状与趋势

三维集成技术的发展是技术与理念的革新过程,本文根据集成封装技术的的发展历程,提出三维集成的发展特点,阐述理念的突破如何引导技术发展,以此为主线,可以更有逻辑性的了解三维集成的发展历史与趋势.封装从器件级向系统级的发展促使了多种系统级封装概念的出现;垂直堆叠方式推动互连长度不断降低;与晶圆级封装的结合可以大幅度降低成本;从同质向异质的转变则集成了多种学科、材料与技术,是实现复杂的系统的基础.     

用于大批量制造环境的薄晶圆处理——传送和加工技术

在半导体生产商不断推进器件和圆片厚度薄型化的形势下,为满足与新产品和加工工艺有关的生产工艺挑战,必须采用更新的分裂方法。新面世的产品射频识别标签,更完善的IC卡以及集成度更高的存储器件,随着更新的从逻辑到存储器及图像传感器各种产品先进封装技术的来临,需要越来越薄基片。对此提出了一种基于临时键合以及新颖的粘接剂技术的适合于薄圆片传送和处理加工的完全解决方案(设备,材料以及工艺过程)。这种方法与25μm以下厚度圆片以及在原有设备没有变更的现有生产线进行薄圆片产品发展路线图加工工艺相适应。     

Three-Dimensional Integration Technology Based on Wafer Bonding With Vertical Buried Interconnections

A three-dimensional (3-D) integration technology has been developed for the fabrication of a new 3-D shared-memory test chip. This 3-D technology is based on the wafer bonding and thinning method. Five key technologies for 3-D integration were developed, namely, the formation of vertical buried interconnections, metal microbump formations, stacked wafer thinning, wafer alignment, and wafer bonding. Deep trenches having a diameter of 2 mum and a depth of approximately 50 mum were formed in the silicon substrate using inductively coupled plasma etching to form vertical buried interconnections. These trenches were oxidized and filled with n+ polycrystalline silicon or tungsten. The 3-D devices and 3-D shared-memory test chips with three-stacked layers were fabricated by bonding the wafers with vertical buried interconnections after thinning. No characteristic degradation was observed in the fabricated 3-D devices. It was confirmed that fundamental memory operation and broadcast operation between the three memory layers could be successfully performed in the fabricated 3-D shared-memory test chip     

几种新的封装工艺

文章介绍了几种新的封装工艺,如新型圆片级封装工艺——OSmium圆片级封装工艺,它能够把裸片面积减少一半;新型SiP封装工艺——Smafti封装工艺,它改进了传统SiP封装工艺,把传输速度提高了10倍;超薄型封装工艺,超薄型变容二极管和Wi-Fi系统功率放大器;CDFN封装工艺和RCP封装工艺等。     

带有TSV的硅基大功率LED封装技术研究

介绍了一种带有凹槽和硅通孔(through silicon via,TSV)的硅基制备以及晶圆级白光LED的封装方法。针对硅基大功率LED的封装结构建立了热传导模型,并通过有限元软件模拟分析了这种封装形式的散热效果。模拟结果显示,硅基封装满足LED芯片p-n结的温度要求。实验结合半导体制造工艺,在硅基板上完成了凹槽和通孔的制造,实现了LED芯片的有效封装。热阻测试仪测得硅基的热阻为1.068K/W。实验结果证明,这种方法有效实现了低热阻、低成本、高密度的LED芯片封装,是大功率LED封装发展的重要方向。     

圆片清洗过程中静电控制

随着半导体技术的不断发展,对集成电路封装过程中的静电控制要求也越来越高。传统清洗机清洗圆片时,通常会产生大量的静电电压,可能引起芯片失效、损伤造成漏电流增大从而导致电路的损坏。如何降低清洗机清洗圆片时产生的静电电压,对减少封装过程中因ESD引起的芯片失效有着比较重要的意义。为此我们利用高压喷雾旋转清洗机针对圆片清洗这个步骤进行了一系列的试验。文中涉及控制清洗液的电阻率,并尝试改变清洗过程中的相关清洗条件,最终达到封装过程中要求的±200V的静电控制要求。     

Test structures for MCM-D technology characterization

In this paper we present a set of classic and novel test structures addressed to fully characterize multichip module (MCM) technologies. The structures have been implemented and fabricated in our D-type, flip-chip, ball grid array, silicon substrate technology. In this technology, a silicon chip is used as a substrate on which other commercial chips are flipped and soldered by a screen-printing method. These complex technologies have specific test problems that are solved with this approach. We have specially focused on the measurement of the effects of wafer rerouting on CMOS parameters, the chip-to-chip ball contact resistance, thermal behavior, yield, and reliability of the technology. Experimental results are shown, proving that this methodology is suitable for our technology and can also be applied to other different MCM technologies     

An enhanced quasi-monolithic integration technology for microwave and millimeter wave applications

A new technology for integration of high frequency active devices into low cost silicon substrate has been introduced. The novel fabrication process gives excellent advantages such as extremely low thermal resistance, and a much lower thermo-mechanical stress than the earlier quasimonolithic integration technology (QMIT) concept . This highly improves the packaging lifetime and electrical characteristics of the active devices. The fabrication process is simple and compatible with fabrication of high-Q passive elements. Successful integration of high-Q passive elements on low resistivity silicon substrate in this technology has been possible for the first time. In comparison to the earlier concept of QMIT, elimination of air-bridges in this technology not only reduces the parasitic elements but also enables the fabrication of the rest of the circuit after measuring the microwave characteristics of the embedded active devices. This makes very accurate microwave and millimeter-wave designs possible. Using the new fabrication process, microwave and millimeter-wave circuits (with both coplanar and microstrip lines) containing power devices have for the first time been possible. Furthermore, the enhanced QMIT can be considered as an organic deposited multi chip module (MCM-D), which is a potential candidate for integration an system on a package (SOP) at microwave and millimeterwave frequencies.     

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。     

Integration of High Aspect Ratio Tapered Silicon Via for Silicon Carrier Fabrication

This paper provides a detailed overview of silicon carrier-based packaging for 3-D system in packaging application. In this work the various critical process modules that play a vital role in the integration and fabrication of silicon carrier with high aspect ratio tapered through-silicon interconnections have been explained and discussed with experimental data. A method of fabricating tapered deep silicon via in a three-step approach has been developed and characterized which controls via depth, sidewall profile, and surface roughness effectively. A low-temperature dielectric deposition process is also developed that has minimum residual stress and good dielectric coverage on the via sidewall. The above processes were then integrated with back-end processes like seed metallization, copper electroplating, chemical mechanical polishing, and wafer thinning to realize a fully integrated silicon carrier fabrication technology. The silicon carriers were finally assembled and tested for through silicon interconnection.      

Novel micro-bump fabrication for flip-chip bonding

This paper describes a new bump-fabrication technique for flip-chip connection between a chip and substrate. We propose a novel idea of forming solder microbumps on the substrate and directly bonding bare chips to the substrate. We successfully achieved the new flip-chip connection by using a 0.05Au-0.95Sn solder bump and a hydrogen-plasma reflow technique. Because the method eliminates the need for any process on the chip wafer, it will be very useful in fabricating flip-chip connections for low-cost packaging.     

片上雷达技术研究进展及发展趋势

本文回顾和梳理了当前片上雷达(Radar on Chip, RoC)的架构和射频前端、天线及信号处理等芯片化研究进展,以及基于异质异构集成、3D先进封装技术的雷达系统集成实现方案。在此基础上,从物理形态、实现工艺及技术发展等方面对片上雷达未来发展趋势进行了分析,指出基于硅基半导体工艺,片上集成多路雷达收发前端、波形产生及信号处理等雷达功能单元,实现片上系统（System on Chip, SoC）;或者通过异质异构及先进封装技术,将高度集成的雷达芯片集成在一个封装内,实现封装系统（System in Package, SiP）,从而满足雷达系统微型化、轻重量、低成本和低功耗的发展需求。同时,基于芯片化可扩充多通道阵列模块也有望构建大型复杂阵列雷达系统。该方案为未来小型化武器装备提供有效的探测感知手段,也为蓬勃发展的民用雷达提供可行的技术路径。     

Time-resolved optical characterization of electrical activity in integrated circuits

If the rate of improvement in the performance of advanced silicon integrated circuits is to be sustained, new techniques for the measurement of electrical waveforms in operating circuits are needed. Critical factors dictating this requirement include the increased speed and complexity of circuits, the growing importance of faults that appear only during high-speed operation, and the use of flip-chip packaging technologies. Two recently developed all-optical methods for measuring the switching activity from the backside of a chip are described and compared. One is a passive approach based on the measurement of hot carrier luminescence emitted from the channel of a CMOS field-effect transistor (FET) during switching. The second uses a laser probe to sense the switching induced modulation of the silicon optical constants near an FET's source and drain.     

SiGe HBT Microprocessor Core Test Vehicle

A major impediment to the continuation of Moore's Law in the years to come is the performance of interconnections in ICs at high frequencies. Microprocessors are using a greater portion of their clock cycle charging and discharging interconnections. Silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) provide a fast track technology for the exploration of the effect of interconnections on high-speed computer design. Industry has pursued low-k dielectrics to decrease wire capacitance. Cu metallization has been used to reduce wire resistance which becomes important as the wire dimensions are scaled down. These are not the only issues for high-frequency interconnections. Some other high-frequency issues include coupling, transmission line propagation, skin effects, and dielectric and substrate loss. These phenomena cause signal attenuation, noise, and dispersion in addition to delay. In the limit of zero device delay, interconnection delay will remain in addition to these problems. Wire shortening has been possible using more layers of interconnections, but this approach may be reaching its limit. An unconventional approach, three-dimensional (3-D) integration, attempts to shorten wiring through increased circuit component placement flexibility. The approach considered here for 3-D integration uses wafer-to-wafer aligning and bonding, wafer thinning and deep, high-aspect-ratio Cu via formation. This provides an intimate interconnection between CPU components and an extremely wide path to memory that would be infeasible in conventional or multichip module packaging. This combination of SiGe HBT BiCMOS and 3-D chip stack technologies enables small computing engines in the 16-32-GHz range.     

焊球阵列转变与绝缘基板技术

在半导体整体的焊球阵列封装(BGA)领域,一份针对数个关键封装形式所进行的分析报告中,显示了造成不同焊球阵列封装形式成长或下跌的原因,并更清楚地点出了目前使用的数种基板技术的缺点。这篇分析报告列出了主要的焊球阵列封装的形式和基板发展潮流,还清楚地指出焊球阵列封装整体的发展延缓了硅芯片技术的演进,这在某些BGA领域中尤其明显,主要是因为缺乏先进的基板技术。因此文后得出结论,封装产业供货供应链基板市场中可能出现新的厂商,其也许来自主机板市场。     

芯片制造的电化学处理技术

电化学处理技术的性价比优势在芯片制造上是一个范例转移。Cu芯片金属化的双大马士革处理和面阵列芯片封装互连的C4(倒装)技术使电化学技术置于最复杂的制造工艺技术之间。这些工艺技术被集成到用于芯片制造的300mm晶圆处理中。新材料和工艺的持续发展来满足微处理器件不断增加性能和小型化的趋势。电迁移问题和集成超低k电介质材料与Cu镀层的新抛光方法是芯片制造中的一个关键问题。发展一个适用成本低的无铅C4芯片封装互连是微电子工业的主要目标,微电子工业正作努力在几年里市场化无铅产品。     

Fabrication of Application Specific Integrated Passive Devices Using Wafer Level Packaging Technologies

Integrated passives have become increasingly popular in recent years. Especially wafer level packaging technologies offer an interesting variety of different possibilities for the implementation of integrated passive components. In this context, particularly the fabrication of integrated passive devices (IPDs) represents a promising solution regarding the reduction of size and assembly costs of electronic systems in package (SiP). IPDs combine different passive components (R,L ,C ) in one subcomponent to be assembled in one step by standard technologies like surface mount device (SMD) or flip chip. In this paper, the wafer level thin film fabrication of integrated passive devices (WL-IPDs) will be discussed. After a brief overview of the different possibilities for the realization of IPDs using wafer level packaging technologies two fabricated WL-IPDs will be presented. Design, technological realization, as well as results from the electrical characterization will be discussed.