超薄芯片真空拾取与贴装工艺机理研究

发布时间：2018-11-27 14:04

【摘要】：芯片真空拾取与贴装是完成芯片从晶圆盘转移至基板电路并实现电气互连组装极为关键的工艺过程。随着IC芯片超薄化和I/0密度越来越高,可靠高效的真空拾取与贴装工艺对降低封装成本,改善封装性能和器件可靠性等具有重要意义。本文从工艺机理建模、工艺分析和实验验证等方面对真空拾取和贴装工艺进行了深入系统地研究,建立了超薄芯片真空拾取与高密度贴装的理论工艺窗口。本文主要研究工作和创新之处在于以下几个方面：1)建立超薄芯片-厚胶层-基板粘接结构的分层理论模型,实现精确的超薄芯片组件翘曲和界面应力理论预测；建立了表面加载分布力载荷的芯片-较薄胶层-基板的力学模型,为描述真空拾取工艺提供理论支撑。2)基于理论解析,建立了真空拾取工艺的理论模型,并通过二分法算法实现了真空吸附作用下有效蓝膜长度的理论计算。引入界面剥离能量释放率和拾取力来评估真空拾取工艺可靠性,揭示了真空吸附作用下的芯片-粘胶-蓝膜结构的界面剥离机理以及芯片大小和厚度、真空负压、蓝膜厚度与材料等因素对工艺可靠性的影响,理论预测了拾取位移不断增大条件下真空拾取超薄芯片的界面剥离过程,建立了超薄芯片真空拾取的理论工艺窗口。3)基于Hele-Shaw挤压流体模型,辅助芯片引脚捕捉导电粒子数量的实验研究,实现了高密度超薄芯片贴装过程的理论描述,研究了引脚间距、各向异性导电胶(ACA)粘度和压力等因素对芯片贴装过程和导电粒子压缩变形的影响。基于分层理论,精确计算了贴装过程中超薄芯片组件发生的翘曲位移,研究了芯片-ACA-柔性基板结构尺寸和材料对芯片翘曲程度的影响,提出了减小超薄芯片组件翘曲的方法。4)搭建真空拾取工艺实验平台,进行了不同真空负压下的拾取力和拾取位移等关键工艺参数的定量测试,验证了本文真空拾取理论模型的有效性；进行了系统的拾取工艺实验研究,提出了一种高效可靠的超薄芯片拾取工艺方法和机械装置。同时,进行了超薄芯片热压贴装实验和翘曲位移测试,实验测试结果与分层理论预测结果基本一致。
[Abstract]:Chip vacuum pickup and mounting is the key process to complete the chip transfer from the wafer to the substrate circuit and to realize the electrical interconnection and assembly. With the IC chip thinning and the increasing density of I / O, the reliable and efficient vacuum pickup and mount process is of great significance to reduce the packaging cost, improve the packaging performance and device reliability. In this paper, the vacuum pickup and mounting process is studied systematically from the aspects of process mechanism modeling, process analysis and experimental verification, and the theoretical process window of vacuum pickup and high density mounting of ultra-thin chip is established. The main research work and innovations in this paper are as follows: 1) to establish a layered theoretical model of ultra-thin chip-thick adhesive lamina-substrate bonding structure to achieve accurate prediction of warping and interfacial stress of ultra-thin chipsets; A mechanical model of chip, thin rubber layer and substrate with distributed force loading on the surface is established, which provides theoretical support for describing vacuum pickup process. 2) based on theoretical analysis, a theoretical model of vacuum pickup process is established. The theoretical calculation of the effective blue film length under vacuum adsorption is realized by the dichotomy algorithm. The reliability of vacuum pickup process is evaluated by introducing the energy release rate and picking force of interface stripping. The mechanism of interface stripping of chip-viscose blue film structure under vacuum adsorption, chip size and thickness, vacuum negative pressure are revealed. The influence of blue film thickness and material on the process reliability is discussed theoretically. The interface stripping process of vacuum pickup ultra-thin chip is predicted under the condition of increasing pickup displacement. The theoretical and technological window of vacuum pickup of ultra-thin chip is established. 3) based on the Hele-Shaw squeeze fluid model, the experimental research on the number of conductive particles in the chip pin is carried out, and the theoretical description of the mounting process of the ultra-thin chip with high density is realized. The effects of pin spacing, viscosity and pressure of anisotropic conductive adhesive (ACA) on the chip mounting process and compression deformation of conductive particles were studied. Based on delamination theory, the warpage displacement of ultra-thin chipsets in the process of mounting is accurately calculated, and the effects of chip ACA- flexible substrate structure size and material on the chip warping degree are studied. A method to reduce the warpage of ultra-thin chipsets is proposed. 4) the experimental platform of vacuum pickup process is built and the key technological parameters such as picking force and pickup displacement under different vacuum negative pressure are measured quantitatively. The validity of the theoretical model of vacuum pickup is verified. An efficient and reliable picking process method and mechanical device for ultra-thin chip are proposed. At the same time, the hot pressing experiment and the warpage displacement test of the ultra-thin chip are carried out, and the experimental results are in good agreement with the prediction results of stratification theory.
【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN405

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