三维电子封装关键结构-TSV的微观与宏观力学行为研究

Through-Silicon Via (TSV) is the key structural unit in the next generation three dimensional packaging technology. Micro- and macro-mechanical behaviors of the TSV are investigated in this project by experimental, theoretical and numerical methods. In the project, a new technique to measure the residual stress in TSV-Cu and a model to predict the residual stress in various electro-plating processes are developed. Micro-mechanical behaviors of the TSV-Cu are investigated,and an approach able to simulate its grain-scale mechanical behaviors is developed, and macro-mechanical models of the TSV-Cu are proposed finally. Failure modes of the TSV-Cu/Ta/SiO2/Si interface under various process and temperature conditions are investigated experimentally, then based on the experimental observations, models to predict micro- and macro-mechanical behaviors of the interface are proposed, and a set of criteria to assess the integration of the TSV interface is established. Deformation mechanism in the TSV is investigated under various temperature conditions, and a model to predict the protrusion/intrusion of the TSV-Cu is proposed. The models and methods derived are applied to carry out reliability analysis of a TSV interposer. Objectives of this project are to provide a clear picture of the micro- and macro-mechanical behaviors of the TSV for engineers working on TSV technology, to provide technical suggestions on TSV etching,Cu-plating and wafer annealing, to provide models and tools for thermo-mechanical reliability design of TSV-based packaging products such as TSV interposer.

针对下一代三维封装技术的关键结构单元-硅通孔（TSV），采用实验、理论分析和数值模拟方法，研究TSV结构的微观-宏观力学行为，建立其分析模型。主要研究内容为：发展一种TSV-Cu残余应力测试方法，研究电镀工艺条件与残余应力的关系，建立残余应力预测模型；研究TSV-Cu的微观力学行为，并建立宏观计算模型；实验研究TSV-Cu/Ta/SiO2/Si界面失效模式，建立界面力学行为的微观和宏观模型，提出界面完整性评价指标和方法；研究TSV-Cu和TSV界面在工艺条件和服役条件下的变形机制，提出TSV-Cu的胀出量/缩进量计算模型；将上述成果集成应用于TSV转接板的热机械可靠性分析。研究目标为：给出TSV结构在主要工艺和服役条件下力学行为的清晰图像，为TSV工艺改进提供依据，为三维TSV封装技术的热机械可靠性设计提供工程化分析模型和工具，为TSV转接板封装产品的热机械可靠性设计提供建议。

硅通孔(TSV)结构是三维电路集成和器件封装的关键结构单元。TSV 结构是由电镀铜填充的Cu-Si复合结构，该结构具有Cu/Ta/SiO2/Si 多层界面，而且界面具有一定工艺粗糙度。TSV结构中，由于Cu和Si的热膨胀系数相差6倍，致使TSV器件热应力水平较高，引发严重的热机械可靠性问题。这些可靠性问题影响TSV技术的发展和应用，也制约了基于TSV 技术封装产品的市场化进程。本项目通过实验研究、理论分析和数值模拟，研究了TSV结构在主要工艺和服役条件下微-宏观力学行为。具体工作包括：发展了一套有限元数值模拟、纲量分析和纳米压痕实验相结合的反演分析方法，对TSV-Cu弹塑性力学性能进行研究，确定了TSV-Cu的幂指数型应力-应变关系。发展了一套有效的TSV-Cu残余应力测试方法，测量镀铜的残余应力，建立残余应力预测模型，为TSV电镀工艺改进提供依据；实验研究了TSV-Cu在工艺条件与温度载荷下的变形行为，建立了工艺条件与微结构特征的联系，研究了TSV-Cu晶粒尺寸与分布对其力学行为的影响，提出了描述TSV-Cu微结构特点的微-宏观计算模型；实验研究TSV-Cu/Ta/SiO2/Si 界面失效模式，建立了TSV界面应力、变形和破坏行为联系。根据研究结果，提出界面完整性评价指标和方法，为TSV结构设计和工艺改进提供依据；提出了TSV转接板封装产品组装工艺的可靠性设计规范建议。