碳纳米管互连的3D芯片硅通孔关键技术及可靠性研究

The silicon through via (TSV) technology is one of the most potential ways to solve the interconnection crisis of the large scale integrated circuits. Currently, the filling of the TSV is achieved by copper plating with high complex process and low reliability, which limit the application of TSV in high density interconnection, so it's urgent to develop new material and process used for the sub-micro interconnection. Based on the key technology research of carbon nanotubes materials used for high-density packaging, the CNT growth mechanism in blind holes, CNT 3D TSV interconnection integrating technology and integrated chips reliability are investigated. The detail content includes: investigating the mechanism problems research of CNT growth in blind via and practical application under different processes, catalysts, key factors and control methods; developing the CNTs densification method, low temperature transfer and 3D integration process; fabricating the multilayer CNT TSV chips (more than 3 layers), and comparing the effect of different integration processes on via interconnection resistance and 3D chips reliability; through reliability results analysis, determining the failure mode and its failure mechanism to improve the CNT growth, filling and 3D integration processes.

硅通孔（TSV）技术是解决大规模集成电路互连危机最具潜力的方案之一。目前TSV主要通过电镀铜实现，但工艺复杂和可靠性等问题，限制了其在高密度互连中的运用，因此迫切需要发展亚微米级下的互连材料和工艺。本项目在课题组应用碳纳米管（CNT）材料于高密度封装关键技术研究基础上，对CNT在盲孔中的生长机理、CNT互连3D TSV的集成工艺及集成后器件的可靠性进行深入研究。具体内容包括：CNT在盲孔的生长及运用中出现的机理性问题研究（不同工艺参数、催化剂等条件下的CNT结构与形貌、形成差异性的关键因素及控制方法）；CNT簇致密方法、低温间接转移及其3D TSV集成工艺开发；制作多层（3层以上）CNT TSV芯片，对比并分析不同集成工艺对互连通路的电阻及可靠性（热循环、跌落和电迁移等）的影响；通过可靠性试验结果分析，确定失效模式及相应的失效机理，进而完善CNT生长、互连和3D集成工艺。

本项目在课题组应用CNT材料于高密度封装关键技术研究基础上，拟对CNT在硅盲孔中的生长以及致密化工艺、CNT填充TSV工艺、CNTs填充TSV的芯片3D组装工艺及集成形成3D器件的可靠性进行深入研究。工艺优化后得到的高质量CNT经过致密化处理后，用低温转移技术将其转移到TSV中。为了填充CNT和TSV之间的空隙，聚合物作为填料固定CNT，经过化学机械抛光平整化处理后形成一个稳定的硅通孔结构。虽然填充工艺被尽可能优化，但是这种CNT与聚合物复合结构填充的硅通孔电阻率与铜相比还是过高。为了解决这个问题，我们开发了CNT与铜复合结构填充硅通孔，不但使其电阻率与铜在同一个数量级，而且其热膨胀系数与硅相近，大大提高了三维器件的可靠性。同时，该工艺与现有半导体制造工艺相兼容，因此很有潜力极大改变未来超摩尔定律发展的微电子散热与互连前景。