三维集成电路工作热载荷工况的有限元仿真

Finite Element Simulation for 3D-IC of Working Process under Thermal Loads

建立了三维集成电路过孔互连结构的有限元数值模拟分析模型,对芯片内部存在极小热源时极易出现的畸形网格问题给出了解决办法,该方法能很好的处理三维集成电路中尺度不成比例结构的网格划分问题。针对工作过程中的散热问题,进行了热耦合分析。计算结果表明,由芯片到底面的热通路为散热的主要通道。为防止局部过热,应该把发热功率大的器件放在三维集成电路的下层芯片的器件层。仔铜基片所受应力较大,仔铜基片与铜柱接触面的边角处有应力集中,容易发生开裂失效。

3D finite element numerical simulation models were established for Cu via structures of 3D integrated circuits.A real solution was given for abnormal mesh problems when heat sources existing in inter-wafers,which could be applied to solve the mesh problems of disproportionate structures for 3D IC.Based on the heat dissipation of working process,the temperature field and the thermal induced stresses of 3D IC structures were obtained.The numerical results indicate that the heat path from chip to the bottom surface is the main way for the heat dissipation.To avoid local overheating,the large power devices should be put on the lower levels.The stresses are larger in the Cu seed pads,the stress concentration occurs in the interface between the Si and the Cu vias,which is easier to crack.