A novel solid-liquid inter-diffusion (SLID) bonding process is developed allowing to use thin layers of the Au-Sn material in wafer-level microelectromechanical systems (MEMS) packaging while providing a good bonding strength. The bond material layers are designed to have a robust bond material configuration and a metallic bond with a high re-melting temperature, which is an important advantage of SLID bonding or with its alternative name, transient liquid phase (TLP) bonding. The liquid phase in SLID bonding is the gold-rich eutectic liquid of the Au-Sn material system, where the bonding temperature is selected to be 320 °C for a reliable bonding. The average shear strength of the bonds is measured to be 38± 1.8 MPa. The hermeticity of the package is tested with the He-Leak test according to MIL-STD 883, which yields a leak value lower than $0.1 \times 10^{-9}\,\, atm.cm^{\textit {3}}/s$ . The vacuum inside the package without a getter is calculated as 2.5 mbar after cap wafer thinning. The vacuum level is well preserved after post-processes such as annealing at 400 °C and the dicing process. These results verify that thin layers of Au-Sn materials can be used reliably with the SLID or TLP bonding technique using the new approach proposed in this study. [2020-0353]

中文翻译：

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用于 MEMS 封装的具有薄 Au-Sn 层的晶圆级低温固液互扩散键合

开发了一种新型固液互扩散 (SLID) 键合工艺，允许在晶圆级微机电系统 (MEMS) 封装中使用薄层 Au-Sn 材料，同时提供良好的键合强度。粘合材料层设计为具有坚固的粘合材料配置和具有高重熔温度的金属粘合，这是 SLID 粘合或其替代名称瞬态液相 (TLP) 粘合的重要优势。SLID 键合中的液相是 Au-Sn 材料系统的富金共晶液，其中键合温度选择为 320 °C 以实现可靠键合。粘合的平均剪切强度经测量为 38±1.8 MPa。根据 MIL-STD 883 使用 He-Leak 测试对封装的气密性进行测试，泄漏值低于 0 美元。1 \times 10^{-9}\,\, atm.cm^{\textit {3}}/s$ 。没有吸气剂的封装内的真空在盖晶片减薄后计算为 2.5 毫巴。在 400°C 退火和切割过程等后处理后，真空度得以很好地保持。这些结果证实，使用本研究中提出的新方法，Au-Sn 材料薄层可以可靠地与 SLID 或 TLP 键合技术一起使用。[2020-0353]