Room-temperature, rapid, solid-state solder bonding technology for future ultra-high-density interconnects manufacturing

Authors：Yang, Mingkun; Huo, Yongjun^*; Zhao, Xiuchen; Guo, Yuzheng; Liu, Yingxia^*

Source：Journal of Materials Research and Technology-JMR&T, 2023, 25: 999-1010.

DOI：10.1016/j.jmrt.2023.05.279

• Cold welding
• 3D integrated circuit (3D IC)
• Solder joints
• Interfacial reactions
• Cu-Cu bonding Technology

Developing ultra-high-density interconnects using current technologies presents certain limitations. It is because traditional solder joint technology employs a liquid-solid interfacial reaction process that makes it difficult to control the shape of the solder joint, thus limiting the size, pitch, and density of interconnects. Although the Cu-Cu direct bonding technique can help fabricate high-density interconnects, its high cost and limited application in consumer electronics present further challenges. In this study, we developed a simple, rapid, and cost-efficient method for fabricating high-density interconnects. We produced homogeneous submicron solder particles as small as 300 nm through ultrasonic treatment. The homogeneous size distribution was achieved by minimizing inter-particle ripening reactions, sluggish diffusion, and low Gibbs-Thomson chemical potential in the medium-entropy Sn-Bi-In-based solder particles. We dispensed the particle solution between two Cu substrates, and they bonded within 5 min at room temperature through a solid-state interfacial reaction. The shear strength of the bonding is around 14.8 +/- 1.2 MPa. Our bonding technology shows potential for use in 3D integration to manufacture ultrahigh-density interconnects.

• Institution
  武汉大学; 北京理工大学