Solid-Liquid Interdiffusion Bonding of Cu-Sn-Cu Interconnection and Sealing for High-Temperature Pressure Sensor Based on Graphene

Cu-Sn-Cu solid-liquid interdiffusion (SLID) bonding for high-temperature pressure sensors based on graphene has been investigated. Square bumps with a length of 160 mu m and an 80-mu m-wide sealing ring were simultaneously fabricated by the evaporation process. The die surface was treated with Ar (5% H-2) plasma before bonding. Chip-level bonding was performed at 260 degrees C for 15 min with a pressure of 9.13 MPa under N-2 atmosphere. Pure Sn and Cu6Sn5 have been exhausted completely, and the as-bonded interface only contains three layers of Cu-Cu3Sn-Cu, with no serious Sn overflow. The average shear strength of 50.6 MPa and an excellent leak rate of around 2.64 x 10(-4) Pa center dot cm(3)/s are achieved. The resistance measurements are similar to the theoretical estimation. After high-temperature storage (HTS) at 300 degrees C for 10 h, the average shear strength slightly decreases to 46.7 MPa and the leak rate increases to 1.01 x 10(-3) Pa center dot cm(3)/s. More importantly, there is no degeneration of the graphene nanofilm during electrical measurement in the bonding process and HTS test. It is concluded that Cu-Sn-Cu SLID bonding is appropriate for high-temperature pressure sensors based on graphene.