Low-Temperature (70°C) Cu-to-Cu Direct Bonding by Capping Metal Layers

• Published in: IEEE electron device letters Vol. 42; no. 10; pp. 1524 - 1527
• Main Authors: Liu, Demin, Chen, Po-Chih, Liu, Yu-Wei, Hu, Han-Wen, Chen, Kuan-Neng
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.10.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: 3D integration; Bonding; Budgets; Capping; Chemical bonds; Chromium; Copper; Cu bonding; Diffusion; Gold; Grain size; Low temperature; Low vacuum; metal passivation; Oxidation; Passivation; Recrystallization; Rough surfaces; Surface roughness; Temperature measurement; Wetting

Cu-Cu direct bonding at low temperature with Cr wetting layer and Au passivation has been developed, and the bonding mechanism has been investigated. A chip-level Cu-to-Cu direct bonding can be achieved under a very low thermal budget condition at 70 °C for 90 s or 150 °C for 15 s, while wafer level...