Evaluation of process requirements for room temperature direct copper bonding

• Main Author: Chen, Qiang.
• Other Authors: Wong Chee Cheong
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Materials::Microelectronics and semiconductor materials::Nanoelectronics and interconnects
• Online Access: http://hdl.handle.net/10356/20415
• Institution: Nanyang Technological University

Direct metal bonding is a method of joining two metal surfaces under ambient conditions without an intermediate layer in between. In this thesis, by coating the copper surface with a self assembled monolayer of alkanethiol prior to bonding, Cu joints can be successfully formed at room temperature in ambient environment, yielding joint shear strength up to 60MPa. Copper bond shear strength of 15 MPa is achieved even at 50MPa at 25°C with copper coated with C18. The densely packed monolayer serves to passivate the copper surface against oxidation under ambient conditions. The ultrathin (1-3 nm) organic monolayer structure, as compared to a bulk oxide layer, could be easily displaced during the mechanical deformation at the bonding interface. Preliminary results have shown copper samples bond even at room temperature with SAMs. Such promising results demonstrate great potential in reducing thermal budget in 3-D integrated devices, thus translating to better reliability and performance device.