Wafer bonding using Cu–Sn intermetallic bonding layers

• Published in: Microsystem technologies : sensors, actuators, systems integration Vol. 20; no. 4-5; pp. 653 - 662
• Main Authors: Flötgen, C., Pawlak, M., Pabo, E., van de Wiel, H. J., Hayes, G. R., Dragoi, V.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.04.2014; Springer
• Subjects: Applied sciences; Electronics; Electronics and Microelectronics; Engineering; Exact sciences and technology; Instrumentation; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Mechanical Engineering; Mechanical instruments, equipment and techniques; Microelectronic fabrication (materials and surfaces technology); Micromechanical devices and systems; Nanotechnology; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Technical Paper; Bonding Time; Wafer Bonding; Transient Liquid Phase; Contact Pressure; Bonding Layer; Temperature distribution; Intermetallic compounds; Thickness; Wafer bonding; Tin alloys; Microelectronic fabrication; Copper alloys; Growth mechanism; Electrodeposition; Kinetics; Sputter deposition; Microstructure; Microelectromechanical device; Fracture mode; Transition element alloys
• ISSN: 0946-7076; 1432-1858
• DOI: 10.1007/s00542-013-2002-x

Wafer-level Cu–Sn intermetallic bonding is an interesting process for advanced applications in the area of MEMS and 3D interconnects. The existence of two intermetallic phases for Cu–Sn system makes the wafer bonding process challenging. The impact of process parameters on final bonding layer quality have been investigated for transient liquid phase wafer-level bonding based on the Cu–Sn system. Subjects of this investigation were bonding temperature profile, bonding time and contact pressure as well as the choice of metal deposition method and the ratio of deposited metal layer thicknesses. Typical failure modes in intermetallic compound growth for the mentioned process and design parameters have been identified and were subjected to qualitative and quantitative analysis. The possibilities to avoid abovementioned failures are indicated based on experimental results.