Cu–Cu hermetic seal enhancement using self-assembled monolayer passivation

• Main Authors: Peng, L., Leong, K. C., Lim, Dau Fatt, Fan, Ji, Tan, Chuan Seng
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Materials::Electronic packaging materials
• Online Access: https://hdl.handle.net/10356/96183; http://hdl.handle.net/10220/18163
• Institution: Nanyang Technological University

Low-temperature Cu–Cu thermocompression bonding enabled by self-assembled monolayer (SAM) passivation for hermetic sealing application is investigated in this work. Cavities are etched to a volume of 1.4 × 10−3 cm3 in accordance with the MIL-STD-883E standard prescribed for microelectronics packaging. The wafer pairs (nonfunctional cavity wafer and cap wafer) are annealed and bonded at 250°C under a bonding force of 5500 N. The encapsulated cavities undergo helium overpressure in a bombing chamber, and the helium leak rate is detected by a mass spectrometer. The measurement results show that the cavities sealed with Cu–Cu bonding after SAM passivation exhibit excellent hermeticity with a leak rate below 10−9 atm cm3/s, which is an improvement of at least 2× compared with the control sample without SAM passivation.