Developing a Low-Temperature Flip-Chip Bonding Technology with In/Au Microbumps to Suppress the Thermal Load on Spintronics Devices

Spin transfer torque magnetic random-access memory (STT-MRAM) with magnetic tunnel junction (MTJ) devices, which are among the spintronics devices, have many advantages, such as high programing speed and sufficient endurance. Therefore, currently, the spintronics devices are being thoroughly studied. However, they suffer from low thermal stability; thus, low-temperature integration and packaging technologies need to be developed. In this study, we applied In/Au microbumps, which have low bonding temperature and high thermal stability, to a flip-chip bonded STT-MRAM onto a Si interposer. No effect of the flip-chip bonding process on the STT-MRAM cell was observed. Investigation results indicated that low-temperature bonding technology with In/Au microbumps are promising for accelerating the integration of spintronics devices.