Process Control and Application of Low-Temperature Si/Si Direct Bonding
In order to meet the urgent need of micro-electromechanical systems(MEMS)for low-temperature Si/Si wafer bonding with high strength,low cost,good flexibility and strong universality,the process control method and application of low temperature Si/Si wafer direct bonding based on oxygen plasma activation are studied.The effects of oxygen plasma activation power,activation time and oxygen flow rate on bonding rate and bonding strength are analyzed through orthogonal experiment,and the plasma activation process is optimized.The bonding rate of Si/Si bonding is 98.52%and the average shear strength is 20.2 MPa after annealing at 350℃for 2 hours in nitrogen atmosphere.There are no obvious holes at the bonding interface,and a 3.58nm amorphous oxide layer is observed,meaning that intermolecular bonding is achieved between two Si wafers.Finally,the limiting encapsulation of the miniature vibration energy harvester is fabricated through three-layer low temperature Si/Si bonding process.The testing results show that the frequency band of the energy harvester is extended to 215 Hz～229 Hz,indicating that this Si/Si bonding process could meet the requirements of processing and application of MEMS devices.
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维普
