Room temperature bonding of Si and Si wafers by using Mo/Au nano-adhesion layers

For realizing the low temperature bonding in the applications such as micro electro mechanical system (MEMS) packaging and semiconductor integration, Mo/Au nano-adhesion layers were applied to bond Si/Si wafers at room temperature, and the bonding quality was evaluated and analyzed. The investigation results show that a extremely low voidage (≤1%) can be obtained for Mo/Au adhesion layers, along with a strong bonding strength higher than the tensile strength of bulk Si. In addition, unlike the commonly used Ti/Au adhesion layers, no metallic oxide can form on the surfaces of Mo/Au adhesion layers during the vacuum annealing process at a temperature of ≤200 °C due to the quite low diffusion coefficient of Mo atoms, and the annealing treatment can not degrade the adhesion quality of bonded Si/Si wafers with Mo/Au intermediate layers.