Effects of surface activation time on Si-Si direct wafer bonding at room temperature

Abstract

Surface activated bonding (SAB) based on argon ion beam irradiation was used to directly bond Si and Si wafers at room temperature, and the effects of the surface activation time on the Si-Si bonding were investigated. The experimental results show that the surface activation treatment with a proper duration is beneficial to the reduction of surface roughness of Si wafers and the realization of high bonding strength. The Si-Si wafers bonded after the surface activation of 420 s has an extremely low percentage of area covered by voids (0.08%) and a high bonding strength (9.45 MPa). Meanwhile, the annealing at 500 °C does not lead to a significant change in the percentage of area covered by voids for Si-Si bonding. Besides, the transmission electron microscope characterization indicates that the argon ion beam irradiation of 180 s can result in the formation of an amorphous Si layer with a thickness of approximately 10.6 nm at the Si-Si bonding interface, and the whole cross-section structure of the Si-Si bonding consists of a Si substrate, an amorphous Si layer and a Si substrate.

Variation in atomistic structure due to annealing at diamond/silicon heterointerfaces fabricated by surface activated bonding

“…23) Similar Ar segregation into a damaged layer at a SAB-fabricated interface is reported. 38) It is hypothesized that inert Ar atoms would segregate so as to fill the vacant spaces at nano-voids and at the vacant defects introduced during the surface activation process. Agglomerates of inert Ar atoms would not impact the electronic properties, while they may impact the thermal properties of the interfaces.…”