Pressureless Silicon Direct Bonding at Room Temperature by Argon Beam Etching

We have developed a new method for the direct bonding of silicon wafers at room temperature. In the method Ar fast atom beam etching is used to modify the surface of the specimens, and they are bonded in the vacuum. With the appropriate Ar beam etching, the bonding prepared at room temperature is as strong as that prepared by conventional wet surface modification treatment and high temperature annealing. In the process, pressing load is not necessary when two specimens are mated. Intimate contact at the bonding interface is supposed to be achieved by the attractive force between the surface. Crystal orientation of the wafer has very small effect on the bonding. Even between the different crystal faces, the bonding is possible. The applicability of this method to the small area bonding was proved by the bonding of 100 |μm wide lines. These results demonstrate the advantages of this method. This method is promising as an assembling and packaging method for micro electro mechanical systems.