Room Temperature Wafer Bonding by Surface Activated ALD- Al2O3

Abstract

Room-temperature Si/Al2O3 and Al2O3/Si wafer bonding has been achieved successfully using activating wafer surfaces by using O2 plasma and following N2 plasma generated by reactive ion etching (RIE) equipment. It is found that the plasma power has a strong influence on the voids formation between the two wafers. The effective bonded area, micro-structure and bond mechanism were investigated in this research. Scanning acoustic microscope (SAM) was utilized to observe the voids. A high quality interfacial layer has been observed by using scanning electron microscope (SEM). To test the bond strength, the wafer pairs are tested by a thinning and cutting process. The reactions on two activated surfaces are used to explain the surface activated bonding process, by taking the formation of Al-OxNy bonds into consideration. This wafer bonding method is theoretically suitable to bond any two wafers, because the technique is not sensitive to the substrate materials.