Direct wafer bonding of atomic layer deposited TiO2 and Al2O3 thin films

In MEMS industry, silicon-on-insulator (SOI) wafers are gaining ground from blank silicon wafers as the main starting substrate. Tailored SOI wafers available in the market contain for example buried cavities or a buried gettering layer. Adding another layer in addition to the thermal SiO₂ insulator, or replacing it with another material altogether, could be a way to tailor the properties of SOI wafers further. In this work, the direct wafer bonding of ALD TiO₂, and Al₂O₃ for reference, is investigated, eventually in order to fabricate SOI wafers with other buried ALD oxides.