Wafer bonding using smooth titanium thin films in air atmosphere

Abstract

Si wafers with smooth Ti thin films were contacted in air atmosphere and annealed at a range of temperatures up to 300 °C to increase the bonding strength. Root-mean-square (RMS) surface roughness of 30 nm thick electron beam evaporated Ti films on Si wafers measured by atomic force microscope (AFM) was 0.3 nm. Bonding strength measured by blade insertion test reached 1.0 J/m2. The proposed wafer bonding process has the advantage of being simple and inexpensive.