Sputtering Technique to Fabricate Smooth Surface Oxide Film for Room Temperature Bonding

200-nm-thick SiO 2 films were deposited on Si wafers using a bias sputtering apparatus with dual cathodes controlled by a plasma-balanced-system (PLABAS). Surface roughness S a of SiO 2 deposited films was extremely small: 0.10 nm. Bonding using the smooth surface was demonstrated.