Applications of aluminium nitride films deposited by reactive sputtering to silicon-on-insulator materials

Self-heating effects in silicon-on-insulator (SOI) devices limit the applicability of SOI materials in electronics in cases where high power dissipation is expected. Aluminium nitride as a potential candidate for buried insulator material in future SOI-structures is investigated. Reactive sputtering was used to manufacture the aluminium nitride films. The deposited films exhibit low stress and fairly low surface roughness. Further, resistivities above 10(14) Omega cm as well as low thermal resistances were obtained. Interfacial problems at the interface between silicon and aluminium nitride were handled by adding a thin (a few nm) film of thermally grown silicon dioxide to that interface. The deposited films could be bonded both directly and through an electrostatic technique to silicon wafers. The presented results show that it is possible to make SOI structures with aluminium nitride as buried insulator by means of wafer bonding and subsequent etch-back.