High-k Gate Dielectrics of Thin Films with its Technological Applications –A Review

High-k gate dielectrics are used to suppress excessive transistor gate leakage and power consumption could speed up the introduction of metal gates in complementary metal oxide semiconductor (CMOS) transistors. Many new oxides are being evaluated as gate dielectrics, such as Al2O3, Y2O3, La2O3, Gd2O3, HfO2, ZrO2, and TiO2, BaZrO3, ZrSiO4 and HfSiO4. Ru, RuO2 and SrRuO3 gate electrodes grown on thermal SiO2. Research metal oxide materials with high k values (e.g., ZrO2, HfO2, Al2O3, Y2O3, La2O3, etc.) have reasonably large conduction band offset (estimated to be in the range of 1.5– 3.0 eV). Gate dielectric for CMOS scaling at the 0.18μm and below becomes the leading front-end integration issue. Gate oxide thickness must be scaled down when the gate length is shrunk down to deep sub-micron region. The direct tunneling through the gate dielectric and gate oxide reliability are the two major concerns for ultra thin gate dielectric films. The scaling of gate dielectric thickness represents a major issue in the development of metal oxide semiconductor field effect transistors (MOSFET).