La2O3/In0.53Ga0.47As metal–oxide-semiconductor capacitor with low interface state density using TiN/W gate electrode

Effect of W and TiN/W gate metal on the interface quality of La2O3/InGaAs metal–oxide-semiconductor (MOS) interface is investigated. Hard X-ray photoelectron spectroscopy revealed that gate metal greatly affects the oxidation states at La2O3/InGaAs interface after post-metallization annealing (PMA). Results demonstrate that TiN/W gate metal can effectively control the reaction at La2O3/InGaAs interface and also suppress the formation of As, Ga, and In oxides. As a result, superior capacitance–voltage (C–V) characteristics with low interface state density (Dit) of 4.6 × 1011 cm−2/eV (∼0.1 eV from midgap) and leakage current below 10−5 A/cm2 was obtained for TiN/W/La2O3 (10 nm)/InGaAs MOS capacitors. The MOS structure integrity was preserved for annealing temperature up to 620 °C.

► La2O3 as a high-k dielectric can react with InGaAs substrate forming an interfacial layer.
► Gate metal greatly affects the reaction at La2O3/InGaAs interface.
► Thermally stable interface with very low interface state density was obtained.
► Suppressing oxygen diffusion through gate metal selection modifies interface reaction.