Engineering chemically abrupt high-k metal oxide/silicon interfaces using an oxygen-gettering metal overlayer

High-k metal oxide gate dielectrics may be required to extend Moore's law of semiconductor device density scaling into the future. However, growth of a thin SiO2-containing interface layer is almost unavoidable during the deposition of metal oxide films onto Si substrates. This limits the scaling benefits of incorporating high-k dielectrics in future transistors. A promising approach, in which oxygen-gettering metal overlayers are used to engineer the thickness of the SiO2-based interface layer between metal oxide and Si substrate after deposition of the metal oxide layer, is reported. Using a Ti overlayer with high solubility for oxygen on ZrO2 or HfO2 dielectrics, the effective removal of the low-k interface layer at 300 K has been confirmed by electron microscopy and spectroscopy techniques. Significant enhancement of the gate capacitance density, while retaining low leakage current densities, has also been demonstrated for these interface-engineered high-k gate stacks. (C) 2004 American Institute of Physics.