Systematic study of interfacial reactions induced by metal electrodes in high-k/InGaAs gate stacks.

We systematically studied the effects of metal electrodes on high-k/InGaAs gate stacks and observed that the remote reactions--both oxidation and reduction--at the interface between the high-k dielectrics and InGaAs were thermodynamically initiated by the metal electrodes. Metal electrodes with negative Gibbs free energies (e.g., Pd) resulted in the oxidation of the InGaAs surface during the forming-gas annealing. In contrast, with TiN electrodes, which have a positive Gibbs free energy, the native III-V oxides underwent the reduction between the high-k dielectrics and InGaAs. We demonstrated that the reduction of native III-V oxides by metal electrodes improved the interface quality of the high-k/InGaAs gate stacks and produced an interface trap density (Dit) at the mid-gap with a value as low as 5.2×1011 cm-2 eV-1 with a scaled capacitanceequivalent thickness. [ABSTRACT FROM AUTHOR]