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

• Published in: Applied physics letters 2016-10, Vol.109 (17)
• Main Authors: Yoshida, S., Lin, D., Vais, A., Alian, A., Franco, J., El Kazzi, S., Mols, Y., Miyanami, Y., Nakazawa, M., Collaert, N., Watanabe, H., Thean, A.
• Format: Article
• Language: English
• Subjects: Applied physics; Dielectrics; Electrodes; Electronics; Free energy; Gibbs free energy; Interface reactions; Oxidation; Palladium; Reduction; Stacks
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4965854

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 (D it) at the mid-gap with a value as low as 5.2 × 1011 cm−2 eV−1 with a scaled capacitance-equivalent thickness.