Effect of oxygen on tuning the TiNx metal gate work function on LaLuO3

This paper presents experimental evidence on effective work function tuning due to the presence of oxygen at the TiNx/LaLuO3 interface. Two complementary techniques, internal photoemission and X-ray photoelectron spectroscopy, show good agreement on the position of the metal gate Fermi level to conduction (2.79 ± 0.25 eV) and valence (2.65 ± 0.08 eV) band edge for TiNx/bulk LaLuO3 gate stacks. The chemical shifts of Ti2p and N1s core levels and different degree in ionicity of TiNx metal gates correlate with the observed valence band offset shifts. The results have significance for setting the band edge work function and resulting low threshold voltage for ultimately scaled LaLuO3-based p-metal oxide semiconductor field effect transistor devices.

► The conduction band offset measured by internal photoemission.
► The valence band offset (VBO) measured by X-ray photoelectron spectroscopy.
► Different degree in ionicity of TiNx correlates with the VBO shifts.
► The effective work function of the gate stacks varies from 4.6 to 5.2 eV.
► Oxygen at the TiNx/LaLuO3 interface increases effective work function.