Effect of Nitrogen on the Physical Properties and Work Function of MoN x Cap Layers on HfO 2 Gate Dielectrics

Abstract

© 2014 The Electrochemical Society. All rights reserved. In this work, MoN x films deposited by reactive sputtering are investigated as cap layers on HfO 2 gate dielectrics. A phase transition from body-centered-cubic Mo phase to face-centered-cubic (FCC) γ-Mo 2 N phase is found with increasing nitrogen content and causes a morphology change. It is found that the crystallinity and grain size decrease when MoN x films are subjected to phase transition. The Mo 3d core levels shift toward higher binding energy due to increments of nitrogen in the MoN x films. The resistivity and work function are also seen to have positive dependence on the nitrogen content. The work functions extracted from the capacitance vs. voltage curves are 4.58 eV for Mo films and 5.10 eV-5.23 eV for MoN x films on HfO 2 gate dielectrics, respectively.