In Depth Analysis of VT Instabilities in HFO2 Technologies by Charge Pumping Measurements and Electrical Modeling

This paper investigates V_T instabilities in HfO₂ /TiN stacks from CP measurements and electrical modeling. CP measurements are well correlated to pulsed Idvg measurements and can be easily used to obtain the Vt instability over a large scale of time from 0.1mus to fews seconds. A complete modeling of the CP and the pulsed Id Vg measurements has been done to localize spatially and energetically the traps in HfO₂. The main band of defects responsible for Vt instabilities was found at ~0.9eV from the HfO₂ conduction band but deep energy levels were also identified. The impact of the detrapping phenomena on CP measurements has been finally investigated. No influence of detrapping of electrons into the gate was found. And the detrapping into the substrate during the half of the ac cycle at Vg=-1.5V is almost complete for the traps filled at low Vg