Flat band voltage (VFB) modulation by controlling compositional depth profile in La2O3/HfO2 nanolaminate gate oxide

We investigated the flat band voltage (V-FB) modulation by insertion of lanthanum oxide (La2O3) into hafnium oxide (HfO2) gate dielectrics. The properties of La2O3/HfO2 nanolaminates were precisely modulated by controlling the position of La2O3 layer at bottom, middle, or top using atomic layer deposition. When the La2O3 layer was positioned closer to the interface (bottom), the reduction in V-FB shift was more effective than the other two cases (middle and top). From our experimental results, we propose that the main mechanism of V-FB modulation using La2O3 layer is dipole moment formation at an interfacial layer between high k gate dielectric and Si substrate. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3369388]