The Relation Between Crystalline Phase, Electronic Structure, and Dielectric Properties in High-K Gate Stacks

As high permittivity dielectrics approach use in metal‐oxide‐semiconductor field effect transistor (MOSFET) production, an atomic level understanding of their electronic and dielectric properties is being rigorously examined. In our work we illustrate studies leading to such an understanding for the important materials HfO2 and ZrO2. Valence and conduction band densities of states for HfO2/SiO2/Si and ZrO2/SiOxNy/n‐Si structures were determined by soft X‐ray photoemission and inverse photoemission. First principles calculations were used to help in assigning valence band maxima and conduction band minima. The energies of defect states at the band edges were determined by comparing the theoretical and experimental results. From this information, we are able to show that both of these dielectric materials have high enough barriers for both electron and hole transfer. We show that the crystal structure in ultrathin ZrO2 films has considerable effects on permittivity as well as bandgap. The films reported her...