Mechanism of Carrier Mobility Degradation Induced by Crystallization of HfO_2 Gate Dielectrics

摘要

We have experimentally shown that crystallization of HfO_2 and the subsequent formation of fixed charges localized at the HfO_2/SiO_2 interface bring about a degradation of electron mobility. Systematic analyses of valence-band photoemission and transmission electron microscopy indicate that the oxygen transfer from the HfO_2 layer to the Si substrate is promoted upon the crystallization of HfO_2 and the fixed charges are generated during the process. These findings highlight the importance of controlling the crystallinity of HfO_2 for realizing high performance metal gate high-κ field-effect transistors.