Self-decomposition of SiO2 due to Si-chemical potential increase in SiO2 between HfO2 and substrate - Comprehensive understanding of SiO2-IL scavenging in HfO2 gate stacks on Si, SiGe and SiC

This work thermodynamically clarifies the scavenging mechanism in HfO₂ gate stacks on Si substrate and generalizes it to other substrates. The key is to pay attention to the Si chemical potential in SiO₂ interface layer (SiO₂-IL) affected by 1) Si in substrate, 2) interfacial energy at hetero-interface and 3) oxygen vacancy (V_o) injected from HfO₂. In addition, thanks to the generalized model, we demonstrate that the scavenging is extendable to new channel materials containing Si such as SiGe and SiC.