Thermodynamic understanding and analytical modeling of interfacial SiO₂ scavenging in HfO₂ gate stacks on Si, SiGe, and SiC

This work thermodynamically and experimentally generalizes the interfacial SiO₂ scavenging in HfO₂ gate stacks from on Si to on other channel materials including SiGe and SiC and proposes a generalized formulation for this process. By paying attention to the Si chemical potential in the SiO₂ interfacial layer (SiO₂-IL) significantly affected by the substrate, it clarifies that Si in the substrate is indispensable to trigger the scavenging process. Thanks to this understanding, we demonstrate that the scavenging is extendable to next generation of channel materials containing Si such as SiGe and SiC with well-controlled high-k gate stacks. In addition, via formulating the diffusion-reaction-diffusion kinetics, an analytical relation like the Deal-Grove model is obtained for SiO₂-IL scavenging in high-k gate stacks.