Growth and understanding of ultrathin novel ferroelectric complex oxides

In recent years, there has been a renewed interest in ferroelectrics for low power integrated electronics such as memory.  The discovery of ferroelectric hafnia has led to scaling of layers to sub 10 nm thicknesses enabling use in modern technology nodes. However, the polymorphic nature of hafnia yields poor endurance and across-wafer repeatability. Complex oxides such as perovskites offer an extremely flexible structure class of materials that offer a wide variety of single-phase ferroelectrics with tunable properties, ideal for next generation ferroelectric memories. It has been shown that polycrystalline BaTiO₃ can be scaled to 10nm thickness while maintaining, if not enhancing, ferroelectric response [1]. However, its high process temperature and low 2P_r make it incompatible with the BEOL processes required for integration. Materials discovery is required to find an alternative to BaTiO₃ with higher 2P_r that can be grown under BEOL compatible conditions. 

The growth and nanoscale engineering of fab-compatible complex oxide ferroelectric thin films will be explored with the aim of scaling these novel materials to below 10nm under challenging BEOL compatible conditions. Strain engineering will be utilized along with growth kinetic manipulation to target the high remanent polarization and low coercive voltages required to enable the two-dimensional integration of these materials in 1T1C FeRAM devices.

[1] Bagul et al., accepted for publication in Advanced Electronic Materials (2024)