In Situ Rapid Thermal Annealing with On-Chip Heater and STEM EBIC Characterization on Ferroelectric HZO

Due to its CMOS compatibility and scalability, hafnium-zirconium oxide (HZO) is a leading candidate for ferroelectric RAMs (FeRAM). However, HZO is polymorphic, and the factors that result in crystallization from the as-deposited amorphous phase into the desired ferroelectric orthorhombic phase are still not well understood. Rapid thermal annealing (RTA) is employed to crystallize HZO, but optimizing RTA is usually a matter of guesswork, as the traditional workflow does not allow for in situ observation of crystallization or polarization measurements. In this work, we engineered an HZO capacitor with an on-chip heater to study the effect of RTA on HZO’s ferroelectricity. Biasing the heater in a scanning transmission electron microscope (STEM), we observe the crystallization process. We use positive-up negative-down (PUND) and STEM electron beam induced current (EBIC) to characterize the macroscopic and microscopic polarization, respectively, as we vary the annealing conditions. These in situ techniques allow us to intelligently optimize the RTA process for ferroelectric thin films.