Deposition, annealing, and integration of ferroelectric HfxZr1−xO2 (HZO) thin films on the high-mobility semiconductor InAs using atomic layer deposition are investigated. Electrical characterization reveals that the HZO films on InAs exhibit an enhanced remanent polarization compared to films formed on a reference TiN substrate, exceeding 20 μC/cm2 even down to an annealing temperature of 370 °C. For device applications, the thermal processes required to form the ferroelectric HZO phase must not degrade the high-κ/InAs interface. We find by evaluation of the capacitance–voltage characteristics that the electrical properties of the high-κ/InAs are not significantly degraded by the annealing process, and high-resolution transmission electron microscopy verifies a maintained sharp high-κ/InAs interface.

We propose a capacitance measurement scheme that enables quantitative characterization of ferroelectric thin films integrated on semiconductors. The film defect density is estimated by measurements of the CV hysteresis and frequency dispersion, whereas important device parameters such as memory window and endurance can be extracted by a unidirectional CV method. The simple measurement scheme and the usage of metal-oxide-semiconductor capacitors rather than MOSFETs make the proposed methods suitable for the future optimization of ferroelectric field effect transistor and negative capacitance field effect transistor gate stacks. Specifically, we present data for the narrow bandgap semiconductor InAs and show that low temperature characterization is critical to reduce the influence of the minority carrier response; however, the methods should be transferrable to room temperature for semiconductors with a wider bandgap. Our results clearly indicate that the defect density of the HfxZr1−xO2 (HZO) films increases at the crystallization temperature, but the increase is modest and remains independent of the annealing temperature at even more elevated temperatures. It is also shown that the shrinkage of the memory window caused by field cycling is not accompanied by an increase in defect density.

Ferroelectric memories based on hafnium oxide are an attractive alternative to conventional memory technologies due to their scalability and energy efficiency. However, there are still many open questions regarding the optimal material stack and processing conditions for reliable device performance. Here, we report on the impact of the sputtering process conditions of the commonly used TiN top electrode on the ferroelectric properties of Hf 1– x Zr x O 2 . By manipulating the deposition pressure and chemistry, we control the preferential orientation of the TiN grains between (111) and (002). We observe that (111) textured TiN is superior to (002) texturing for achieving high remanent polarization ( P r ). Furthermore, we find that additional nitrogen supply during TiN deposition leads to >5× greater endurance, possibly by limiting the scavenging of oxygen from the Hf 1– x Zr x O 2 film. These results help explain the large P r variation reported in the literature for Hf 1– x Zr x O 2 /TiN and highlights the necessity of tuning the top electrode of the ferroelectric stack for successful device implementation.