A novel combinatorial approach to the ferroelectric properties in Hf${}_x$Zr${}_{1-x}$O${}_2$ deposited by atomic layer deposition

Since HfO${}_2$-based ferroelectric films were reported in 2011, several doping/alloying elements have been introduced to secure interesting ferroelectric/antiferroelectric properties of Hf-based fluorite-structured thin films. Using a conventional approach by atomic layer deposition (ALD), an enormous number of experiments would be required to reveal the compositional effects of doping/alloying components in ternary and quaternary systems. Therefore, for a comprehensive study of the ferroelectric properties of Hf${}_x$Zr${}_{1-x}$O${}_2$, a novel combinatorial ALD technique that enables the fabrication of multicomponent films with a different composition ratio and thickness via saturated/non-saturated ALD without changing the supercycle of each material is reported. The gradient of the amount of HfO${}_2$ over a 100 mm substrate is achieved using a lower Hf-precursor temperature that results in an insufficient Hf-precursor dose for saturated deposition. Systematic study on the Hf${}_x$Zr${}_{1-x}$O${}_2$ combinatorial library is carried out by spectroscopic ellipsometry, X-ray photoelectron spectroscopy, and X-ray diffraction. Furthermore, TiN/Hf${}_x$Zr${}_{1-x}$O${}_2$/TiN capacitors are fabricated to measure the remnant polarization. The obtained results clearly show the ferroelectric-antiferroelectric transition according to continuous composition change instead of discrete research. Therefore, a highly productive method for studying ferroelectricity changes in terms of a doping and a composition of HfO${}_2$-based ferroelectric thin films through a novel ALD combinatorial approach is proposed. (© 2021 Wiley-VCH GmbH)