(Invited) ALD HfZrO 2 Films from Ferroelectric to High-k Applications

HfO2 based ferroelectric (FE) materials have gained tremendous attention as a potential candidate for memory applications such as FeFET and FeRAM. Since its first demonstration as a FE material [1], immense research has been done to circumvent the challenges such as scalability, increasing the remnant polarization (Pr), and improving endurance. Among others, Zr-doped HfO2, HfZrO 2 (HZO) is being intensively studied due to its compatibility with complementary metal oxide semiconductor (CMOS) processing and excellent scalability. ALD has been the technique of choice for the deposition of those films, due to the high conformality, high film quality and simplicity of tuning the composition. HZO has excelled in this field, with high polarization, high endurance and retention. Those properties were still further improved by the addition of dopants such as La, which resulted in the record high 2Pr for films fabricated by ASM and imec using metalorganic precursors [2]. In this presentation we take ALD HZO one step forward, and describe how, by tunning the processing parameters of these films , the ferroelectricity can be modulated in a broad range, and how this can be incorporated in applications where high dielectric constants are desired. We discuss significant learnings in this material system regarding phase composition and crystallization dynamics, and how these can be used to modulate HZO from a ferroelectric into a high-k material. The extreme adaptability of ALD HfZrO2 provides an opportunity for its insertion in different applications. This material can extend logic and memory roadmaps, providing high capacitance, low leakage and high 2Pr, all at ultra-scaled thicknesses. References S. Boscke et al, Appl. Phys. Lett. 99, 102903 (2011) I. Popovici and J. Bizindavyi et al, IEDM 2022