Local epitaxial-like templating effects and grain size distribution in atomic layer deposited Hf0.5Zr0.5O2 thin film ferroelectric capacitors

Abstract

The microstructure in fluorite-structure oxide-based ferroelectric thin films, especially when on standard semiconductor manufacturing platforms, is poly-/nano-crystalline, which controls the functionality, performance, and reliability of the device technologies based on them. Understanding the relationships between microstructure, process, and performance for this class of materials has remained challenging. Here, a systematic approach is presented for analyzing and visualizing grains, their size distributions, and interlayer templating effects in ferroelectric thin film systems by utilizing an advanced microscopy technique, namely nanobeam electron diffraction, coupled with dark-field transmission electron microscopy and atomic resolution scanning transmission electron microscopy. A 10\u2009nm TiN/10\u2009nm Hf0.5Zr0.5O2 (HZO)/10\u2009nm TiN ferroelectric heterostructure is probed. A geometric mean of the grain size in HZO of 26.8\u2009nm ranging from 5 to 95\u2009nm with top and bottom TiN layers having a much smaller grain size of approximately 6.8\u2009nm ranging from 3 to 17\u2009nm is observed. Furthermore, there is evidence of templating effects between HZO and TiN grain and domain boundaries showing [111] and [001] growth directions locally for HZO and TiN, respectively.