*Article* **Effect of Process Temperature on Density and Electrical Characteristics of Hf0.5Zr0.5O2 Thin Films Prepared by Plasma-Enhanced Atomic Layer Deposition**

**Hak-Gyeong Kim, Da-Hee Hong, Jae-Hoon Yoo and Hee-Chul Lee \***

Department of Advanced Materials Engineering, Korea Polytechnic University, Siheung 15073, Korea; hakkyung5280@hanmail.net (H.-G.K.); ghdekgml9768@naver.com (D.-H.H.); dbwogns96@gmail.com (J.-H.Y.) **\*** Correspondence: eechul@kpu.ac.kr

**Abstract:** Hf*x*Zr1−*<sup>x</sup>*O2 (HZO) thin films have excellent potential for application in various devices, including ferroelectric transistors and semiconductor memories. However, such applications are hindered by the low remanent polarization (Pr) and fatigue endurance of these films. To overcome these limitations, in this study, HZO thin films were fabricated via plasma-enhanced atomic layer deposition (PEALD), and the effects of the deposition and post-annealing temperatures on the density, crystallinity, and electrical properties of the thin films were analyzed. The thin films obtained via PEALD were characterized using cross-sectional transmission electron microscopy images and energy-dispersive spectroscopy analysis. An HZO thin film deposited at 180 ◦C exhibited the highest o-phase proportion as well as the highest density. By contrast, mixed secondary phases were observed in a thin film deposited at 280 ◦C. Furthermore, a post-annealing temperature of 600 ◦C yielded the highest thin film density, and the highest 2Pr value and fatigue endurance were obtained for the film deposited at 180 ◦C and post-annealed at 600 ◦C. In addition, we developed three different methods to further enhance the density of the films. Consequently, an enhanced maximum density and exceptional fatigue endurance of 2.5 <sup>×</sup> <sup>10</sup><sup>7</sup> cycles were obtained.

**Keywords:** HZO; PEALD; ferroelectric memory; deposition temperature; film density; remanent polarization; fatigue endurance
