Influence of the ozone dose time during atomic layer deposition on the ferroelectric and pyroelectric properties of 45 nm-thick ZrO<sub>2</sub> films

Bohan Xu, Liam Collins, Kristina M. Holsgrove, Thomas Mikolajick, Uwe Schroeder, Patrick D. Lomenzo

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

Over a decade ago, ferroelectricity was discovered in doped HfO2 thin films. The HfO2-based thin films have attracted much attention due to their remarkable scalability and CMOS compatibility. Other than the HfO2-based thin films, the undoped ZrO2 thin films are understudied despite their commonly reported antiferroelectric behavior. However, being of the same fluorite structure as HfO2-based thin films, the undoped ZrO2 also displayed considerable ferroelectricity as demonstrated in recent studies. In this work, 45 nm-thick polycrystalline undoped ZrO2 films are synthesized using atomic layer deposition with different ozone dose times. The ZrO2 films are crystallized after atomic layer deposition at 350 °C without anneals. In general, the longer ozone dose time causes a lower in-plane tensile stress and oxygen vacancy content, which help facilitate an irreversible non-polar tetragonal to polar orthorhombic phase transition with electric-field cycling. However, the lower in-plane tensile stress and oxygen vacancy content also stabilize the monoclinic phase so that a long ozone dose time (>17.5 s) reduces the ferroelectric behavior. After wake-up cycles, the ZrO2 thin film with an ozone dose time of 17.5 s exhibits a remanent polarization of 6 μC·cm–2 and a pyroelectric coefficient of −35 μC·K–1·m–2. Moreover, the wake-up behavior is consistent between the ferroelectric and pyroelectric response. As essential factors in optimizing the growth of fluorite-structure thin films for ferroelectric applications, the in-plane tensile stress and oxygen vacancy content significantly influence the ferroelectric and pyroelectric properties. Additionally, the low thermal budget for processing ferroelectric ZrO2 thin films is valuable for semiconductor back-end-of-line processes.
Original languageEnglish
Pages (from-to)2288–2295
JournalACS Applied Electronic Materials
Volume5
Issue number4
Early online date30 Mar 2023
DOIs
Publication statusPublished - 25 Apr 2023

Keywords

  • Materials Chemistry
  • Electrochemistry
  • Electronic, Optical and Magnetic Materials

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