Impact of annealing temperature on the ferroelectric properties of W/Hf 0.5 Zr 0.5 O 2 /W capacitor

• Published in: Chinese physics B 2023-08, Vol.32 (9), p.97701
• Main Authors: Wang, Dao, Zhang, Yan, Guo, Yongbin, Shang, Zhenzhen, Fu, Fangjian, Lu, Xubing
• Format: Article
• Language: English
• ISSN: 1674-1056
• DOI: 10.1088/1674-1056/aca9c6

Crystallization annealing is a crucial process for the formation of the ferroelectric phase in HfO 2 -based ferroelectric thin films. Here, we systematically investigate the impact of the annealing process, with temperature varied from 350 °C to 550 °C, on the electricity, ferroelectricity and reliability of a Hf 0.5 Zr 0.5 O 2 (HZO; 7.5 nm) film capacitor. It was found that HZO film annealed at a low temperature of 400 °C can effectively suppress the formation of the monoclinic phase and reduce the leakage current. HZO film annealed at 400 °C also exhibits better ferroelectric properties than those annealed at 350 °C and 550 °C. Specifically, the 400 °C-annealed HZO film shows an outstanding 2 P r value of 54.6 μC⋅cm −2 at ± 3.0 MV⋅cm −1 , which is relatively high compared with previously reported values for HZO film under the same electric field and annealing temperature. When the applied electric field increases to ± 5.0 MV⋅cm −1 , the 2 P r value can reach a maximum of 69.6 μC⋅cm −2 . In addition, the HZO films annealed at 400 °C and 550 °C can endure up to bout 2.3 × 10 8 cycles under a cycling field of 2.0 MV⋅cm −1 before the occurrence of breakdown. In the 400 °C-annealed HZO film, 72.1% of the initial polarization is maintained while only 44.9% is maintained in the 550 °C-annealed HZO film. Our work demonstrates that HZO film with a low crystallization temperature (400 °C) has quite a high ferroelectric polarization, which is of significant importance in applications in ferroelectric memory and negative capacitance transistors.