Impact of Oxygen Vacancy Content in Ferroelectric HZO films on the Device Performance

Interplay between oxygen defects and dopants: effect on structure and performance of HfO2-based ferroelectrics

“…15a). Analogous trends were found by Mittmann et al 47 By increasing the O 3 dose time from 0.1 to 20 s when depositing Hf 0.5 Zr 0.5 O 2 layers via ALD, they reported a decrease in number of cycles before hard breakdown from 5 × 10 8 to 10 6 cycles. This observation was accompanied by a drastic increase in device leakage current.…”

“…Mittmann reported that after poling the sample in one polarization direction for 24 h at 85 and 125°C, they observed that the films with the highest po-phase fraction had the highest P r also showed the best retention performance. 47 Depolarization fields caused a degradation of the retained state for oxygenpoor films, as detected in the relaxed polarization measured at room temperature after one second relaxation time, which for samples deposited with 0.1 s ozone dose time showed a reduction of 16%. Similar findings were reported by Chouprik et al 100 who studied the mechanism of retention loss and imprint.…”

“…Mittmann et al 47 also investigated the influence of oxygen content in ferroelectric Hf 0.5 Zr 0.5 O 2 films on o-vs. t-phase formation by exposing the film stack to different temperatures from room temperature up to 400°C and subsequent measurement of the pristine ferroelectric hysteresis. In fact, highly monoclinic or orthorhombic layers showed a constant P r of around 4 and 22 µC cm −2 with temperature, respectively, whereas films which were suspected of containing a mixture of both orthorhombic and tetragonal phases seemed to undergo a phase transition that caused a gradual and almost linear loss in switching polarization with O 3 pulse time.…”

“…To determine data retention for long periods of time, accelerated measurements at high temperatures are conducted. 47 Together with data retention, imprint is very often discussed as a key reliability issue since it causes a rigid shift of the ferroelectric hysteresis towards positive or negative voltages depending on the written polarization direction. Mittmann reported that after poling the sample in one polarization direction for 24 h at 85 and 125°C, they observed that the films with the highest po-phase fraction had the highest P r also showed the best retention performance.…”

Aging in Ferroelectric Si‐Doped Hafnium Oxide Thin Films

“…Very recently, it has been reported that the dosage of oxygen during deposition has a significant impact on the retention characteristics in HfO 2 -based NVM. [34] The manipulation of oxygen content could be an interesting pathway toward increasing the long-term stability of HfO 2 -based applications and warrants further research. From our findings, it is further concluded that the choice of the electrode material may have a significant impact on the aging behavior.…”