Annealing behavior of ferroelectric Si-doped HfO2 thin films

Lomenzo, Patrick D.; Takmeel, Qanit; Moghaddam, Saeed; Nishida, Toshikazu

doi:10.1016/j.tsf.2016.07.009

Cited by 76 publications

(51 citation statements)

References 25 publications

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“…In fact, in some cases P r seemed compromised compared to TiN. Other studies showed the impact of annealing conditions and Hf 1‐ x Zr x O 2 stoichiometries on the wake‐up behavior, which proves that the interplay between ferroelectric and electrodes is more complex. Simply exchanging the electrode material is not expedient and a careful adjustment of other process parameters is additionally mandated to make HfO 2 fully competitive for memory applications.…”

Section: Discussionmentioning

confidence: 98%

Structural Changes Underlying Field‐Cycling Phenomena in Ferroelectric HfO₂ Thin Films

Grimley

Schenk

Sang

et al. 2016

Adv Elect Materials

341

280

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of crucial relevance for the performance of ferroelectric memories. [ 12,13 ] The phenomenon of wake-up refers to the transition from a pinched hysteresis with a low remanent polarization P r to an open (depinched) hysteresis during a certain amount of initial switching cycles. Internal bias fi elds [ 12 ] have recently been shown to account for this behavior and have been speculated to be caused by charged oxygen vacancies at top and bottom electrodes. [ 5,7 ] The phenomenon of polarization fatigue is characterized by a gradual decrease in P r with continued application of switching cycles beyond wake-up. [ 14,15 ] Despite the importance of these phenomena, they have yet to be thoroughly explained for these rather new ferroelectrics. To address this lack of understanding, we chose a combined approach of sophisticated electrical and structural analysis. We report the fi rst impedance spectroscopy measurements of ferroelectric-doped HfO 2 thin fi lms using TiN-Gd:HfO 2 -TiN metal-ferroelectric-metal (MFM) capacitors at different stages of cycling lifetime. These fi ndings are then correlated to aberration-corrected atomicresolution scanning transmission electron microscopy (STEM) measurements. Direct evidence for the evolution of multiple aspects of fi lm structure during fi eld cycling is shown to underlie the observed electrical behavior. ResultsThe electrical response of the Gd:HfO 2 MFM capacitors exhibits typical behavior of HfO 2 ferroelectrics. Figure 1 a shows the manifestation of both wake-up and fatigue in the polarization hysteresis whereas Figure 1 b depicts the evolution of P r throughout the course of continuous fi eld cycling. Besides the aforementioned changes in the polarization-voltage ( P -V ) hysteresis (loop opening and P r increase followed by a decrease in P r ), the slopes of the saturated hysteresis branches hint at changes in relative permittivity of the fi lm. These changes become even more apparent when measuring the small-signal capacitance as a function of applied bias voltage. As expected from the P -V hysteresis, the peaks in the butterfl y-like hysteresis in relative permittivity ε r that result from additional domain wall capacitance during polarization switching [ 16 ] fi rst increase Since 2011, ferroelectric HfO 2 has attracted growing interest in both fundamental and application oriented groups. In this material, noteworthy wake-up and fatigue effects alter the shape of the polarization hysteresis loop during fi eld cycling. Such changes are problematic for application of HfO 2 to ferroelectric memories, which require stable polarization hystereses. Herein, electrical and structural techniques are implemented to unveil how cyclic switching changes nanoscale fi lm structure, which modifi es the polarization hysteresis. Impedance spectroscopy and scanning transmission electron microscopy identify regions with different dielectric and conductive properties in fi lms at different cycling stages, enabling development of a structural model to explain the wake-up and fatigue phenomen...

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Section: Discussionmentioning

confidence: 98%

Structural Changes Underlying Field‐Cycling Phenomena in Ferroelectric HfO₂ Thin Films

Grimley

Schenk

Sang

et al. 2016

Adv Elect Materials

341

280

View full text Add to dashboard Cite

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“…However, in the case of Si: HfO 2 thin films, the Ir capped capacitor exhibited 13-14% lower P r than the TiN capped capacitor, which was attributed to different thermal expansion coefficients and the potential scavenging effect of TiN. 53 30 where no capping layers were used before the films were crystallized but the ferroelectricity was almost unaffected. These results suggest that the role of the capping layer is positive but not critical in inducing the formation of ferroelectric o-phase.…”

Section: Origins Of Ferroelectricity In Hfo 2 -Based Materialsmentioning

confidence: 99%

“…Besides the commonly used TiN, various capping layer materials have been studied, such as Pt, 51 RuO2, 52 TaN, 40 and Ir/IrO x . 53,54 In particular, using Ir/ IrO x as electrodes has successfully solved the long-standing fatigue issue of PZT 55 and is therefore of great interest to be applied to HfO 2 -based devices. However, in the case of Si: HfO 2 thin films, the Ir capped capacitor exhibited 13-14% lower P r than the TiN capped capacitor, which was attributed to different thermal expansion coefficients and the potential scavenging effect of TiN.…”

Section: Origins Of Ferroelectricity In Hfo 2 -Based Materialsmentioning

confidence: 99%

Ferroelectric HfO₂-based materials for next-generation ferroelectric memories

2016

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Ferroelectric random access memory (FeRAM) based on conventional ferroelectric perovskites, such as Pb(Zr,Ti)O 3 and SrBi 2 Ta 2 O 9 , has encountered bottlenecks on memory density and cost, because those conventional perovskites suffer from various issues mainly including poor complementary metal-oxide-semiconductor (CMOS)-compatibility and limited scalability. Nextgeneration cost-efficient, high-density FeRAM shall therefore rely on a material revolution. Since the discovery of ferroelectricity in Si:HfO 2 thin films in 2011, HfO 2 -based materials have aroused widespread interest in the field of FeRAM, because they are CMOScompatible and can exhibit robust ferroelectricity even when the film thickness is scaled down to below 10 nm. A review on this new class of ferroelectric materials is therefore of great interest. In this paper, the most appealing topics about ferroelectric HfO 2 -based materials including origins of ferroelectricity, advantageous material properties, and current and potential applications in FeRAM, are briefly reviewed.

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“…S6), being the permittivity values comparable to those of polycrystalline films. 27,28 Applied Physics Letters 114, 222901 (2019); DOI: https://doi.org/10.1063/1.5096002…”

mentioning

confidence: 99%

Enhanced ferroelectricity in epitaxial Hf0.5Zr0.5O2 thin films integrated with Si(001) using SrTiO3 templates

Lyu

Fina

Bachelet

et al. 2019

Applied Physics Letters

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a) Corresponding authors: ignasifinamartinez@gmail.com, fsanchez@icmab.es SrTiO3 templates have been used to integrate epitaxial bilayers of ferroelectric Hf0.5Zr0.5O2 and La2/3Sr1/3MnO3 bottom electrode on Si(001). The Hf0.5Zr0.5O2 films show enhanced properties in comparison to equivalent films on SrTiO3(001) single crystalline substrates. The films, thinner than 10 nm, have very high remnant polarization of 34 µC/cm 2 . Hf0.5Zr0.5O2 capacitors at operating voltage of 4 V present long retention time well beyond 10 years and high endurance against fatigue up to 10 9 cycles. The robust ferroelectric properties displayed by the epitaxial Hf0.5Zr0.5O2 films on Si(001) using SrTiO3 templates paves the way for the monolithic integration on silicon of emerging memory devices based on epitaxial HfO2.

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Annealing behavior of ferroelectric Si-doped HfO2 thin films

Cited by 76 publications

References 25 publications

Structural Changes Underlying Field‐Cycling Phenomena in Ferroelectric HfO₂ Thin Films

Structural Changes Underlying Field‐Cycling Phenomena in Ferroelectric HfO₂ Thin Films

Ferroelectric HfO₂-based materials for next-generation ferroelectric memories

Enhanced ferroelectricity in epitaxial Hf0.5Zr0.5O2 thin films integrated with Si(001) using SrTiO3 templates

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Annealing behavior of ferroelectric Si-doped HfO2 thin films

Cited by 76 publications

References 25 publications

Structural Changes Underlying Field‐Cycling Phenomena in Ferroelectric HfO2 Thin Films

Structural Changes Underlying Field‐Cycling Phenomena in Ferroelectric HfO2 Thin Films

Ferroelectric HfO2-based materials for next-generation ferroelectric memories

Enhanced ferroelectricity in epitaxial Hf0.5Zr0.5O2 thin films integrated with Si(001) using SrTiO3 templates

Contact Info

Product

Resources

About

Structural Changes Underlying Field‐Cycling Phenomena in Ferroelectric HfO₂ Thin Films

Structural Changes Underlying Field‐Cycling Phenomena in Ferroelectric HfO₂ Thin Films

Ferroelectric HfO₂-based materials for next-generation ferroelectric memories