Large ferroelectric polarization of TiN/Hf0.5Zr0.5O2/TiN capacitors due to stress-induced crystallization at low thermal budget

Kim, Si Joon; Narayan, Dushyant; Lee, Jae-Gil; Mohan, Jaidah; Lee, Joy S.; Lee, Jaebeom; Kim, Harrison S.; Byun, Youngchul; Lucero, Antonio T.; Young, Chadwin D.; Summerfelt, Scott R.; San, Tamer; Colombo, Luigi; Kim, Jiyoung

doi:10.1063/1.4995619

Cited by 233 publications

(197 citation statements)

References 22 publications

Supporting

Mentioning

179

Contrasting

Unclassified

Order By: Relevance

“…Dopant dependent different elastic properties or crystallization behavior might be two potential origins (see Supporting Information S2) that could give rise to different stress states. [28,29] Theoretical [30][31][32] and first experimental [33][34][35] works have been dedicated to elucidating the role of strain on the enhancement or suppression of the dipole in fluorite-type ferroelectrics (hafnia and zirconia). [25][26][27] The top electrode capping, which was shown to promote the ferroelectricity, has been suggested to be related with a stress effect already in the original publications.…”

Section: Spontaneous Polarization Stress and Strainmentioning

confidence: 99%

“…According to Batra et al, [31] the FE Pca2 1 phase can be promoted by both compressive hydrostatic and equibiaxial strain in the bc-plane (according to the definitions of a, b, and c used here). [20,[33][34][35] However, deriving a unified picture is not yet possible and a deeper discussion is beyond the scope of this work. However, the energy promotion from the strain was not predicted as sufficient to stabilize the FE Pca2 1 over the monoclinic and nonpolar orthorhombic Pbca phase and thus, an additional destabilization mechanism for these two phases must be assumed.…”

Section: Spontaneous Polarization Stress and Strainmentioning

confidence: 99%

See 1 more Smart Citation

On the Origin of the Large Remanent Polarization in La:HfO₂

Schenk

Fancher

Park

et al. 2019

Adv Elect Materials

View full text Add to dashboard Cite

extraordinary result. [2][3][4][5][6][7] A physical explanation for these results has remained elusive. The dopant size has been speculated to be a key parameter and larger dopants seem in general favorable compared to dopants with a smaller ionic radius than Hf. [2,8] This trend has been confirmed theoretically by Batra et al., [5] who additionally conclude that trivalent dopants in general are a good choice to favor the polar phase in HfO 2 . Large trivalent dopants, as the lanthanoid series are therefore especially suitable to promote ferroelectricity. In comparison to Gd, as another lanthanoid, La lowers the total energy difference to the monoclinic ground state the most. Also, they derived general trends that a larger ionic radius and a lower electronegativity of a dopant are favorable for the FE phase. Batra et al. [5] did not firmly conclude that La is the most favorable dopant to promote ferroelectricty in hafnia because a clear identification of the relaxed structures was not always possible and assumptions required concerning the distribution of oxygen vacancies and dopants in the high-throughput computational approach. They rather focused on the aforementioned general chemical trends of dopant attributes that promote the FE Pca2 1 phase. Further clarification of this trend could be provided by Materlik et al., [6] who compared La with Al and Y (also trivalent, but different in atomic radius) andThe outstanding remanent polarization of 40 µC cm -2 reported for a 10 nm thin La:HfO 2 film in 2013 has attracted much attention. However, up to now, no explanation for this large remanent polarization has been presented. Density functional theory and X-ray diffraction are used to shine light onto three major aspects that impact the macroscopically observed remanent polarization: phase fraction, spontaneous polarization, and crystallographic texture. Density functional theory calculations show that the spontaneous polarization (P s ) of La:HfO 2 is indeed a bit larger than for other HfO 2 -or ZrO 2 -based compounds; however, the P s is not large enough to explain the observed differences in remanent polarization. While neither phase fractions nor spontaneous polarization nor strain are significantly different from those in other HfO 2 films, a prominent 020/002 texture distinguishes La doped from other HfO 2 -based ferroelectric films. Angulardependent diffraction data provide a pathway to calculate the theoretically expected remanent polarization, which is in agreement with the experimental observations. Finally, an interplay of the in-plane strain and texture is proposed to impact the formation of the ferroelectric phase during annealing. Further aspects of the special role of La as a dopant are collected and discussed to motivate future research.

show abstract

Section: Spontaneous Polarization Stress and Strainmentioning

confidence: 99%

Section: Spontaneous Polarization Stress and Strainmentioning

confidence: 99%

On the Origin of the Large Remanent Polarization in La:HfO₂

Schenk

Fancher

Park

et al. 2019

Adv Elect Materials

View full text Add to dashboard Cite

show abstract

“…The relative amount of the orthorhombic phase and the ferroelectric properties depend on the annealing conditions and film thickness. 3,[6][7][8][9][10][11][12][13] The ferroelectric orthorhombic phase can be also stabilized in epitaxial films. [14][15][16][17][18][19][20][21] In epitaxial films, the orthorhombic phase is generally formed during deposition at high temperature, without need of annealing.…”

Section: Introductionmentioning

confidence: 99%

Growth Window of Ferroelectric Epitaxial Hf_0.5Zr_0.5O₂ Thin Films

Lyu

Fina

Solanas

et al. 2019

ACS Appl. Electron. Mater.

208

View full text Add to dashboard Cite

The metastable orthorhombic phase of hafnia is generally obtained in polycrystalline films, whereas in epitaxial films its formation has been much less investigated. We have grown Hf0.5Zr0.5O2 films by pulsed laser deposition and the growth window (temperature and oxygen pressure during deposition, and film thickness) for epitaxial stabilization of the ferroelectric phase is mapped. The remnant ferroelectric polarization, up to 24 C/cm 2 , depends on the amount of orthorhombic phase and interplanar spacing and increases with temperature and pressure for a fixed film thickness. The leakage current decreases with an increase in thickness or temperature, or when decreasing oxygen pressure. The coercive electric field (EC) depends on thickness (t) according the EC -t -2/3 scaling, which is observed by the first time in ferroelectric hafnia, and the scaling extends to thickness down to around 5 nm. The proven ability to tailor functional properties of high quality epitaxial ferroelectric Hf0.5Zr0.5O2 films paves the way toward understanding their ferroelectric properties and prototyping devices.

show abstract

“…This ratio can be easily realized using common deposition techniques like atomic layer deposition (ALD) with a homogenous concentration throughout the film. 2) The FE properties of HZO films can be achieved at low process temperatures of about 400 °C . This is most likely due to the low crystallization temperature of ZrO 2 compared with other potential high‐k oxides .…”

Section: Introductionmentioning

confidence: 99%

“…It was shown that thin HZO films could be crystallized successfully in the desired FE phase by applying rapid thermal annealing (RTA) at 400 °C and even 300 °C for 30 or 60 s. Furthermore, phase transition kinetics were studied (at prior RTA crystallized films) during supplementary annealing at different temperatures and durations to simulate the thermal profile present during the formation of the interconnects, where high‐temperature processes (up to 400 °C) occur several times and last from some minutes to hours.…”

Section: Introductionmentioning

confidence: 99%

Back‐End‐of‐Line Compatible Low‐Temperature Furnace Anneal for Ferroelectric Hafnium Zirconium Oxide Formation

Lehninger

Olivo

Ali

et al. 2020

Physica Status Solidi (a)

View full text Add to dashboard Cite

The discovery of ferroelectricity in thin doped hafnium oxide films revived the interest in ferroelectric (FE) memory concepts. Zirconium‐doped hafnium oxide (HZO) crystallizes at low temperatures (e.g., 400 °C), which makes this material interesting for the implementation of FE functionalities into the back end of line (BEoL). So far, the FE phase of prior amorphous HZO films is achieved by using a dedicated rapit thermal annealing (RTA) treatment. However, herein, it is shown that this dedicated anneal is not needed. A sole furnace treatment given by the thermal budget present during the interconnect formation is sufficient to functionalize even ultrathin 5 nm HZO films. This result helps to optimize the integration sequence of HZO films (e.g., involving a minimum number of BEoL process steps), which saves process time and fabrication costs. Herein, metal–FE–metal capacitors with Hf0.5Zr0.5O2 films of different thicknesses (5–20 nm) are fabricated annealed at 400 °C for various durations within different types of ovens (RTA and furnace). Structural and electrical characterization confirms that all furnace‐annealed samples have similar X‐ray diffraction patterns, remanent polarization, endurances, and thickness dependencies as RTA‐annealed ones. With respect to remanent polarization, leakage current, and endurance, the HZO film of 10 nm thickness shows the most promising results for the integration into the BEoL.

show abstract

Large ferroelectric polarization of TiN/Hf0.5Zr0.5O2/TiN capacitors due to stress-induced crystallization at low thermal budget

Cited by 233 publications

References 22 publications

On the Origin of the Large Remanent Polarization in La:HfO₂

On the Origin of the Large Remanent Polarization in La:HfO₂

Growth Window of Ferroelectric Epitaxial Hf_0.5Zr_0.5O₂ Thin Films

Back‐End‐of‐Line Compatible Low‐Temperature Furnace Anneal for Ferroelectric Hafnium Zirconium Oxide Formation

Contact Info

Product

Resources

About

Large ferroelectric polarization of TiN/Hf0.5Zr0.5O2/TiN capacitors due to stress-induced crystallization at low thermal budget

Cited by 233 publications

References 22 publications

On the Origin of the Large Remanent Polarization in La:HfO2

On the Origin of the Large Remanent Polarization in La:HfO2

Growth Window of Ferroelectric Epitaxial Hf0.5Zr0.5O2 Thin Films

Back‐End‐of‐Line Compatible Low‐Temperature Furnace Anneal for Ferroelectric Hafnium Zirconium Oxide Formation

Contact Info

Product

Resources

About

On the Origin of the Large Remanent Polarization in La:HfO₂

On the Origin of the Large Remanent Polarization in La:HfO₂

Growth Window of Ferroelectric Epitaxial Hf_0.5Zr_0.5O₂ Thin Films