Mechanism of low temperature hydrogen-annealing-induced degradation in Pb(Zr0.4Ti0.6)O3 capacitors

Seo, Sunae; Yoon, Jong‐Gul; Song, Tae-Ho; Kang, Bo Soo; Noh, Tae Won; Lee, Y. K.; Kim, Ch. J.; Park, Y. S.

doi:10.1063/1.1492006

Cited by 15 publications

(5 citation statements)

References 17 publications

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“…). This ‐OH activation energy was also predicted as 0.20 eV theoretically by Park and Chadi, 60 and found experimentally in a different manner by Seo et al 62 …”

Section: [3d] Systemssupporting

confidence: 80%

Recent Materials Characterizations of [2D] and [3D] Thin Film Ferroelectric Structures

Scott

Morrison

Miyake

et al. 2005

Journal of the American Ceramic Society

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A review is given of ceramic and single-crystal thin film ferroelectric oxides, emphasizing perovskite phases, together with some new developments on hafnia films. It is shown that singlecrystal barium titanate films behave as bulk down to at least 77 nm, with no finite size effects, no phase transition temperature shifts, and no dielectric peak broadening or change from first-to second-order transitions, suggesting that the gradient defect model of Bratkovsky and Levanyuk correctly describes such effects as extrinsic in experimental studies of equally thin ceramic thin films. In ceramic barium-strontium titanate (BST) thin films, it is shown that there is also no intrinsic broadening or shifts in phase transitions, with sharp, unshifted, bulk-like transitions observed only as re-entrant upon warming from cryogenic temperatures; this shows that phase transitions in ceramic thin films are dominated by kinetics and not thermodynamics and are definitely not equilibrium measurements. At high fields (41 GV/m), the films exhibit space charge-limited conduction; no variable-range hopping is observed, contrary to recent studies on SrTiO 3 . Some novel, unconventional switching processes are discussed, comparing the ''perimeter effect'' (non-equilibrium, ballistic) with Molotskii's equilibrium model. Theory and experiment are described for [3D] nanotubes, nanorods, and nanoribbons (or micro-ribbons). The layered-structure-perovskitepyrochlore conversion in bismuth titanate is described together with the PbO1TiO 2 phase separation in lead zirconate titanate during electrical breakdown, as are novel HfO 2 precursors that demonstrate enhanced temperature crystallization from the amorphous state and hence commercial advantages for frontend processing. II. [2D] SystemsIn planar structures, both fine-grained ceramics and single crystals offer intriguing materials science in the 4-100 nm thickness regime. Several authors 2-4 have indicated that thin films might exhibit second-order phase transitions that, in bulk form, are first order; then, the question is exactly what thicknesses constitute ''thin''? Although the International FRAM ''Roadmap'' suggests 5 that FRAM structures must become [3D] by 2007 to accommodate requisite capacitance, at present, all FRAMs are planar-stacked devices. Therefore, we begin with the [2D] systems' materials science. J ournal

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“…). This ‐OH activation energy was also predicted as 0.20 eV theoretically by Park and Chadi, 60 and found experimentally in a different manner by Seo et al 62 …”

Section: [3d] Systemssupporting

confidence: 80%

Recent Materials Characterizations of [2D] and [3D] Thin Film Ferroelectric Structures

Scott

Morrison

Miyake

et al. 2005

Journal of the American Ceramic Society

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“…All three mechanisms are considered to be strongly linked to imprint (one preferred polarization direction over the other) after FGA, which is a serious issue to study the ferroelectric memories. The imprint effect from the reduced ferroelectric materials has been well studied by several researchers 14–16. As reported, annealing PZT films in oxygen deficient atmospheres (N 2 ), which can induce oxide loss, does not influence their ferroelectric properties, and FGA induced ferroelectric degradation can be recovered by post‐annealing in the N 2 atmosphere 10.…”

Section: Resultsmentioning

confidence: 98%

“…Oxygen loss could produce vacancies and electrons, thereby, increase the film conductivity. Thirdly, other defect charges created in the FGA process can also pin PZT domains 14. The pinning is similar to the OH − , which works as a defect dipoles.…”

Section: Resultsmentioning

confidence: 99%

“…Lots of efforts are paid by a lot of research groups to clarify this issue in several aspects, such as the study of polarization hysteresis loops, catalytic role of top electrode, recovery methods after FGA 6, 7, 9–11. So far, there are at least three mechanisms to interpret the FGA induced degradation, which are the incorporation of hydrogen into the PZT lattice, the oxygen loss in the reducing ambient and the defect charges created in the annealing process 12–14. However, most works focus on degradation induced by low‐temperature forming gas anneals below 400 °C.…”

Section: Introductionmentioning

confidence: 99%

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Mechanism of high temperature hydrogen reduced polarization degradation in Pb(Zr_1−xTi_x)O₃ ferroelectric thin film capacitors

Hui

Chen

Liu

et al. 2012

Physica Status Solidi (a)

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Annealing Pb(Zr 1Àx Ti x )O 3 (PZT) thin films in the hydrogen ambient can result in the unacceptable degradation of ferroelectric properties due to interaction of H 2 forming gas with the ferroelectric materials. Since the understanding of this degradation mechanism is limited, this issue arouses a big problem for the application of PZT in high-density non-volatile ferroelectric random access memories (NVFRAM). In order to resolve this problem, we investigate Pt/PZT/Pt capacitors before and after H 2 annealing at various temperatures. The capacitors lost their ferroelectric properties during hydrogen annealing. The measurements of polarization hysteresis loops and leakage currents suggest that there are different degradation mechanisms for the reduced PZT films. Although hydrogen induced degradation can be partially recovered by postannealing of the thin films in the O 2 ambient, all the remanent polarizations after recovery are much smaller than their virgin values, which indicates the irreversible damage of the ferroelectricity during the forming gas annealing (FGA) process. In order to investigate the degradation mechanism, X-ray diffraction was performed before and after FGA, and atomic force microscopy images were taken to observe the topograghy and microstructure changes. A conductive Pt-coated piezoelectric force microscope probe was used as a mobile top electrode to check ferroelectric and piezoelectric properties within microregions of PZT films before and after FGA.

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“…However, poor fatigue endurance of the Pt/PZT/Pt structure hinders the commercial realization of FeRAMs using such a simple electrode. 5,6) To overcome this problem, several conductive oxide electrodes have been proposed, such as IrO 2 , RuO 2 , SrRuO 3 (SRO), and (La,Sr)CoO 3 (LSCO). 4,[7][8][9] To develop FeRAMs that have competitive performance and high density, a thin film technology with fine processing ability is required.…”

Section: Introductionmentioning

confidence: 99%

Composition and Crystal Phase Control of Chemical-Vapor-Deposited Pb(Zr_x,Ti_1-x)O₃ Films on Various Oxide Electrodes with Reactants Pb(C₂H₅)₄, Zr(O-t-C₄H₉)₄, Ti(O-i-C₃H₇)₄ and O₂

Cheng¹,

Hong²

2005

Jpn. J. Appl. Phys.

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The film-composition-determining path of lead zirconate titanate chemical vapor deposition (PZT-CVD) in a cold-wall reactor operated at 773 K was studied using Pb(C2H5)4, Zr(O-t-C4H9)4, Ti(O-i-C3H7)4, and O2 as the reactants. The differences in composition and crystalline properties of PZT films grown on various oxide substrate surfaces under the same reaction conditions revealed that a heterogeneous reaction between Pb(C2H5)4 and O2 to form PbO as an intermediate plays a decisive role in determining the PZT composition in this multi-component CVD system. To explain these substrate-dependent differences in growth behavior, a reaction model was then developed that utilizes the electronegativity difference of O between the PbO and the oxide substrate as the affinity index for chemisorption of Pb(C2H5)4. This model explains well why PZT grown on IrO2 (with a strong affinity) tends to be Pb-rich in composition but Pb-deficient on (La,Sr)CoO3 (with a weak affinity).

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Mechanism of low temperature hydrogen-annealing-induced degradation in Pb(Zr0.4Ti0.6)O3 capacitors

Cited by 15 publications

References 17 publications

Recent Materials Characterizations of [2D] and [3D] Thin Film Ferroelectric Structures

Recent Materials Characterizations of [2D] and [3D] Thin Film Ferroelectric Structures

Mechanism of high temperature hydrogen reduced polarization degradation in Pb(Zr_1−xTi_x)O₃ ferroelectric thin film capacitors

Composition and Crystal Phase Control of Chemical-Vapor-Deposited Pb(Zr_x,Ti_1-x)O₃ Films on Various Oxide Electrodes with Reactants Pb(C₂H₅)₄, Zr(O-t-C₄H₉)₄, Ti(O-i-C₃H₇)₄ and O₂

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Mechanism of low temperature hydrogen-annealing-induced degradation in Pb(Zr0.4Ti0.6)O3 capacitors

Cited by 15 publications

References 17 publications

Recent Materials Characterizations of [2D] and [3D] Thin Film Ferroelectric Structures

Recent Materials Characterizations of [2D] and [3D] Thin Film Ferroelectric Structures

Mechanism of high temperature hydrogen reduced polarization degradation in Pb(Zr1−xTix)O3 ferroelectric thin film capacitors

Composition and Crystal Phase Control of Chemical-Vapor-Deposited Pb(Zrx,Ti1-x)O3 Films on Various Oxide Electrodes with Reactants Pb(C2H5)4, Zr(O-t-C4H9)4, Ti(O-i-C3H7)4 and O2

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Mechanism of high temperature hydrogen reduced polarization degradation in Pb(Zr_1−xTi_x)O₃ ferroelectric thin film capacitors

Composition and Crystal Phase Control of Chemical-Vapor-Deposited Pb(Zr_x,Ti_1-x)O₃ Films on Various Oxide Electrodes with Reactants Pb(C₂H₅)₄, Zr(O-t-C₄H₉)₄, Ti(O-i-C₃H₇)₄ and O₂