Time‐Dependent Imprint in Hf0.5Zr0.5O2 Ferroelectric Thin Films

Takada, Kenshi; Takarae, Shuya; Shimamoto, Kento; Fujimura, Norifumi; Yoshimura, Takeshi

doi:10.1002/aelm.202100151

Cited by 22 publications

(10 citation statements)

References 41 publications

(49 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This phenomenon has been described as a signature of charge trapping into the interfacial layers during the delay time (Tagantsev and Gerra, 2006). The imprint effect provides valuable information on the redistribution of charges during the delay time and could further be investigated for its timedependence (Chernikova and Markeev, 2021;Takada et al, 2021). In this paper however, we focus primarily on quantifying the polarization loss as an integral of the switching current.…”

Section: Pulse Train For Quantifying Backswitched Polarizationmentioning

confidence: 99%

Investigating charge trapping in ferroelectric thin films through transient measurements

Lancaster

Lomenzo

Engl

et al. 2022

Front. Nanotechnol.

View full text Add to dashboard Cite

A measurement technique is presented to quantify the polarization loss in ferroelectric thin films as a function of delay time during the first 100s after switching. This technique can be used to investigate charge trapping in ferroelectric thin films by analyzing the magnitude and rate of polarization loss. Exemplary measurements have been performed on Hf0.5Zr0.5O2 (HZO) and HZO/Al2O3 films, as a function of pulse width and temperature. It is found that the competing effects of the depolarization field, internal bias field and charge trapping lead to a characteristic Gaussian dependence of the rate of polarization loss on the delay time. From this, a charge trapping and screening model could be identified which describes the dynamics of polarization loss on short timescales.

show abstract

Section: Pulse Train For Quantifying Backswitched Polarizationmentioning

confidence: 99%

Investigating charge trapping in ferroelectric thin films through transient measurements

Lancaster

Lomenzo

Engl

et al. 2022

Front. Nanotechnol.

View full text Add to dashboard Cite

show abstract

“…However, a potential benefit lies in that the decrease of oxygen vacancy concentration near the TE, where crystallization first occurs, can suppress the formation of the t ‐phase. [ 43 ] It is well‐known that the t ‐phase is the one among HfO 2 /ZrO 2 polymorphs that can tolerate the most amount of oxygen vacancies. [ 24,44,45 ] Consequently, Sample T contains less t ‐phase, but more m ‐phase.…”

Section: Wake‐up Free Ferroelectric Capacitors Through Designmentioning

confidence: 99%

Designing Wake‐Up Free Ferroelectric Capacitors Based on the HfO₂/ZrO₂ Superlattice Structure

Bai

Xue

Huang

et al. 2022

Adv Elect Materials

View full text Add to dashboard Cite

In contrast to traditional ferroelectrics such as perovskite Pb(Zr,Ti)O 3 , SrBi 2 Ta 2 O 9 , and organic polyvinylidene fluoride polymers, a special wake-up phenomenon has been widely observed in hafnia-based ferroelectric capacitors, which implies that the switchable polarization is subject to variation during the initial period of capacitor lifetime. [13] Although the spontaneous polarization is actually being enhanced during wake-up, [14] the variable device parameter can cause severe problems in applications. It has been reported that the crystallization temperature is highly relevant to the wakeup process. [13,[15][16][17] In particular, a high crystallization temperature could effectively render wake-up-free ferroelectric capacitors based on HZO. [17] Therefore, raising the processing temperature is a potential solution to get rid of the wake-up phenomenon.Nevertheless, using high crystallization temperature leads to other serious problems. On the one hand, hafnia-ferroelectric capacitors usually involve TiN or TaN electrodes, which are oxygen scavenger materials at high temperature. [18] On the other hand, high temperature crystallization tends to generate the thermodynamically stable monoclinic P2 1 /c phase (m-phase) for HfO 2 or HZO, which is paraelectric. [16,19] The robust stability of monoclinic phase hinders its transformation into the ferroelectric orthorhombic Pca2 1 phase (o-phase). Hence, in most published works, the crystallization temperature was controlled at around 500 °C. [17,20,21] In this work, we attempt a special design for the ferroelectric layer that can avoid the above two problems, thus permitting a higher crystallization temperature. First of all, the concept of HfO 2 /ZrO 2 superlattice enables crystallization from the ZrO 2 side. This is possible when ZrO 2 is adjacent to an inert electrode and the heat source is only from that electrode side during rapid thermal annealing (RTA). Standard RTA instruments typically possess heating modes from upper lamps, lower lamps and both. As is well-known, the m-phase of ZrO 2 can be less stable than its tetragonal phase due to surface energy consideration, as long as the grain dimension is sufficiently small. [22][23][24] Hence, even high temperature RTA may not transform nanoscale ZrO 2 into m-phase. Secondly, an inert electrode like Pt can be selected in conjunction with the ZrO 2 layer that isThe wake-up phenomenon widely exists in hafnia-based ferroelectric capacitors, which causes device parameter variation over time. Crystallization at a higher temperature has been reported to be effective in eliminating wakeup, but high temperature may yield the monoclinic phase or generate more oxygen vacancies. In this work, a unidirectional annealing method is proposed for the crystallization of Hf 0.5 Zr 0.5 O 2 (HZO) superlattice ferroelectrics, which involves heating from the Pt/ZrO 2 interface side. It is demonstrated that 600 °C annealing only leads to a moderate content of monoclinic phase in HZO, and the TiN/HZO/Pt capacitor exhibits wake-up...

show abstract

“…Due to imprint, these memories can have a loss in endurance and retention at high operation temperatures or voltage. Imprint causes raised operation voltage and reduced retention [ 28 ] and may lead to failure. Imprint is correlated with an internal electric field that may be caused by charge injection, trapping, migration, and inhomogeneous redistribution of charges in the FE materials as well as at the interfaces of electrodes and the FE layer.…”

Section: Introductionmentioning

confidence: 99%

“…Imprint is correlated with an internal electric field that may be caused by charge injection, trapping, migration, and inhomogeneous redistribution of charges in the FE materials as well as at the interfaces of electrodes and the FE layer. [ 26,28,30 ] Yuan et al explained that in FE HZO, carrier injection followed by electron detrapping results in internal field variation and consequently leads to imprint behavior. [ 32 ] In order to improve endurance and retention characteristics, and therefore the performance of

{HfO}_{2}

‐based FE memory devices, it is necessary to have a deep understanding of the imprint issue.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Study on Imprint Behavior of Ferroelectric Hafnium Oxide Caused by High‐Temperature Annealing

Sünbül

Lehninger

Lederer

et al. 2023

Physica Status Solidi (a)

View full text Add to dashboard Cite

Hafnium oxide is found to be a favorable material for ferroelectric nonvolatile memory devices. Its compatibility with complementary metal–oxide–semiconductor processes, the relatively low crystallization temperature when zirconium‐doped, and the thickness scaling are among the advantageous properties of hafnium oxide. Different requirements must be fulfilled for different applications of hafnium oxide. Herein, high‐temperature annealing and operation conditions are analyzed in order to investigate nonvolatile memories for automotive applications. A strong imprint behavior (shift in coercive voltages) is observed after annealing hafnium–zirconium–oxide thin films at temperatures varied between 100 and 200 °C. The imprint behavior is a significant challenge in many applications. Therefore, to reduce/recover the undesirable imprint behavior caused by high‐temperature treatment, two different ways are successfully examined and delineated here: endurance cycling and applying high electric fields.

show abstract

Time‐Dependent Imprint in Hf_0.5Zr_0.5O₂ Ferroelectric Thin Films

Cited by 22 publications

References 41 publications

Investigating charge trapping in ferroelectric thin films through transient measurements

Investigating charge trapping in ferroelectric thin films through transient measurements

Designing Wake‐Up Free Ferroelectric Capacitors Based on the HfO₂/ZrO₂ Superlattice Structure

A Study on Imprint Behavior of Ferroelectric Hafnium Oxide Caused by High‐Temperature Annealing

Contact Info

Product

Resources

About

Time‐Dependent Imprint in Hf0.5Zr0.5O2 Ferroelectric Thin Films

Cited by 22 publications

References 41 publications

Investigating charge trapping in ferroelectric thin films through transient measurements

Investigating charge trapping in ferroelectric thin films through transient measurements

Designing Wake‐Up Free Ferroelectric Capacitors Based on the HfO2/ZrO2 Superlattice Structure

A Study on Imprint Behavior of Ferroelectric Hafnium Oxide Caused by High‐Temperature Annealing

Contact Info

Product

Resources

About

Time‐Dependent Imprint in Hf_0.5Zr_0.5O₂ Ferroelectric Thin Films

Designing Wake‐Up Free Ferroelectric Capacitors Based on the HfO₂/ZrO₂ Superlattice Structure