Enhanced Reliability of Ferroelectric HfZrO<sub>
                     <i>x</i>
                  </sub> on Semiconductor by Using Epitaxial SiGe as Substrate

Chen, Kuen-Yi; Huang, Y. L.; Kao, Ruei-Wen; Lin, Yan-Xiao; Hsieh, K.C.; Wu, Yung-Hsien

doi:10.1109/ted.2019.2921825

Cited by 14 publications

(10 citation statements)

References 11 publications

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“…However, both types of devices do not show the wake-up effect for Fe-HZO and it is due mainly to the fact that the oxygen vacancies-induced undesirable effect has been effectively reduced by NH 3 plasma treatment at the metal/ferroelectric interface . Besides characterizing endurance performance, retention behaviors that include same-state (SS) retention and opposite-state (OS) retention were also investigated where SS is typically affected by the depolarization effect, whereas OS is highly correlated to both depolarization and imprint effect Figure d shows the SS and OS retention of P r at 85 °C for devices with poly-Ge and poly-GeSn channels.…”

Section: Resultsmentioning

confidence: 99%

“…22 Besides characterizing endurance performance, retention behaviors that include same-state (SS) retention and opposite-state (OS) retention were also investigated where SS is typically affected by the depolarization effect, whereas OS is highly correlated to both depolarization and imprint effect. 23 Figure 2d shows the SS and OS retention of P r at 85 °C for devices with poly-Ge and poly-GeSn channels. SS retention has been tested at 85 °C and insignificant degradation is observed for both types of devices.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…These defects would lead to charge trapping at the HZO/poly-GeSn interface and build an internal field, inducing the coercive voltage shift and P r degradation. 23,25 From the XRD patterns shown in Figure 1, it can be inferred that the grain size of HZO with poly-GeSn and poly-GeSn itself is larger than the counterpart because of the sharper and smaller fwhm of the diffraction peak. A film with a larger grain size typically corresponds to a lower grain boundary density and fewer defects, which lead to better HZO/poly-GeSn interfacial quality.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Junctionless Poly-GeSn Ferroelectric Thin-Film Transistors with Improved Reliability by Interface Engineering for Neuromorphic Computing

Chou

Lin

Huang

et al. 2019

ACS Appl. Mater. Interfaces

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Ferroelectric HfZrO x (Fe-HZO) with a larger remnant polarization (P r) is achieved by using a poly-GeSn film as a channel material as compared with a poly-Ge film because of the lower thermal expansion that induces higher stress. Then two-stage interface engineering of junctionless poly-GeSn (Sn of ∼5.1%) ferroelectric thin-film transistors (Fe-TFTs) based on HZO was employed to improve the reliability characteristics. With stage I of NH3 plasma treatment on poly-GeSn and subsequent stage II of Ta2O5 interfacial layer growth, the interfacial quality between Fe-HZO and the poly-GeSn channel is greatly improved, which in turn enhances the reliability performance in terms of negligible P r degradation up to 106 cycles (±2.7 MV/1 ms) and 96% P r after a 10 year retention at 85 °C. Furthermore, to emulate the synapse plasticity of the human brain for neuromorphic computing, besides manifesting the capability of short-term plasticity, the devices also exhibit long-term plasticity with the characteristics of analog conductance (G) states of 80 levels (>6 bit), small linearity for potentiation and depression of −0.83 and 0.62, high symmetry, and moderate G max/G min of 9.6. By employing deep neural network, the neuromorphic system with poly-GeSn Fe-TFT synaptic devices achieves 91.4% pattern recognition accuracy. In addition, the learning algorithm of spike-timing-dependent plasticity based on spiking neural network is demonstrated as well. The results are promising for on-chip training, making it possible to implement neuromorphic computing by monolithic 3D ICs based on poly-GeSn Fe-TFTs.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

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Junctionless Poly-GeSn Ferroelectric Thin-Film Transistors with Improved Reliability by Interface Engineering for Neuromorphic Computing

Chou

Lin

Huang

et al. 2019

ACS Appl. Mater. Interfaces

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“…17,21,22 By characterizing MFS capacitors, it has been reported that semiconductor substrates have a significant effect on the ferroelectric properties. 23,24 On the other hand, there are two concerns with the characterization of separate MFS capacitors as a method to predict the ferroelectricity of ferroelectric gates insulators in FeFETs. First, high doping concentration in the order of 10 19 to 10 20 cm -3 is usually employed in the semiconductor substrates of MFS capacitors (called here as MFS + ) to minimize the substrate depletion.…”

mentioning

confidence: 99%

Evaluation of polarization characteristics in metal/ferroelectric/semiconductor capacitors and ferroelectric field-effect transistors

Toprasertpong

Tahara

Takenaka

et al. 2020

Applied Physics Letters

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In this study, we propose a measurement technique for evaluating ferroelectric polarization characteristics in ferroelectric field-effect transistors (FeFETs). Different from standard metal/ferroelectric/metal capacitors, the depletion and inversion phenomena in semiconductor substrates have to be carefully taken into account when evaluating the ferroelectric properties using fast voltage sweep as input. The non-equilibrium deep depletion is found to be the limiting factor for the accurate evaluation of ferroelectric properties in metal/ferroelectric/semiconductor capacitors. By connecting the source, drain, and substrate of the FeFET together during the polarization measurement, the deep depletion can be suppressed and the ferroelectricity of the ferroelectric gate can be accurately evaluated. The present technique is a powerful method for capturing the polarization states in FeFETs, enabling new approaches for device characterization and fundamental study, and overcomes the limitation found in the conventional polarization measurement on 2-terminal metal/ferroelectric/semiconductor capacitors.Ferroelectric field-effect transistors (FeFETs), in which ferroelectric thin films are employed as FET gate insulators, are promising for non-volatile memory devices 1-3 and synaptic devices in computing-in-memory applications. 4-6 A substantially increasing interest in FeFETs can be seen after the discovery of ferroelectric HfO 2 7 thanks to its scalability and CMOS compatibility, 3 with FeFETs having excellent performance being continuously reported. [8][9][10][11] So far, the characterization of FeFETs is mainly limited to the standard evaluation of I d -V g characteristics and threshold voltage shift ∆V T as well as their retention and endurance properties. 3,5,[8][9][10][11][12][13][14][15][16][17] On the other hand, the ferroelectric properties of the ferroelectric gate insulators are usually evaluated in an indirect manner, by preparing separate metal/ferroelectric/metal (MFM) capacitors for characterization. 3,5,8,[14][15][16] It is usually assumed that the ferroelectric properties of the separately-prepared MFM capacitors can well reproduce those of the ferroelectric gate insulators in the FeFETs. However, it is questionable whether MFM capacitors can represent the ferroelectricity of the ferroelectric gate insulators, particularly for metal/ferroelectric/semiconductor (MFS, or sometimes called MFIS if the dielectric insulator layer should be emphasized)-type FeFETs, as it is well recognized that the ferroelectric properties of HfO2 is strongly dependent on the underlying and capping layers. [17][18][19][20] To carry out more accurate characterization, MFS capacitors are frequently employed to reproduce the same substrate condition as the ferroelectric gates in FeFETs. 17,21,22 By characterizing MFS capacitors, it has been reported that semiconductor substrates have a significant effect on the ferroelectric properties. 23,24 On the other hand, there are two concerns with the characterization of separate MFS capaci...

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“…27 In contrast, reducing the IL thickness using microwave annealing that provides a lower thermal budget than conventional rapid thermal annealing (RTA) lowered V sw but did not effectively inhibit IL formation during annealing, and the P r was less than 5 μC cm −2 . 28,29 Alternatively, the improvement of endurance and retention properties by intentionally forming high- k IL of SiON instead of SiO 2 using a high-temperature nitridation 30,31 and by using an epitaxial SiGe substrate that forms less IL compared to the Si substrate 32 has been reported. Moreover, oxygen scavenging, examined in high- k /metal gate technology to reduce or eliminate IL, was conducted for IL scaling in the MFM structure, 33,34 MFIS structure, 35 and template layer, 36 but the effect on endurance and retention properties of MFIS structure is still unclear.…”

Section: Introductionmentioning

confidence: 99%

Oxygen scavenging of HfZrO₂-based capacitors for improving ferroelectric properties

et al. 2022

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Enhanced Reliability of Ferroelectric HfZrO_x on Semiconductor by Using Epitaxial SiGe as Substrate

Cited by 14 publications

References 11 publications

Junctionless Poly-GeSn Ferroelectric Thin-Film Transistors with Improved Reliability by Interface Engineering for Neuromorphic Computing

Junctionless Poly-GeSn Ferroelectric Thin-Film Transistors with Improved Reliability by Interface Engineering for Neuromorphic Computing

Evaluation of polarization characteristics in metal/ferroelectric/semiconductor capacitors and ferroelectric field-effect transistors

Oxygen scavenging of HfZrO₂-based capacitors for improving ferroelectric properties

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Enhanced Reliability of Ferroelectric HfZrO x on Semiconductor by Using Epitaxial SiGe as Substrate

Cited by 14 publications

References 11 publications

Junctionless Poly-GeSn Ferroelectric Thin-Film Transistors with Improved Reliability by Interface Engineering for Neuromorphic Computing

Junctionless Poly-GeSn Ferroelectric Thin-Film Transistors with Improved Reliability by Interface Engineering for Neuromorphic Computing

Evaluation of polarization characteristics in metal/ferroelectric/semiconductor capacitors and ferroelectric field-effect transistors

Oxygen scavenging of HfZrO2-based capacitors for improving ferroelectric properties

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Enhanced Reliability of Ferroelectric HfZrO_x on Semiconductor by Using Epitaxial SiGe as Substrate

Oxygen scavenging of HfZrO₂-based capacitors for improving ferroelectric properties