ZrO2 Negtive Capacitance Field-Effect Transistor with Sub-60 Subthreshold Swing Behavior

doi:10.21203/rs.3.rs-77514/v1

Download PDF

Nano Express

ZrO₂ Negtive Capacitance Field-Effect Transistor with Sub-60 Subthreshold Swing Behavior

https://doi.org/10.21203/rs.3.rs-77514/v1

This work is licensed under a CC BY 4.0 License

Journal Publication

published 02 Feb, 2021

Read the published version in Discover Nano →

You are reading this latest preprint version

Here we report the ZrO2 - based Negative capacitance (NC) FETs with 45.06 mV/decade subthreshold swing (SS) under ±1 V V GS range, which can achieve new opportunities in furture voltage-scalable NCFET applications. The ferroelectric-like behavior of the Ge/ZrO2/TaN capacitors is proposed to be originated from the oxygen vacancy dipoles. The NC effect of the amorphous HfO2 and ZrO2 films devices can be proved by the sudden drop of gate leakage, the negative differential resistance (NDR) phenomenon, the enhancement of I DS and sub-60 subthreshold swing. 5 nm ZrO2 - based NCFETs achieve a clockwise hysteresis of of 0.24 V, lower than 60 mV/decade SS and an 12% I DS enhancement compared to the control device without ZrO2 . The suppressed NC effect of Al2O3/HfO2 NCFET compared with ZrO2 NCFET is related to the partical swiching of oxygen vacancy dipoles in the forward sweeping due to negative interfical dipoles at the Al2O3 /HfO2 interface.

Atomic and Molecular Physics

Amorphous ZrO2

Ferroelectric

FET

Subthreshold Swing

Negative Capacitance

As complementary metal oxide semiconductor (CMOS) devices scaling down constantly, the integrated circuit (IC) technique has entered into the era of “more than Moore era”. The driving force of IC industry and technology becomes the reduction of power consumption, instead of the miniaturization of transistors [1,2]. However, the Boltzmann tyranny of MOSFETs, more than 60 mV/decade SS has restricted the energy/power effificiency [3]. In recent years, many proposed novel devices have the ability to achieve sub–60 mV/decade threshold swing, including impact ionization MOSFETs, tunnel FETs and NCFETs [4–7]. Due to the simple structure, the steep SS and imporved drive current, NCFETs with a ferroelectric (FE) film have been regarded as an attractive alternative among these emerging devices [8–10]. The reported experiments on NCFETs mainly include PbZrTiO₃ (PZT), P(VDF-TrFE) and HfZrO_x (HZO) [11–17]. Even though the ferroelectricity of these materials satisfies the requirement of the state-of-the-art technology nodes [18], the relatively high remant polarization (P_r) and coercive filed (E_c) lead to rather strong depolarization and much high power consumption [19–26]. Recently, ferroelectricity in the amorphous Al₂O₃ and ZrO₂filmsenabled bythe voltage-modulated oxygen vacancy dipoleshas been investigated [27–29]. This enables mass experiments about ZrO₂-based FeFET for nonvoile memory and analog synapse applications [30–35]. However, the systematical investigation on one-transistor ZrO₂-based NCFET has not been carried out.

In this work, Ge NCFETs with 5 nm ZrO₂ferroelectric dielectric layer and 5 nm Al₂O₃/HfO₂ ferroelectric dielectric layer have been proposed, respectively. We experimentally observed sub–60 mV/decade steep slope in ZrO₂(5 nm) NCFET, which can be attributed to the NC effect of ZrO₂ ferroelectric layer. And we analyzed the polrazation P as function of applied voltage V for the Ge/ZrO₂/TaN capacitors. The ferroelectric-like behavior of the Ge/ZrO₂/TaN capacitors is induced by the voltage-induced oxygen vacancy dipoles. Moreover, we attributed the improved I_DS and the sudden drop of I_G in the Al₂O₃/HfO₂ NCFETs and ZrO₂ NCFETs to the NC effect. We also observed the NDR phenomenon in the Al₂O₃/HfO₂ NCFETs and ZrO₂ NCFETs. In addition, we further analyzed the physical mechanism of interfical dipoles-induced decreased NC effect in the Al₂O₃/HfO₂ NCFET. The ZrO₂ NCFETs with sub–60 mV/decade steep slope, improved drain voltage and low operating voltage will be suit for the design of NCFETs with low power consumption in the “more than Moore era”.

Key process steps for NCFETs with ZrO₂ and Al₂O₃/HfO₂ fabrication are shown in Fig. 1 (a). Different gate dielectric insulators, including Al₂O₃/ amorphous HfO₂(5 nm) films and amorphous ZrO₂(4.2 nm)films were grown on n-Ge (001) substrates by atomic layer deposition (ALD) at 300^oC. TMA, TDMAHf, TDMAZr and H₂O vapor were used as the precursors of Al, Hf, Zr and O, respectively. A TaN top gate electrode was then deposited on HfO₂orZrO₂ surfaces by reactive sputtering. Source/drain (S/D) regions were defined by lithography patterning and dry etching. After that, source/drain (S/D) regions were implanted with boron (B⁺) and nickel (Ni) was deposited in source/drain (S/D) regions. Finally, rapid thermal annealing (RTA) at 350 ^oC for 30 s was carried out. Fig. 1 (b) and (d) show the schematics of the fabricated Al₂O₃/HfO₂NCFETs and ZrO₂ NCFETs. High-resolution transmission electron microscope (HRTEM) image in Fig. 1 (c) depicts the amorohous HfO₂(5 nm) film on Ge(001) with Al₂O₃ interfacial layer. HRTEM image in Fig. 1 (e) depicts the amorohous ZrO₂(4.2 nm) film on Ge (001).

Fig. 2 (a) shows the measured curves of polarization P v.s. applied voltage V characteristics for the Ge/ZrO₂/TaN capacitors at 3.3 kHz. The gate length (L_G) of the capacitors are 8 μm. It is observed that the P_rof the Ge/ZrO₂/TaN capacitors can be enhanced with larger sweeping range of V. The ferroelectric-like behavior of the amorphous ZrO₂ film in the Fig. 2 (a) is proposed to be originated from the oxygen vacancy dipoles [36]. Fig. 2 (b) shows the measured P-V curves for the Ge/ZrO₂/TaN capacitors under different frequencies from 200 Hz to 10 k Hz. We can see that the ferroelectric-like behaviorof the amorphous ZrO₂ film remain stable for all frequencies. However, the P_r of the amorphous ZrO₂ film is reduced with the increased frequencies. This phenomenon can be explained by the incomplete dipoles switching under high measurement frequencies [37,38].

Fig. 3 (a) shows the measured I_DS-V_GS curves of a ferroelectric Al₂O₃/HfO₂ NCFET at the V_DS of - 0.05 V and - 0.5 V. The L_G of the devices are 3 μm. The hysteresis loops of 0.14 V (V_ds = - 0.05 V, I_ds = 1 nA/μm) and 0.08 V (V_ds = - 0.5 V, I_ds = 1 nA/μm) are demonstrated, respectively. The clockwise hysteresis loops are attributed to the migration of oxygen vacancies and accompanied negative charges. The oxygen vacancy dipoles accumulate (deplete) in the Ge/Al₂O₃ interface under positive (negative) V_GS. Therefore, the threshold voltage (V_TH) increases (decreases) under forward (reverse) sweeping of gate voltages. As shown in Fig. 3 (b), the output characteristics of the Al₂O₃/HfO₂ NCFET and the control FET are compared. The saturation current of the Al₂O₃/HfO₂ NCFET exceeds 26 μA/μm, with a rise of 23 % compared to that of the control FET at |V_GS-V_TH| = |V_DS| = 0.8 V. The current enhancement is induced by the increased inversion charge intensity (Q_inv) in the reverse polarization electric field and the amplication of surface potential [39,40]. In addition to current enhancement, the obtained obvious NDR proves the NC effect of the amorphous HfO₂ film. The NDR effect is caused by the incomplete switching of oxygen vacancy dipoles due to the coupling of drain-to-channel as V_DSincreases [41,42]. Fig. 3 (c) compares the measured gate leakage I_G-V_GScurves for the 5 nm Al₂O₃/HfO₂ NCFET at the V_DS of - 0.05 V and –0.5 V. The sudden drops of I_Gonlyduring the reverse sweeping indicate the decreased voltage in the amorphous HfO₂film and the amplication of surface potential [43]. The absence of NC effect during the forward sweeping is caused by the partical switching of oxygen vacancy dipoles in the amorphous HfO₂ film [44]. The different ability to contain oxygen atoms between Al₂O₃ and HfO₂ layer leads to oxygen redistribution and negative interfacial dipoles at the Al₂O₃/HfO₂ interface [45–47]. Due to the presense of negative interfacial dipoles, it is difficult for the amorphous HfO₂ film to realize complete polarization swiching (NC effect) in the forward sweeping.

Fig. 4 (a) shows the measured transfer curves of a ferroelectric ZrO₂ NCFET at the V_DS of - 0.05 V and - 0.5 V. The L_G of the two devices are 4 μm. The clockwise hysteresis loops of 0.24 V (V_ds = - 0.05 V, I_ds = 1 nA/μm) and 0.14 V (V_ds = - 0.5 V, I_ds = 1 nA/μm) are demonstrated, respectively. As shown in Fig. 4 (b), the output characteristics of the ZrO₂ NCFET and the control FET are compared. The saturation current of the ZrO₂ NCFET exceeds 30 μA/μm, with a rise of 12 % compared to that of the control FET at |V_GS-V_TH| = |V_DS| = 1 V. The improved current enhancement and more obvious NDR indicate the enhanced NC effect of the amorphous ZrO₂ film (5 nm) contrast to that of 5 nm HfO₂ film. Fig. 3 (c) compares the measured gate leakage I_G-V_GScurves for the 5 nm ZrO₂ NCFET at the V_DS of - 0.05 V and - 0.5 V. Compared to the sudden I_Gdrops of Al₂O₃/HfO₂ NCFET only during reverse sweeping in Fig. 3 (c), the sudden drops of I_Gboth in forward and reverse sweeping also prove the enhanced NC effect in the amorphous ZrO₂ film.

Fig. 5 (a) and (b) shows the point SS as function of I_DS for the Al₂O₃/HfO₂ and ZrO₂ NCFET at the V_DS of - 0.05 V and - 0.5 V. Sub–60 mV/decade subthreshold swing (SS) can be achieved during forward or reverse sweeping of V_GSat the V_DS of - 0.05 V and - 0.5 V. When V_DS is - 0.05 V, a point forward SS of 45.1 mV/dec and a point reverse SS of 55.2 mV/dec were achieved. When V_DS is - 0.5 V, a point forward SS of 51.16 mV/dec and a point reverse SS of 46.52 mV/dec were achieved. Due to the different ability of scavenging effect for the Al₂O₃/HfO₂ and ZrO₂layer, the partical dipoles switching is caused in the Al₂O₃/HfO₂NCFET. Therefore, the more obvious NC effect with sub–60 mV/decade SS is achieved in 5 nm ZrO₂ NCFET.

We report the demonstration of ferroelectric NC ZrO₂ pFETs with the sub–60 mV/decade SS, low operating voltage of 1 V and a hysteresis of less than 60 mV. The impact of the amorphous ZrO₂ films on the ferroelectric behavior is explained by the oxygen vacancy dipoles. The improved I_DS and NDR phenomenon are also obtained in Al₂O₃/HfO₂ NCFETs and ZrO₂NCFETs compared to the control device. The suppressed NC effect of the Al₂O₃/HfO₂ NCFET can be attributed to partical dipole swiching due to interfical dipoles at the Al₂O₃/HfO₂ interface. The ZrO₂ NCFETs with sub–60 mV/decade steep slope, improved drain voltage and low operating voltage pave a new way for future low power consumption NCFETs design.

TaN: Tantalum nitride; ZrO₂: Zirconium dioxide; ; TDMAZr: Tetrakis (dimethylamido) zirconium; P_r: remnant polarization; E_c: coercive electric field; MOSFETs: Metal-oxide-semiconductor field-effect transistors; Ge: Germanium; ALD: Atomic layer deposition; B⁺: Boron ion; Al₂O₃: aluminum oxide; HRTEM: High-resolution transmission electron microscope; Ni: Nickel; RTA: repaid thermal annealing; I_DS: drain current; V_GS: gate voltage; V_TH: threshold voltage; NCFET: negative capacitance field-effect transistor.

Acknowledgments

Not applicable.

Funding

The authors acknowledge support from the National Key Research and Development Project (Grant No. 2018YFB2202800, 2018YFB2200500, and 2018YFA0307300) and the National Natural Science Foundation of China (Grant No. 61534004, 91964202, 61874081, 61851406, and 61775092).

Competing interests

The authors declare that they have no competing interests.

Author’s contributions

SQZ and HL drafted the manuscript and carried out the experiments. YL designed the experiments. YL and JRZ helped to revise the manuscript. YH and GQH supported the study. All the authors read and approved the final manuscript.

Author’s information

¹State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, School of Microelectronics, Xidian University, Xi’an 710071, China, *email: [email protected]

^§These authors contribute equally to this work

Availability of Data and Materials

The datasets supporting the conclusions of this article are included in the article.

Lundstrom MS. The MOSFET revisited: device physics and modeling at the nanoscale. IEEE Int. SOI Conf. 2006;1-3.
Sakurai T. Perspectives of low-power VLSI’s. IEICE Trans. Electron. 2004;429–436.
Sze S, Ng KK. Physics of Semiconductor Devices, 3rd Edition. Wiley Interscience; 2006.
Baba T. Proposal for surface tunnel transistors. Jpn. J. Appl. Phys. 1992;31:4.
Sarkar D, Xie X, Liu W, et al. A subthermionic tunnel field-effect transistor with an atomically thin channel. Nature. 2015;526:91–95.
Gopalakrishnan K, Griffifin P, Plummer J. Impact ionization MOS (IMOS)-Part I: Device and circuit simulations. IEEE Tran. Elec. Dev. 2005;52:69–76.
Salahuddin S, Datta S. Use of negative capacitance to provide voltage amplifification for low power nanoscale devices. Nano Lett. 2008;8:405–410.
Li KS, Chen PG, Lai TY, et al. Sub-60mV-swing negative-capacitance FinFET without hysteresis. IEEE International Electron Devices Meeting. 2016.
Khan AI, Yeung CW, Hu C, et al. Ferroelectric negative capacitance MOSFET: Capacitance tuning & antiferroelectric operation. IEDM Tech Dig. 2011.
Salahuddin S, Datta S. Use of negative capacitance to provide voltage amplification for low power nanoscale devices. Nano Letters, 2008;8(2):405-410.
Dasgupta S, Rajashekhar A, Majumdar K, et al. Sub-kT/q Switching in Strong Inversion in PbZr₅₂Ti_0.48O₃ Gated Negative Capacitance FETs. IEEE J Exploratory Solid-State Comput. Devices Circuits. 2017;1:43-48.
Bakaul S, Serrao C, Lee M, et al. Single crystal functional oxides on silicon. Nat Commun. 2016;7:10547.
Rusu A, Salvatore GA, Jimenez D, et al. Metal-Ferroelectric-Metal-Oxide-Semiconductor Field Effect Transistor with Sub-60mV/decade Subthreshold Swing and Internal Voltage Amplification. Electron Devices Meeting. IEDM Tech Dig. 2010.
Jo J, Shin C. Negative Capacitance Field Effect Transistor With Hysteresis-Free Sub-60-mV/Decade Switching. IEEE Electron Device Lett. 2016;37:245-248.
Lee MH, Wei YT, Chu KY, et al. Steep Slope and Near Non-Hysteresis of FETs With Antiferroelectric-Like HfZrO for Low-Power Electronics. IEEE Electron Device Lett. 2015;36:294-296.
Cheng CH, Chin A. Low-Voltage Steep Turn-On pMOSFET Using Ferroelectric High-k Gate Dielectric. IEEE Electron Device Lett. 2014;35:274-276.
Lee MH, Chen PG, Liu C, et al. Prospects for ferroelectric HfZrO_x FETs with experimentally CET=0.98nm, SS_for=42mV/dec, SS_rev=28mV/dec, switch-OFF <0.2V, and hysteresis-free strategies. IEEE International Electron Devices Meeting. 2015.
Müller J, Yurchuk E, Schlsser T, et al. Ferroelectricity in HfO₂ enables nonvolatile data storage in 28 nm HKMG. Symposium on VlSI Technology. 2012.
Schroeder U, Yurchuk E, Müller J, et al. Impact of different dopants on the switching properties of ferroelectric hafnium oxide. Jpn J Appl Phys. 2014;53:85-89.
Mueller S, Muller J, Schroeder U, et al. Reliability characteristics of ferroelectric Si:HfO₂ thin films for memory applications. IEEE T Device Mat Re. 2013;13:93-97.
Park MH, Kim HJ, Kim YJ, et al. Effect of Zr content on the wake-up effect in Hf_1–xZr_xO₂ ACS Appl Mater Inter. 2016;8:15466-15475.
Schroeder U, Richter C, Park MH, et al. Lanthanum-doped hafnium oxide: a robust ferroelectric material. Inorg Chem. 2018;57:2752-2765.
Chernikova AG, Kozodaev MG, Negrov DV, et al. Improved Ferroelectric Switching Endurance of La-Doped Hf₅Zr_0.5O₂ Thin Films. ACS Appl. Mater. Interfaces. 2018;10:2701-2708.
Hyuk PM, Hwan LY, Thomas M, et al. Review and perspective on ferroelectric HfO2-based thin films for memory applications. MRS Comm. 2018;8:795-808.
Mueller S, Yurchuk E, Slesazeck S, et al. Performance investigation and optimization of Si:HfO₂ FeFETs on a 28 nm bulk technology. Joint IEEE International Symposium on Applications of Ferroelectric and Workshop on Piezoresponse Force Microscopy. 2013;248-251.
Zhou J, Zhou Z, Wang X, et al. Demonstration of Ferroelectricity in Al-doped HfO₂ with a Low Thermal Budget of 500 °C. IEEE Electron Device Lett. 2020;41:1130-1133.
Liu H, Peng Y, Han G, et al. ZrO₂ Ferroelectric Field-Effect Transistors Enabled by the Switchable Oxygen Vacancy Dipoles. Nanoscale Res Lett. 2020;15:120.
Peng Y, Han G, Liu F, et al. Non-Volatile Field-Effect Transistors Enabled by Oxygen Vacancy Related Dipoles for Memory and Synapse Applications. IEEE Electron Device Lett. 2020.
Peng Y, Han G, Liu F, et al. Ferroelectric-like Behavior Originating from Oxygen Vacancy Dipoles in Amorphous Film for Non-volatile Memory. Nanoscale Res Lett. 2020;15:134.
Park MH, Kim HJ, Kim YJ, et al. Thin Hf_xZr_1-xO₂ Films: A New Lead-Free System for Electrostatic Supercapacitors with Large Energy Storage Density and Robust Thermal Stability. Adv Energy Mater. 2014;4:1400610.
Schroeder U, Yurchuk E, Mueller J, et al. Impact of different dopants on the switching properties of ferroelectric hafniumoxide. Jpn J Appl Phys. 2014;53:08LE02.
Liu H, Peng Y, Han G, et al. ZrO₂ ferroelectric field-effect transistors enabled by the switchable oxygen vacancy dipoles. Nanoscale Research Lett. 2020;15:120.
Peng Y, Xiao W, Liu F, et al. Non-volatile field-effect transistors enabled by oxygen vacancy related dipoles for memory and synapse applications. IEEE Electron Device Lett. 2020;67:3632-3636.
Peng Y, Han G, Liu F, et al. Ferroelectric-like behavior originating from oxygen vacancy dipoles in amorphous film for non-volatile memory. Nanoscale Research Lett. 2020;5:134.
Zhang S, Liu Y, Zhou J, et al. Low Voltage Operating 2D MoS₂ Ferroelectric Memory Transistor with Hf_1-xZr_xO₂ Gate Structure. Nanoscale Research Lett. 2020;15:157.
Glinchuk MD, Morozovska AN, Lukowiak A, et al. Possible electrochemical origin of ferroelectricity in HfO₂ thin films. J Alloy Compod. 2020;830:153628.
Ishibashi Y, Orihara H. A theory of D-E hysteresis loop. Integr Ferroelectr. 1995;9:57-61.
Scott JF, Dawber M. Atomic-scale and nanoscale self-patterning in ferroelectric thin films. AIP Conference Proceedings. 2000;535:129.
Chen HP, Lee VC, Ohoka A, et al. Modeling and Design of Ferroelectric MOSFETs. IEEE Trans Electron Devices. 2011;58:2401-2405.
Zhou J, Peng Y, Han G, et al. Hysteresis reduction in negative capacitance ge pfets enabled by modulating ferroelectric properties in HfZrO_x. IEEE J Electron Dev. 2017;6:41-48.
Saha AK, Sharma P, Dabo I, et al. Ferroelectric transistor model based on self-consistent solution of 2D Poisson's, non-equilibrium Green's function and multi-domain Landau Khalatnikov equations. IEEE International Electron Devices Meeting. 2018.
Zhou J, Han G, Li J, et al. Negative differential resistance in negative capacitance FETs. IEEE Electron Device Lett. 2018;39:622-625.
Zhou J, Han G, Li Q, et al. Ferroelectric HfZrO_x Ge and GeSn PMOSFETs with Sub-60 mV/decade subthreshold swing, negligible hysteresis, and improved I_ds. IEEE International Electron Devices Meeting. 2017.
Sharma P, Tapily K, Saha AK, et al. Impact of total and partial dipole switching on the switching slope of gate-last negative capacitance FETs with ferroelectric hafnium zirconium oxide gate stack. Symposium on VlSI Technology. 2017.
Lin L, Robertson J. Atomic mechanism of electric dipole formed at high-K: SiO₂ J Appl Phys. 2011;109:9.
Sharia O, Demkov AA, Bersuker G, et al. Theoretical study of the insulator/insulator interface: band alignment at the SiO₂/HfO₂ Phys Rev B. 2007;75:3.
Kim G, Kim T, Jeon S. Interfacial Dipole Modulation Device with SiO_X Switching Species. IEEE Electron Device Lett. 2020.

Download PDF

Journal Publication

published 02 Feb, 2021

Read the published version in Discover Nano →

Editorial decision: Major revision
31 Oct, 2020
Review #1 received at journal
27 Oct, 2020
Review #2 received at journal
26 Oct, 2020
Reviewer #1 agreed at journal
16 Oct, 2020
Reviewer #2 agreed at journal
16 Oct, 2020
Reviewers invited by journal
29 Sep, 2020
Editor assigned by journal
14 Sep, 2020
First submitted to journal
13 Sep, 2020
Submission checks completed at journal
13 Sep, 2020
Editor invited by journal
13 Sep, 2020

You are reading this latest preprint version

ZrO₂ Negtive Capacitance Field-Effect Transistor with Sub-60 Subthreshold Swing Behavior

Status:

Journal Publication

Version 1

Abstract

Figures

Background

Methods

Results And Discussion

Conclusions

Abbreviations

Declarations

References

Status:

Journal Publication

Version 1