Search query: TiN HZO ferroeletric

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abstract: Deposition, annealing, and integration of ferroelectric Hf x Zr 1 x O 2 (HZO) thin films on the high mobility semiconductor InAs using atomic layer deposition are investigated. Electrical characterization reveals that the HZO films on InAs exhibit an enhanced remanent polarization compared to films formed on a reference TiN substrate, exceeding 20 m C cm 2 even down to an annealing temperature of 370 degC. For device applications, the thermal processes required to form the ferroelectric HZO phase must not degrade the high k/InAs interface. We find by evaluation of the capacitance voltage characteristics that the electrical properties of the high k/InAs are not significantly degraded by the annealing process, and high resolution transmission electron microscopy verifies a maintained sharp high k/InAs interface. (Less)
author_names: Anton E O Persson

Robin Athle

Pontus Littow

Karl-Magnus Persson

Johannes Svensson

Mattias Borg

Lars-Erik Wernersson
title: Reduced annealing temperature for ferroelectric HZO on InAs with enhanced polarization
year: 2020

abstract: In this letter, the endurance property of Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub>(HZO) based ferroelectric capacitor has been improved using Ru electrodes. Compared to the widely used TiN/HZO/TiN capacitor, the Ru/HZO/Ru capacitor shows comparable remnant polarization <inline formula> <tex math notation="LaTeX"\sim }20~\mu C/cm^{2} /tex math>/inline formula> lower leakage current <inline formula> <tex math notation="LaTeX"$5.67\times 10^ 5}A/cm^{2} /tex math>/inline formula> and higher breakdown electric field ~4 MV/cm) at room temperature. The reduction of the leakage current and the enhancement of the breakdown electric field, which are ascribed to the small number of defects and vacancies in HZO thin films with Ru electrodes, prompt the endurance improvement of HZO based capacitor from <inline formula> <tex math notation="LaTeX"$3\times 10^{10} /tex math>/inline formula> cycles for TiN electrodes at 3 MV/cm to more than <inline formula> <tex math notation="LaTeX"$1.2 \times 10^{11} /tex math>/inline formula> cycles for Ru electrodes at 3.5 MV/cm. This work provides an effective way to reduce the leakage current and improve the endurance property of HZO based capacitors.
author_names: Rongrong Cao

Qi Liu

Ming Liu

Bing Song

Dashan Shang

Yang Yang

Qing Luo

Shuyu Wu

Yufeng Li

Hangbing Lv
title: Improvement of Endurance in HZO Based Ferroelectric Capacitor Using Ru Electrode
venue: IEEE Electron Device Letters
year: 2019

abstract: The wake up effect is a major issue for ferroelectric HfO2 based memory devices. Here, two TiN/HZO/TiN structures deposited by magnetron sputtering on silicon are compared. The maximum remanant pol.
author_names: Jordan Bouaziz

Pedro Rojo Romeo

Nicolas Baboux

Bertrand Vilquin
title: Huge Reduction of the Wake Up Effect in Ferroelectric HZO Thin Films
venue: ACS Applied Electronic Materials
year: 2019

abstract: Nanosheet line tunnel field effect transistors (NLTFETs) are for the first time proposed by utilizing the advantages of ferroelectricity through HZO materials. Three ferroelectric line TFETs have been proposed and investigated. Among these, the metal ferroelectric semiconductor (MFS) structure has shown superior performance than the other two variants. The factors of electric field and electron barrier tunneling have been addressed to govern the performance of these structures. In addition, the effects of the ferroelectric (Hf0.5 Zr0.5 O2) thickness (tFE) and the dielectric constant have been discussed. The MFS NLTFETs can effectively utilize the advantages of ferroelectric than the other variants. High on current of 175.6 \mu \mathrm{A}\mu \mathrm{m} and low off current of 38.4 aA/\mu \mathrm{m} are achieved at tFE of 4 nm through proper utilization of gate overlap on to the drain side. Furthermore, the proposed MFS structure successfully delivers low average and minimum subthreshold swings even at very thin tFE.
author_names: Narasimhulu Thoti

Yiming Li

Sekhar Reddy Kola

Seiji Samukawa
title: High Performance Metal Ferroeletric Semiconductor Nanosheet Line Tunneling Field Effect Transistors with Strained SiGe
venue: 2020 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD)
year: 2020

abstract: We report the observation of ferroelectricity in hafnium zirconium oxide thin films in the as deposited state, namely, after deposition at a low temperature of 300 degC without post metallization annealing. The Hf0.5Zr0.5O2 (HZO) thin film was interposed between two TiO2 interlayers, and all films were produced by plasma enhanced atomic layer deposition and integrated into a TiN based metal insulator metal capacitor. The ferroelectric nature of the as deposited HZO film was evaluated by a polarization voltage hysteresis loop, and a 2Pr value of ~7.4 mC/cm2 was achieved. Grazing incidence x ray diffraction measurements and atomic resolution scanning transmission electron microscopy characterization revealed the co existence of fully crystallized polar orthorhombic and monoclinic phases of the dielectric in the as deposited sample. We concluded that the nucleation and growth of the crystalline polar non centrosymmetric orthorhombic phases in the 10 nm HZO thin film were prompted by the available energy from the plasma and the tensile lattice mismatch strain provided by the TiO2 interlayer.
author_names: Yuanshen Qi

Xianbin Xu

Igor Krylov

Moshe Eizenberg
title: Ferroelectricity of as deposited HZO fabricated by plasma enhanced atomic layer deposition at 300 degC by inserting TiO2 interlayers
year: 2021

abstract: The discovery of ferroelectricity in HfO2 based materials in 2011 provided new research directions and opportunities. In particular, for atomic layer deposited Hf0.5Zr0.5O2 (HZO) films, it is possible to obtain homogenous thin films with satisfactory ferroelectric properties at a low thermal budget process. Based on experiment demonstrations over the past 10 years, it is well known that HZO films show excellent ferroelectricity when sandwiched between TiN top and bottom electrodes. This work reports a comprehensive study on the effect of TiN top and bottom electrodes on the ferroelectric properties of HZO thin films (10 nm) Investigations showed that during HZO crystallization, the TiN bottom electrode promoted ferroelectric phase formation (by oxygen scavenging) and the TiN top electrode inhibited non ferroelectric phase formation (by stress induced crystallization) In addition, it was confirmed that the TiN top and bottom electrodes acted as a barrier layer to hydrogen diffusion into the HZO thin film during annealing in a hydrogen containing atmosphere. These features make the TiN electrodes a useful strategy for improving and preserving the ferroelectric properties of HZO thin films for next generation memory applications.
author_names: Si Joon Kim

Jaidah Mohan

Harrison Sejoon Kim

Su Min Hwang

Namhun Kim

Yong Chan Jung

Akshay Sahota

Kihyun Kim

Hyun-Yong Yu

Pil-Ryung Cha

Chadwin D Young

Rino Choi

Jinho Ahn

Jiyoung Kim
title: A Comprehensive Study on the Effect of TiN Top and Bottom Electrodes on Atomic Layer Deposited Ferroelectric Hf0.5Zr0.5O2 Thin Films
venue: Materials
year: 2020

abstract: Ferroelectric Hf0.5Zr0.5O2 (HZO) films were grown by the atomic layer deposition (ALD) technique on an ALD or physical vapor deposited (PVD, sputtering) TiN bottom electrode (BE) The PVD TiN film showed small grains with flat surface morphology, mainly consisting of the (111) crystallographic plane. In contrast, the ALD TiN film exhibited a larger diameter and faceted grain shapes, with the (200) crystallographic surface planes. The 10 nm thick HZO film on the ALD TiN BE showed a lower internal field, enhanced endurance >1 x 1010 cycle at 2.5 MV/cm) and decreased leakage current than identical HZO films on the PVD TiN BE. Lower interfacial oxidation of the ALD TiN BE as a result of the smaller grain boundary area of the ALD TiN induced a lower defect density in the HZO film. The higher work function of the ALD TiN film also contributed to the lowering of the leakage current.
author_names: Baek Su Kim

Seung Dam Hyun

Ho Hyun Kim
title: Study of ferroelectric characteristics of Hf0.5Zr0.5O2 thin films grown on sputtered or atomic layer deposited TiN bottom electrodes
year: 2020

abstract: In this paper, we propose a method to improve the performance of TiN/Hf0.5Zr0.5O2 (HZO)/TiN Nano capacitors used in memory devices. Instead of direct fabrication of the TiN/HZO/TiN device, our method involves an intermediate step in which W metal is used as a capping material to induce a large in plane tensile strain during rapid thermal annealing, resulting in a total suppression of the monoclinic phase and the appearance of the ferroelectric phase. Consequently, after removing the W capping electrode through an etching process and the post deposition of a TiN top electrode at room temperature, a high remnant polarization of approximately 40 uC/cm2 and a 65% increase of coercive field were obtained. Moreover, the leakage current was reduced by an order of magnitude compared to the normal TiN/HZO/TiN capacitor; this result is attributed to the presence (absence) of the W/HZO (TiN/HZO) top interface during thermal annealing. The formation of a TiOx interfacial layer at elevated temperatures, which pulls oxygen from the HZO layer, resulting in the formation of oxygen vacancies, is the main cause of the high leakage current through the TiN/HZO/TiN stacks. It was confirmed that the re capped TiN/HZO/TiN capacitor has a comparable endurance to a normal capacitor. Our results offer the re capping process as a promising approach to fabricating HfO2 based ferroelectric memory devices with various electrode materials.
author_names: Hyungwoo Kim

Alireza Kashir

Seung-Yong Oh

Hyunsang Hwang
title: A new approach to achieving strong ferroelectric properties in TiN/Hf0.5Zr0.5O2/TiN devices.
venue: Nanotechnology
year: 2020

abstract: In recent years, hafnium zirconium oxide (HZO) has received significant attention of the research community due to the demontsrattion of ferroelectricity at sub 10 nm thickness and good CMOS compatibility. However, ferroelectricity in HZO is dependent on various factors such as the HZO composition, materials used as top or bottom electrode, post metallization technique, annealing pressure and temperature etc. Herein, we have systematically investigated the effect of high pressure post metallization annealing (HPPMA) temperature on the ferroelectric properties of TiN/Hf0.25Zr0.75O2/TiN capacitors. Hf0.25Zr0.75O2, that show antiferroelectric behavior in rapid thermal annealing, demonstrate antiferroelectric to ferroelectric phase transition depending on the HPPMA temperature. Maximum remanent polarization (Pr) of ~29mC/cm2 is achieved for HPPMA temperature 550 degC whereas the maximum dielectric constant (k) of ~46 is achieved for HPPMA temperature 350 degC. The interfacial capacitance of the MFM capacitors increased with increasing the HPPMA annealing temperature. The results obtained in this study open up the possibility of achieving high k ferroelectric capacitors using Zr rich HZO films that can be applicable to various electronic devices.
author_names: Sanghun Jeon

Dipjyoti Das

Venkateswarlu Gaddam
title: Effect of High Pressure Annealing Temperature on the Ferroelectric Properties of TiN/Hf0.25Zr0.75O2/TiN Capacitors
venue: 2020 4th IEEE Electron Devices Technology Manufacturing Conference (EDTM)
year: 2020

abstract: Introduction The HfO2 based ferroelectric fieldeffect transistor (FeFET) has attracted a significant interest because of its scalability and CMOS process compatibility for possible applications such as memory and neuromorphic computing [1, 2] Here, the interfacial layer (IL) plays a critical role in the FeFET performance. Formation of the ferroelectric ophase in doped HfO2 is largely dependent on the boundary conditions provided by IL [3] In addition, scaling the thickness of IL is crucial for achieving low voltage operation [4] Moreover, the inversion charge density [5] of FeFETs is much lower than in theoretical prediction because of the strong electron trapping in or near the ILs. In this work, the effects of Al2O3 ILs in the ferroelectric characteristics of TiN/Hf0.5Zr0.5O2 (HZO)/Si gate stacks are studied in comparison with SiOx ILs by the positive up negative down (PUND) measurements. The effects of annealing time and ambient between N2 and forming gas (FG) are also examined. Experimental The key process steps of the device fabrication are shown in Fig. 1(a) 1 nm thick Al2O3 was grown on a HF last pre cleaned p+ Si substrates before the deposition of 8.6, 10.2, 11.2, and 12.2 nm HZO by ALD. For comparison, we also prepared capacitors without intentional ILs, where SiOx ILs has been formed on Si [5] caused by OH dense atmosphere before the nucleation of HZO [6] Then, 60 nm TiN was sputtered followed by the thermal evaporation of 100 nm Al as the top electrode. After patterning, annealing for 1 min or 20 min in N2, or 20 min in FG, was carried out at 400 C for inducing ferroelectricity. The ferroelectric characteristics were evaluated by the PUND method with a 4 V/1k Hz triangular waveform after 100 wake up cycles with 4 V/1k Hz. Results and Discussion Fig. 1(b) shows the relationship between the capacitance equivalentthickness (CET) and the physical thickness of the HZO stacks with Al2O3 or SiOx IL. The physical thickness of HZO and CET were determined by ellipsometry and the Q V measurement, respectively. CET of ILs obtained from the intercept, and the kvalues of HZO obtained from the slope, are almost the same between the two types of stacks (5 A and 23, respectively) Thus, same voltage 4 V) is used in the following PUND measurements to ensure equal effective electric field (EOX) for the two stacks. The representative P V and I V curves for the 11.2 nm thick HZO stacks with SiOx and Al2O3 IL are shown in Fig. 2(a) 2Pr and VC extracted for 8.6, 10.2, 11.2, and 12.2 nm thick HZO are shown in Fig.2(b) and (c) respectively. It is found that the capacitors with Al2O3 IL consistently show larger 2Pr and |VC| Since CET of the stacks at the given HZO thickness and ILs is almost the same between SiOx and Al2O3 IL, we can conclude that the better ferroelectricity of the gate stacks with Al2O3 IL is due to the change of HZO properties, rather than the difference in the voltage divider effect due to ILs [7] The physical origin of this improvement needs to be further investigated. The effects of annealing time and ambient for the 12.2 nm thick HZO stacks with Al2O3 and SiOx IL are shown in Fig. 3(a) and (b) respectively. It is observed that 2Pr of the stack with SiOx IL decreases after long time annealing, while that with Al2O3 IL has negligible change. The present phenomenon may be attributable to higher stability against transformation from o phase to m phase of HZO for stack with Al2O3 IL during long time annealing [4] and/or to suppression of any intermixing between HZO and Si [8] by Al2O3 IL as a diffusion barrier. Moreover, it is found that FGA has little impact to capacitors with SiOx and Al2O3 IL. Conclusion We have demonstrated the improvement of 2Pr for the TiN/HZO/Si ferroelectric gate stacks with Al2O3 IL in comparison with conventional SiOx IL. Moreover, higher robustness against long time annealing has also been achieved with Al2O3 IL.
author_names: T -E Lee

H Z Tang

Kasidit Toprasertpong

Mitsuru Takenaka

Shinichi Takagi
title: Improvement of ferroelectric properties of TiN/Hf0.5Zr0.5O2/Si gate stacks by inserting Al2O3 interfacial layers
year: 2020