Plasma Enhanced Atomic Layer Deposited HfO2 Ferroelectric Films for Non-volatile Memory Applications (original) (raw)
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Journal of Materials Science: Materials in Electronics, 2019
For this proposed work, the comparison of structural, electrical, dielectric, and ferroelectric properties of HfO 2 film deposited by plasma-enhanced atomic layer deposition (PEALD) and radio frequency (RF) sputtering technique. Various characteristics has been obtained by fabricating the metal-ferroelectric-silicon (MFeS) and metal-ferroelectric-metal (MFeM) capacitors with different thickness of HfO 2 (5, 10, 15, 20 nm) as a ferroelectric layer deposited on silicon and TiN/Silicon. The structural properties such as crystallographic phase, grain size with composition and refractive index of the deposited film were measured by X-ray diffraction, Field emission scanning electron microscopy with energy dispersive spectroscopy (FESEM-EDS) and multiple angle ellipsometry with the variation in annealing temperature. MFeS and MFeM structure were fabricated to obtain electrical and ferroelectric properties such as memory window, leakage current density, closed loop hysteresis, remnant polarization, charge, coercive field voltage, data retention time, endurance, and breakdown voltage of the deposited film. MFeS structure shows the memory window and flat band voltage shift of 4 V and 1.72 V, respectively for 10 nm PEALD-deposited HfO 2 layer. For the sputtered 15 nm film, maximum memory window of 4.32 V and leakage current density of 1.2 × 10 8 A/cm 2 has been observed at the annealing temperature of 800 °C. Remnant polarization of 4 and 1.2 μC/cm 2 obtained for PEALD and sputtered HfO 2 film. The fabricated structure shows data retention for greater than 10 years and fatigue resistance for higher than 10 12 read/write cycles. The reliability of the thin film was investigated by measuring the breakdown voltages of MFeS structure for different film thickness.
Ferroelectrics Letters Section, 2019
Sr 0.8 Bi 2.2 Ta 2 O 9 (SBT) ferroelectric and HfO 2 dielectric layers were successively deposited onto the p-type (100) Si substrate via RF sputtering. Metal-Ferroelectric-Insulator-Silicon (MFIS) capacitors were fabricated with 200 nm SBT and 10 nm HfO 2 film shows the improved memory window of 1.811 V as compared to the 1.27 V in Metal-Ferroelectric-Silicon (MFS) structures. Improvement in leakage current and breakdown voltage was also observed in the MFIS structures as compared to the MFS structures. Degradation of ferroelectric polarization was not pronounced even after applying 8 Â 10 12 bipolar cycles in MF (200nm) I (10nm) S structures and the device shows significant data retention time of more than 2.5 hours.
IOP conference series, 2014
Metal-ferroelectric (Mn-substituted BiFeO 3)-insulator (HfO 2)-semiconductor has been fabricated by cosputtering technique. X-ray diffraction (XRD) patterns have proven the existence of a substitution phase. The shift in binding energy of Fe ions and the change in atom ratio of Mn to Fe were analyzed by X-ray photoelectron spectra (XPS). The memory windows as functions of insulator film thickness and annealing temperature were compared. The maximum memory window is 3 V at the sweep voltage of 8 V with thicker (60 nm) HfO 2. The leakage current and the charge injection effect can be reduced with increasing the amount of substituting Mn for Fe-site.
Materials Science & Engineering R-reports, 2001
We present in this article a review of the status of thin film ferroelectric materials for nonvolatile memories. Key materials issues relevant to the integration of these materials on Si wafers are discussed. The effect of film microstructure and electrode defect chemistry on the ferroelectric properties relevant to a high density nonvolatile memory technology are discussed. The second part of this review focuses on approaches to integrate these capacitor structures on a filled poly-Si plug which is a critical requirement for a high density memory technology. Finally, the use of novel surface probes to study and understand broadband polarization dynamics in ferroelectric thin films is also presented. # 2001 Published by Elsevier Science B.V.
Applied Physics Letters, 2020
The reliability of Hf0.5Zr0.5O2 (HZO) metal-ferroelectric-semiconductor capacitors grown by plasma assisted atomic oxygen deposition on Ge substrates is investigated with an emphasis on the influence of crystallization annealing. The capacitors show very weak wake-up and imprint effects allowing reliable operation in excess of 10 years, which is attributed partly to the clean, oxide-free Ge/HZO bottom interface. The weak temperature dependence as well as the observed asymmetries between polarization up and down states and between positive and negative coercive voltage shifts, lead to the conclusion that imprint is controlled by carrier injection at the top electrode interface. The latter mechanism is associated with trapping at interfacial oxygen-vacancy defects. On the other hand, using ultrafast (millisecond) flash annealing improves the leakage current by at least an order of magnitude and the endurance by a factor of 3 compared to conventional rapid thermal annealing, which makes them suitable for low power non-volatile memory applications where (ultra)thin HZO is an essential requirement.
Phys. Chem. Chem. …, 2010
We have used a sol-gel spin-coating process to fabricate a new metal-insulator-metal (MIM) capacitor comprising a 10 nm-thick high-k thin dielectric HfO 2 film on a flexible polyimide (PI) substrate. The surface morphology of this HfO 2 film was investigated using atomic force microscopy and scanning electron microscopy, which confirmed that continuous and crack-free film growth had occurred on the film surface. After oxygen (O 2 ) plasma pretreatment and subsequent annealing at 250 1C, the film on the PI substrate exhibited a low leakage current density of 3.64 Â 10 À9 A cm À2 at 5 V and a maximum capacitance density of 10.35 fF mm À2 at 1 MHz. The as-deposited sol-gel film was completely oxidized when employing O 2 plasma at a relatively low temperature (ca. 250 1C), thereby enhancing the electrical performance. We employed X-ray photoelectron spectroscopy (XPS) at both high and low resolution to examine the chemical composition of the film subjected to various treatment conditions. The shift of the XPS peaks towards higher binding energy, revealed that O 2 plasma treatment was the most effective process for the complete oxidation of hafnium atoms at low temperature. A study of the insulator properties indicated the excellent bendability of our MIM capacitor; the flexible PI substrate could be bent up to 10 5 times and folded to near 3601 without any deterioration in its electrical performance. w Electronic supplementary information (ESI) available: Low resolution XPS spectra of sol-gel deposited HfO 2 film on Cr/PI substrate for as deposited-baking and annealing at 250 1C treated samples. See
Scientific reports, 2015
We introduce a novel lead-free ferroelectric thin film (1-x)BaTiO3-xBa(Cu1/3Nb2/3)O3 (x = 0.025) (BT-BCN) integrated on to HfO2 buffered Si for non-volatile memory (NVM) applications. Piezoelectric force microscopy (PFM), x-ray diffraction, and high resolution transmission electron microscopy were employed to establish the ferroelectricity in BT-BCN thin films. PFM study reveals that the domains reversal occurs with 180° phase change by applying external voltage, demonstrating its effectiveness for NVM device applications. X-ray photoelectron microscopy was used to investigate the band alignments between atomic layer deposited HfO2 and pulsed laser deposited BT-BCN films. Programming and erasing operations were explained on the basis of band-alignments. The structure offers large memory window, low leakage current, and high and low capacitance values that were easily distinguishable even after ~10(6) s, indicating strong charge storage potential. This study explains a new approach t...
Applied Physics Letters, 2020
The reliability of Hf0.5Zr0.5O2 (HZO) metal-ferroelectric-semiconductor capacitors grown by plasma assisted atomic oxygen deposition on Ge substrates is investigated with an emphasis on the influence of crystallization annealing. The capacitors show very weak wake-up and imprint effects allowing reliable operation in excess of 10 years, which is attributed partly to the clean, oxide-free Ge/HZO bottom interface. The weak temperature dependence as well as the observed asymmetries between polarization up and down states and between positive and negative coercive voltage shifts, lead to the conclusion that imprint is controlled by carrier injection at the top electrode interface. The latter mechanism is associated with trapping at interfacial oxygen-vacancy defects. On the other hand, using ultrafast (millisecond) flash annealing improves the leakage current by at least an order of magnitude and the endurance by a factor of 3 compared to conventional rapid thermal annealing, which makes them suitable for low power non-volatile memory applications where (ultra)thin HZO is an essential requirement.
Plasma treatment of HfO2-based metal–insulator–metal resistive memories
Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 2011
This work focuses on Au/HfO 2 /TiN nonvolatile resistive memory [resistive random access memories (RRAMs)] stacks, where HfO 2 is deposited by the atomic layer deposition technique on TiN electrodes. For as-grown RRAMs, no Reset is observed (the structure remains locked in a low resistive state). It is observed that an NH 3 plasma treatment of the HfO 2 /TiN bilayer can restore a Reset stage. X-ray photoelectron spectroscopy analyses showed that the Reset recovery is related to a modification of the HfO 2 /TiN interface via transformation of the TiON interfacial layer. Thus, postdeposition plasma treatments of the oxide/electrode interface are identified as a valuable tool to improve the switching properties of oxide-based RRAMs. V