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Due to its ferroelectricity, hafnium oxide has attracted a lot of attention for ferroelectric memory devices. Amongst different dopant elements, zirconium is found to be beneficial due to the relatively low crystallization temperature of hafnium‐zirconium‐oxide (HZO), thus it is back‐end‐of‐line (BEoL) compatible. The thickness of HZO has a significant impact on ferroelectric device reliability. High operation temperatures and high endurance are important criteria depending on the application. Herein, various HZO thicknesses (7, 8, and 10 nm) in MFM (metal‐ferroelectric‐metal) capacitors are investigated at varying operation temperatures (25 to 175 °C) at varying electric fields (±3 to ±5.4 MV cm−1) with respect to polarization, leakage current, endurance, and retention. 7 nm HZO showed promising results with an endurance of 107 cycles, with a low leakage current density, and almost no retention loss after 10 years. Extrapolated results at operation conditions (±2 MV cm−1 and 10 MHz) showed an endurance of 1010 cycles. [ABSTRACT FROM AUTHOR]

The properties of hybrid ferroelectric (FE) and antiFE (AFE) films integrated in a single capacitor stack is reported. The stack lamination (4 × 5 nm) or (2 × 10 nm) using an Alumina (Al2O3) interlayer, material type (Si‐doped HfO2 (HSO) and Zr doped HfO2 (HZO)), precursor condition (TEMA‐Hf and Hf/ZrCl4), or dopant concentration (Si and Zr) are investigated for laminate stack properties. Optimized FE properties (higher 2Pr and a lower fraction of the monoclinic phase) are observed at (2 × 10 nm) laminates compared to a single 20 nm film thickness. The hybrid laminate stack as FE‐FE, AFE‐FE, DE‐FE, or DE‐AFE using (2 × 10 nm) based laminates are explored in terms of the output FE hysteresis (2Pr, 2Ec) and structural properties by X‐ray diffraction. The hybrid AFE‐FE stack shows the potential of tailoring the output FE hysteresis 2Ec by varying the fraction of the AFE phase. The hybrid AFE‐FE stack is studied for the HSO and HZO materials at optimal FE content for the first laminate layer while varying the Si or Zr content to stabilize different degrees of an AFE phase in the second laminate layer. The superposition of the hybrid AFE‐FE hysteresis shows a systematic 2Ec control. A model is developed to describe the tailored output FE hysteresis via the tuning of a hybrid AFE‐FE stack. The role of stack lamination at hybrid‐stabilized phases inside a single stack is explored with the aim for a controlled and optimized FE hysteresis shape toward a low power (2Ec) operation. [ABSTRACT FROM AUTHOR]

Ferroelectricity in crystalline hafnium oxide thin films is strongly investigated for the application in non-volatile memories, sensors and other applications. Especially for back-end-of-line (BEoL) integration the decrease of crystallization temperature is of major importance. However, an alternative method for inducing ferroelectricity in amorphous or semi-crystalline hafnium zirconium oxide films is presented here, using the newly discovered effect of electric field-induced crystallization in hafnium oxide films. When applying this method, an outstanding remanent polarization value of 2P R = 47 μ C/cm 2 is achieved for a 5 nm thin film. Besides the influence of Zr content on the film crystallinity, the reliability of films crystallized with this effect is explored, highlighting the controlled crystallization, excellent endurance and long-term retention. [ABSTRACT FROM AUTHOR]

In this article, we present the capacitance–voltage (${C}$ – ${V}$) characteristics of HfxZr1−xO2 metal–ferroelectric–metal (MFM) thin-film capacitors with various Zr doping, thicknesses, and annealing temperatures. The influence of doping, electric field cycling, and annealing temperature on tuning characteristics (tunability) was analyzed and an optimized bias region for the maximum tunability was defined. Additional focus was made on an antiferroelectric-like (AFE) behavior, which occurs for > 50% Zr doping. The presence of both the ferroelectric and the AFE phase manifests itself in specific ${C}$ – ${V}$ behavior, where a reduced bias range is required for tuning, however, at the cost of a smaller tunability. The suitability of this behavior for varactor applications is also discussed. [ABSTRACT FROM AUTHOR]

Ferroelectric hafnium oxide (HfO2) is considered a very prospective material for applications in integrated devices due to its considerably large spontaneous polarization and superior thickness scaling. In fact, the evolution of the ferroelectric hysteresis upon field cycling plays an important role in most applications; especially the so‐called wake‐up effect that describes the increase of remanent polarization for initial field cycling, needs a profound understanding in HfO2. Herein, the discovery of electric field–induced crystallization in hafnium oxide is reported. In addition, differences in the wake‐up behavior are addressed that finally can be categorized into five different cases, all being relevant when describing the evolution of ferroelectricity. Moreover, analysis of the temperature dependence and transmission Kikuchi diffraction provides insight into the underlying physical mechanisms of different wake‐up behavior scenarios, and proves ferroelastic switching as the origin for the observed antiferroelectric‐like behavior. This knowledge provides clear procedures of 1) how to experimentally quantify and 2) how to prepare and manufacture hafnium oxide phases for the five different wake‐up types. [ABSTRACT FROM AUTHOR]

A novel hybrid antiferroelectric (AFE)-based charge trap (CT) memory is reported focusing on an amplified tunnel oxide field (ETO) via the dynamic of an AFE hysteresis dipole switching. The role of dynamic permittivity increase and the saturated polarization at the instant of the write operation are explored for enhanced ETO. The hybrid CT concept is studied by benchmarking the controlled properties of the HfO2 CT layer via the Si elemental doping in order to stabilize the linear dielectric (DE), ferroelectric (FE), or AFE response. The Si-doped HfO2 (HSO) with AFE stabilized phase shows the largest memory window (4.5 V) compared to the DE- or FE-based CT layers. The dynamic AFE dipole switching enables a maximized ETO at the instant of switching such that a high-speed and low-power CT memory is realized. The role of the tailored hysteresis shape on the ETO magnitude is studied for different Si contents and benchmarked to the Zr-doped hafnium oxide (HZO). The AFE CT multilevel coding as 1–3 bit/cell, the role of the pass voltage disturb, and a mini-NAND array operation are demonstrated. The global variability and area scalability of the HSO CT devices are studied to indicate the effect of Si content distribution and the area dependence of the AFE film variability. AFE CT devices are characterized for a switching speed (< 1 μs), ten-year data retention, and 105 endurance. Moreover, the improved CT characteristics by the AFE dipole switching are explored for enhanced long-term potentiation and depression of a synaptic device. [ABSTRACT FROM AUTHOR]

Increasing demands for new computer architectures may require embedded non-volatile memories as for example in-memory computing. Ferroelectric field-effect transistors (FeFETs) add further advantages besides their outstanding properties due to the availability of both n-type and p-type transistors. The latter favor a different channel materials, like SiGe, due to the low hole mobility in silicon. In this article, we demonstrate the integration of ferroelectric hafnium oxide on SiGe as well as working p-type FeFETs, possessing a large memory window of about 1.1 V and low variability. Such architectures were co-integrated into a standard high-k metal gate (HKMG) CMOS platform. Furthermore, we report on the impact of annealing temperature on the interface and ferroelectric layer, which appears to be universal for SiGe and Si substrates. Here, a growth of the interface layer during annealing at higher temperatures was observed as well as a reduction of the wake-up effect for the ferroelectric layer. [ABSTRACT FROM AUTHOR]

The discovery of ferroelectricity in thin doped hafnium oxide films revived the interest in ferroelectric (FE) memory concepts. Zirconium‐doped hafnium oxide (HZO) crystallizes at low temperatures (e.g., 400 °C), which makes this material interesting for the implementation of FE functionalities into the back end of line (BEoL). So far, the FE phase of prior amorphous HZO films is achieved by using a dedicated rapit thermal annealing (RTA) treatment. However, herein, it is shown that this dedicated anneal is not needed. A sole furnace treatment given by the thermal budget present during the interconnect formation is sufficient to functionalize even ultrathin 5 nm HZO films. This result helps to optimize the integration sequence of HZO films (e.g., involving a minimum number of BEoL process steps), which saves process time and fabrication costs. Herein, metal–FE–metal capacitors with Hf0.5Zr0.5O2 films of different thicknesses (5–20 nm) are fabricated annealed at 400 °C for various durations within different types of ovens (RTA and furnace). Structural and electrical characterization confirms that all furnace‐annealed samples have similar X‐ray diffraction patterns, remanent polarization, endurances, and thickness dependencies as RTA‐annealed ones. With respect to remanent polarization, leakage current, and endurance, the HZO film of 10 nm thickness shows the most promising results for the integration into the BEoL. [ABSTRACT FROM AUTHOR]

This paper reports a semi-empirical, SPICE compatible and computationally efficient compact model for ferroelectric capacitors (Fe-CAP) description. This compact model is inspired by the Jiles–Atherton model of ferromagnets, which features significantly smaller computational effort than other state-of-the-art models. It successfully computes the evolution of the memory window and hysteresis of ferroelectric capacitors for any arbitrary signal. We have successfully calibrated this model with the experimentally characterized polarization switching dynamics of fabricated 10 nm silicon-doped hafnium oxide based Fe-CAP. • Transfer of the Jiles–Atherton model to ferroelectrics. • Semi-empirical compact model description of ferroelectric capacitors. • Analytical description of ferroelectric field effect transistor gate capacitors. [ABSTRACT FROM AUTHOR]