In this letter, we systematically studied the relationship between ferroelectricity/anti-ferroelectricity and the corresponding phase structures in Hf1-xZrxO2 (HZO) films. Our findings, obtained through ab initio simulations, indicate that the orthorhombic-I phase exhibits greater stability compared to the orthorhombic-III and tetragonal phases in the HZO system. Atomic-resolution C s-corrected scanning transmission electron microscopy revealed a direct correlation between anti-ferroelectricity and orthorhombic-I phase in HZO materials. Furthermore, the reversible transition between the tetragonal and orthorhombic-I phases has been identified as a contributing factor to the anti-ferroelectric properties observed in thin HZO films. The development of phase-engineered AFE HZO, as demonstrated in this work, holds significant promise for advanced embedded DRAM and non-volatile memory applications.

In this letter, wake-up free La-doped HfO2-ZrO2 (HZO) ferroelectrics are experimentally fabricated using an atomic layer-specific doping (ALSD) technique, which selectively introduces La dopants at effective locations to facilitate the formation of ferroelectric orthorhombic phase. With this technique, robust La-doped HZO ferroelectric devices that are mostly free from the undesired wake-up effect and anti-ferroelectricity were demonstrated over a large La doping range (from 2.9 to 11.5%). Moreover, large remanent polarization and good endurance were achieved at the same time (>107 cycles). The outstanding performances can be attributed to the effective stabilization of ferroelectric orthogonal phase and the suppression of tetragonal phase, through controlling of the dopants’ local environment. Thus, ALSD is an effective approach to achieve reliable, wake-up free and CMOS-compatible HZO-based ferroelectrics.

A two-step oxygen vacancy (V _O ) engineering technique is presented to enhance the ferroelectricity of Hf _0.5 Zr _0.5 O ₂ (HZO) film with superior dielectric reliability. The V _O engineering consists of two steps: 1) V _O formation in the HZO film to stabilize the orthorhombic phase and 2) V _O passivation to annihilate the V _O -related defects without degrading the ferroelectric properties. In addition, we further investigate the feasibility of the two-step V _O engineering at a low thermal budget process (400 °C) for back-end-of-line (BEOL) applications. Superior remnant polarization (2P $_{\text {r}} = 43\,\,\mu \text{C}$ /cm ² ) and high endurance of $> 10^{{8}}$ cycles are demonstrated in HZO thin films processed at 400 °C, which are comparable to those processed at high temperatures.

HfO₂-based resistive random-access memory (RRAM) with a Ti buffer layer has been extensively studied as an emerging nonvolatile memory (eNVM) candidate because of its excellent resistive switching (RS) properties and CMOS process compatibility. However, a detailed understanding of the nature of Ti thickness-dependent RS and systematic thermal degradation research about the effect of post-metallization annealing (PMA) time on oxygen vacancy distribution and RS performance still needs to be included. Herein, the impact of Ti buffer layer thickness on the RS performance of the Al/Ti/HfO₂/TiN devices is first addressed. Consequently, we have proposed a simple strategy to regulate the leakage current, forming voltage, memory window, and uniformity by varying the thickness of the Ti layer. Moreover, it is found that the device with 15 nm Ti shows the minimum cycle-to-cycle variability (CCV) and device-to-device variability (DDV), good retention (10⁵ s at 85 °C), and superior endurance (10⁴). In addition, thermal degradation of the Al/Ti(15 nm)/HfO₂/TiN devices under different PMA times at 400 °C is carried out. It is found that the leakage current increases and the forming voltage and memory window decrease with the increase in PMA time due to the thermally activated oxidation of the Ti. However, when the PMA time increases to 30 min, the Ti can no longer capture oxygen from HfO₂ due to the formation of self-limited TiO_x. Therefore, the device shows superior thermal stability with a PMA time of 90 min at 400 °C and no degradation of the memory window, uniformity, endurance, or retention. This work demonstrates that the Ti/HfO₂-based RRAM shows superior back-end-of-line compatibility with high thermal stability up to 400 °C for over an hour.

In this work, we developed a nonvolatile ternary content addressable memory (TCAM) with a cell size of $0.01~\mu \text{m}^{{2}}$ utilizing the Ge-based memory diode (MD), which has the most area-efficient TCAM design reported. The MDs have a high current ratio between ON and OFF states and a large rectifying ratio, showing the potential usage in large-dimension TCAM arrays. Besides, the functionality of parallel search was demonstrated with a 2-bit MD-TCAM array by experiment, and the electrical characterization showed expected results. With the help of the sub-ns ultrafast measurement system, it is confirmed that the search energy of MD-TCAM could reach as low as 1.0 fJ/bit/mismatch, and one search operation can be performed within 200 ps. Furthermore, the circuit-level simulation results verified that the MD-TCAM developed in this study shows good performance in 128-bit parallel searching, which is promising for the ultrafast and low-power data search applications in the coming IoT era.

In this work, a forming-free HfOx-based resistive random access memory (RRAM) with improved uniformity is successfully demonstrated without an additional doping process, ionic injection, or special layer deposition. The significantly enhanced performances can be attributed to the self-doping of Ge atoms from the Ge bottom electrode (BE) into the HfO2 layer during the postdeposition annealing (PDA) process. Besides, the RRAM provides a lower reset current and a higher ON/OFF ratio than the reported forming-free RRAM. These excellent properties are beneficial to the application of power-saving RRAM and its circuit operation.