Orientation Independent Growth of Uniform Ferroelectric Hf_0.5Zr_0.5O₂ Thin Films on Silicon for High‐Density 3D Memory Applications

Abstract

The highly scalable ferroelectric hafnia‐based thin films can be easily integrated into ferroelectric field‐effect transistors (FeFETs) by existing Si technology, which are regarded as one of the promising candidates for fast read/write, energy‐efficient, and high‐density nonvolatile memories. However, device‐to‐device variation in threshold voltage (VTH) caused by non‐uniformity of ferroelectric properties is a serious challenge for implementing hafnia‐based FeFETs in high‐density nonvolatile memories. Here, the substrate‐orientation independent growth of Hf0.5Zr0.5O2 (HZO) thin films is realized with uniform ferroelectricity by using HfO2 seed layers. The HfO2 seed layers are beneficial to improving the ferroelectric polarization of HZO thin films grown on differently oriented Si substrates and reducing the variation in ferroelectric properties. Moreover, device simulation confirms that the proposed scheme contributes to realizing uniform memory properties in 3D vertical HZO‐based FeFETs. This study suggests the possibility to implement hafnia‐based FeFETs into 3D vertical high‐density memory.

Ferroelectric Enhancement in a TiN/Hf1–xZrxO2/W Device with Controlled Oxidation of the Bottom Electrode

“…This implies a more pristine interface (free from traps or defects) facilitating the unimpeded development of polar characteristics. 35 The PFM phase window of the WO 3 -cap appears larger than that of the other two samples, which suggests that local point measurements within the WO 3 -cap HZO domain exhibit superior characteristics compared to other samples. Figure 7a, b presents performance benchmarks, including maximum 2P r and endurance, of HZO within the MFM structure as functions of the annealing temperature.…”

“…The asymmetry in the PFM amplitude of the WO x -cap sample is more obvious than the other two, particularly at the maximum applied voltage (±7 V). This implies a more pristine interface (free from traps or defects) facilitating the unimpeded development of polar characteristics . The PFM phase window of the WO 3 -cap appears larger than that of the other two samples, which suggests that local point measurements within the WO 3 -cap HZO domain exhibit superior characteristics compared to other samples.…”

Highly Enhanced Polarization Switching Speed in HfO2‐based Ferroelectric Thin Films via a Composition Gradient Strategy

“…Therefore, the 111 o /101 t peak is believed to be strongly associated with ferroelectric properties. [ 30,31 ] The three samples also show a diffraction peak at 2θ≈35.4° corresponding to the ferroelectric orthorhombic phase or tetragonal phase. The intensities of diffraction peaks at 2θ of 30.5°, and 35.4° are almost the same in the three HZO thin films, indicating that they have the same crystal phase composition.…”

Enhanced Endurance and Imprint Properties in Hf0.5Zr0.5O2−δ Ferroelectric Capacitors by Tailoring the Oxygen Vacancy

“…Ferroelectric HfO 2 -based materials have recently attracted much attention for both memory and logic device applications, owing to their high compatibility with complementary metal-oxide-semiconductor (CMOS) technology, incredible thickness scalability up to 1 nm, and ultrafast switching speed. − However, the device applications are hampered by the reliability issues including endurance and imprint. − Compared to the conventional perovskite-based ferroelectric capacitors with endurance exceeding 10 12 cycles, HfO 2 -based devices are impeded by two main endurance problems: polarization degradation and breakdown after certain field cycles. In addition, the imprint effect causes the shifts of ferroelectric hysteresis loops along the bias axis, leading to the fluctuation of read current and even write error.…”