Fabrication of Ferroelectric Gate Thin‐Film Transistors with a Lanthanum‐Doped HZO Gate Insulator and Indium‐Tin‐Oxide Channel via a Solution Process

Abstract

In recent years, lanthanum‐doped hafnium–zirconium dioxide (La‐HZO) has garnered attention as a material for application in ferroelectric devices; moreover, atomic layer deposition has been applied to prepare La‐HZO films with metal–ferroelectric–metal structures. This article describes the fabrication of ferroelectric La‐HZO thin films on Pt/Ti/SiO2/Si substrates via a solution process. The dependence of the electrical properties on the La concentration of La‐HZO films annealed at 800 °C in vacuum is also discussed. The film with a La concentration of 8 at% exhibits the highest remanent polarization, whereas undoped HZO exhibits paraelectric behavior. Additionally, the leakage current of La‐HZO specimens tends to be significantly lower than that of undoped HZO. Furthermore, a higher annealing temperature corresponds to better ferroelectric properties and a lower leakage current. The characterization of fabricated ferroelectric gate thin‐film transistors (FGTs) with an 8 at% La‐HZO gate insulator and indium‐tin‐oxide channel is shown to confirm typical n‐channel transistor operation, i.e., a counterclockwise hysteresis loop in the transfer curve; this is attributable to the ferroelectric nature of the La‐HZO gate insulator. The results demonstrate that the proposed FGT design offers a low subthreshold voltage swing, high on/off drain current ratio of 106, large on‐current, and large memory window.

Impact of CeOx layer insertion on ferroelectric properties of Hf-Zr-O films prepared by chemical solution deposition

“…The preparation of thin films by CSD is similar to that reported in our previous works. 29,30) In this work, CeO x /Y-HZO or Y-HZO/CeO x layered structures were fabricated by CSD on Pt/Ti/SiO 2 /Si substrate. Source solution was prepared using hafnium (IV) acetylacetonate (Hf(acac) 4 ), zirconium (IV) acetylacetonate (Zr(acac) 4 ) and yttrium (III) acetylacetonate (Y(acac) 3 ) were used for Y-HZO layers, and cerium (III) acetylacetonate (Ce(acac) 3 ) was used for CeO x deposition as precursors.…”

“…[26][27][28] We have previously investigated ferroelectric Y-and La-doped HZO thin films prepared by CSD and reported that good ferroelectric properties can be obtained by reduced pressure annealing without O 2 supply, which promotes the growth of o-phase probably because of the oxygen vacancy introduction. 29,30) The reduced pressure crystallization anneal is also applicable to sputtered HZO films to obtain good ferroelectric properties and stability. 31) In addition, even the irradiation of catalytically generated atomic hydrogen into as-deposited sputtered HZO films improves the ferroelectric properties, which is believed to be due to the introduction of oxygen vacancies.…”

Electrical properties of ferroelectric Y-doped Hf–Zr–O thin films prepared by chemical solution deposition

“…Similar behavior of the peak shift was reported for CSD La-doped HZO and Ce-doped ZrO 2 films. 45,46) The P-E loops of the Y-HZO films with Y concentrations of 0.6%, 3.2%, 6.3%, and 9.3% along with the current responses are shown in Fig. 2.…”

Low‐Temperature Nanosecond Laser Process of HZO‐IGZO FeFETs toward Monolithic 3D System on Chip Integration

“…In FeFET devices, dielectric leakage current significantly impacts information retention, stability, response speed, and power consumption. [ 40 ] Additionally, if the breakdown point is too low, the function generator becomes susceptible to transient overshoots. This is a crucial consideration in memory system operation.…”