Enabling large memory window and high reliability for FeFET memory by integrating AlON interfacial layer

Abstract

A thin film of AlON with a nitrogen concentration of 13% was developed as the interfacial layer (IL) of HfZrOx-based ferroelectric field-effect transistor (FeFET) memory devices on a Si substrate. Compared to the conventional SiO2/SiON IL, due to a higher dielectric constant value that allows a smaller voltage drop across it and a larger valence band offset (ΔEv) with respect to Si along with prominent passivation of Si dangling bonds that effectively suppress hole trapping, memory devices with the AlON IL demonstrate a large memory window (MW) of 3.12 V by ±4 V gate voltage sweeping, robust endurance after 105 cycles with a long pulse width of 10−4 s, and a stable MW of 2.95 V up to 10 years, standing out from other HfZrOx-based FeFET memory reported in the literature. Furthermore, the AlON IL can be integrated with HfZrOx in the same atomic layer deposition step, which greatly simplifies the process. From the device performance and process integration points of view, the AlON IL unleashes the potential of FeFET memory by enabling high reliability with a large MW.

High Speed and Large Memory Window Ferroelectric HfZrO₂ FinFET for High-Density Nonvolatile Memory

“…2 illustrates the transfer I D -V G curves for direct current (DC) sweepings of ±2, ±4, and ±6 V, with V D being 0.1 V. The I D -V G curve for a DC sweeping of ±2 V exhibits an inadequate MW due to insufficient polarization switching. The I D -V G curves for DC sweepings of ±4 and ±6 V illustrate counterclockwise hysteresis and indicate that the dipole was completely polarized [16]. The largest MW occurred at ±4 V for 1.45 V, where the MW was extracted from the threshold voltage (V T ) difference, and V T was determined at a constant current of 10 −9 A.…”

Phases in HfO2-Based Ferroelectric Thin Films and Their Integration in Low-Power Devices

“…(h) Extraction of memory window for various IL cases. Reproduced with permission from ref . Copyright 2021 American Institute of Physics.…”

“…(i) Endurance comparison of SiO 2 -IL- and AlON-IL-based FeFETs. Reproduced with permission from ref . Copyright 2021 American Institute of Physics.…”

Neuromorphic devices based on fluorite‐structured ferroelectrics

“…In contrast, FTJs are less sensitive to trapped charges during the readout process than FeFETs; however, similar reliability issues exist in FTJs based on ferroelectric/dielectric bilayers 191 . Several interfacial engineering methods, such as using a high‐k interlayer such as SiON, AlON, SiN x , ZrO 2 , Al 2 O 3 , or TiO 2 as the interlayer to replace SiO x , utilizing a scavenging layer, and optimizing annealing conditions, have been proposed to overcome these challenges, 27,124,125,169,192–203 and have showed impressive stability 96,99,192,204 . In addition to the properties related to device reliability, other key device performance parameters are scalability, switching speed, and programming energy.…”

“…AlON, SiN x , ZrO 2 , Al 2 O 3 , or TiO 2 as the interlayer to replace SiO x , utilizing a scavenging layer, and optimizing annealing conditions, have been proposed to overcome these challenges, 27,124,125,169,[192][193][194][195][196][197][198][199][200][201][202][203] and have showed impressive stability. 96,99,192,204 In addition to the properties related to device reliability, other key device performance parameters are scalability, switching speed, and programming energy.…”