Low-Power and Highly Reliable Multilevel Operation in $ \hbox{ZrO}_{2}$ 1T1R RRAM

Abstract

The Ti/ZrO 2 /Pt resistive memory devices with one transistor and one resistor (1T1R) architecture are successfully fabricated in this letter. The tested devices show low operation current (20 μA), low switching voltage (set/reset, 0.8/−1 V), and reliable data retention for low-resistance state (LRS) with a 20-μA set current at 80 • C (over ten years) via an excellent current limiter, namely, a metal-oxide-semiconductor field-effect transistor (MOSFET). In addition, multilevel storage characteristics are also demonstrated by modulating the amplitude of the MOSFET gate voltage. The various LRS levels obtained are possibly attributed to the formation of different numbers and sizes of conducting filaments consisting of oxygen vacancies caused by an external electric field. Moreover, reproducible resistive switching characteristics up to 2000 switching cycles are achieved in the same device. Our 1T1R ZrO 2 -based resistive switching access memory with low-power and highly reliable multilevel operation has high potential for practical applications.Index Terms-Low power, multilevel, nonvolatile memory, resistive switching, resistive switching access memory (RRAM), ZrO 2 .

A quantization-aware regularized learning method in multilevel memristor-based neuromorphic computing system

“…In a memristorbased NCS, however, programming the resistance of the memristors suffers from intrinsic device parametric and switching variabilities. The number of resistance levels realized on the memristors is often limited, usually only four with reasonable implementation and energy costs of programming circuitry [8]. Mapping the neural network with floating point weights onto the memristors with multi-level resistance states inevitably causes computation accuracy loss, namely, quantization loss.…”

“…Hence, the number of the resistance levels that a memristor can be programmed to is further limited by memristor device variations in addition to the resolution of the programming circuitry. In offline training, obtaining a high precision of memristor resistance levels, say, more than four levels (2-bit), requires precise output signal monitoring and programming signal control [8]. The overheads quickly become unaffordable when the scale of the NCS increases.…”

Superior unipolar resistive switching in stacked ZrOx/ZrO2/ZrOx structure

“…[9][10][11][12][13][14] Among these, zirconium oxide appears to be one of the most promising candidates because of its high thermodynamic stability, large bandgap, high dielectric constant and compatibility with the CMOS process. 15,16 Recently, zirconium-oxide based RRAM has emerged as a superior resistive switching layer, 17,18 and several methods have been proposed to improve its performance in bipolar or unipolar operations. Using a Mo inserting layer, 19 and an Au nanocrystal (NC) embedded 20 in the ZrO 2 films, can improve the RRAM performance in bipolar resistance switching (BRS).…”

Mechanism of High Temperature Retention Property (up to 200 °C) in ZrO2-Based Memory Device With Inserting a ZnO Thin Layer

“…ZrO 2 is one of the promising high-k dielectric materials in the advanced complementary metal oxide semiconductor (CMOS) technology, which has been extensively studied for RRAM application because of its simple construction and compatibility with standard CMOS technology [5]- [7]. Excellent endurance, low power operation, high speed, and multilevel properties have been demonstrated in ZrO 2 -based RRAM device [8], [9]. However, the wide variation in both high resistance state (HRS) and low resistance state (LRS) during endurance test leads the small resistance ratios of HRS/LRS [8].…”

“…Besides, the high temperature retention property in ZrO 2 -based RRAM device is not stable. It cannot maintain its memory window after few hundred seconds at 200°C [9]. The retention failure is due to the oxygen ions/vacancies generate/recombine under the high temperature ambient [10].…”