Impacts of Cu-Doping on the Performance of La-Based RRAM Devices

Yongte Wang,Lu Zhao,Hongxia Liu,Xing Wang

doi:10.1186/s11671-019-3064-1

Abstract

In this paper, the effects of Cu insertion layer and rapid thermal annealing on the resistive switching behaviors of La-based resistive switching access memory (RRAM) devices have been investigated. Compared with the undoped control sample (Cu/LaAlO3/Pt), the Cu-embedded devices show higher device yield and reset stop voltage, which indicates that the reliability of La-based RRAM has been effectively improved. However, the unannealed Cu/LaAlO3: Cu/Pt RRAM device still suffers from serious dispersion of parameters. It was proved that the RRAM device with Cu insertion layer and annealing treatment exhibits the best resistive switching characteristics such as low forming voltage, high on/off ratio and fine electrical uniformity. These improvements can be attributed to the diffusion of Cu atoms and the formation of Cu nanocrystals (Cu-NCs) after annealing process, since the diffused Cu atoms and the Cu-NCs could enhance the local electric field and weaken the randomness of the formation/rupture of conductive filaments.

Highlights

Resistive random access memory (RRAM) is considered as a development direction for the next-generation nonvolatile memory devices, which has been attracting much attention due to its simple structure, low power consumption, high scalability, fast operation speed and multi-value storage capacity [1]
The Cu atoms are observed in the whole LaAlO3 film after annealing treatment, i.e. after etching for 30 s, 60 s, and 90 s, obvious Cu 2p peaks can be observed in S3
The X-ray photoelectron spectroscopy (XPS) results confirm that hightemperature annealing will lead to redistribution of the doped Cu atoms, which may help to improve the electrical characteristics of La-based RRAMs

Summary

Introduction

Resistive random access memory (RRAM) is considered as a development direction for the next-generation nonvolatile memory devices, which has been attracting much attention due to its simple structure, low power consumption, high scalability, fast operation speed and multi-value storage capacity [1]. RRAM is often fabricated into a metal–insulator–metal (M–I–M) sandwich structure, and the intermediate dielectric layer has a significant influence on its resistive switching (RS) performance. Good resistance switching characteristics, such as low operating voltage, high resistance window, long holding time, long cycle endurance, and good consistency, have been found in La-based RRAMs, owing to the advantages of excellent uniformity, precise thickness control and compatibility with CMOS process, atomic layer deposition (ALD) technology has been one of the most commonly used growth methods to produce La-based dielectric films [8]. Undesirable high forming voltages are always required in ALD-deposited RRAM devices because of the good quality dielectric films, which may lead to a high failure rate, low on/off ratio, poor endurance, and wide dispersion of the devices [9]. In order to obtain RRAM devices with better RS performance, materials/device structure engineering, including ion implantation [10], dopant diffusion [11], or inserting nanocrystals (NCs) [12], need to be adopted in the ALD-prepared La-based RRAMs

Methods

Results

Conclusion