Excellent resistive switching properties of atomic layer-deposited Al2O3/HfO2/Al2O3 trilayer structures for non-volatile memory applications.

Lai-Guo Wang,Lai-Guo Wang,Lai-Guo Wang,Zheng-Yi Cao,Xu Qian,Di Wu,Di Wu,Yan-Qiang Cao,Yan-Qiang Cao,Guo-Yong Fang,Guo-Yong Fang,Ai-Dong Li,Zheng-Yi Cao,Ai-Dong Li

doi:10.1186/s11671-015-0846-y

Abstract

We have demonstrated a flexible resistive random access memory unit with trilayer structure by atomic layer deposition (ALD). The device unit is composed of Al2O3/HfO2/Al2O3-based functional stacks on TiN-coated Si substrate. The cross-sectional HRTEM image and XPS depth profile of Al2O3/HfO2/Al2O3 on TiN-coated Si confirm the existence of interfacial layers between trilayer structures of Al2O3/HfO2/Al2O3 after 600°C post-annealing. The memory units of Pt/Al2O3/HfO2/Al2O3/TiN/Si exhibit a typical bipolar, reliable, and reproducible resistive switching behavior, such as stable resistance ratio (>10) of OFF/ON states, sharp distribution of set and reset voltages, better switching endurance up to 103 cycles, and longer data retention at 85°C over 10 years. The possible switching mechanism of trilayer structure of Al2O3/HfO2/Al2O3 has been proposed. The trilayer structure device units of Al2O3/HfO2/Al2O3 on TiN-coated Si prepared by ALD may be a potential candidate for oxide-based resistive random access memory.

Highlights

With traditional memories approaching their scaling limit, new memory concepts and materials in ultralarge-scale integration have drawn much attention
After the conventional RTA cleaning of the Si wafers without removing native oxide with the diluted HF solution, 30-nm-thick TiN was deposited on Si as bottom electrode at 400°C using TiCl4 at room temperature (RT) and NH3 plasma gas as the Ti and N sources by plasma-enhanced atomic layer deposition (PEALD)
In summary, reliable and uniform Resistive random access memory (RRAM) units based on trilayer structure of Al2O3/HfO2/Al2O3 on TiN-coated Si have been prepared by ALD

Summary

Introduction

With traditional memories approaching their scaling limit, new memory concepts and materials in ultralarge-scale integration have drawn much attention. Resistive random access memory (RRAM) is one of the most promising candidates for next-generation non-volatile memory applications due to its simple structure, low power consumption, high-speed operation, nondestructive readout, and high-density integration [1]. Ruptures of the conducting filaments with various sizes at random locations are thought as the main reason for the non-uniformity of resistive switching parameters [20,21]. The bilayer structure devices have been confirmed with improved resistive switching behaviors [24,25]. Shrinkage of the active memory unit area to sub-100-nm size using a plug-contact-type bottom electrode was able to obtain a sharp distribution in switching parameters

Methods

Results

Conclusion