AVS 59th Annual International Symposium and Exhibition
    Electronic Materials and Processing Wednesday Sessions
       Session EM+OX-WeA

Paper EM+OX-WeA7
Resistive Switching Characteristics of Al­2O­3/TiO2 Bilayer ReRAM dependent on Al2O­3 Thickness

Wednesday, October 31, 2012, 4:00 pm, Room 009

Session: Oxides and Dielectrics for Novel Devices and Ultra-dense Memory
Presenter: H.Y. Jeon, Hanyang University, Korea
Authors: H.Y. Jeon, Hanyang University, Korea
J.S. Lee, Hanyang University, Korea
J.G. Park, Hanyang University, Korea
W.C. Jang, Hanyang University, Korea
H.T. Jeon, Hanyang University, Korea
Correspondent: Click to Email
The next generation nonvolatile memory (NGNVM) devices should satisfy the device properties such as high density, fast operation speed, low power consumption, and high reliability. Recently, many type-NGNVM candidates are extensively considered to replace the conventional nonvolatile memory devices; polymer random access memory (PoRAM), phase change random access memory (PRAM), spin transfer torque random access memory (STT-RAM), and resistive switching random access memory (ReRAM). Among the many type-NGNVMs, ReRAM has attracted a great deal of attention in semiconductor industry mainly due to its high density integration, long retention time, small cell size, and fast switching speed. Also, the ReRAM has the simple structure like metal/insulator/metal (MIM) structure allowing the fabrication of 3 dimensional stack and nano cross-bar structure. There are two types of resistive switching for ReRAM. One is unipolar resistive switching (URS) and the other is bipolar resistive switching (BRS). The URS means the operation of set (program) and reset (erase) are under the same polarity of bias, whereas the polarity of bias for set operation is opposite to that of bias for reset operation in the BRS. The URS type ReRAM needs current compliance to prevent hard breakdown of transition metal oxide (TMO) when measuring the resistive switching. The URS is usually observed in ReRAM using binary transition metal oxides such as NiO, TiO2, and Al2O3, while the BRS appeared in ReRAM using perovskite materials like Cr:SrZrO3, Pr0.7Ca0.3MnO3. Among many deposition methods for metal oxide, atomic layer deposition (ALD) has recently received a great interest for manufacture of ReRAM. Especially, remote plasma ALD is expected to enhance the reactivity between metal-organic precursor and reactant gas with minimal plasma damage on substrate, allowing the low impurity content and high density of the deposited films. In RPALD, plasma is generated remotely outside of chamber. And the radicals and ions generated in plasma region enter into the chamber by a downstream flow for chemical reaction of deposition. In this study, we investigated URS switching behaviors of ReRAM using Al2O3/TiO2 bilayer deposited by remote plasma atomic layer deposition (RPALD) method. The thickness of Al2O3 layers was varied to observe the discrepancy of set/reset voltage and operation current level. The deposited Al2O3 and TiO2 films are perfectly amorphous structures and their binding states have nearly stoichiometric composition. When operating the ReRAM with different thickness ratio, the dependence of operation voltage and current level on the thickness of Al2O3 layers was observed.