Memory Characteristics of Filament Confined in Tiny ReRAM Structure
- PDF / 1,092,041 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 9 Downloads / 224 Views
Memory Characteristics of Filament Confined in Tiny ReRAM Structure S. G. Koh1, K. Kinoshita1, 2, T. Fukuhara1, Y. Sawai1 and S. Kishida1, 2 Department of Information and Electronics, Graduate School of Engineering, Tottori University, 4-101 Koyama-Minami, Tottori 680-8552, Japan. 2 Tottori Univ. Electronic Display Research Center, 522-2 Koyama-Kita, Tottori 680-0941, Japan. 1
ABSTRACT Clarification of memory characteristics of tiny cell is important for practical use of resistive random access memory (ReRAM). However, limitation of semiconductor microfabrication technology hinders to obtain memory characteristics in tiny cell with an area comparable to the size of filaments. In this paper, we established a method to prepare a very small memory cell by fabricating ReRAM structure on the tip of a cantilever of atomic force microscope (AFM). We also established a method to avoid the overshoot of set current. As a result, reset current was successfully reduced enough to suppress serious damage to the cantilever. The effective cell size was estimated to be less than 10 nm in diameter due to electric field concentration at the tip of the cantilever, which was confirmed by an electric field simulator based on finite element method. We performed a unique experiment to verify the presence of oxygen pool in an anode, by utilizing removable bottom electrode structure. The result was not consistent with resistive switching models that require the anode to play a role as an oxygen reservoir. INTRODUCTION NAND Flash memory will face a miniaturization limit after 20 nm generation [1]. In this background, the development of a new memory that is suitable for miniaturization is required. One of the best candidates is resistive random access memory (ReRAM). ReRAM has an advantage in miniaturization, because of its very simple structure that is constructed simply by sandwiching a transition metal oxide film with top and bottom electrodes [2]. In addition, ReRAM has merits such as fast switching speed [3-5], good endurance [6, 7] and good data retention [8]. In terms of practical use of ReRAM, clarification of memory characteristics of tiny memory cell is important. However, the limitation of semiconductor micro-fabrication technology hinders to obtain memory characteristics in tiny cell with an area comparable to the size of filament [9]. In this paper, we propose a method to prepare a very small memory cell using an atomic force microscope (AFM) cantilever. By depositing a transition metal oxide film on the tip of a cantilever and contacting a bottom electrode with the cantilever, a tiny ReRAM structure is formed at the contact area. This method is easy, does not need lithography, and provides ReRAM cell with small effective area by utilizing electric field concentration at the tip of a cantilever. We performed a unique experiment to verify the presence of oxygen pool in an anode, by utilizing removable bottom electrode structure. EXPERIMENT A Pt film with the thickness of 20 nm was deposited on an AFM cantilever with the tip
radi
Data Loading...
