HfOx Thin Films for Resistive Memory Device by Use of Atomic Layer Deposition
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0997-I07-04
HfOx Thin Films for Resistive Memory Device by Use of Atomic Layer Deposition Pang Shiu Chen1, Heng-Yuan Lee2, Ching-Chiun Wang3, Ming-Jinn Tsai3, and Kou-Chen Liu4 1 Department of Materials Science and Engineering, MingShin University of Science and Technology, Hsinchu, 30401, Taiwan 2 Electronics and Optoelectronics Research Laboratory, Industrial Technology Research Institute, Chutung, HsinChu, 304, Taiwan 3 Electronics and Optoelectronics Research Laboratory, Industrial Technology Research Institute, Chutung, Hsinchu, 304, Taiwan 4 Department of Electronic Engineering, Chang Gung University, Tao-Yuan, 333, Taiwan ABSTRACT The materials properties and resistance switching characteristics of hafnium oxide-based binary oxide were investigated for next generation memory device application. A nonstoichometric hafnium oxide (HfOx) film with a mixture structure of monoclinic and tetragonal phase and some metallic Hf-Hf bonds on TiN/Si were prepared by atomic layer chemical vapor deposition (ALCVD). Resistance random access memory devices consisting of Pt/HfOx/TiN/Si with low power operation (< 0.4 mW) and reset current (< 100 µA) were fabricated. The resistance ratio of high resistance state to low resistance state maintains 100~1000 and after 1000 cycles of repetitively switching. A 1-nm-thick Al2O3 film in the interface between top electrode and HfOx films, the Pt/Al2O3/HfOx/TiN/Si memory devices were found that soft-error of set and reset process often occurred. Interface states in the anode side may play an important role in maintaining a stable resistive switching for HfOx-based memory devices. INTRODUCTION Several new types of nonvolatile memory (NVM), such as magnetic random access memory (MRAM) [1], phase changeable memory (PCM) [2], resistive random access memory (RRAM) [3], were though to be the promising candidates as the replacement of flash memory in the next memory application. Among these various memories, RRAM using binary oxide, like NiO [4], TiO2 [5], ZrO2 [6], begins to attract attention recently. Since it is applicable to simple memory array architecture of 1T1R [4] or 1D1R unit cell. However, several issues are encountered in the development of this technology. One of them is the issue of high switching current, which is always larger than 1 mA in the literatures [4-6]. High switching current will make this memory less competitive as it need more space for transistor. Stoichiometry of the binary oxide was reported to influence the switching current [7]. HfOx films were considered to be the gate dielectric in advanced metal-oxide-semiconductor devices. However, there were few papers to discuss the resistance switching behavior of hafnium-based oxide [4]. Meanwhile, scaling down of films thickness is also an important issue for the devices that are operated at low voltage. Atomic layer deposition was used to control the films thickness precisely and avoid the radiation damage. In the previously study, a nonstoichiometric HfOx film has been grown on TiN /Si substrate successfully [8]. A s
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