The Role of Si and Sb in the Si-Sb-Te Phase-change Material
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The Role of Si and Sb in the Si-Sb-Te Phase-change Material Liangcai Wu1, Xilin Zhou1, Zhitang Song1, Henan Ni1, Feng Rao1, Kun Ren1, Cheng Peng1, Sannian Song1, Ting Zhang1, Bo Liu1, Songlin Feng1, and Bomy Chen2 1 State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 200050, P. R. China 2 Silicon Storage Technology, Inc., 1171 Sonora Court, Sunnyvale, CA 94086, U. S. A. ABSTRACT Sb-rich Si-Sb-Te phase change materials with different Si contents were proposed and fabricated, and the role of Si and Sb in the Si-Sb-Te alloys was discussed. The resistance-temperature and retention properties of the Sb-rich Si-Sb-Te alloys were studied. Devices based on the Sb-rich Si-Sb-Te alloys were fabricated by a 0.18 μm CMOS technology and device properties were studied by pulsed mode resistance-voltage (R-V) measurements. Experimental results show that the crystallization temperature and data retention ability of the Sb-rich Si-Sb-Te alloys were obviously improved with increasing Si content, but the electrical properties degenerate if too much Si was added. Sb is helpful to promote the crystallization process, but excessive Sb decreases the thermal stability. So, in order to obtain practicable Sb-rich Si-Sb-Te phase change materials, suitable Si and Sb contents are required to balance the device performances between electrical switching property and thermal stability or data retention ability. INTRODUCTION Recently, phase-change random access memory (PCRAM), a rapidly emerging technology, has been considered as one of the most promising candidates for the next generation nonvolatile memory. In PCRAM the pronounced difference in electrical resistivity, which is depending upon the atomic arrangement of the phase-change material, i.e. the amorphous or crystalline phase, is utilized to store information. For commercial application of the technology, good data retention, low power consumption, etc. are the most important issues among the critical aspects [1-3]. In order to approach these goals, many efforts including improving the properties of conventional Ge-Sb-Te (GST) phase change materials [4, 5], optimizing the geometrical structure of the memory cell as well as inserting a heating layer between electrode and phase change materials [6, 7] have been carried out. In addition, developing new phase change materials is another effective way to improve the performance of PCRAM. Considering the outstanding properties of high speed and low power consumption in the phase transition, Si-Sb-Te (SST) series phase change materials have also been proposed in previous work [8, 9]. In this paper, as a further study on our previous work, Sb-rich phase change materials were proposed and the role of Si and Sb was discussed.
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EXPERIMENTAL DETAILS Firstly, 200-nm-thick SixSb2Te (x=0.33, 1, 2) thin films were deposited on thermally oxidized (100) Si substrate and pure Al foil, respectively, by radio-frequency magnetron sputtering at roo
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