Cu对用于高速相变存储器的Sb2Te薄膜的结构及相变的影响研究  

Effect of Cu on the structure and phase-change characteristics of Sb_2Te film for high-speed phase change random access memory

作　　者：王东明[1] 吕业刚[1] 宋三年[2] 王苗[1] 沈祥[3] 王国祥[3] 戴世勋[3] 宋志棠[2] 

机构地区：[1]宁波大学信息科学与工程学院,宁波315211 [2]中国科学院上海微系统与信息技术研究所,上海200050 [3]宁波大学高等技术研究院,红外材料及器件实验室,宁波315211

出　　处：《物理学报》2015年第15期397-403,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61306147,61377061);宁波市自然科学基金(批准号:2014A610121);宁波大学王宽城幸福基金资助的课题~~

摘　　要：采用原位X射线衍射仪、拉曼光谱仪和X射线反射仪分别研究了Cu-Sb2Te薄膜的微结构、成键结构和结晶前后的密度变化.Sb2Te薄膜的结晶温度随着Cu含量的增加而增大.在10 at.%和14 at.%Cu的Sb2Te薄膜中,Cu与Te成键,结晶相由六方相的Cu7Te4、菱形相的Sb及六方相的Sb2Te构成.10 at.%和14 at.%Cu的Sb2Te薄膜在结晶前后的厚度变化分别约为3.2%和4.0%,均小于传统的Ge2Sb2Te5(GST)薄膜.制备了基于Cu-Sb2Te薄膜的相变存储单元,并测试了其器件性能.Cu-Sb2Te器件均能在10 ns的电脉冲下实现可逆SET-RESET操作.SET和RESET操作电压随着Cu含量的增加而减小.疲劳测试结果显示,Cu含量为10 at.%和14 at.%的PCRAM单元的循环操作次数分别达到1.3×104和1.5×105,RESET和SET态的电阻比值约为100.Cu-Sb2Te可以作为应用于高速相变存储器(PCRAM)的候选材料.In this paper, in-situ X-ray diffratometer, Raman spectrometer, and X-ray reflectometer are employed to study the crystal structure, bonding states, and density change upon crystallization of Cu-Sb2 Te films. It is shown that the crystallization temperature increases with increasing Cu content due to much more energy being required to overcome the rigid atomic network for the atoms rearrangement as a result of the complex branching and cross links. In X-ray diffraction pattern, both hexagonal Cu7Te4 and Sb2Te peaks have nearly the same peak positions, while the rhombohedral Sb peaks shift obviously their positions toward a small angle upon heating, suggesting a significant increase in lattice parameters of Sb phase. A Cu-Te bond is formed in Sb2 Te films containing 10 at% and 14 at% Cu which are crystalized into hexagonal Cu7Te4, rhombohedral Sb and hexagonal Sb2 Te three phases. When Cu concentration increases to 19 at%, Cu-Te bond becomes full, and the excess of Cu will bond with Sb. Compared with Ge2Sb2Te5（GST）, Sb2 Te films with 10 at%and 14 at% Cu have lower density changes upon crystallization which are about 3.2% and 4.0%, respectively. Phase change random access memory（PCRAM） based on Cu-Sb2 Te is successfully fabricated and characterized. Operations of set-reset can be realized in a 10 ns pulse for Cu-Sb2 Te based PCRAM. The value of set and reset operation voltage decreases with increasing Cu content. The endurance test shows that the operation cycle numbers can reach 1.3 × 10^4 and 1.5 × 10^5 for the 10 at% and 14 at% Cu-based PCRAMs, respectively. The resistance ratio of reset and set states maintains a balance of about 100. Cu-Sb2 Te film may be considered as one of the promising candidates for high-speed PCRAM.

关 键 词：相变存储器 相变存储材料 结构 

分 类 号：O484[理学—固体物理]