Cu_xSi_yO阻变存储器尺寸微缩、均匀性和操作极性的研究

发布时间：2018-06-28 07:03

本文选题：阻变存储器 + 尺寸微缩　；参考：《复旦大学》2013年硕士论文

【摘要】：随着器件尺寸不断地缩小,传统的Flash存储技术即将到达它的物理极限。阻变存储器因其结构简单、可微缩化、读写速度快、功耗低、与CMOS工艺兼容性好、成本低等优点,被认为是最有可能替代Flash的新型存储技术之一。本文基于新型的CuxSiyO阻变存储技术对阻变存储器研究领域中一系列热点和难点问题展开了研究。这些问题包括器件尺寸的微缩能力、参数的均匀性、bipolar和unipolar两种操作模式。为了能够在高密度存储领域替代NAND Flash,阻变存储器需要证明其器件尺寸至少能够微缩到20nm技术代。本文基于0.13um逻辑工艺制造的1Mbit CuxSiyO阻变存储器芯片,采用了spacer pattern工艺制造了通孔尺寸为40nn、55nm、70nm和90nm(分别对应22nm、32nm、45nm、65nm技术代)的阻变单元。测试结果表明,CuxSiyO阻变存储器能正常工作在22nm技术代,具有很好的器件尺寸微缩能力。另一方面,当器件尺寸小于90nm后,低阻态阻值会随着器件尺寸的减小而增大,RESET相应地呈线减小。对于40nm器件,其RESET电流仅为30uA,是190nm器件的1/5。这进一步增强了小尺寸阻变存储器的优势。参数不均匀性是阻变存储器应用的最大难题之一。参数不均匀会导致电压、电阻窗口变小甚至消失,也导致器件操作需要更复杂的算法和电路来实现。本文提出了阻变存储器芯片的测试方法和测试平台,从而能在大容量的阵列上采集均匀性相关的数据。本文同时讨论了如何用物理手段和电学手段来检测电阻的不均匀性。测试结果表明CuxSiyO阻变存储器的初始态不均匀性是由CuxSiyO薄膜的品质和厚度不均匀造成的。本文还研究了制备工艺条件以及阵列的大小对均匀性的影响,并提出了优化了的工艺条件和阵列大小。阻变存储器可以按SET/RESET的操作电压方向是否相同分为bipolar型和unipolar型。Bipolar型具有无SET/RESET干扰、操作电流小等优点；unipolar型具有操作简单、与二极管兼容等优势。传统的CuxSiyO阻变存储器能够稳定的工作在bipolar模式下。本文研究发现,在一定的forming条件下CuxSiyO阻变存储器也能稳定工作在unipolar模式下。低阻态传导特性和电阻温度曲线的测量表明：bipolar是由空穴导电的,而unipolar型是由金属离子导电的。本文亦提出了,通过控制操作条件,CuxSiyO存储器可以根据不同应用场合的需要分别工作在bipolar和unipolar模式下。希望通过这些问题的研究和讨论,能够加深对阻变机理的认识、加快阻变存储器的应用。
[Abstract]:As the device size continues to shrink, the traditional Flash memory technology is about to reach its physical limit. Resistive memory is considered to be one of the most possible new memory technologies to replace Flash because of its advantages such as simple structure, miniaturization, fast reading and writing speed, low power consumption, good compatibility with CMOS process and low cost. Based on the new CuxSiyO resistive storage technology, a series of hot and difficult problems in the field of resistive memory are studied in this paper. These problems include the miniaturization capability of the device, the uniformity of parameters and the operation mode of unipolar and bipolar. In order to replace NAND flash in high-density memory, the resistive memory needs to prove that its device size can at least be reduced to the 20nm technology generation. Based on the 1Mbit CuxSiyO resistive memory chip fabricated by 0.13um logic process, the through hole size of 40nnnnnmnmnmO70nm and 90nm (corresponding to 22nmmP32nmP45nm / 65nm technology) has been fabricated by using spacer pattern process in this paper. The test results show that CuxSiyO resistive memory can work normally in 22nm technology, and it has a good capability of miniature device size. On the other hand, when the device size is smaller than 90nm, the low resistance state resistance will increase with the decrease of device size. For 40nm devices, the RESET current is only 30 UA, which is 1 / 5 of the 190nm device. This further enhances the advantage of small size resistive memory. Parameter inhomogeneity is one of the most difficult problems in the application of resistive memory. Nonuniform parameters will lead to voltage, resistance window become smaller or even disappear, and device operation needs more complex algorithms and circuits to achieve. In this paper, the test method and test platform of resistive memory chip are presented, which can collect homogeneity related data on large capacity array. This paper also discusses how to detect nonuniformity of resistance by physical and electrical means. The results show that the initial state inhomogeneity of CuxSiyO resistive memory is caused by the inhomogeneity of the quality and thickness of CuxSiyO films. The effects of the preparation conditions and the size of the array on the uniformity were also studied, and the optimized process conditions and the size of the array were proposed. Resistive memory can be divided into bipolar type and unipolar type .Bipolar type according to whether or not the operating voltage direction of set / RESET is the same or not. It has the advantages of simple operation and compatibility with diodes without set / RESET interference, low operating current and so on. The traditional CuxSiyO resistive memory can work stably in bipolar mode. In this paper, it is found that CuxSiyO resistive memory can work stably in unipolar mode under certain forming conditions. The measurements of the conduction characteristics of low resistance states and the resistance temperature curves show that the unipolar type is conductive by metal ions while the unipolar type is conductive by holes. It is also proposed that the CuxSiyO memory can be operated in bipolar and unipolar mode according to the needs of different applications by controlling the operating conditions. It is hoped that through the research and discussion of these problems, we can deepen the understanding of resistance mechanism and accelerate the application of resistive memory.
【学位授予单位】：复旦大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TP333

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