相变存储器单元高速擦写测试方法研究
发布时间：2018-11-07 14:38
【摘要】：相变存储器是一种新型固态非易失性存储器，它的存储单元面积较小，并且有进一步小型化的潜力，适合制造大容量固态存储器。另外它的擦写速度很快，目前已经开始量产的相变存储器芯片工作速度较闪存芯片平均快10倍以上。擦写速度是存储器的一项关键性能指标,相变存储器在很宽的脉冲宽度范围内都可以实现擦写操作，在良好的工艺条件和测试条件下，相变存储器单元的SET和RESET脉冲宽度可以到纳秒级，RESET脉冲宽度更是可以降到1ns以下，开展相变存储器单元的高速擦写特性研究对拓展相变存储器的应用领域具有重要的意义。 本文的重点是研究相变存储器单元在皮秒RESET电脉冲作用下的非晶化行为。首先研究了高频测量中的测试系统带宽和信号完整性对测试的影响，并设计了相变存储器单元的高速擦写特性测试电路，分别测试了相变材料层厚度为50nm、100nm、150nm的三组相变存储器单元样品的皮秒RESET操作特性，实现了最短脉冲宽度为0.2ns的重复RESET操作。针对存储单元阵列规模的拓展，同时为了提高测试的效率，，设计并研制了一套相变存储器阵列高速擦写特性测试系统，该测试系统硬件部分包括半导体特性测试仪、皮秒脉冲发生器、数字示波器、编译码模块、驱动模块、单稳态触发延时模块和高速脉冲信号通道等;软件部分为C语言程序，运行在半导体特性测试仪内置的计算机上。测试系统各部分通过GPIB电缆连接，测试系统整体具有高速脉冲信号通道带宽大，测量精确、使用方便的优点。 本文还利用SPICE建模对高速脉冲测试电路进行了时域瞬态仿真，验证了高速脉冲测试方案。并研究了在皮秒电压脉冲作用下相变材料的非晶化的机理,认为其非晶化是不依赖热量的产生。提出了局部强电场引发材料内部出现冲击电离的模型，较合理地解释了相变材料在皮秒脉冲作用下的非晶化相变现象。
[Abstract]:Phase change memory (PCM) is a new type of solid state nonvolatile memory. Its storage cell area is small, and it has the potential of further miniaturization, so it is suitable for manufacturing large capacity solid state memory. In addition, its writing speed is very fast, and the phase-change memory chip, which has already been produced in mass production, works more than 10 times faster than the flash memory chip on average. Writing speed is a key performance index of memory. Phase change memory can be used in a wide pulse width range, under good process conditions and test conditions, The pulse width of SET and RESET can reach nanosecond order and the width of RESET pulse can be reduced to less than 1ns. It is of great significance to develop the high-speed erasure characteristics of phase-change memory cell in order to expand the application field of phase-change memory. The emphasis of this paper is to study the amorphous behavior of phase change memory cells under the action of picosecond RESET electric pulse. In this paper, the influence of the bandwidth and signal integrity of the high frequency measurement system on the test is studied, and the high speed erasure characteristic test circuit of the phase change memory cell is designed. The thickness of the phase change material layer is measured to be 50 nm / 100 nm, respectively. The picosecond RESET operation characteristics of three groups of phase change memory cell samples in 150nm are used to realize the repeated RESET operation with the shortest pulse width being 0.2ns. Aiming at the expansion of memory cell array scale, and in order to improve the efficiency of testing, a high speed erasure characteristic test system of phase change memory array is designed and developed. The hardware part of the test system includes semiconductor characteristic tester. Picosecond pulse generator, digital oscilloscope, code and decode module, drive module, Monostable trigger delay module and high-speed pulse signal channel. The software part is C language program, running on the computer built in the semiconductor characteristic tester. Each part of the test system is connected by GPIB cable. The whole test system has the advantages of high speed pulse signal channel bandwidth, accurate measurement and convenient use. The time domain transient simulation of high speed pulse test circuit is carried out by using SPICE modeling, and the scheme of high speed pulse test is verified. The mechanism of non-crystallization of phase change material under picosecond voltage pulse is studied. It is considered that the non-crystallization of phase change material is heat independent. A model of shock ionization in the materials initiated by local strong electric field is proposed. The phenomenon of amorphous phase transition of phase change materials under picosecond pulse is explained reasonably.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TP333
本文编号：2316670
[Abstract]:Phase change memory (PCM) is a new type of solid state nonvolatile memory. Its storage cell area is small, and it has the potential of further miniaturization, so it is suitable for manufacturing large capacity solid state memory. In addition, its writing speed is very fast, and the phase-change memory chip, which has already been produced in mass production, works more than 10 times faster than the flash memory chip on average. Writing speed is a key performance index of memory. Phase change memory can be used in a wide pulse width range, under good process conditions and test conditions, The pulse width of SET and RESET can reach nanosecond order and the width of RESET pulse can be reduced to less than 1ns. It is of great significance to develop the high-speed erasure characteristics of phase-change memory cell in order to expand the application field of phase-change memory. The emphasis of this paper is to study the amorphous behavior of phase change memory cells under the action of picosecond RESET electric pulse. In this paper, the influence of the bandwidth and signal integrity of the high frequency measurement system on the test is studied, and the high speed erasure characteristic test circuit of the phase change memory cell is designed. The thickness of the phase change material layer is measured to be 50 nm / 100 nm, respectively. The picosecond RESET operation characteristics of three groups of phase change memory cell samples in 150nm are used to realize the repeated RESET operation with the shortest pulse width being 0.2ns. Aiming at the expansion of memory cell array scale, and in order to improve the efficiency of testing, a high speed erasure characteristic test system of phase change memory array is designed and developed. The hardware part of the test system includes semiconductor characteristic tester. Picosecond pulse generator, digital oscilloscope, code and decode module, drive module, Monostable trigger delay module and high-speed pulse signal channel. The software part is C language program, running on the computer built in the semiconductor characteristic tester. Each part of the test system is connected by GPIB cable. The whole test system has the advantages of high speed pulse signal channel bandwidth, accurate measurement and convenient use. The time domain transient simulation of high speed pulse test circuit is carried out by using SPICE modeling, and the scheme of high speed pulse test is verified. The mechanism of non-crystallization of phase change material under picosecond voltage pulse is studied. It is considered that the non-crystallization of phase change material is heat independent. A model of shock ionization in the materials initiated by local strong electric field is proposed. The phenomenon of amorphous phase transition of phase change materials under picosecond pulse is explained reasonably.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TP333
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