SRAM存储单元抗单粒子翻转研究

发布时间：2018-01-08 18:33

本文关键词：SRAM存储单元抗单粒子翻转研究　出处：《安徽大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着人类对外太空深入探索,航天电子设备所要面临辐射环境也愈复杂。对于航天器中的集成电路而言,存储器占据极其重要的地位。存储器的抗辐射性能的高低直接影响航天设备的稳定性。当单个粒子入射电路时,可能会导致存储单元数据变化,即单粒子翻转。随着工艺尺寸的不断缩减,电路集成度逐步提高,单个粒子对存储器的危害日益严重。传统的加固技术,如:SOI工艺,其成本高且自身寄生的效应对电路带来的危害是不可忽视的,而通过增加冗余存储节点的电路级加固技术需要额外的面积开销,同时电路集成度的提高导致这种设计思想已面临失效。本文针对单粒子对SRAM存储单元的影响进行研究,并提出一种相应的加固方法。论文工作内容如下:首先简单介绍辐射环境以及电离辐射效应,并从电路、工艺、版图、系统四个层次介绍国内外现有的存储单元加固方法;对于电离辐射效应,详细介绍几种常见单粒子效应及其产生的机理,其中包括单粒子轰击半导体器件后电荷的产生以及收集过程;从电路级、器件级、.电路与器件混合级这三个方面阐述了单粒子效应的建模方法,并对本文仿真用到的SentaurusTCAD软件进行详细的介绍。其次介绍了 SRAM6T存储单元的结构及工作原理,并使用SentaurusTCAD采用混合模拟方法对存储单元进行物理建模与器件仿真,主要包括对PMOS管进行工艺校准,并使用PMOS管与集总参数模型的NMOS管搭建6T单元,并对其读写功能进行仿真验证;使用不同能量的单粒子轰击存储单元,其存储信息会发生单粒子翻转(Single Event Upset,SEU)和翻转恢复(Upset Reversal)两种现象,在此基础上研究不同角度入射、工作电压、管间距对两种现象的临界LET(Linear Energy Transfer)阂值的影响,仿真结果表明可以利用翻转恢复效应这一机理对存储单元进行抗辐射加固。最后通过模拟不同工艺掺杂浓度的变化对存储单元翻转恢复效应的影响,发现改变器件模型中P+深阱浓度、N阱浓度、调阈掺杂浓度会影响存储单元翻转恢复的时间和临界LET阂值。本文通过对掺杂浓度进行调整,减小了翻转恢复所需的时间,并降低恢复效应的临界LET阈值,从而实现了对SRAM存储单元的加固。
[Abstract]:With the in-depth exploration of outer space, aerospace electronic equipment will face radiation environment more complex. For the integrated circuit in the spacecraft, memory occupies an extremely important position. The stability of memory anti radiation performance directly affects the level of aerospace equipment. When a single particle incident circuit, may lead to changes in the data storage unit, i.e. SEU. With the shrinking size of integrated circuit technology, and gradually improve, the harm to the memory of the single particle becomes more and more serious. The traditional reinforcement technology, such as SOI technology, the harm of high cost and its effect on the parasitic circuit can not be ignored, and the circuit level redundancy storage node reinforcement technology need area overhead, and the integrated circuit are improving the design idea has been facing failure. Based on the single particle of SRAM storage single Research on the influence of element, and proposes a corresponding reinforcement method. The contents are as follows: first introduces the radiation environment and the effects of ionizing radiation, and from the circuit, process, layout, the four level system introduced the domestic and foreign existing storage unit for reinforcement method; the effects of ionizing radiation, introduces several common single mechanism the effect of particles, including the charge generation of single particle bombardment of semiconductor devices and the collection process; from the circuit level, the device level, mixed level circuit and device. The three aspects of the modeling method of single particle effect, and a detailed introduction to the use of SentaurusTCAD simulation software. Secondly introduces the structure and the working principle of SRAM6T storage unit, and use the SentaurusTCAD hybrid simulation method for modeling and Simulation of the physical device storage unit, including the PMOS tube The process of calibration, and use PMOS to build the 6T pipe unit and the lumped parameter model of NMOS tube, and simulated the read write function; single particle bombardment using different energy storage unit, which stores the information will occur SEU (Single Event, Upset, SEU) and turn (Upset Reversal) two recovery a study on the phenomenon, different incident angle, on the basis of working voltage, critical LET tube spacing on the two phenomena (Linear Energy Transfer) of the threshold value, the simulation results show that using inversion recovery effect of this mechanism on the storage unit of radiation hardened. Finally with different doping concentration recovery process simulation effect of storage unit in turn, found that changing device model in deep well P+ concentration, N concentration of wells, adjusting the threshold concentration will affect the storage unit to turn over the recovery time and the critical LET threshold based on the mixed. The miscellaneous concentration is adjusted to reduce the time needed for the reversal recovery and reduce the critical LET threshold of the recovery effect, thus strengthening the SRAM storage unit.

【学位授予单位】：安徽大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP333

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