ＳＲＡＭセルにおけるばらつきの影響とその抑制方法

SRAM 单元变化的影响以及如何抑制它们

• 批准号: 15J09095
• 负责人: QIU HAO
• 金额: $ 1.47万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for JSPS Fellows
• 财政年份: 2015
• 资助国家: 日本
• 起止时间: 2015-04-24 至 2017-03-31
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15J09095/
• 关键词: SRAM; variability; write stability; low voltage; write butterfly curve; reliability

We have gained further understanding of two write stability methods (write butterfly curve and write N-curve).Firstly, the reason why write noise margin (WNM) in write N-curve deviates from a normal distribution at low VDD is clarified. Two modes are found in WNM's distribution. And the new mode is ascribed to cell transistor's sub-Vth operation.Secondly, a new write stability method based on write butterfly curve is proposed. By extending the voltage sweeping range of two internal nodes in SRAM, the extended write butterfly curve can be obtained. It is found that the extended WNM (E-WNM) follows a normal distribution even at low VDD. In addition, good correlation between E-WNM and WNM of bit-line method is obtained. Thus, the proposed one is a good candidate for low-VDD yield estimation.

对两种写稳定方法(写蝶形曲线和写N曲线)有了进一步的了解。首先，阐明了写N曲线在低VDD时写噪声裕度偏离正态分布的原因。在WNM的分布中发现了两种模式。其次，提出了一种新的基于写蝶形曲线的写稳定方法。通过扩展SRAM中两个内部节点的电压扫描范围，可以得到扩展的写入蝶形曲线。研究发现，即使在低VDD的情况下，扩展的WNM(E-WNM)也服从正态分布。此外，E-WNM与位线方法的WNM具有较好的相关性。因此，所提出的模型是低VDD成品率估计的一个很好的候选。

项目成果

A New Write Stability Metric for Yield Estimation in SRAM Cells at Low Supply Voltage

用于估计低电源电压下 SRAM 单元良率的新写入稳定性指标

• 发表时间: 2016
• 作者: Hao Qiu;Kiyoshi Takeuchi;Tomoko Mizutani;Takuya Saraya;Masaharu Kobayashi;Toshiro Hiramoto
• 通讯作者: Toshiro Hiramoto

Statistical Write Stability Characterization in SRAM Cells at Low Supply Voltage

低电源电压下 SRAM 单元的统计写入稳定性表征

• DOI: 10.1109/ted.2016.2612678
• 发表时间: 2016
• 期刊: IEEE Transactions on Electron Devices
• 影响因子: 3.1
• 作者: Hao Qiu;Tomoko Mizutani;Yoshiki Yamamoto;Hideki Makiyama;Tomohiro Yamashita;Hidekazu Oda;Shiro Kamohara;Nobuyuki Sugii;Takuya Saraya;Masaharu Kobayashi;Toshiro Hiramoto
• 通讯作者: Toshiro Hiramoto

A New Write Stability Metric Using Extended Write Butterfly Curve for Yield Estimation in SRAM Cells at Low Supply Voltage

一种新的写入稳定性指标，使用扩展写入蝴蝶曲线来估计低电源电压下 SRAM 单元的良率

• 发表时间: 2016
• 作者: Hao Qiu;Kiyoshi Takeuchi;Tomoko Mizutani;Takuya Saraya;Masaharu Kobayashi;Toshiro Hiramoto
• 通讯作者: Toshiro Hiramoto

Impact of Random Telegraph Noise (RTN) on Write Stability in Silicon-on-thin-BOX (SOTB) SRAM Cells in Sub-0.4V Regime

随机电报噪声 (RTN) 对低于 0.4V 体制下硅基薄盒 (SOTB) SRAM 单元写入稳定性的影响

• 发表时间: 2015
• 作者: Hao Qiu;Tomoko Mizutani;Yoshiki Yamamoto;Hideki Makiyama;Tomohiro Yamashita;Hidekazu Oda;Shiro Kamohara;Nobuyuki Sugii;Takuya Saraya;Masaharu Kobayashi;Toshiro Hiramoto
• 通讯作者: Toshiro Hiramoto

Impact of Random Telegraph Noise on Write Stability in Silicon-on-Thin-BOX (SOTB) SRAM Cells at Low Supply Voltage in Sub-0.4V Regime

在低于 0.4V 的低电源电压下，随机电报噪声对薄盒硅 (SOTB) SRAM 单元写入稳定性的影响

• 发表时间: 2015
• 作者: Hao Qiu;Tomoko Mizutani;Yoshiki Yamamoto;Hideki Makiyama;Tomohiro Yamashita;Hidekazu Oda;Shiro Kamohara;Nobuyuki Sugii;Takuya Saraya;Masaharu Kobayashi;Toshiro Hiramoto
• 通讯作者: Toshiro Hiramoto