2015 Fiscal Year Annual Research Report
| Project/Area Number |
15J09095
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| Research Institution | The University of Tokyo |
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Principal Investigator |
QIU HAO 東京大学, 生産技術研究所, 特別研究員(PD)
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| Project Period (FY) |
2015-04-24 – 2017-03-31
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| Keywords | SRAM / variability / reliability / low voltage |
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| Outline of Annual Research Achievements |
We have finished performing variability and reliability analysis of write stability in silicon-on-thin-BOX (SOTB) SRAM cells at low VDD.
Firstly, in order for a good yield estimation, four write stability methods (write butterfly curve, write N-curve, bit-line method, and word-line method) are compared. It is found that the latter two methods are good candidates. In addition, the reason why write noise margin (WNM) of write butterfly curve deviatse from a normal distribution is clarified.
Besides, the impact of random telegraph noise (RTN) is discussed. Based on our experimental results, a statistical model is proposed and it is concluded that RTN degrades Vmin - lowest VDD that SRAM can operate - by 48 mV at capacity of around 6.3 sigma, which should be paid attention to in SRAM design.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
Thanks to the guidance of my advisor as well as kind help from lab members, good results than expected have been successfully obtained.
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| Strategy for Future Research Activity |
The following work will go to details about write stability metrics in silicon-on-thin-BOX (SOTB) SRAM cells at low VDD. There are two main problems as follows.
Firstly, the reason why write noise margin (WNM) from write N-curve deviates from a normal distribution is still not clear. Assuming that two modes exist, cell transistors' conditions are to be compared for each mode and the distribution pattern for each mode is to be plotted.
Secondly, a new write stability metric based on our present work is to be proposed. Write butterfly curve is a popular method among engineers due to its simplicity though with its own drawbacks. Based on our understanding, a new method is to be proposed to replace conventional write butterfly curve for yield estimation at low VDD.
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Research Products
(4 results)
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[Presentation] Impact of Random Telegraph Noise (RTN) on Write Stability in Silicon-on-thin-BOX (SOTB) SRAM Cells in Sub-0.4V Regime2015
Author(s)
Hao Qiu, Tomoko Mizutani, Yoshiki Yamamoto, Hideki Makiyama, Tomohiro Yamashita, Hidekazu Oda, Shiro Kamohara, Nobuyuki Sugii, Takuya Saraya, Masaharu Kobayashi, Toshiro Hiramoto
Organizer
JSAP Autumn Meeting
Place of Presentation
Nagoya Congress Center, Nagoya
Year and Date
2015-09-13 – 2015-09-16
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[Presentation] Impact of Random Telegraph Noise on Write Stability in Silicon-on-Thin-BOX (SOTB) SRAM Cells at Low Supply Voltage in Sub-0.4V Regime2015
Author(s)
Hao Qiu, Tomoko Mizutani, Yoshiki Yamamoto, Hideki Makiyama, Tomohiro Yamashita, Hidekazu Oda, Shiro Kamohara, Nobuyuki Sugii, Takuya Saraya, Masaharu Kobayashi, Toshiro Hiramoto
Organizer
IEEE Symposium on VLSI Technology
Place of Presentation
Rihga Royal Hotel Kyoto, Kyoto
Year and Date
2015-06-16 – 2015-06-19
Int'l Joint Research
