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[Author] Yasumasa TSUKAMOTO(2hit)

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  • Realistic Scaling Scenario for Sub-100 nm Embedded SRAM Based on 3-Dimensional Interconnect Simulation

    Yasumasa TSUKAMOTO  Tatsuya KUNIKIYO  Koji NII  Hiroshi MAKINO  Shuhei IWADE  Kiyoshi ISHIKAWA  Yasuo INOUE  Norihiko KOTANI  

     
    PAPER

      Vol:
    E86-C No:3
      Page(s):
    439-446

    It is still an open problem to elucidate the scaling merits of an embedded SRAM with Low Operating Power (LOP) MOSFETs fabricated in 50, 70 and 100 nm CMOS technology nodes. Taking into account a realistic SRAM cell layout, we evaluated the parasitic capacitance of the bit line (BL) as well as the word line (WL) in each generation. By means of a 3-Dimensional (3D) interconnect simulator (Raphael), we focused on the scaling merit through a comparison of the simulated SRAM BL delay for each CMOS technology node. In this paper, we propose two kinds of original interconnect structure which modify ITRS (International Technology Roadmap for Semiconductors), and make it clear that the original interconnect structures with reduced gate overlap capacitance guarantee the scaling merits of SRAM cells fabricated with LOP MOSFETs in 50 and 70 nm CMOS technology nodes.

  • An Analysis of Local BTI Variation with Ring-Oscillator in Advanced Processes and Its Impact on Logic Circuit and SRAM

    Mitsuhiko IGARASHI  Yuuki UCHIDA  Yoshio TAKAZAWA  Makoto YABUUCHI  Yasumasa TSUKAMOTO  Koji SHIBUTANI  Kazutoshi KOBAYASHI  

     
    PAPER

      Pubricized:
    2021/05/25
      Vol:
    E104-A No:11
      Page(s):
    1536-1545

    In this paper, we present an analysis of local variability of bias temperature instability (BTI) by measuring Ring-Oscillators (RO) on various processes and its impact on logic circuit and SRAM. The evaluation results based on measuring ROs of a test elementary group (TEG) fabricated in 7nm Fin Field Effect Transistor (FinFET) process, 16/14nm generation FinFET processes and a 28nm planer process show that the standard deviations of Negative BTI (NBTI) Vth degradation (σ(ΔVthp)) are proportional to the square root of the mean value (µ(ΔVthp)) at any stress time, Vth flavors and various recovery conditions. While the amount of local BTI variation depends on the gate length, width and number of fins, the amount of local BTI variation at the 7nm FinFET process is slightly larger than other processes. Based on these measurement results, we present an analysis result of its impact on logic circuit considering measured Vth dependency on global NBTI in the 7nm FinFET process. We also analyse its impact on SRAM minimum operation voltage (Vmin) of static noise margin (SNM) based on sensitivity analysis and shows non-negligible Vmin degradation caused by local NBTI.