Design margin exploration of spin-transfer torque RAM (STT-RAM) in scaled technologies

  • Authors:
  • Yiran Chen;Xiaobin Wang;Hai Li;Haiwen Xi;Yuan Yan;Wenzhong Zhu

  • Affiliations:
  • Seagate Technology, Bloomington, MN;Seagate Technology, Bloomington, MN;Department of Electrical & Computer Engineering, Polytechnic Institute of NYU, Brooklyn, NY;Seagate Technology, Bloomington, MN;Hitachi Global Storage Technologies, San Jose, CA;Seagate Technology, Bloomington, MN

  • Venue:
  • IEEE Transactions on Very Large Scale Integration (VLSI) Systems
  • Year:
  • 2010

Quantified Score

Hi-index 0.00

Visualization

Abstract

We propose a magnetic and electric level spin-transfer torque random access memory (STT-RAM) cell model to simulate the write operation of an STT-RAM. The model of a magnetic tunneling junction (MTJ) is modified to take into account the electrical response of the MOS transistor that is connected to the MTJ. A dynamic design flow is also proposed to minimize any unnecessary design margin in an STT-RAM cell design by leveraging from the new STT-RAM cell model. The design of an STT-RAM cell with a one-transistor-one-MTJ (1T1J) structure shows that our technique can reduce more than 22% of the STT-RAM cell area, compared with a conventional STT-RAM cell model at a TSMC 90-nm technology node. The performance and the reliability of the memory cell were unaffected. By using our model, we analyzed the scalability of STT-RAM technology down to a 22-nm Bulk-CMOS technology node. The tradeoffs among the MTJ switching current, the thermal stability of the MTJ and the MOS transistor driving strength are discussed. Some magnetic- and circuit-level solutions to achieve 9F2 STT-RAM cell area at 22-nm technology node are also discussed.