Layout-aware optimization of STT MRAMs

Sumeet Kumar Gupta, Sang Phill Park, Niladri Narayan Mojumder, Kaushik Roy

Research output: Chapter in Book/Report/Conference proceedingConference contribution

48 Scopus citations

Abstract

We present a layout-aware optimization methodology for spin-transfer torque (STT) MRAMs, considering the dependence of cell area on the access transistor width (WFET), number of fingers in the access transistor and the metal pitch of bit- and source-lines. It is shown that for WFET less than a critical value (∼7 times the minimum feature length), one-finger transistor yields minimum cell area. For large WFET, minimum cell area is achieved with a two-finger transistor. We also show that for a range of WFET, the cell area is limited by the metal pitch of bit- and source-lines. As a result, in the metal pitch limited (MPL) region, W FET can be increased with no change in the cell area. We analyze the impact of increase in WFET in the MPL region on the write margin and cell tunneling magneto-resistance (CTMR) of different genres of STT MRAMs. We consider conventional STT MRAM cells in the standard and reverse-connected configurations and STT MRAMs with tilted magnetic anisotropy for the analysis. By increasing WFET from the minimum to the maximum value in the MPL region (at iso-cell area) and reducing read voltage to achieve iso-read disturb margin, 2X improvement in write margin and 27% improvement in CTMR is achieved for the reverse-connected STT MRAM. Similar trends are observed for other STT MRAM cells.

Original languageEnglish (US)
Title of host publicationProceedings - Design, Automation and Test in Europe Conference and Exhibition, DATE 2012
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages1455-1458
Number of pages4
ISBN (Print)9783981080186
DOIs
StatePublished - 2012
Event15th Design, Automation and Test in Europe Conference and Exhibition, DATE 2012 - Dresden, Germany
Duration: Mar 12 2012Mar 16 2012

Publication series

NameProceedings -Design, Automation and Test in Europe, DATE
ISSN (Print)1530-1591

Other

Other15th Design, Automation and Test in Europe Conference and Exhibition, DATE 2012
CountryGermany
CityDresden
Period3/12/123/16/12

All Science Journal Classification (ASJC) codes

  • Engineering(all)

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