Title
Layout-aware optimization of STT MRAMs
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, WFET 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.
Year
DOI
Venue
2012
10.1109/DATE.2012.6176595
DATE
Keywords
Field
DocType
reverse-connected stt mram,mpl region,layout-aware optimization,metal pitch,large wfet,cell area,stt mram cell,iso-cell area,conventional stt mram cell,stt mrams,minimum cell area,magnetic anisotropy,noise measurement,metals,optimization,stt mram,critical value,layout,transistors
Quantum tunnelling,Torque,Noise measurement,Computer science,Voltage,Magnetoresistive random-access memory,Transistor,Electrical engineering,Write margin
Conference
ISSN
Citations 
PageRank 
1530-1591
20
1.54
References 
Authors
1
4
Name
Order
Citations
PageRank
Sumeet Gupta1110657.47
Sang Phill Park253531.56
Niladri Narayan Mojumder3665.38
Kaushik Roy47093822.19