Jeff HannaNanoscale Electronics

4.23.09

Gameplan•Why is memory important?•Background of MRAM•Basic Elementsof MRAM•Fabrication •Comparison•Applications•Current Value of Market

! Early MRAMs – anisotropic magnetoresistance" B is mag field, when off current

flows between rims" When on, the resistance between

rims goes up

! Giant Magnetoresistance" Triggered the new field of

electronics called spintronics

! Demohttp://www.research.ibm.

com/research/demos/gmr/1.swf

! Conventional MRAM" Single step write op" Substaintial current

needed" Overlapping fields occur

when scaling below 180nm

! Toggle­mode MRAM" Utilizes multi­step writing" Can be scaled much smaller" Less power needed

! 1 transistor 1 magnetic tunnel junction (1T1MTJ)

! Read: ­V applied to BL relative to SL. Current flows through MTJ. Sense amplifier decides “1” or ‘0”

! Write: “0” +V applied to SL and BL and vice versa when writing “1”

Note: The smaller the MTJ is or the longer the writing pulse is applied, the less critical switching current is needed

! Magnetic Tunnel Junction (MTJ) is storage element

! Tunnel magnetoresistance (TMR) defined by:" !R/R = (RAP !"#$")%#$

! Aerospace and military systems! Digital cameras! Notebooks! Smart cards! Mobile telephones! Cellular base stations! Personal Computers! Battery-Backed SRAM replacement! Datalogging specialty memories

(black box solutions)! Media players! Book readers

! Memory is important! MRAM has evolved past R&D! MTJ provide low power nonvolatile memory ! Fabrication is similar to current techniques! MRAM is comparable to become universal

memory! The memory market is estimated to sky rocket

and MRAM could grab a majority of market share