Jeff Hanna Nanoscale Electronics 4.23.09 Gameplan Why is memory - - PowerPoint PPT Presentation

Jeff Hanna Nanoscale Electronics 4.23.09

Gameplan

• Why is memory

important?

• Background of MRAM
• Basic Elements
• f 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

! Demo

http://www.research.ibm. com/research/demos/g mr/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