mram 4 dieny.pdf
Post on 01-Dec-2015
44 Views
Preview:
DESCRIPTION
TRANSCRIPT
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Part 4: Advanced MRAM concepts
A
P
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
•Ultrafast precessional STTRAM
•Race track memories
•3-terminal devices
•Voltage controlled MRAM
•Comparison of STTRAM with resistive RAM
Part 4: Advanced MRAM concepts
OUTLINE
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
•Ultrafast precessional STTRAM
•Race track memories
•3-terminal devices
•Voltage controlled MRAM
•Comparison of STTRAM with resistive RAM
Part 4: Advanced MRAM concepts
OUTLINE
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Several families of MRAM
Thermally Assisted (TAS) STT-TAS
Hx
Hy
Field-driven STT (STT MRAM)
Perpendicular
Precessional
Planar
DW motion
Spin-orbit torque(spin-Hall, Rashba)
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
5
Idea: elaborate a Spin Transfer Torque ‐MRAM with an ultrafast switching to achieve the sub nano second‐scale writing time
Storage disk drive
TB~ms
Main memoryDRAMGB
50‐10 ns
CacheSRAMkB – MB~0.5 à 2 ns
Register
Processor
2 GHz
~100 MHz
Density
Speed
Memory Hierarchy
• Replacing SRAM memory• Building non volatile logic circuits with low‐energy consumption
Ultrafast MRAM :
p-STTRAM Need for a sub-ns switching MRAM
Need for ultrafast STTRAM for SRAM-like applications
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Stochastic switching in conventional STTRAM approaches
Tra
nsm
itte
d
volt
age
(mV
)
Time after pulse (ns)
Referencelayer
MgO
In-plane Out-of-plane
→→→→
××=Γ )( MPMa j
Spin-transfer torque:
Mr
Mr
Pr
Pr
•Stochastic reversal • incubation time preceding a large thermal fluctuation•Slows down the STTRAM writing
Devolder et al. Phys. Rev. Let. vol 100 (2008)
MgO based in-plane MTJ
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
7
MRAM with orthogonal polarizer and analyzer
O. Redon, B. Dieny andB. Rodmacq, US Patent FR0015893 (2000),
US6532164B2
A.Kent et al, APL 84, 3897 (2004)
Free Layer
Reference Layer
(Analyzer)
Perpendicular Polarizer
→→→→→→→
→→→→
××+××+×+×−= )()(0 MPMaMAMadt
MdM
MHM
dt
MdjPerpJLong
S
effαγ
Equation of motion
→ STT from Perpendicular polarizer:Out‐of‐plane oscillations of free layer
magnetization
Switching in less than 1ns
No incubation delay (PM)
→ STT from in‐plane analyzer:Bipolar switching of free layer
magnetization
2 STT contributions
MgO
Ar
Pr
Mr
MgO (lower RA) or Cu
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
RF oscillator with perpendicular to plane polarizer
(SPINTEC patent + Lee et al, Appl.Phys.Lett.86, 022505 (2005) )
D.Houssamedine et al,Nat.Mat 2007
Injection of electrons with out-of-plane spins;Steady precession of the magnetizationof the soft layer adjacent to the tunnel barrier.
Precession (2GHz-40GHz) + Tunnel MR ⇒ RF voltageInteresting for frequency tunable RF oscillators ⇒ Radio opportunism
Cu
PtMn
Cu
CoFeCoFe
Al2O3
(Pt/Co)
J
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Free Layer
Reference Layer
(Analyzer)
Perpendicular Polarizer
Depending on the relative influence of STT from perpendicular polarizer and in-plane analyzer, different switching behaviors can be observed:
-If STT from perpendicular Polarizer dominates→ Oscillatory switching probability versus current pulse duration. Switching whatever the current direction.More difficult to control in STTRAM devices since requires controlling the current pulse duration at ±50ps. Requires read before write.
→→→→→→→
→→→→
××+××+×+×−= )()(0 MAMaMPMadt
MdM
MHM
dt
MdjLongjPerp
S
effαγ
Ar
Pr
How to conveniently tune the relative influence of these two STT contributions?
-If STT from in-plane Analyzer dominates→Non-oscillatory switching probability vs pulse duration. Final state determined by current direction. No need to read before write.
MRAM with orthogonal polarizer and analyzer
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Tuning the relative STT influence of Tuning the relative STT influence of perpperp polarizer and polarizer and inin--plane analyzer by playing on the cell aspect ratioplane analyzer by playing on the cell aspect ratio
→ STT from perpendicular polarizer:
→ STT from in‐plane analyzer:
2g(0)
M 2
2g(0)
M 2 2s0s0 μαμα Fs
KFLong
c
teMH
tej ⎟
⎠⎞
⎜⎝⎛≈⎟
⎠⎞
⎜⎝⎛ +⎟
⎠⎞
⎜⎝⎛=
hh
2/2)g(
M 2 s0 KFPerpc
Htej
πμ
⎟⎠⎞
⎜⎝⎛=h
To get bipolar non-oscillatory switching probability versus pulse duration:
Longc
Perpc jjj >> implying
Hk = in-plane shape anisotropy field
1<Perpc
Longc
j
ji.e ( )
( ) 1
02 <
K
s
H
M
g
g απ
The easiest way to fulfill this relationship is to increase HK by increasing the cell aspect ratio (AR)
Typically,
7.0)0(/)2/( ,01.0~ ,6.1~0.01,~ 00 ≈ggTHTM Ks πμμα with AR~2 so that ratio~1.1
J.Sun, PRB 62, 570 (2000) (SI units)
K.J.Lee et al, APL 86, 022505 (2005)
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Elliptical nanopillars270x80 nm
TMR~65% and RA~16 Ω.µm2
Annealing 300oC; 90 minutes under in‐plane field
→Synthetic antiferromagnetic layers reduce the magnetostatic interactions between layers
MRAM with orthogonal polarizer and analyzer
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
time (ns)Mag
neto
resi
stan
ce(a
.u.)
Current density (1010 A/m2)0 5 10 15F
requ
ency
(G
Hz)
0
10
20
Cur
rent
dens
ity(x
1010
A/m
2 )
Pulse width (ns)0%
50%
100%Out-of-plane precession of the free layer magnetization due to STT from perpendicular polarizer
Cell size : 80nm*160nm Macrospin simulation:Proba of switching under STT from perp polarizer only
PAP
Dynamics dominated by the STT contributionfrom perpendicular polarizer (AR=2)
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
AP and P reference signals measured under sufficiently large magnetic field to maintain the AP and P configurations during the current pulse. Field switched off afterwards.
As expected, the perpendicular polarizer induces a large amplitude precession around the normal to the plane
P stateCell size : 80nm*160nm
AP initial state
Single-shot transmitted signal (AR=2)
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
2.00E-008 2.50E-008 3.00E-008 3.50E-008 4.00E-008 4.50E-008-0.08
-0.07
-0.06
-0.05
-0.04
-0.03
-0.02
-0.01
0.00
0.01
Single pulse Average of 100 traces Reference signal
Vo
ltag
e (
V)
time after pulse2.00E-008 2.50E-008 3.00E-008 3.50E-008 4.00E-008 4.50E-008
-0.08
-0.07
-0.06
-0.05
-0.04
-0.03
-0.02
-0.01
0.00
0.01
Single pulse Average of 100 traces Reference signal
0,6GHz
Vol
tage
(V
)
time after pulse (s)
2.00E-008 2.50E-008 3.00E-008 3.50E-008 4.00E-008 4.50E-008
-0.07
-0.06
-0.05
-0.04
-0.03
-0.02
-0.01
0.00
0.01
Single pulse Average of 100 traces Reference signal
Vol
tage
(V
)
time after pulse (s)2.00E-008 2.50E-008 3.00E-008 3.50E-008 4.00E-008 4.50E-008
-0.07
-0.06
-0.05
-0.04
-0.03
-0.02
-0.01
0.00
0.01
Single pulse Average of 100 traces Reference signal
Vol
tage
(V
)
time after pulse (s)
1GHz
500mV
708mV630mV
563mV
Precession frequency depends linearly on the
current density
7 8 9 10 11 120.7
0.8
0.9
1.0
1.1
1.2
Fre
qu
ency
(G
Hz)
Current Density (x1010 A/m²)
Lee et al, APL86, 022505 (2005)
Frequency vs current density (AR=2)
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
15
0 1 2 3 4 5 6 7 8 9 10
Single shot traces at 1.4V
Time after pulse (ns)
De-phasing of precessionalmotion explains the probability amplitude decay observed in probability measurements
Acknowledgement to T. Devolder at IEF in Paris for real time measurements
Pulse duration (ns)
Sw
itchi
ng p
roba
bilit
y (%
)
Precession decoherence (AR=2)
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Cu
PtMn
Cu
CoFeCoFe
Cu
(Pt/Co)
JD.Houssamedine et al,Nat.Mat 2007
F re q u e n c y vs Tim e
f (H z )
t (s
)
7 . 1 7 .2 7 .3 7 .4 7 .5 7 .6 7 .7 7 .8
x 1 09
2
4
6
8
1 0
1 2
x 1 0-7
0.90 mA1.25 µs
Time evolution of spectrumTime domain measurement
5 1 0 1 5
x 1 0-8
-0 .0 2
-0 .0 1 5
-0 .0 1
-0 .0 0 5
0
0 .0 0 5
0 .0 1
0 .0 1 5
0 .0 2
t (s )
V (
V)
0.90 mASlidingwindow
FFT
0 150 nstime f(GHz)7.1 7.80
1
t(μs)
Δf~200MHz
nsf 5/1 ≈Δ≈τ
Precession decoherence also seen in STT oscillators: contribution to linewidth
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Pulse width (ns)
0%
50%
Cur
rent
dens
ity(x
1010
A/m
2 )
100%Switching probability (initial=P)
When the condition is fulfilled:
Non-oscillatory bipolar switching can be achieved.If the current is too large, oscillatory switching
probability is recoveredUltrafast reversal without incubation time
Longc
Perpc jjj >>
Cell size = 50nm*250nm
Pulse width (ns)
Switching probability (initial=AP)
P AP
AP P
Cur
rent
dens
ity(x
1010
A/m
2 )
Dynamics dominated by STT contribution from in-plane analyzer (AR=5)
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
0.0 0.2 0.4 0.6 0.8 1.0 1.2
AP
mag
neto
resi
stan
ce (
a.u.
)
time (ns)
4.5e10 A/m2 5.5e10 A/m2 6.5e10 A/m2 7.5e10 A/m2P
0.0 0.2 0.4 0.6 0.8 1.0 1.2
AP
Pma
gnet
ore
sist
anc
e (a
.u.)
time (ns)
Without perpendicular polarizer(STT from in-plane analyzer only)
J = 25 1010 A/m²
Incubationtime
STT from both in-plane and perpendicular polarizer
No stochastic incubation timeReduced switching currentSwitching time is reduced to 300ps by increasing the current density
Dynamics dominated by STT contribution from in-plane analyzer (AR=5)
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
0 2 4 6 8 10
0.0
0.2
0.4
0.6
0.8
1.0
Sw
itch
ing
Pro
bab
ility
Pu lse w idth (ns)
500m V 562m V 631m V centered b ias 631m V A P b ias 631m V P b ias 708 794m V
Fullfilling the condition allows for bipolar non-oscillatory switching of the storage layer magnetization suitable for SRAM type of applications
⇒ precession stops at stable state after half a precession period.
Switching with 90fJ
Similar results:Liu et al, APL97, 242510 (2010)
Cell size = 50nm*250nm
Longc
Perpc jjj >>
Dynamics dominated by STT contribution from in-plane analyzer (AR=5)
Marins de castro Sousa et al,
Journal of Applied Physics 111 (2012) 07C912
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
• Ultrafast STT switching with combined STT influences from perpendicular polarizer and in-plane analyzer
• Successful integration of a perpendicular polarizer in an in-plane magnetized MTJ with good TMR signal (~60-70%).
• Oscillation of the switching probability associated with dominant STT influence from perpendicular polarizer
• Bipolar non-oscillatory switching can be achieved for ultrafast reliable writing in STTRAM by using elongated cells. Drawback is larger footprint.
• Sub-ns switching and low energy consumption can be achieved (90fJ range)
Summary on ultrafast STTRAM with orthogonal polarizers
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
•Ultrafast precessional STTRAM
•Race track memories
•3-terminal devices
•Voltage controlled MRAM
•Comparison of STTRAM with resistive RAM
Part 4: Advanced MRAM concepts
OUTLINE
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Field driven DW motion Current driven DW motion
Magnetic fieldH = -20mT
Positive current Negative currentH=0
(a)
(b) (c) (d)
Current Induced Domain Wall (DW) motion
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Current Induced Domain Wall (DW) motionSTT used to push domain walls:
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Reading
Writing
Vertical racetrack
Horizontal racetrack
Racetrackstorage array
A
B
C
D
E
Race-track memories
Parkin et al, IBM (2004)
Shift register based on coherent domain wall displacements induced by current
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Race-track memories
Injection of domain walls:
Injection by field
Injection by STT through a tunnel barrier can also be used or using the fringing field from a domain wall in an underlying wire (see previous slide).
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Race-track memories
Race-track: a multibit MRAM with extended storage layer.
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Parkin et al, IEDM 2011
Race-track memories
Successful demonstration on a 8μm long shift register:
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Race-track memories
Remaining challenges:
-Use perpendicular-to-plane materials for narrower domain walls and weak pinning energies.
-Avoid pinning defects which locally trap domain walls. One single pinning defect along a given track may prevent that whole track to properly work.
-Homogeneity of properties if using vertical dimension.
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
•Ultrafast precessional STTRAM
•Race track memories
•3-terminal devices
•Voltage controlled MRAM
•Comparison of STTRAM with resistive RAM
Part 4: Advanced MRAM concepts
OUTLINE
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Several families of MRAM
Thermally Assisted (TAS) STT-TAS
Hx
Hy
Field-driven STT (STT MRAM)
Perpendicular
Precessional
Planar
DW motion
Spin-orbit torque(spin-Hall, Rashba)
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
3-terminal MRAM cell based on current-induced domain wall propagation
Advantages : -Less electrical stress on the barrier during write (improved reliability)-Less current required to write since thickness<<width-Multibit possible
referencebarrier
Storage stripe
Disadvantage : Larger cell
0 1 2 30
100
200
300
400
DW
vel
oci
ty (
m/s
)
Current density (x 1012 A/m2)
V ~ 250m/s100nm ~ 400ps
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
3-terminal MRAM cell based on current-induced domain wall propagation
NEC
The memory cell has a shape such that a magnetic wall is necessarily exist.Domain wall moved by STT influence from in-plane current.
Potential of 0.1-mA and 2-ns writing with sufficient thermal stability,
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
3-terminal MRAM cell based on current-induced domain wall propagation
Multibit MRAM (shift register) based on DW propagation
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Several families of MRAM
Thermally Assisted (TAS) STT-TAS
Hx
Hy
Field-driven STT (STT MRAM)
Perpendicular
Precessional
Planar
DW motion
Spin-orbit torque(spin-Hall, Rashba)
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
AlOx 2 nmCo 0.5 nmPt 3 nm
2 2
1 1
1 /v
c vB E
c= ×
−
r rr
Breaking of inversion symmetry – Rashba effect
Co-dz²
O-pz Charge transfer at Co/MOxinterface⇒Interfacial E field
Er
Jr
Jr
Er
Rashba effect in MTJ electrodes with in-plane current
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
36
M.Miron et al, Nature 476,189 (2011)
Magnetization reversal by Rashba effectin MTJ electrode with in-plane current
Writing with in-plane current
Reading with current through barrier
Switching induced by spin-orbit torque: Rashba or Spin-Hall
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
•Ultrafast precessional STTRAM
•Race track memories
•3-terminal devices
•Voltage controlled MRAM
•Comparison of STTRAM with resistive RAM
Part 4: Advanced MRAM concepts
OUTLINE
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Voltage controlled MRAM
STTRAM are written by a pulse of current flowing through the MTJ.The main source of energy consumption during write is the Jouledissipation:
tRIE 2=In STTRAM, the energy per write event is in the range 0.1pJ-10pJ (depending on the retention).
If we could control the magnetic properties of the storage layer by voltage without significant current flow through the MTJ, then the energy consumption could be reduced to
2
2
1CVE = Could be in the range of fJ provided
V is below 1V
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Voltage controlled MRAM
Several approaches:
-Using multiferroïc materials : materials which exhibit coupled structural, electrical and magnetic properties (piezoelectric, magneto-electric, magneto-elastic). Example: BiFeO3
-Using synthetic multiferroïc materials :
Piezo-electric
Magneto-elastic
-Using the influence of interfacial electric field on the perpendicular anisotropy at magnetic metal/oxide interface
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Voltage controlled MRAM
At metal/oxide interface, density of states at Fermi energy can be tuned by electrical field. However very short penetration depth of electrical field in metal (<2Å): interfacial effect. Can be used to tune the CoFeB/MgO anisotropy by electrical field.Can very much reduce the power consumption compared to STT if operates at V<1V
Intrinsically weak effect. Large manifestation if close to condition of anisotropy reorientation (for instance compensation between in-plane demagnetizing energy and perp interfacial energy). But difficult to use in actual device because condition fulfilled at only one temperature.
Endo et al, APL96, 212503(2010)
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
•Ultrafast precessional STTRAM
•Race track memories
•3-terminal devices
•Voltage controlled MRAM
•Comparison of STTRAM with resistive RAM
Part 4: Advanced MRAM concepts
OUTLINE
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
STT-MRAMReRAM
ITRS ERD Roadmap 2010
Vwr1~0.9V@5nsVwr0~-0.9VVread~0.3V
Vwr1~0.9V@5nsVwr0~-0.9VVread~0.3V
Vwr1~0.9V@5nsVwr0~-0.9VVread~0.3V
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
STT-MRAM ReRAM
COMPARISON MRAM / ReRAM
Statistical phenomenon associated with migration of vacancies or metallic ions
J.Lee et al, Gwanju IST, Korea (IEDM2010)
eVEF
0EF
F1 F2
Spin-dependent quantum mechanical tunneling of electrons (as polarizer/analyzer in optics).Switching of magnetization described by LLG equation:
θ
( )2
cos1min
θ−Δ+= RRR
( ) ( )dt
dMMMMMaIMbIHM
dt
dMppeff ×+××++×−= αγγ . .
0 100 200 300 400 500 600 700 800 900 100010
-6
10-5
10-4
10-3
10-2
10-1
100
Resistance
No
rmal
ise
dC
oun
t
0 100 200 300 400 500 600 700 800 900 100010
-6
10-5
10-4
10-3
10-2
10-1
100
10-1
100
Resistance
No
rmal
ise
dC
oun
t
Rmin Rmax
>25σ
0 100 200 300 400 500 600 700 800 900 100010
-6
10-5
10-4
10-3
10-2
10-1
100
Resistance
No
rmal
ise
dC
oun
t
0 100 200 300 400 500 600 700 800 900 100010
-6
10-5
10-4
10-3
10-2
10-1
100
10-1
100
Resistance
No
rmal
ise
dC
oun
t
Rmin Rmax
>25σ
1Mbit chip TA-MRAM
Resistance (kΩ)0 10.5
8kbit ReRAM(K.Kit, SAIT, SamsungIEDM 2010)
R distributions:
(2011)
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Multilevel capabilityMemristor functionality with large ΔR amplitude
J.Lee et al, Gwanju IST, Korea (IEDM2010)
0
40
80
120
160
TM
R(%
)
-300 -200 -100 0 100 200 300
H(Oe)
MgO based MTJ
•Binary resistance levels•Multilevel and memristor possible but with much less ΔR amplitude than with ReRAM. Not so easy to implement (R(θ), DW or stacking of several MTJ)
Multilevel capability:
Cyclability:
W.C.Chien et al, Macronix, Hsinchu, Taiwan, (IEDM2010)>1016 cycles
10 6 10 7 10 8 10 9 10 10 10 11 10
120
140
160
180
200
220
240
RmaxRmin
Number of pulses
12
Res
ista
nce
(Ω)
Vwrite
COMPARISON MRAM / ReRAM (2011)
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
W.C.Chien et al, Macronix, Hsinchu, Taiwan, (IEDM2010)
Retention:
Speed:
Y.T.Cui et la, PRL104, 097201(2010)
STT switching in MTJ
W.C.Chien et al, Macronix, Hsinchu, Taiwan, (IEDM2010)
⎥⎥⎦
⎤
⎢⎢⎣
⎡⎟⎟⎠
⎞⎜⎜⎝
⎛⎟⎟⎠
⎞⎜⎜⎝
⎛−−−−=
WR
cell
Bchip I
I
Tk
EtmF 1expexp1
0τ
Takemura et al, IEEE Journ of Solid State Circuits, 45, 869 (2010)
E/KBT>67
OK with perpendicular MTJOK with TAS
COMPARISON MRAM / ReRAM (2011)
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Possibility of crossbar architecture:
Difficulty is the in-stack diode
MTJ+diode
http://www.unitysemi.com/
M.-J. Lee et al., Samsung, IEDM 2007
COMPARISON MRAM / ReRAM (2011)
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
Summary of differences MRAM / ReRAM
“Unlimited” cyclability (>1016 cycles) Cyclability ~ 108 cycles, more than FLASH
Narrow distribution of Rmin / Rmax
5kΩ±0.3kΩ1Mbit: / 12kΩ±0.8kΩ
Larger distribution of Rmin / Rmax
3-6kΩ /6Kbit: 10kΩ - 300kΩ
Bilevel resistanceMultilevel possible but not straighforward
“Natural” continuous change of RMultilevel capability easier to implement
Moderate ΔR : Rmax/Rmin ~2-3 Large ΔR : Rmax/Rmin ~5 - 50
Applications
DRAM, SRAM, e-SRAM, logic-in-memory,Embedded-NVM
e-SRAM, Embedded-NVM, FLASH,Memristor, neuromorphic architecture
Bernard.Dieny@cea.fr July 2013 Part 4 inMRAMinMRAM2013
R.SousaS.BandieraY.Hadj-LarbiB.RodmacqS.AuffretM.SouzaL.NistorJP Nozieres
B.DelaetM.T.DelayeM.C.Cyrille
L.Buda-PrejbeanuM.ChshievH.BeaS.AmaraV.BaltzJ.MoritzP.Y.ClementC.BaraducL.CuchetB.LacosteQ.StainerG.Vinai
B.CambouI.L.PrejbeanuK.MackayL.LombardE.GapihanC.DucruetY.ConrauxC.Portemont
Work partly supported by the projects
NANOINNOV SPIN (2009)
HYMAGINE (ERC2009)
Acknowledgements
top related