Technology, Manufacturing and Markets ofMagnetoresistive Random Access Memory (MRAM)
Brad Engel, VP- Product Development & Quality© Everspin Technologies, Inc. 2011

Everspin – Electron Spin is ForeverIndustry-first and leading MRAM supplierTechnology leader in Toggle MRAM and ST-MRAM
Shipped over 2.5M units with over 300 active customers to date
Over 15 years of design and production experience with MRAM

Embedded TechnologyStandalone Products

Break through non-volatile memory products and IP70 Products in 3 Memory Families
Asynchronous x8, x16 and Serial SPI

600 Active Patents and Applications WW
176 Issued / 47 Pending US Patents

Backed by leading VC Investors (Spin-out from Freescale in June, 2008)
 Global Footprint

Headquarters: Chandler, AZ, USA
Sales Offices: USA, Europe, China, Japan
Manufacturing: USA, Singapore, Thailand, China Design Center: Austin, TX, USA© Everspin Technologies, Inc. 2011

What is MRAM Technology?
Simple 1 transistor + 1 MTJ memory cellMagnetic polarization stores dataMTJResistance levels represent bit values
compared to electron charge levels
 Highly reliable non-volatile memoryTransistor

Unlimited cycling endurance

Low latency enabling instant on/off

Cross-sectional view
magnetic layer 1
free layer
tunnel barriermagnetic layer 2
fixed layer
Circuit© Everspin Technologies, Inc. 2011

low resistancehigh resistanceMRAM - Technology Comparison
Toggle Write

Write accomplished by magnetic
fields from current passing throughbit and word lines.
In volume production© Everspin Technologies, Inc. 2011

Spin-Torque Write

Write accomplished by spinpolarized current passing
through the MTJ.
In development

Everspin MRAM Advantages
Parameter

Capability

Non-volatilecapability

Data retention of the bit cell > 20 years

PerformanceSymmetric read/write – 35ns / 40MHz SerialEndurance

Unlimited cycling endurance

CMOS integration

Easily integrates into back-end process
Compatible with embedded designs  No effect on CMOS
Allows for flexible manufacturing

Temperature range -40ºC < T < 150ºC operation demonstrated
High Temp Storage Intrinsic reliability > 20 years lifetime at 125ºC

Soft error immunity

Alpha radiation soft error rate too low to measure (<0.1 FITper Mb) – Everspin partners offer radiation hardened MRAM

Environmentallyfriendly

No battery/caps, RoHS/REACH compliant, instant-on© Everspin Technologies, Inc. 2011

How is MRAM made?
 Leverage CMOS semiconductor ecosystem
 Everspin MRAM layer added to standard CMOS

 Standard packages with protective internal shield Common standard package types
 Drop in replacement fits footprints forexisting printed circuit board designs
 Pin for Pin functionally equivalent BBSRAM, SPI NVM, nvSRAM and FeRAM
ShieldDie© Everspin Technologies, Inc. 2011

Memory Performance© Everspin Technologies, Inc. 2011

ST-MRAM

Memory Performance© Everspin Technologies, Inc. 2011

Current Toggle MRAM Products
48-BGA

16-bit I/OPart Number Density Configuration

Temp

MR4A16B

16Mb

1M x 16

C,I,A

MR2A16A

4Mb

256K x 16

C,I,E,A

MR0A16A

1Mb

64K x 16

C,I,E,A

x8 Asynchronous parallel I/O
x16 Asynchronous parallel I/O
x8 Asynchronous parallel 1.8V I/O

44-TSOPII, 54-TSOP
8-bit I/O

Part Number Density Configuration

Temp



x8 Asynchronous parallel I/O
x16 Asynchronous parallel I/O

MR4A08B

16Mb

2M x 8

C,I,A

MR2A08A

4Mb

512K x 8C,I

8-DFN

MR0A08B

1Mb

128K x 8C,I

MR256A08B

256Kb

32K x 8C,I

MR0D08B

1Mb

128K x 8, 1.8v I/O

C

MR256D08

256Kb

32K x 8, 1.8v I/O

C32-SOIC

SPI-compatible serial I/O
40 MHz; No write delayx8 Asynchronous parallel I/O

TemperaturesSPI I/OPart Number Density Configuration

Temp

Commercial

0 to +70 ºC

MR25H40

4Mb

512K x 8

I, A

Industrial-40 to +85 ºC

MR25H101Mb

128K x 8I, A

Extended-40 to +105 ºC

MR25H256

256Kb

32K x 8I, A

Automotive-40 to +125 ºC© Everspin Technologies, Inc. 2011

MRAM Markets & Applications
Storage Systems & ServersAutomotive & Transportation

Telecom & Datacom

Logos, trademarks, images and copyright references are the property of the respective companies noted.

© Everspin Technologies, Inc. 2011

Industrial Automation & Robotics

Energy Management

Consumer, POS, GamingToggle MRAM Used by Top Companies
Siemens Recognizes Everspin Technologies for Perfect MRAM Quality - May, 2009

Automation Technology“After two years of high volume production and more than 100K systems in thefield, we are very happy with the perfect quality and reliability of Everspin’s
products in our industrial automation systems”
http://www.semiconductor.net/article/CA6658902.html
Everspin's automotive-temperature MRAM meets harsh environment demands in BMW
S1000 RR racing bikeEverspin introduces AEC-Q100 MRAM products to serve broad automotive applications; 4Mb
MRAM stores critical calibration data for BMW Motorsport Super Bike

Everspin Technologies’ MRAM Selected by Emerson Network Power toDeliver Critical Storage for Industrial Computing Boards
Non-volatile MRAM technology provides a robust, reliable memory solution for VME
and Compact PCI boards.

Everspin Technologies to provide Airbus with MRAM
products for advance wide body aircraft
Flight Control Computer on A350 XQB aircraft uses MRAM forcritical program and data storage in extreme environment
applications.

Logos, trademarks, images and copyright references are the property of the respective companies noted.

© Everspin Technologies, Inc. 201111

MRAM Writes and Reads
 Write Current Flows Down
Write Line 1 & 2
 Magnetic Tunnel Junction(MTJ) At Cross-Point Is
Polarized
 Polarization State Is Read
By Selecting Pass
Transistor to Sense
Resistance of Specific MTJ© Everspin Technologies, Inc. 201112

MRAM Integration
Metal 5Cu

Metal 4Cu

MRAMmodule

Via 3
Metal 3

Metal 5Al

MTJ MTJVia 2
Metal 4

Metal 2

Al

Metal 4
Via 1
Metal 1

AlContact

Bit cell© Everspin Technologies, Inc. 201113MTJ Bit Materials
Top electrode
Free Synthetic
Antiferromagnet (SAF)
Tunnel barrier
Pinned Synthetic
Antiferromagnet (SAF)

Free M2
Ru
Free M1
AlOx
Fixed
Ru
PinnedAF pinning layer

TaEg, NiFe, CoFe,CoFeB

Eg, NiFe, CoFe,CoFeB
Eg, PtMn, IrMn

Seed
Base electrode© Everspin Technologies, Inc. 201114Ta/TaNMTJ Vertical Profile Ultra-thin layers require precision control formanufacturing© Everspin Technologies, Inc. 201115

Toggle MRAM: Write Mechanism
Toggle MRAM is a unique approach that provides both robust
switching performance and manufacturability
 Response of synthetic antiferromagnetic free layer is the key.
Conventional MRAM
Single Layer

H=0pinned

Toggle MRAM
Synthetic Antiferromagnet

H≠0

H=0pinned

pinnedAligns with applied field© Everspin Technologies, Inc. 2011H≠0pinned

Rotates perpendicular
to applied field16

Toggle Write Operation
Low-R
State

H1

H1 + H2

I2

High-R
State

H2

I2
pinnedpinned

I1

I1

MTJ
I1

I2
Advantages: Eliminates disturb - Large operating window© Everspin Technologies, Inc. 201117

Robust Toggle-Bit Selection
 Robust bit disturb

margin All bits along ½-selectedcurrent lines haveincreased energy barrier
during programming© Everspin Technologies, Inc. 2011

No switching

Current I1

Toggle Switching Characteristics

SwitchingRegion

No switching

Current I2© Everspin Technologies, Inc. 201119

Toggle-bit Array Characteristics
H24Mb, March6N Toggle Map181

IV

I

172
163

toggling
toggling

154
145

No disturb

Operatingregion
No disturb

136
127
118
109
100
91
82
73ibitNo disturb

6354
45

No disturb

0% switching region(no disturbs)

toggling
toggling
IIIII07202718
9014 21 28 35 42 49 56 63 70 77 84 91 98 105 112 119 126 133 140idigit© Everspin Technologies, Inc. 2011

3699%-10
98%-9997%-98
96%-97
95%-96
94%-9593%-9492%-93
91%-92
90%-91
89%-9088%-8987%-8886%-87
85%-86

Write Operating Region at 125 °C
 Large write window at Automotive temperatures
300

Hsat

250

OperatingRegion
T = 125 ºC

Digit Line Current(Oe)20015010050Hsw

0050

100150Non-SwitchingRegion
Bit Line Current

Temp (°C)•Hsat, Hsw decrease linearly w/Temp, reducing window© Everspin Technologies, Inc. 201121

Read Sense Amplifier
Capacitanceat nodeIntegrates
IRef
Current Difference

Vcgref

IBIT
Word Line

VD D
m17
m16n3

IRef

IRef

m13

m14

m15

n0n1n5RB it

RH ig hRL o w

m1m2

m3n4

IRef = (IHigh + ILow)/2© Everspin Technologies, Inc. 2011

m18

Local references createdfrom two MTJ: one high andone low resistance stateMagnetoresistance and Distributions
MR = DR/Rlow , DR=Rhigh– Rlow

Array: Rcell Histogram Signal = Rcell – Rref

 ½ of DR available for sensing

 Circuit works at finite bias
 MR is reduced by bias

dependence of MR Must sense all bits in thearray Circuit must work with bits in tailsof the R distribution
Resistance distribution reduces useable MR.
For six-sigma yield in the array, need: DR/2 > 6s

© Everspin Technologies, Inc. 201123

Read Distribution within an Array
2500
2000

#bits

Critical Factors:
1. Tunnel barrier quality
2. Pattern fidelity

Low StateHigh StateDR/s = 30
typical1500

Optimized for MRAM

s~0.8%1000500

10 nm
01415161718Bit Resistance [k]

© Everspin Technologies, Inc. 2011

2419V1/2~+0.7/-0.55 V

MTJ Deposition on 200mm Wafers
Measured uniformity—200 mm
MR=45%, s=2%

RA=10.4 k-mm2, s=6%43.9 44.5 44.6 44.8 44.5 43.1
44.4 45.0 45.2 46.0 45.8 46.0 44.6 43.1
44.1 45.4 42.9 45.6
45.6 45.8 44.5
44.5 46.1 44.3 45.1 45.5 45.8 46.0 45.0
44.5 45.8 43.4 45.4 45.9 45.7 45.9 44.7
44.2 45.3 45.7 45.5 43.9 45.8 45.4 44.0
44.1 45.3 45.9 45.6 45.0 44.7
43.4 44.0 44.8 44.1

11.3 11.0 10.5 10.5 10.9 12.3
11.7 10.3 9.74 9.88 9.65 9.80 10.2 11.5
10.3 9.54 10.9 10.6
10.3 9.74 10.5
10.1 9.68 10.4 10.8 10.8 10.7 9.85 10.7
9.80 10.9 10.5 10.8 10.5 9.86 10.2
10.3 9.45 10.1 10.4 10.6 9.87 9.62 10.9
10.2 9.52 9.43 9.56 9.59 10.2
11.2 10.2 10.4 11.0

Manufacturable wafer level uniformity and wafer-to-wafer repeatability• optimization of deposition tool, process, and material stack© Everspin Technologies, Inc. 201125

Toggle MRAM High Reliability
 Predicted lifetime from accelerated testing Robust reliability at Automotive temperatures
1.E+12Magnetic Layers
Write Line EM

1.E+11MTJ R Drift
MTJ TDDB
20 year life
10lifeLifetime (h)1.E+10
1.E+09
1.E+081.E+07
1.E+06
1.E+05
1.E+04
55

65

75

85

95105

Average Junction Temperature (C)© Everspin Technologies, Inc. 2011

26115

125

Summary MRAM is ahighly reliable, high-performance,
nonvolatile memory IC, with unlimited endurance
 Has the unique characteristics of a working memory whileproviding non-volatility Current MRAM products are used in a wide varietyof applications
 Data Storage, Industrial Control, Medical Systems,Transportation, Metering and GamingEverspin Continues MRAM leadership: Expanding MRAM into new markets and applications
 On track to deliver the industry’s first ST-MRAM© Everspin Technologies, Inc. 201127