SPICE Model for Magnetic Tunnel Junctions - nanoHUB

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Xuanyao Fong, Sri Harsha Choday, Georgios Panagopoulos Charles Augustine, and Kaushik Roy

Department of Electrical and Computer Engineering, Purdue University, West Lafayette, IN

https://engineering.purdue.edu/NRL/index.html

SPICE Model for Magnetic Tunnel Junctions

Overview

1 2 3101

103

105

107

tMgO (nm)

RA

( -

m2 )

EF=2.25eV, EB=0.865eV, =0.315eV,mFM=0.748, mOX=0.462, T=300K, VMTJ=10mV

Anti-ParallelParallel

-0.8 -0.4 0 0.4 0.85

10

15

20

VMTJ (V)

RA

MTJ

( -

m2 )

NEGF (AP)NEGF (P)

Data (AP)Data (P)

(a) (b)

0 5 10

10

20

30

Time (ns)

RM

TJ (

k )

StandardReversed

0 5 10

10

20

30

Time (ns)

RM

TJ (k

)

StandardReversed

(c)

a) S. Yuasa et al., Nature Materials vol. 3, no. 12, pp. 868-871, Dec. 2004, b) C. J. Lin et al., IEDM, Dec. 2009, pp. 11.6.1-11.6.4,c) T. Kishi et al., IEDM, Dec. 2008, pp. 12.6.1-12.6.4.

SPICE MTJ Model

Device Simulation, Analysis & Calibration to Experimental Data

NEGF Based Transport Simulator

Experimental Measurements

Update Model Parameters

θ , VMTJ , Temperature

Micromagnetics in Object-Oriented MicroMagnetic

Framework (OOMMF)

Circuit Level Simulation of Bit-Cells in SPICE Circuit Simulator

SPICE MTJ ModelCompact Model or Lookup Table

Stochastic Magnetization

Dynamics (LLG)

I-V Characteristic from NEGF Results (Compact Model or

Lookup Table)

NEGF / Slonczewski /Four-Component

Spin-TorqueCompact Model or

Lookup Table

IMTJ

∆θ

Parameters for calibration of device levelsimulation go into SPICE model for circuitlevel simulations.

Where To Get The Files?NanoHub.orghttps://nanohub.org/resources/19048

Where To Get The Files?NanoHub.orghttps://nanohub.org/resources/19048

Archive ContentsNRL_SPICE_MTJ_LIB_stable100413.tgzContains a directory “mtj_libs_encoded”

NRL_SPICE_MTJ_LIB_Example.tgzContains a directory “stt”

Archive ContentsNRL_SPICE_MTJ_LIB_stable100413.tgzContains a directory “mtj_libs_encoded”

NRL_SPICE_MTJ_LIB_Example.tgzContains a directory “stt”

Include file for convenience

Main library files

Readme file: your best resourceAlso contains default values, description

of model parameters, etc.

Example SPICE Netlist

Calibration Results

Example Netlist - Header

SPICE include file in archive for convenience

SPICE options given in the file were used to correct for accuraciesdue to different numerical integration method used in SPICE and inOOMMF.

Always ensure simulation results converge!!!

Example Netlist - Instantiation

MgO

node2

node1IMAMTJ

MgO

node2

node1PMAMTJ

Free layer

Pinned layer

Example Netlist - Instantiation

MgO XMTJ2I2

100μA

MgO XMTJ1I1

100μAe1 e2Free layer

Pinned layer

Example Results (P to AP)

0 0.5 1 1.5 2 2.5 3x 10-9

-1

0

1

Time (sec)

MX

0 0.5 1 1.5 2 2.5 3x 10-9

-1

0

1

Time (sec)

MY

0 0.5 1 1.5 2 2.5 3x 10-9

-1

0

1

Time (sec)

MZ

OOMMFNRL SPICE Model

Tested in HSPICE-G-2012.06

Example Results (AP to P)

0 0.5 1 1.5 2 2.5 3x 10-9

-1

0

1

Time (sec)

MX

0 0.5 1 1.5 2 2.5 3x 10-9

-1

0

1

Time (sec)

MY

0 0.5 1 1.5 2 2.5 3x 10-9

-1

0

1

Time (sec)

MZ

OOMMFNRL SPICE Model

Tested in HSPICE-G-2012.06

How to Change MTJ Resistance Model?Contains MTJ resistance or I-V characteristic

All terminals must exist!!!

• Module name must be preserved (MTJ_res)

• t1 – free layer• t2 – pinned layer• MTJ_curr – current flow

from t1 to t2• Directionality must be

preserved for LLG

How to Change MTJ Resistance Model?

Point to the file containing your MTJ_res module description

All terminals must exist!!!

• Module name must be preserved (MTJ_res)

• t1 – free layer• t2 – pinned layer• MTJ_curr – current flow

from t1 to t2• Directionality must be

preserved for LLG

This file needs to be able to locate LLG.lib and LLGThermRandNum.va. It must also know the definition of MTJ_res with the terminals hard coded into the example

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Questions?