rram based analog synapse device for neuromorphic … semiconductor integrated device & process...
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SIDP Semiconductor Integrated
Device & Process laboratory
RRAM based analog synapse device
for neuromorphic system
Kibong Moon, Euijun Cha, and Hyunsang Hwang
The 13th Korea-U.S. Forum on Nanotechnology, Sep. 26-27, Seoul, Korea
Pohang University of Science and Technology (POSTECH), Korea
SIDP Semiconductor Integrated
Device & Process laboratory
Outline
• Introduction and Motivation
• Mo/PCMO synapse device
• Pattern recalling system
• Summary
SIDP Semiconductor Integrated
Device & Process laboratory
Introduction
Source: HP Neuron (~1011) + Synapse (~1015) + Learning Rule
Low energy (~10fJ) synapse and neuron devices
SIDP Semiconductor Integrated
Device & Process laboratory
Introduction Stanford Univ., IEDM 2013 CEA-LETI, IEDM 2012
Various new synapse devices were proposed (CBRAM, PCM, 3T-
FeMEM, and RRAM)
Univ. of Nat. Chiao Tung, IEDM 2014 Panasonic, VLSI 2013
SIDP Semiconductor Integrated
Device & Process laboratory
Introduction CEA-LETI, NEWCAS 2011 IBM, TED 2013
Problems : Large device area, power consumption, circuit
complexity etc..
SIDP Semiconductor Integrated
Device & Process laboratory
Introduction Carnegie Mellon Univ., VLSI 2015 Pennsylvania Univ., IEDM 2014
VO2 Insulator-Metal-Transition temperature ~ 67°C
: Not practical for device application
SIDP Semiconductor Integrated
Device & Process laboratory
Mo/PCMO synapse device
-4 -2 0 2
10-11
10-9
10-7
10-5
10-1
101
103
10-9
10-7
10-5
10-3
Mo/PCMO
Cu
rren
t [A
]
Voltage [V]
Cycles
1st
100thILRS
@ -0.5V
Cu
rren
t [A
]Active area [㎛2]
O2- O2-
VReRAM < 0V
<SET>
PCMO
B. E.
O2- O2-
VReRAM > 0V
<RESET>
Mo
MoOx
PCMO
B. E.
Mo
MoOx
Current level ∝ Active area
Field-induce oxygen migration & redox reaction at the interface
: Control thickness of interface oxide and device resistivity
SIDP Semiconductor Integrated
Device & Process laboratory
Mo/PCMO synapse device
4nm 4nm
PCMO PCMO
Mo Mo
~2.3nm ~4.2nm
LRS HRS
MoOx MoOx
11k-bit array
Well fabricated without mixing
(Mo/PCMO)
Direct evidence of redox
reaction at the interface
SIDP Semiconductor Integrated
Device & Process laboratory
Mo/PCMO synapse device
0 200 400 600 800 1000
0
2n
4n
6n
8n
10n
0 200 400 600 800 1000
5n
10n
15n
20n
25n
Vbias
(1ms) =
1V
1.5V
2V
2.5V
PotentiationV
bias (1ms) =
-2.5V
-3V
-3.5V
-4V
Depression
Cu
rren
t [A
]# of pulses
Vread
= -0.5V
Cu
rren
t [A
]
-3 -2 -1 0
0.0μ
0.3μ
0.6μ
0.9μ
1.2μ
0 1 2 3
0.5μ
0.4μ
0.3μ
0.2μ
0.1μ
0.0μ
Cu
rren
t [A
]
Voltage [V]
Reset
Set
1st
2nd
3rd
4th
5th
Cu
rren
t [A
]
Voltage [V]
Potentiation (-V)
: Increase conductance
: Strengthen synaptic weight
DC property AC property
Depression (+V)
: Decrease conductance
: Weaken synaptic weight
SIDP Semiconductor Integrated
Device & Process laboratory
NbO2 neuron device
0.4 0.8 1.2
0
2m
4m
6m
Roff
(~15㏀)
Ron
(~1.9㏀)
800us
Time
Voltage
1.5V
NbO2
AC I-V
Cu
rre
nt
[A]
Voltage [V]
0
1
0
1
0
1
0 1 2 3 4 5
0
50
Vin
I ou
t [m
A]
Vin
I ou
t [u
A]
Time [us]
Super-threshold input ∆V=1.6V
Sub-threshold input ∆V=0.9V
Neuron Synapse Input Output
NbO2 based oscillation characteristics with synapse device
Above critical threshold voltage Oscillation behavior
SIDP Semiconductor Integrated
Device & Process laboratory
Pattern recalling system
V1 V42
~
~
~
~
I1
I42
Upper threshold
Lower threshold
Noisy
input
…
Output
~ ~ ~ ~
SEM image Operation of Hopfield network on 11k-bit array
Packaging Standard
Pattern
Neuromorphic application using 11k-bit array Mo/PCMO synapse
device and NbO2 IMT oscillator neuron devices
SIDP Semiconductor Integrated
Device & Process laboratory
Pattern recalling system
Synapse weight mapping : Binary and Analog synapse based Hop-
field neural network
Analog synapse shows much better pattern recognition accuracy
SIDP Semiconductor Integrated
Device & Process laboratory
Summary
Mo/PCMO analog synapse device
- Field-induced oxygen migration for switching of Mo/PCMO device
- Fabrication of large scale synapse array device on 8-inch wafer
- Evaluating synapse characteristics for an artificial synapse
Hardware implmenetation of neuromorphic application
- NbO2 oscillator as an artificial neuron
- Integrating Mo/PCMO synapse array and NbO2 neuron
- Improved pattern recalling accuracy using analog synapse
SIDP Semiconductor Integrated
Device & Process laboratory
This research was supported by the Pioneer Research Center Program through
the National Research Foundation of Korea funded by the Ministry of Science,
ICT & Future Planning (2012-0009460)
Thank you for your
attention…!