Self-Heating and Interface Traps Assisted Early Aging Revelation and Reliability
Analysis of Negative Capacitance FinFET
Rajeewa Kumar Jaisawal1, Sunil Rathore1, Navneet Gandhi1, P. N. Kondekar1, Shashank
Banchhor2, V Bharath Sreenivas3, Young Suh Song4, and Navjeet Bagga5**
PDPM-IIITDM Jabalpur, India, 2IIT Roorkee, India, 3VIT Chennai, India, 4Korea Military Academy, Seoul, Korea
5
IIT Bhubaneswar, India
**
( Email: navjeet.bagga9@gmail.com, navjeet@iitbbs.ac.in)
2023 7th IEEE Electron Devices Technology & Manufacturing Conference (EDTM) | 979-8-3503-3252-0/23/$31.00 ©2023 IEEE | DOI: 10.1109/EDTM55494.2023.10103127
1
Abstract- The realization of a Negative Capacitance
(NC) phenomenon in TCAD, considering several
realistic aspects of transport physics, remains
challenging. In this paper, we investigated the aging
and reliability of the NC-FinFET considering the selfheating effect (SHE) and interface trap charges with
varying concentration and energy location. In general,
the FEPolarization and hydrodynamic models cannot
be coupled at the same simulation flow; thus, we
employed the iterative approach. Due to SHE, the
lattice temperature increases, which impacts the
Landau parameters and, in turn, the NC behavior.
Moreover, we also evaluated the impact of ambient
temperature on device performance with and without
(w/o) considering SHE.
(Keywords: Negative capacitance (NC), Self-heating
effect, Interface traps, End of a lifetime (EOL),
Silicon-on-insulator FinFET).
Introduction
The idea of negative capacitance was proposed to
realize the steep subthreshold slope (SS) devices and
obtain
the
low-power,
high-performance
characteristics [1]. The ferroelectric (FE) layer
possesses stabilized NC characteristics when/if
implemented with a dielectric (DE) layer of
appropriate thickness and permittivity, resulting in
capacitance matching [2]. The realization of the NC
phenomenon in TCAD is governs by the
FEPolarization model, which is strongly influenced
by the well-known Landau parameters (α, β, γ, ρ, g).
In our recent publication [3], we explored the impact
of varying Landau parameters for different HfO2doped FE layers; however, still, the TCAD setup
needs attention to realize a realistic NC-FinFET.
One of the vital concerns is implementing the SHE
along with the NC, as SHE influenced the lattice
temperature and, thus, the Landau parameters. The
primary issue with realizing SHE in NC-FinFET is
that the models, i.e., hydrodynamics (for SHE) and
FEPolarization (for NC), could not be coupled in the
same simulation flow. Till date, only a few literatures
explored the SHE with NC; however, only by
considering the average lattice temperature and did
not consider the hydrodynamic models, which is not
exactly up to the mark [4]-[5]. Therefore, for the first
time, in this paper, we considered the impact of SHE
in NC-FinFET simulation by iterative approach. Our
simulation precisely considers the impact of SHE on
Landau parameters. Further, we also analyze the
impact of the Si-SiO2 interface trap concentration
(Nit) and its location on the device's reliability. All in
all, the deviation and modulation of the threshold
voltage ( ∆
) of the NC-FinFET is thoroughly
investigated for aging analysis, i.e., End of life (EOL)
defined as when Vth is shifted by ~50mV. Key
contribution: we investigated (i) the inclusion of
SHE in NC-FinFET while realizing in Sentaurus
TCAD through an iterative approach; (ii) the impact
of donor and acceptor traps while separately
considering the impact of SHE and without SHE; (iii)
the impact of various trap locations around the
conduction (valance) band CB/VB; (iv) the combined
impact of ambient temperature and SHE induced
performance deterioration; and (v) the device aging
(i.e., ΔVth=50mV) for the optimal reliability of the
NC-FinFET.
Device Structure and Simulation Methodology
A 14nm industry-standard FinFET has opted as a
baseline reference (Fig.1 inset), which is well
calibrated against the experimental data [6] (Fig. 1).
TCAD setup includes the drift/diffusion model
coupled with Poisson equation solver to include the
carrier transport. SRH and Auger models are included,
which govern the carrier generation-recombination.
IAL mobility, MLDA, and high-field saturation
models have been included to consider the mobility
degradation effect [7]. Table-1 deduces the various
device parameters. Further, the NC-FinFET is
realized by placing a doped-HfO2 FE layer at the gate
stack of appropriate thickness, considering the
uniform domain (i.e., g= 1×10-4 cm3/F). The
FEPolarization model is used to include the NC
phenomenon in the polarization-field (P-E) curve of
the FE layer, which is well calibrated for the MFIM
cap (Fig.2a). A transient simulation is carried out
through mixed mode to turn on the dipole
polarization, superimposed by the steady-state
analysis (i.e., ρ= 2.25×104 Ω-cm). To include SHE,
we added thermodynamic and hydrodynamics
models, but they cannot be coupled with the
FEPolarization model. Thus, we proposed the
iterative approach (Fig.3a) to incorporate the SHE
into NC-FinFET, and based on increased lattice
temperature, the Landau parameters have been tuned.
Hence, the impact of SHE is incorporated in NCFinFET and shows the ION degradation (Fig.3b). In
further analysis, we evaluated the impact of trap
charges with and without consideration of SHE. The
random interface traps are generated using sIFM with
Poisson distribution function [7]-[8].
2023 Electron Devices Technology and Manufacturing Conference (EDTM)
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Results and Discussion
The reliability of the NC-FinFET is investigated by
considering the Vth, SS, ION, and IOFF with considering
acceptor and donor trap concentration and their
location around the mid-band gap, as shown in Fig. 4.
Increasing the donor trap concentration (Nit) reduces
the Vth (Fig.4a); however, with the inclusion of SHE,
the drastic Vth shift is observed at higher Nit. This is
due to the fact that SHE increases the lattice
temperature (TL), which supports more mobile charge
transport and thus increases the IOFF (Fig.4b).
Whereas, increase in TL reduces the Landau
parameter (α) [1] in turn, reduces the ION. Therefore,
ION remains constant, which is a counter-effect of
SHE and donor traps. While considering the acceptor
traps, the Vth increases (Fig.4c), i.e., the presence of
acceptor traps reduces the effective mobile charge
transport in the conduction band (CB); thus, it
requires higher gate voltage (VGS). However, with
SHE, Vth reduces (Fig.4d) as the increases in TL result
in increased carrier energy over the ionization energy.
Moreover, the degradation in ION due to SHE is
counter-balanced by a higher Nit value, as the
increase in TL modulates the Landau parameter.
Further, to precisely investigate the impact of SHE
with the presence of traps, we considered both the
traps (i.e., donor and acceptor) and simulated 200
samples. We found that the standard deviation (σ) of
Vth with and without considering SHE is almost the
same (Fig.4e), thus, revealing the insignificance of
SHE at the subthreshold regime. Whereas the ION was
significantly affected owing to the dominance of
charged acceptor traps over neutral donor traps
(Fig.4f). Further, we explored the different trap
locations around the mid-gap energy (Fig.5). The trap
energy locations vary from the conduction band (CB)
to valence band (VB) for donor and acceptor traps,
respectively (Fig. 5a,d). Results reveal that the
acceptor traps significantly affected the ION when
found near the VB. Further, with and w/o considering
the SHE, the Vth is extracted for various traps location
placed in the bandgap energy (Fig.5b,e). The impact
of SHE with the acceptor (donor) trap location near
VB (CB) shows opposite trends due to the movement
of acceptor traps towards the VB, causing more of
them to be negatively charged, resulting in Vth
increases. Based on the above-mentioned analysis,
we evaluated the NC-FinFET aging, i.e., EOL
considering Vth shift by ~50mV. For a fixed trap
location and trap concentration, the impact of varying
ambient temperature (TA) is investigated (Fig. 6a-b).
An increase in TA reduces the EOL trap concentration,
over which the presence of the acceptor shows more
vulnerability to TA. Finally, with and w/o SHE, the
EOL is investigated for acceptor (donor) traps
(Fig.6c-d) and found that acceptor traps are more
immune to SHE, causing more sustainability and
reliability of NC-FinFET (Fig.6d).
Conclusion
In this paper, we proposed an iterative approach to
include the self-heating effect (NC) in a TCAD flow
along with the negative capacitance (NC)
phenomenon, as hydrodynamic and FEPolarization
models could not be coupled at the same instance.
SHE increases the lattice temperature, further
modulating the Landau parameters, which is
appropriately addressed in our simulation setup.
Moreover, the impact of interface trap concentration
and their location around the mid-gap energy is
investigated. Acceptor traps provide more resilience
against SHE in the optimal performance of NCFinFET.
References
[1] R. K. Jaisawal, et.al., “Role of temperature on
linearity and analog/RF performance merits of a
negative capacitance FinFET,” Semiconductor
Science and Technology, vol. 37, Sep. 2022, pp.
115003, doi: 10.1088/1361-6641/ac9250.
[2] M. Hoffmann, et.al., "Demonstration of Highspeed Hysteresis-free Negative Capacitance in
Ferroelectric Hf0.5Zr0.5O2, " 2018; 31.6.1-31.6.4;
IEEE International Electron Devices Meeting
(IEDM), doi: 10.1109/IEDM.2018.8614677.
[3] R. K. Jaisawal, et. al., "Reliability of TCAD study
for HfO2-doped Negative capacitance FinFET with
different Material-Specific dopants", Solid-State
Electronics, Vol. 199, Jan. 2023, pp. 108531,
doi:10.1016/j.sse.2022.108531.
[4] O. Prakash, et.al., "Impact of Self-Heating on
Negative-Capacitance FinFET: Device-Circuit
Interaction," in IEEE Transactions on Electron
Devices, vol. 68, no. 4, pp. 1420-1424, April 2021,
doi: 10.1109/TED.2021.3059180.
[5] S. Rathore, et.al., "Design Optimization of ThreeStacked Nanosheet FET from Self-Heating Effects
Perspective," 2022; IEEE Transactions on Device
and
Materials
Reliability,
doi:
10.1109/TDMR.2022.3181672.
[6] C-H. Lin, et al., “High performance 14nm SOI
FinFET CMOS technology with 0.0174µm2
embedded DRAM and 15 levels of Cu
metallization,"
2014;3.8.1-3.8.3,
IEEE
International Electron Devices Meeting. doi:
10.1109/IEDM.2014.7046977.
[7] Synopsys TCAD, “Sentaurus Device User Guide,
Mountain View CA,” 2021; Synopsys, Inc.
[8] N. Seoane, et.al, "Simulations of Statistical
Variability in n-Type FinFET, Nanowire, and
Nanosheet FETs," 2021;(42);1416-1419;10, IEEE
Electron
Device
Letters.
doi:
10.1109/LED.2021.3109586.
2023 Electron Devices Technology and Manufacturing Conference (EDTM)
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VGS= 0.05V
Metal
10-5
HfO2 Doped
FE Layer
10-6
SiO2
10-3
Simulation
Experiment
Ec= 1.2 MV/cm
Pr = 18 µC/cm2
10
10-5
0
10
(a)
BOX
-30-3
1.2
1.0
-2
-1
0
1
2
3
0.6
Lg = 20 nm
10-10
0.4
(b)
10-9
Electric Field, Efe (MV/cm)
0.8
V DS = 0.7 V
-7
10-8
-20
10-8
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
1.4
~23% ION
enhanced
10-6
-10
10-7
1.6
BL-FinFET
NC-FinFET
10-4
20
α= -8.6x1010 cm/F
β= 1.3x1020 cm5/C2F 0.2
γ= 0 cm9/C4F
0.0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
Table 1: Device Parameter
Drain Current, I DS (mA/µA)
SOI-FinFET
10-4
30
Drain Current, I DS (A/µm)
Polarization, P (µC/cm2)
VDS= 0.8V
Exp. data
Sim. data
Fin
D rain Current, I DS (A/µm )
10-3
Gate Voltage (V)
Fig. 2 (a) shows the fitted S-shaped P-E curve with the
Fig. 1 Calibration of IDS-VGS experimental MFIM capacitanor [2]; (b) demonstration
with experiment data [6] of current improvement in IDS-VGS curve due to internal
(inset: baseline SOI FinFET). voltage amplification effect in BL FinFET.
Gate Voltage, VGS (V)
80
60
40
5
w/o SHE FinFET 11.2 %
w SHE FinFET
w/o SHE NCFinFET
w SHE NCFinFET
IDS (µA)
50
40
50
10
55
50
3
45
2
(d)
40
35
VGS= 0.8V
30
0 VDS= 0.8 V
1011
25
1012
Trap Conc. (cm-2)
1013
12
10
10
w/o SHE NCFinFET
w SHE NCFinFET
250
45
11
ION (µA)
IDS (µA)
IOFF (nA)
60
(b)
Acceptor 60
Line: w/o SHE
4 Dash: w SHE
1
100
55
0
1x1011 5x1011 1x1012 5x1012 1x1013
Trap Conc. (cm-2)
(a)
Line: w/o SHE
Dash: w SHE
50
20
0
150
300
60
ION (µA)
V th (m V)
100
IOFF (nA)
(a)
VGS= 0.8V
VDS= 0.8V
200
200 Acceptor
(c)
150
100
50
0
13
1x1011 5x1011 1x1012 5x1012 1x1013
Trap Conc. (cm-2)
Trap Conc. (cm-2)
70
w/o SHE NCFinFET VDS= 0.8V
60
w SHE NCFinFET
50
σVth= 5 mV
40
σVth= 6 mV
30
20
(e)
σ= 0.2 eV
10
Nit= 1x1012 cm-2
0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
VGS (V)
60
σVth
Nit
50
IDS (µA)
120
V th (m V )
250 Donor
w/o SHE NCFinFET
w SHE NCFinFET
140 Donor
11
σV
w/o SHE w SHE
-2 4mV
1x10 cm
2mV
40 1x1012 cm-2 5mV 6mV
13
-2 24mV 26mV
30 1x10 cm
(f)
20 BL NCFinFET
10 VDS= 0.8V
Line: w/o SHE
Dash: w SHE
0
0.0
11
0.2
0.4
0.6
0.8
VGS (V)
13
-2
Fig. 4. impact of varying the trap concentration from 10 to 10 cm on (a-b) Vth,
IOFF and ION with donor traps variation; (c-d) Vth, IOFF and ION with acceptor traps
(b)
10
variation with and without (w/o) SHE. The donor [acceptor] traps decrease
V = 0.8V
0
[increases] the Vth, which is counter-balanced by SHE that affects the Landau
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
VGS (V)
coefficient (α) due to increase in TL. (e) IDS-VGS characteristics with 200 random
Fig. 3. shows (a) the flow chart of
coupling SHE with NC in TCAD; samples of NC-FinFET with uniform trap concentration resulting in a small
(b) impact of SHE on baseline and variation in σVth with and w/o SHE. (f) the variation is observed at higher traps
[acceptor and donor] concentration, which is further worsen with SHE.
NC-FinFET characteristics.
30
6.5 %
20
DS
10-8
10-9
10-10
0.0
120
90
60
Line: w/o SHE NCFinFET
Dash: w SHE NCFinFET
0.2
0.4
0.6
0.8
VGS (V)
IDS (µA)
Dash: w SHE
10-5 V =0.8V
DS
10-7
10-6
10-7
10-8
10-9
0.0
10-8
σ= 0.2 eV
Nit= 1x1012 cm-2
(d)
10-9
0.00
0.2
0.03
0.4
VGS (V)
0.06
0.09
0.6
0.12
0.8
EC Left EM Right EV
-20
-30
1.5
-40
1.0
-50
w SHE NCFinFET
w/o SHE NCFinFET
0.0
160
w SHE NCFinFET
Donor
w/o SHE NCFinFET
140
(e) VGS= 0.8V
VDS= 0.8V
120
100
80
60
40
20
0
EC Left EM Right EV
V th (V)
10-4 Line: w/o SHE Donor
(c)
0.5
30
0
2.0
-60
(a)
60
∆ V th (m V )
(a)
10-7
VGS= 0.8V
TA= 250 K
TA= 300K
TA= 350 K
EOL Trap Conc.
Donor
-10
50
EM 3Eg/4
20 (b)
6.5
Donor
6.0
5.5
5.0
4.5
(f)
4.0
3.5
3.0 σ= 0.2 eV12 -2
N = 1x10 cm
2.5 it
0
0
VDS=0.8V
EC Left EM Right EV
Fig. 5. shows the impact of trap location (interval: φF= ∕ ln( ℎ/ ), where
Nch(ni) is channel (intrinsic) doping, (a-c) IDS-VGS curves for acceptor traps
moves towards CB then Vth decreases, thus IOFF increases. (d-f) the donor
traps variation, where Vth and IOFF decrease when donor moves toward VB.
SHE modulates the TL, and in turn, α, which counter the effect of traps.
-2
0
w/o SHE NCFinFET
w SHE NCFinFET
-10
-30 Donor
-40
-50
-60
(c)
8.3x10
6.3x1012
End-of-Line [EOL]= 50mV
0 1 2 3 4 5 6 7 8 9
Trap Conc. (*1012 cm-2)
3
4
End-of-Life [EOL]= 50mV
50
Acceptor
3.8x1012
30
12
2
60
40
-20
1
Trap Conc. [Nit (*1012 cm-2)]
Trap Conc. [Nit (*10 cm )]
w SHE
w/o SHE
TA= 250 K
TA= 300 K
TA= 350 K
10
Device EOL [Vth= 50 mV]
12
EC
EOL Trap Conc.
30 Acceptor
0 1 2 3 4 5 6 7 8
EV Eg/4
Device EOL [Vth= 50 mV]
40
∆ V th (m V )
Nit= 1x1012 cm-2
σ= 0.2 eV
DS
∆ V th (m V )
150
10-6
(b)
0
3.0 Acceptor
2.5
w SHE NCFinFET Acceptor
w/o SHE NCFinFET
V = 0.8V
∆ V th (m V )
180
VDS=0.8V
V th (V)
I DS (A)
10
210
Acceptor
I OFF (nA)
-5
IOFF (nA)
10-4
20
4.6x1012
(d)
10
w/o SHE NCFinFET
w SHE NCFinFET
0
0
1
2
3
4
Trap Conc. (*1012 cm-2)
5
Fig. 6. shows (a-b) the impact of ambient
temperature on EOL trap concentration;
(c-d) the Vth shift for donor and acceptor
traps with and w/o SHE. Acceptor traps
are susceptible; however, provides more
resilience against the SHE.
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