HiSIM-SOI - TechConnect World

Complete Surface-Potential Modeling Approach
Implemented in the HiSIM Compact Model Family
for Any MOSFET Type
WCM in Boston
15. June, 2011
M. Miura-Mattausch, M. Miyake, H. Kikuchihara, U. Feldmann and H. J. Mattausch
HiSIM Team, Hiroshima University
HiSIM 1

Basic Device Equations
s
• Gradual-Channel Approximation
• Charge-Sheet Approximation
reduced to surface potential φ s
HiSIM 2

Property of Surface-Potential Model
Q(φ)
=
ν = μ E: velocity
: mobility
The surface potential consistently determines charges,
capacitances and currents under all operating conditions.
HiSIM 3

Relationship among Device Properties
(at drain side)
(at source side)
HiSIM 4

Specific Feature of Surface-potential Model
one equation for all bias conditions
HiSIM 5

Model Extraction for 45nm Technology
W g /L g =2μm/200nm
W g /L g =2μm/40nm
Measurement
HiSIM2
one model for any device sizes without binning
HiSIM 6

Current Derivatives for 45nm Technology
Measurement
HiSIM
W g /L g =
2μm/40nm
Beyond the 45nm generation nonphysical effects
are getting obvious.
HiSIM 7

Universal Mobility
V ds =0.1V
impurity concentration
carrier concentration
carrier mobility
HiSIM 8

Requirements for RF Applications
Harmonic Distortions
Non-Quasi-Static Effect
Noise Characteristics
HiSIM 9

Feature of Potential-Based Model
Current Equation: I = qnμE
All physical quantities are function of surface potentials.
Solution of Poisson’s Equation
Important RF characteristics are originated by
the potential distribution along the channel.
I-V characteristics reflect all important RF properties.
Accurate parameter extraction for I-V characteristics
is important.
S. Matsumoto et al., IEIEC T E, E88-C, p. 247, 2005.
S. Hosokawa et al., Ext. Abs. SSDM, pp. 20, 2003.
M. Miura-Mattausch et al., IEEE TED, 2006.
HiSIM 10

Descendant of MOSFET
MG-MOSFET
SOTB-MOSFET
TFT
SOI-MOSFET
MOSFET
HV-MOSFET
MOS-Varactor
IGBT
HiSIM 11

HiSIM Family
Bulk-MOSFET
HiSIM2
High-Voltage MOSFET
HiSIM_HV
SOI MOSFET
HiSIM-SOI
Thin-Film Transistor
Double-Gate MOSFET
Insulated-Gate Bipolar Transistor
HiSIM-TFT
HiSIM-DG
HiSIM-IGBT
HiSIM
12

SOI-MOSFET Modeling
many possible conditions
Si
Si substrate
HiSIM
13

Poisson’s Equation + Gauss’s Law
V
φ
φ
gs fb s,SOI
b,SOI
s,SOI
Q+Q + Q + Q
- V = φ -
CFOX
Qs,bulk
= φs,bulk
-
CBOX
1
Q
s,bulk
+ Qdep
= φ
2
b,SOI
-
C
i dep b,SOI s,bulk
SOI
Three surface potentials are solved
simultaneously by iteration.
Q b,SOI
φ b.SOI
φ s.SOI
Calculation results
HiSIM
14

Smooth Transition among Conditions
T SOI T BOX Conditi
on
Device1 150 110 PD
Device2 50 110 DD
Device3 50 50 DD
Device4 25 110 FD
HiSIM
15

C-V Characteristics
T SOI =150nm
T BOX =110nm
: HiSIM-SOI
: 2D-Device Sim.
T SOI =50nm
T BOX =110nm
T SOI =50nm
T BOX =50nm
DEVICE1
DEVICE2
T SOI =25nm
T BOX =110nm
DEVICE3
DEVICE4
HiSIM
16

Potential Distribution in Thin-Body MOSFET
device surface
insulator
Back surface potential is strongly dependent on T SOI .
Consistent solution of Poisson’s equation
HiSIM
17

Device 4: Thin-Body SOI-MOSFET
back-gate bias V bs dependence
V bs
φ b.SOI
φ s.SOI
HiSIM
18

Floating-Body Effect
φ b.SOI is unstable.
symbol: 2D-Sim.
line: HiSIM-SOI
SOI
bulk
φ s.bulk
φ b.SOI
φ s.SOI
BOX
φ b.SOI reduction change from FD to PD
HiSIM
19

Charge Accumulation
Impact Ionization:
• Include accumulation charge in the Poisson equation
• Increase the surface potential φ s0.SOI
• Increase the inversion charge Q i according to V ds increase
HiSIM
20

History Effect
Transient Characteristics of the Floating-Body Effect
Τ d : Time constant of Q h accumulation
T d
H. Toda et al., SSDM 2010.
HiSIM
21

I d -V d Comparison with Measurements
gds gds’ gds’’
V sub = 0.0V V sub = 0.0V V sub = 0.0V V sub = 0.0V
V sub = -1.5V V sub = -1.5V V sub = -1.5V V sub = -1.5V
measurement
HiSIM-SOI
HiSIM
22

I d -V d Characteristics as a function of N SOI
W g =0.25mm, L g =0.15mm
N SOI (cm -3 ) = 1.0e16 2.0e16 5.0e16
Vds
Vds
Vds
Vds
Vds
Vds
Ids
Ids
Ids
Ids
Ids
Ids
Ids
1.0e17 2.0e17 5.0e17
Ids
Ids
1.0e18 2.0e18 5.0e18
Vds
Vds
Vds
enhanced floating body effect with increased N SOI
HiSIM 23

Scalability Tests
V th vs. N SOI for various V bs
0.6
V ds =0.05V, W g =10μm, L g =0.15 μm
Threshold Voltage (V)
0.4
0.2
0.0
-0.2
Vsub = 0 to -3V step -1.0V
-0.4
1.0e16 1.0e17 1.0e18 1.0e19
N SOI (cm -3 )
automatic FD PD shift
HiSIM
24

HiSIM-SOI
- Considering all possible induced charges in the Poisson equation
- Solving the Poisson equation iteratively
- Deriving accurate analytical solution as initial values
Solving the Poisson equation in a consistent way is
only a possibility to model all different structures and
conditions within one model framework.
HiSIM
25

carrier concentration
T si =10nm
gate
gate
HiSIM-DG
V gs =1V
V ds =0V
T si
T si =20nm
gate
gate
T si =40nm
gate
gate
T si
Body potential is floating.
The floating body potential makes modeling difficult.
HiSIM 26

Potential Dependence on T si and N sub
N sub
T Si
φ s0 (V)
φ s0 (V)
HiSIM 27

C-V Characteristics
Reduction of T si has only a small influence
on the capacitance characteristics.
HiSIM 28

Carrier Traps in TFT
Source
Gate
Drain
1.E-05
Trap density
small
x
y
φ S0
Poly-Si
φ SL
Id(A)
1.E-07
1.E-09
large
φ b0
Display Substrate
(Insulator)
φ bL
1.E-11
Traps
1.E-13
-2 -1 0 1 2 3 4
Vg(V)
HiSIM
29

Modeling of Trap Density
Grain Boundaries
Poly-Si
film
Traps uniformly distributed
in crystal Si
Simplified Model for Density of States
Log(Density of States)
Tail States
Donor-type
Acceptor-type
Log(Density of States)
Donor-type
⎛ EV
− E
g
D
E = gC1
exp⎜
⎝ Es
( ) ⎟
⎠
⎞
Acceptor-type
⎛ E − EC
⎞
( E) = g exp ⎟
⎠
g
A
C1
⎜
⎝
Es
E V
Deep States
E C
E V
E C
Add into the Poisson equation
HiSIM
30

I-V characteristics
6.0
measurements
simulations
L=2μm
1.E+00
Ids(a.u.)
4.0
2.0
L=2μm
Ids(a.u.)
1.E-02
1.E-04
1.E-06
1.E-08
measurements
simulations
0.0
0 1 Vds(V) 2 3
1.E-10
-5 -3 -1 1 3 5
Vgs(V)
Ids(a.u.)
5.0
4.0
3.0
2.0
1.0
measurements
simulations
L=0.5μm
Ids(a.u.)
L=0.5μm
1.E+00
1.E-02
1.E-04
1.E-06
1.E-08
measurements
simulations
0.0
0 1 Vds(V) 2 3
1.E-10
-5 -3 -1 1 3 5
Vgs(V)
S. Miyano et al., Proc. SISPAD, 2008.
HiSIM
31

HiSIM-HV
a few hundred volts > Bias Range > a few volts
modeling
MOSFET + Resistor
HiSIM 32

Potential Drop in Drift
symbol: HiSIM‐HV
line: 2D‐Device
N drift =10 17 cm ‐3 : low resistive
N drift =10 16 cm ‐3 : high resistive
: without resistance
HiSIM
33

Specific Feature of HV MOSFET
Rd = f(V gs , V ddp , model parameters)
HiSIM
34

Current-Voltage Characteristics
Relatively Low Breakdown Voltage
Relatively High Breakdown Voltage
Y. Oritsuki et al., IEEE TED, Oct. 2010; A. Tanaka et al, July, 2011.
HiSIM 35

HiSIM-IGBT: Bias Range > 500V
Schematic structure of a modern trench-IGBT
Jn
n - (base)
Simplified circuit diagram of the HiSIM-IGBT model
Consistent potential extension in HiSIM-IGBT is achieved by
calculation based on Kirchhoff’s law.
HiSIM 36

N base Dependence of I-V Characteristics
M. Miyake et al., IEEE PESC, pp. 998-1003, June 2008.
HiSIM 37

Summary
HiSIM is a compact surface-potential-based MOSFET with
a minimum number of approximations, due to its iterative
surface-potential determination.
HiSIM allows to preserve a consistent potential-based
modeling in its extension to other integrated-device
structures containing a MOSFET core.
A compact-model family covering all integrated devices
containing a MOSFET core and sharing the same modeling
concepts could be developed.
HiSIM 38