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 


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. 


Relationship among Device Properties 

(at drain side) 

(at source side) 


Specific Feature of Surface-potential Model 

one equation for all bias conditions 


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 


Current Derivatives for 45nm Technology 

Measurement 

HiSIM 

W g /L g = 

2μm/40nm 

Beyond the 45nm generation nonphysical effects 

are getting obvious. 


Universal Mobility 

V ds =0.1V 

impurity concentration 

carrier concentration 

carrier mobility 


Requirements for RF Applications 

Harmonic Distortions 

Non-Quasi-Static Effect 

Noise Characteristics 


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. 


Descendant of MOSFET 

MG-MOSFET 

SOTB-MOSFET 

TFT 

SOI-MOSFET 

MOSFET 

HV-MOSFET 

MOS-Varactor 

IGBT 


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 


12

SOI-MOSFET Modeling 

many possible conditions 

Si 

Si substrate 


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 


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 


15

C-V Characteristics 

T SOI =150nm 

T BOX =110nm 

: HiSIM-SOI 

: 2D-Device Sim. 


T BOX =110nm 


T BOX =50nm 

DEVICE1 

DEVICE2 


T BOX =110nm 

DEVICE3 

DEVICE4 


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 


17

Device 4: Thin-Body SOI-MOSFET 

back-gate bias V bs dependence 

V bs 




18

Floating-Body Effect 

φ b.SOI is unstable. 

symbol: 2D-Sim. 

line: HiSIM-SOI 

SOI 

bulk 

φ s.bulk 



BOX 

φ b.SOI reduction change from FD to PD 


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 


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. 


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 



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 


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 


24


- 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. 


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. 


Potential Dependence on T si and N sub 

N sub 

T Si 

φ s0 (V) 

φ s0 (V) 


C-V Characteristics 

Reduction of T si has only a small influence 

on the capacitance characteristics. 


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) 


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 


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. 


31

HiSIM-HV 

a few hundred volts > Bias Range > a few volts 

modeling 

MOSFET + Resistor 


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 


33

Specific Feature of HV MOSFET 

Rd = f(V gs , V ddp , model parameters) 


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-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. 


N base Dependence of I-V Characteristics 

M. Miyake et al., IEEE PESC, pp. 998-1003, June 2008. 


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-SOI - TechConnect World

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