BSIM3SOI Version 2.1 (FD, DD and PD)
Models Released in SmartSpice

Introduction

The Berkeley BSIM3SOI version 2.1 models, released in September 1999, have been implemented in SmartSpice. The three new models are selected according to LEVEL selector.

• LEVEL = 26 selects the BSIM3SOI2FD (Fully depleted) model


• LEVEL = 27 selects the BSIM3SOI2DD (Dynamic depletion) model


• LEVEL = 29 selects the BSIM3SOI2PD (Partially depleted) model

The SmartSpice implementation of the three models is close but not identical to the UC Berkeley releases. The SmartSpice implementation provides a number of improvements and additional parameters currently unsupported in Berkeley's BSIM3SOIv2 models.

In the SmartSpice implementation of the BSIM3SOIv2 models, enhanced convergence is obtained by properly handling the GMIN and DCGMIN control options during transient and DC analysis.

The GMIN option connects a conductance in parallel with the bulk diodes. This conductance is very useful when the diode model has a very high off-resistance. The conductance DCGMIN is connected between drain and source.

The present section provides all the information needed to understand and use the three models.

BSIM3SOI FD (Fully Depleted) version 2.1 (Model LEVEL = 26)

Major Features
BSIM3SOI FD v2.1 is a suite of BSIM3SOI FD v2.0 released in February 1999. The version 2.0 is a derivative of BSIM3SOI v1.3 (level=25 in SmartSpice). BSIM3SOIFDv2.0 has improved simulation efficiency and noise modeling. The basic IV for this model is modified from BSIM3v3.1 equation set. The major features are summarized as follows [1]:

• Supports external body bias and backgate bias : a total of 5 external nodes;
  
• Self-heating implementation improved over the alpha version of Berkeley (LEVEL 23 in SmartSpice);
  
• New depletion charge model (EBCI) introduced for better accuracy in capacitive coupling prediction. An improved BSIM3v3 based model is added as well;
  
• Single I-V expression as in BSIM3v3.1 to guarantee continuities of Ids, Gm, and Gds and their derivatives for all bias conditions.

New version BSIM3SOI FDv2.1 includes the binning feature to enhance the model flexibility and fixes some bugs found in the previous version 2.0.

Model Parameters
The additional parameters to BSIM3v3 listed in Table 1 correspond to the BSIM3SOI FD Version 2.1 model.

Parameter	Description	Units	Default
SHMOD	Flag for self-heating 0 - no self-heating 1 - self-heating	-	0
TSI	Silicon film thickness	m	1e-7
TBOX	Buried oxide thickness	m	3e-7
VBSA	Transition body voltage offset	V	0
DELP	Constant for limiting Vbseff to Phis	V	0.02
KB1	Coefficient of Vbs0 dependency on Ves	-	1
KB3	Coefficient of Vbs0 dependency on Vgs at subthreshold region	-	1
DVBD0	First coefficient of Vbs0 dependency on Leff	V	0
DVBD1	Second coefficient of Vbs0 dependency on Leff	V	0
MXC	Fitting parameter for Abeff calculation	-	-0.9
ADICE0	DICE bulk charge factor	-	1
ISDIF	Body to source/drain injection saturation current	A/m2	0.0
ISREC	Recombination in depletion saturation current	A/m2	1e-5
RBODY	Intrinsic body contact sheet resistance		0
RBSH	Extrinsic body contact sheet resistance	/m2	0
CGE0	Gate substrate overlap capacitance per unit channel length	F/m	0.0
VSDFB	Source/drain bottom diffusion capacitance flatband voltage	V	calculated
VSDTH	Source/drain bottom diffusion capacitance threshold voltage	V	calculated
CSDMIN	Source/drain bottom diffusion minimum capacitance	F	calculated
ASD	Source/drain bottom diffusion minimum parameter	-	0.3
CSDESW	Source/drain sidewall fringing capacitance per unit length	F/m	0
CTH0	Normalized thermal capacity	m.°C/(W*s)	0
RTH0	RTH0 Normalized thermal resistance	m.°C/W	0

Silvaco Improvements
Options
The options VZERO and EXPERT are supported in the SmartSpice BSIM3SOI FD v2.1 model. The option VZERO=2 allows faster runtime when large circuits are used.

The EXPERT option can be specified to detect possible problems in models, before and during simulation, such as:

• negative conductances GM, GDS and GMBS,
  
• negative gate capacitances.

New Model Parameters
New model parameters are listed in the following table :

The VERSION model parameter is used to switch between the current versions 2.0 and 2.1. The four others new model parameters are used for binning to select a model. For the binning, Silvaco has also added new binned model parameters that are displayed in Table 2.

Table 2. Silvaco's new binned model parameters.

BSIM3SOI DD (Dynamic Depletion) Version 2.1 Model (LEVEL=27)

Major Features
BSIM3SOI DD v2.1 is a suite of BSIM3SOI DD v2.0 released in February 1999. The version 2.0 is a derivative of BSIM3SOI v1.3 (level=25 in SmartSpice). BSIM3SOI DD v2.0 has improved simulation efficiency and noise modeling. The BSIM3SOI DDv2.0 model can be used for both Partially Depleted (PD) and Fully Depleted (FD). The basic IV for this model is modified from BSIM3v3.1 equation set. The major features are summarized as follows [2]:

• Dynamic depletion approach is applied on both I-V and C-V. Charge and drain current are scalable with Tbox and Tsi continuously
  


• Supports external body bias and backgate bias : a total of 5 external nodes
  
• Real floating body simulation in both I-V and C-V. Body potential is properly bounded by diode and C-V formulation
  
• Self-heating implementation improved over the alpha version of Berkeley (LEVEL 23 in SmartSpice)
  
• An improved impact ionization current model
  
• Various diode leakage components and parasitic bipolar current included
  
• New depletion charge model (EBCI) introduced for better accuracy in capacitive coupling prediction. An improved BSIM3v3 based model is added as well
  
• Dynamic depletion can suit different requirements for SOI technologies
  
• Single I-V expression as in BSIM3v3.1 to guarantee continuities of Ids, Gm, and Gds and their derivatives for all bias conditions

New version BSIM3SOI DDv2.1 includes the binning feature to enhance the model flexibility and fixes some bugs found in the previous version 2.0.


Model Parameters
The additional parameters to BSIM3v3 listed below in Table 3 correspond to the BSIM3SOI DD Version 2.1 model.

Parameter	Description	Units	Default
SHMOD	Flag for self-heating 0 - no self-heating 1 - self-heating	-	0
TSI	Silicon film thickness	m	1e-7
TBOX	Buried oxide thickness	m	3e-7
VBSA	Transition body voltage offset	V	0
DELP	Constant for limiting Vbseff to Phis	V	0.02
KB1	Coefficient of Vbs0 dependency on Ves	-	1
KB3	Coefficient of Vbs0 dependency on Vgs at subthreshold region	-	1
DVBD0	First coefficient of Vbs0 dependency on Leff	V	0
DVBD1	Second coefficient of Vbs0 dependency on Leff	V	0
ABP	Coefficient of Abeff dependency on Vgst	-	1
MXC	Fitting parameter for Abeff calculation	-	-0.9
ADICE0	DICE bulk charge factor	-	1
ALPHA1	The second parameter of impact ionization current	m/V	1.0
AII	First Vds dependence Ecrit parameter	-	0
BII	Second Vds dependence Ecrit parameter	m	0
CII	Vgsteff dependence Ecrit parameter	1/m	0
DII	Vbseff dependence Ecrit parameter	1/m	-1.0
AGIDL	GIDL constant	W-1	0
BGIDL	GIDL exponential coefficient	V/m	0
NGIDL	GIDL Vds enhancement coefficent	V	1.2
NTUN	reverse tunneling non-ideality factor	-	10.0
NDIODE	Diode non-ideality factor	-	1.0
ISBJT	BJT injection saturation current	A/m2	1e-6
ISDIF	Body to source/drain injection saturation current	A/m2	0.0
ISREC	Recombination in depletion saturation current	A/m2	1e-5
ISTUN	Reverse tunneling saturation current	A/m2	0
EDL	Electron diffusion length	m	2e-6
KBJT1	Parasitic bipolar early effect coefficient	m/V	0
RBODY	Intrinsic body contact sheet resistance	/m2	0
RBSH	Extrinsic body contact sheet resistance	/m2	0
CGE0	Gate substrate overlap capacitance per unit channel length	F/m	0.0
TT	Diffusion capacitance transit time coefficient	s	1e-12
VSDFB	Source/drain bottom diffusion capacitance flatband voltage	V	calculated
VSDTH	Source/drain bottom diffusion capacitance threshold voltage	V	calculated
CSDMIN	Source/drain bottom diffusion minimum capacitance	F	calculated
ASD	Source/drain bottom diffusion minimum parameter	-	0.3
CSDESW	Source/drain sidewall fringing capacitance per unit length	F/m	0
CTH0	Normalized thermal capacity	m.°C / (W*sec)	0
RTH0	Normalized thermal resistance	m.°C/W	0
XBJT	Power dependence of jbjt on temperature	-	2
XDIF	Power dependence of jdif on temperature	-	2
XREC	Power dependence of jrec on temperature	-	20
XTUN	Power dependence of jtun on temperature	-	0
NOIF	Floating body excess noise ideality factor	-	1.0

---

Table 3. The additional parameters to BSIM3v3 correspond
to the BSIM3SOI DD Version 2.1 model.

• negative conductances GM, GDS and GMBS


• negative gate capacitances

• if SMART = 0: the original Berkeley model is used with its different versions



• if SMART > 0: the Berkeley model is used with the following improvements:
• problem with RBODY model parameter has been fixed;
• some derivatives related to body tied have been corrected;
• the limitation of vb has been modified.

2.1 Model (LEVEL = 29)
Major Features
BSIM3SOI PD v2.1 is a suite of BSIM3SOI PD v2.01 released in April 1999. The version 2.01 is a derivative of BSIM3SOI v1.3 (level=25 in Smartspice). Many enhanced features are included in BSIM3SOI PD v2.0.1. BSIM3SOI PD v2.0.1 has the following new features relative to BSIM3SOIv1.3 [3]:

• Real floating body simulation in both C-V and I-V. The body potential is determined by the balance of all the body current components
  
• Enhancements in the threshold voltage and bulk charge formulation of the high positive body bias regime
  
• An improved parasitic bipolar current model. This includes enhancements in the various diode leakage components, second order effects (high-level injection & early effect), diffusion charge equation and temperature dependence of the diode junction capacitance
  
• An improved impact ionization current model. The contribution from BJT current is also modeled by the parameter FBJTII
  
• Instance parameters (PDBCP, PSBCP, AGBCP, AEBCP, NBC) are provided to model the parasitics of devices with various body-contact and isolation structures
  
• An external body node (the 6th node) and other improvements are introduced to facilitate the modeling of distributed body-resistance
  
• Self-heating: an external temperature node (the 7th node) is supported to facilitate the simulation of thermal coupling among neighboring devices
  
• A unique SOI low frequency noise model, including a new excess noise resulting from the floating body effect
  
• Width dependence of the body effect is modeled by parameters (K1, K1W1, K1W2)
  
• Improved history dependence of the body charges with two new parameters (FBODY, DLCB)
  
• An instance parameter vbsusr is provided for users to set the transient initial condition of the body potential

Silvaco Improvements
Options
The options VZERO and EXPERT are supported in the SmartSpice BSIM3SOI PD v2.1 model.

The option VZERO=2 allows faster runtime when large circuits are used.

The EXPERT option can be specified to detect possible problems in models, before and during simulation, such as:

• negative conductances GM, GDS and GMBS
  
• negative gate capacitances.

The SMART model parameter allows to switch on Silvaco improvements which are not compatible with original Berkeley model. The SMART model parameter has been created as follows :

• if SMART = 0: the original Berkeley model is used with its different versions
  
• if SMART > 0: the Berkeley model is used with the following improvements:
• incorrect implementation of model parameter AHLI has been fixed;
• the limitation of vb has been modified.

Figure 1 : Example of Id-Vds curves with FD and DD models
(default model card from Berkeley)

Figure 2 : Example of Id-Vds curves with PD
model (default model card from Berkeley)

Figure 3. Self-heating effect with PD model
(default model card from Berkeley)

Figure 4. Example of a ring oscillator with PD
model (default model card from Berkeley)

1. BSIM3SOIFDv2.1 User's Manual, 1999, Department of EECS, University of California, Berkeley


2. BSIM3SOIDDv2.1 User's Manual, 1999, Department of EECS, University of California, Berkeley


3. BSIM3SOIPDv2.1 User's Manual, 1999, Department of EECS, University of California, Berkeley

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