Device Parameters

This guide explains all the device parameters available in the simulator and their effects on device performance.

Gate Stack

Oxide Thickness ( )

Property	Value
Range	0.5 - 10 nm
Default	2 nm
Unit	nm

Physical Significance:

The gate oxide thickness directly affects oxide capacitance:

Effects:

Lower	Higher
↑ Gate capacitance	↓ Gate capacitance
↑ Drive current	↓ Drive current
↓ Threshold voltage	↑ Threshold voltage
↑ Gate leakage	↓ Gate leakage
Better SCE control	Worse SCE control

Scaling Limits

Below ~1.5nm (SiO₂), direct tunneling becomes significant. Modern processes use high-k dielectrics (HfO₂) to maintain physical thickness while achieving low EOT.

Channel Length ( )

Property	Value
Range	20 - 500 nm
Default	90 nm
Unit	nm

Physical Significance:

Channel length determines current capacity and short-channel susceptibility:

Effects:

Shorter L	Longer L
↑ Current density	↓ Current density
↑ Speed (lower RC)	↓ Speed
↑ SCE (DIBL, Vth roll-off)	↓ SCE
↑ Leakage	↓ Leakage

Gate Work Function ( )

Property	Value
Range	4.0 - 5.5 eV
Default	4.15 eV (n+ poly), 5.25 eV (p+ poly)
Unit	eV

Common Materials:

Material	Work Function (eV)	Use
n+ poly-Si	4.05 - 4.15	nMOS
p+ poly-Si	5.15 - 5.25	pMOS
TiN	4.4 - 4.6	nMOS (HKMG)
TaN	4.8 - 5.0	pMOS (HKMG)

Effect on Threshold:

Adjusting shifts approximately 1:1.

Channel

Channel Doping ( )

Property	Value
Range	10¹⁵ - 10¹⁹ cm⁻³
Default	5×10¹⁷ cm⁻³
Unit	cm⁻³

Physical Significance:

Channel doping sets the body charge that must be depleted to form an inversion layer:

Effects:

Higher	Lower
↑ Threshold voltage	↓ Threshold voltage
↓ DIBL	↑ DIBL
↓ Mobility (scattering)	↑ Mobility
↑ Body effect	↓ Body effect
↓ Depletion width	↑ Depletion width

Design Trade-off

High channel doping improves SCE control but degrades mobility. Modern devices use retrograde doping (low surface, high subsurface) for optimal trade-off.

Doping Profile Type

Option	Description
Uniform	Constant doping throughout channel
Retrograde	Low surface doping, peak below surface
SSR	Super-steep retrograde

Source/Drain

S/D Doping ( )

Property	Value
Range	10¹⁸ - 10²¹ cm⁻³
Default	10²⁰ cm⁻³
Unit	cm⁻³

Physical Significance:

High S/D doping reduces:

• Contact resistance
• Series resistance
• Junction built-in potential

Effects:

Higher	Lower
↓ Series resistance	↑ Series resistance
↓ Contact resistance	↑ Contact resistance
↑ Junction capacitance	↓ Junction capacitance
↑ Band-to-band tunneling	↓ Tunneling

Junction Depth ( )

Property	Value
Range	10 - 200 nm
Default	50 nm
Unit	nm

Physical Significance:

Junction depth affects the characteristic length:

Good SCE control requires .

Effects:

Shallower	Deeper
↓ SCE	↑ SCE
↑ Series resistance	↓ Series resistance
↓ Junction capacitance	↑ Junction capacitance

LDD Doping ( )

Property	Value
Range	10¹⁷ - 10²⁰ cm⁻³
Default	5×10¹⁸ cm⁻³
Unit	cm⁻³

Purpose:

Lightly Doped Drain (LDD) extensions:

• Reduce peak electric field at drain
• Mitigate hot carrier effects
• Improve reliability

LDD Length ( )

Property	Value
Range	5 - 50 nm
Default	20 nm
Unit	nm

Trade-offs:

Longer LDD	Shorter LDD
↓ Peak E-field	↑ Peak E-field
↑ Series resistance	↓ Series resistance
Better HCI immunity	Worse HCI immunity

Substrate

Substrate Doping ( )

Property	Value
Range	10¹⁴ - 10¹⁸ cm⁻³
Default	10¹⁷ cm⁻³
Unit	cm⁻³

Physical Significance:

Sets the body effect coefficient:

And depletion width:

Geometry

Channel Width ( )

Property	Value
Range	50 - 2000 nm
Default	360 nm (nMOS), 720 nm (pMOS)
Unit	nm

Physical Significance:

Width directly scales current:

PMOS Sizing

PMOS is typically 2× wider than NMOS to compensate for lower hole mobility:

Gate-S/D Overlap ( )

Property	Value
Range	0 - 20 nm
Default	5 nm
Unit	nm

Effects:

• Contributes to overlap capacitance:
• Affects Miller effect in switching
• Reduces effective channel length

Advanced Parameters

Fixed Oxide Charge ( )

Property	Value
Range	±10¹² cm⁻²
Default	0
Unit	cm⁻²

Effect:

Shifts flat-band and threshold voltage:

Positive charge shifts negative.

Interface Trap Density ( )

Property	Value
Range	0 - 10¹³ cm⁻² eV⁻¹
Default	0
Unit	cm⁻² eV⁻¹

Effects:

• Increases subthreshold swing
• Causes frequency dispersion in C-V
• Degrades mobility (Coulomb scattering)

Series Resistance ( , )

Property	Value
Range	0 - 1000 Ω
Default	0
Unit	Ω

Effects:

• Reduces effective :
• Limits maximum current
• Causes negative feedback

Components:

• Contact resistance
• Silicide resistance
• LDD resistance
• Spreading resistance

Parameter Scaling Guidelines

For scaling to a new technology node:

Parameter	Scaling Factor	45nm → 28nm
	0.7×	45 → 28 nm
	0.7×	180 → 120 nm
	0.8×	1.5 → 1.2 nm
	0.9×	1.0 → 0.9 V
	0.7×	30 → 20 nm
	1.4×	10¹⁸ → 2×10¹⁸ cm⁻³

Non-Ideal Scaling

Real scaling is constrained by:

• Gate leakage (can't scale indefinitely)
• Threshold variation (limits scaling)
• Power density (thermal limits)