Ultimate Device Scaling: Intrinsic Performance Comparisons of Carbon-based, InGaAs, and Si Field-eff...
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Mathieu Luisier 1 , Mark Lundstrom 2 , Dimitri Antoniadis 3 , and Jeffrey Bokor 4 PowerPoint PPT Presentation


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Ultimate Device Scaling: Intrinsic Performance Comparisons of Carbon-based, InGaAs, and Si Field-effect Transistors for 5 nm Gate Length. Mathieu Luisier 1 , Mark Lundstrom 2 , Dimitri Antoniadis 3 , and Jeffrey Bokor 4

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Mathieu Luisier 1 , Mark Lundstrom 2 , Dimitri Antoniadis 3 , and Jeffrey Bokor 4

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Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

Ultimate Device Scaling: Intrinsic Performance Comparisons of Carbon-based, InGaAs, and Si Field-effect Transistors for 5 nm Gate Length

Mathieu Luisier1, Mark Lundstrom2,

Dimitri Antoniadis3, and Jeffrey Bokor4

1ETH Zurich, 2Purdue University, 3MIT, and 4University of California at Berkeley


Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

Outline


Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

Motivation


Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

Motivation: Future of Moore’s Law

65nm (2005)

3-D Si FinFETs for ever?

What will be the dominant limiting factors when Lg<10nm?

45nm (2007)

32nm (2009)

22nm (2011)

5nm (2020)

Source: Intel Corporation

??

Gate Length Reduction in planar Si MOSFETs:

=> increase of short-channel effects (SCE)

=> poor electrostatic control (single-gate)

Gate Length Reduction in planar Si MOSFETs:

=> increase of short-channel effects (SCE)

=> poor electrostatic control (single-gate)

=> SOLUTION: 3-D FinFET since 2011


Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

Leakage Sources in Ultrascaled Devices

IBT/

S-to-D

BTBT1

HIBL

BTBT2

Band Diagram of Lg=5nm Nano-transistor


Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

How can we minimize leakage?

Best device structure at Lg=5nm:

The least sensitive to leakage

Solution:

Quantum Transport Solver

Nanowire

Graphene

III-V UTB

CNT

Y.Q. Wu et al., EDL 30, 700 (2009)

P. Hashemi et al., EDL 30, 401 (2009)

Supratik Guha,

IBM Research

L. Tapasztó et al., Nat. Nano. 3, 397 (2008)

NEEDED:Fast, cheap, and reliable platform to investigate the performance of next-generation ultrascaled nano-transistors beyond 3-D FinFETs


Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

Simulation Approach


Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

State-of-the-art Nano-TCAD Tool

Physical Models

Simulation Capabilities

  • Industrial-Strength Nano-electronic Device Simulator

  • Multi-Geometry Capabilities

  • Investigate Performance of Ultra-Scaled Nano-Devices before Fabrication

  • 3D Quantum Transport Solver

  • Different Flavors of Atomistic Tight-Binding Models

  • Multi-Physics Modeling: From Ballistic to Dissipative (e-ph) Electron/Hole Transport

OMEN

More Features

Bias

  • Schrödinger-Poisson Solver with NEGF and WF

  • Finite Element Poisson

  • Accelerate Simulation Time through Massive and Multi-Level Parallelization

Momentum

Energy

TB: sp3d5s*

Efficient Parallel Computing

Space

Si Bandstructure

Freitag, 22. August 2014

8


Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

Model Verifications

BTBT Diode

III-V HEMT

CNT FET

For more information, see presentation 23.7 by Aaron Franklin:

“Sub-10 nm Carbon Nanotube Transistor”

Expt: J. del Alamo @ MIT

Expt: A. Franklin @ IBM YH

Expt: S. Rommel @ RIT S. Datta @ PSU

NDR

Current

Zener

Current


Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

General Scaling Considerations


Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

Device Characteristics

One Single Quantum Transport Solver

One Single FEM Poisson Solver

SG-AGNR

CNT

NW

DG-UTB

DG-AGNR


Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

Id-Vgs at Vds=0.5 V in Carbon Devices

AGNR width: 2.1 nm / CNT diameter: 1.49 nm / Band Gap Eg=0.56 eV

HfO2

EOT=0.64nm

SiO2

EOT=0.64nm

HIBL/IBT

BTBT

  • Observations:

  • same EOT gives very different electrostatic gate-channel coupling

  • as long as Eg>Vds, BTBT remains weak, but still intra-band tunneling


Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

Intra-Band Tunneling: Electrostatics

Spectral current through GAA CNT FETs with d=1.49 nm,

Eg=0.563 eV, different dielectrics, and EOT=0.64 nm

  • Fringing Fields:

  • stronger when spacer with large εR

  • effective channel length is longer

  • same effect as gate underlap doping


Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

Intra-Band Tunneling: Material (1)

  • OBSERVATIONS:

  • Current flows through the potential barrier, almost no thermionic component

Fix electrostatic potential (Gaussian-like barrier)

Investigate how semiconductor properties influence IBT

Id=4.4nA

Si NW d=3nm

Eg=1.404eV

Id=91nA

  • Smaller band gap (and m*) gives higher intra-band tunneling current

  • Need to understand why

CNT d=1nm

Eg=0.817eV


Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

Intra-Band Tunneling: Material (2)

What is needed: Under-the-Barrier (UB) model

Same principle as Top-of-the-Barrier (ToB), but with

Complex Bandstructure instead of Real Bandstructure

ToB

Eg=1.408eV

Eg=1.404eV

Eg=1.378eV

Eg=0.817eV

UB

Transmission through potential barrier: T(E)=exp(-2*Κ(E)*L)


Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

Ohmic vs Schottky Contacts

Id-Vgs transfer characteristics for Si NW and CNT FETs with Ohmic and Schottky Contacts

Ohmic

Schottky


Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

Performance Comparisons


Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

Id-Vgs at Vds=0.5 V in CNT, NW, and UTB

  • Features:

  • CNT with d=0.6nm and Si/InGaAs NW with d=3nm have same band gap: Eg=1.4eV

  • CNT with d=1nm has band gap: Eg=0.82eV

  • EOT=0.64nm made of 3.3nm HfO2

  • No AGNR since worse than CNT

  • Intrinsic characteristics

VDD=0.5 V

  • d=1nm GAA-CNT (high IBT) and DG-UTB (bad electrostatics) scale poorly

  • 3-D devices with same “large” band gap (Eg=1.4 eV) scale better (low IBT)

  • if CNT with d<1 nm and Eg>1 eV possible, then at least as good as NW

  • CHALLENGE: trade-off between high injection velocity (low m*) and low SS (high m*) needed, new constraint at short gate lengths


Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

Conclusion


Mathieu luisier 1 mark lundstrom 2 dimitri antoniadis 3 and jeffrey bokor 4

Conclusion and Outlook


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